Abstract: Records of bird species observed by F.L. Whitlock near Wilson Inlet in the period 1905-19 (mostly 1907, 1909 and 1910), hitherto unpublished, were collated from museum specimens and archives. Whitlock noted 94 species comprising 65 landbirds, 10 waterbirds, 7 seabirds, and 12 non-breeding waders. Records of bird species made by other ornithologists from 1889 to 1913 indicate that the original avifauna of this region comprised 81 landbird species. In the past century four of these species (Burhinus grallarius, Pezoporus wallicus, Atrichornis clamosus and Dasyornis longirostris), as well as the waterbird Ixobrychus flavicollis, appear to have become locally extinct. Deforestation for agricultural development, with the subsequent creation of parkland and pasture, has allowed 10 landbird and 8 waterbird species to colonize the area. Whitlock's records of the seabird species Eudyptula minor and Pterodroma macroptera nesting on islands in Wilson Inlet are otherwise unreported in the literature. A comprehensive synthesis of eyewitness accounts of Aboriginal burning practices in the period 1791-1840 indicates that anthropogenic fire was frequent, prevalent in summer, and spatially extensive but in patches varying in area from c. 10-2000 ha, with a tendency for riparian vegetation to be burnt less often than uplands. Such fires could be set at the hottest part of the day, with multiple ignitions on the one day, and under windy conditions. Three bird species that are sensitive to frequent fire and now considered to be extinct locally are presumed to have had patchy distributions confined to those limited parts of the landscape naturally protected from frequent burning (vegetation along higher order streams, on steep south-facing slopes, or surrounded by expanses of granite). In addition, some of these sites may have had totemic significance to Aborigines and were thus protected from more intense or frequent fire by periodic burning using low intensity fire in spring, late autumn or early winter. The vulnerability of naturally insularized populations to inappropriate intensity or frequency of fire may explain the early demise of these species following European settlement. Few other parts of Western Australia have an avifauna so well documented at a time when agricultural development had only recently commenced. The Denmark area would therefore provide an appropriate focal region for documenting ongoing environmental change as indicated by the avifauna.
Abstract: Fire is widely used for conservation management in the savannah landscapes of northern Australia, yet there is considerable uncertainty over the ecological effects of different fire regimes. The responses of insects and other arthropods to fire are especially poorly known, despite their dominant roles in the functioning of savannah ecosystems. Fire often appears to have little long-term effect on ordinal-level abundance of arthropods in temperate woodlands and open forests of southern Australia, and this paper addresses the extent to which such ordinal-level resilience also occurs in Australia's tropical savannahs. The data are from a multidisciplinary, landscape-scale fire experiment at Kapalga in Kakadu National Park. Arthropods were sampled in the two major savannah habitats (woodland and open forest) using pitfall traps and sweep nets, in 15-20 km2 compartments subjected to one of three fire regimes, each with three replicates: 'early' (annual fires lit early in the dry season), 'late' (annual fires lit late in the dry season), and 'unburnt' (fires absent during the five-year experimental period 1990-94). Floristic cover, richness and composition were also measured in each sampling plot, using point quadrats. There were substantial habitat differences in floristic composition, but fire had no measured effect on plant richness, overall composition, or cover of three of the four dominant species. Of the 11 ordinal arthropod taxa considered from pitfall traps, only four were significantly affected by fire according to repeated-measures ANOVA. There was a marked reduction in ant abundance in the absence of fire, and declines in spiders, homopterans and silverfish under late fires. Similarly, the abundances of only four of the 10 ordinal taxa from sweep catches were affected by fire, with crickets and beetles declining in the absence of fire, and caterpillars declining under late fires. Therefore, most of the ordinal taxa from the ground and grass-layer were unaffected by the fire treatments, despite the treatments representing the most extreme fire regimes possible in the region. This indicates that the considerable ordinal-level resilience to fire of arthropod assemblages that has previously been demonstrated in temperate woodlands and open forests of southern Australia, also occurs in tropical savannah woodlands and open forests of northern Australia.
Prescribed fires have been used as a forest vegetation management tool in the eastern United States during the past decade, but concerns havebeen raised about direct or indirect adverse effects on Neotropical migrant birds species that nest in forest interior habitats. Prescribed fires were set in 1993 and 1995 in a mature hardwood forest in southern Indiana, USA, to reduce shade-tolerant understory woody vegetation and thereby increase the abundance and diversity of ground layer vegetation and seedlings of tree species that require moderate light levels (e.g., Quercus L. spp.). The objective of this study was to determine if prescribed fires reduced the abundance or reproductive success of ground- and shrub-nesting Neotropical migrant bird species. The burned area and an adjacent unburned area were studied during the summers of 1996 and 1997. An unlimited-radius point count method was used to determine relative abundance. Nests were monitored to determine fledging success. Vegetation structure was quantified at nest sites and at random points to assess fire effects and bird nest-site selection. Abundance of birds in this nesting guild was greater in the unburned area during both years. The greatest difference in abundance was for ovenbird (Seiurus aurocappilus Linnaeus). The probability of nest success for all bird species in this nesting guild combined, determined by the Mayfield method, was significantly lower in the burned area (0.125) than in the unburned area (0.291). Abundance of the brood parasite brown-headed cowbird (Molothus ater Boddaert) did not differ between burned and unburned areas. However, the probability of nest success for parasitized nests (0.140) was lower than that of unparasitized nests (0.735). The mean number of host young fledged from successful nests was significantly lower in parasitized nests (1.3) than from unparasitized nests (3.0). Prescribed fires significantly reduced vegetative cover in the burned area. Nest sites in the burned area had higher vegetative cover than random points, indicating that birds may have selected nest sites that were less affected by the fire. While prescribed fires that burn in a "natural" hit-or-miss pattern may retain nesting habitat for bird species in this nesting guild, lower nest success in the burned area indicates that management for desirable vegetation and for this nesting guild may not be compatible within the same forest stand at the same time. This argues for planning at a landscape level to attain objectives for both vegetation composition and maintenance of bird species diversity.
Abstract: After a large crown fire in Arizona, we examined the direct and indirect effects of fire and herbivory (and their interaction) on the regeneration of aspen (Populus tremuloides) and arthropod species richness and abundance. We used elk exclosures covering 150 ha and other experiments to examine these interactions. Several major patterns emerged. First, in the absence of elk, there is a positive relationship between burn severity and the regeneration of aspens via asexual reproduction. Specifically, aboveground biomass of aspen resprouts was 10 times greater at sites of high burn severity than in sites of intermediate burn severity, and there was virtually no aspen regeneration without fire. Second, elk selectively browsed aspen ramets in high-severity burn sites two times more intensely than aspen ramets in intermediate-severity burn sites, largely negating the enhanced regeneration that would have otherwise occurred, thus resulting in three times greater regeneration in intermediate burn sites than in high burn sites. Third, fire and elk browsing had opposing impacts on an arthropod community composed of 33 taxa from 11 orders and 21 families. Fire severity alone showed no effect on arthropod richness and abundance; however, intermediate-severity fire and moderate levels of elk browsing resulted in 30% greater richness and almost 40% greater abundance. In contrast, high-severity fire and high levels of elk browsing resulted in 69% lower arthropod richness and 72% lower abundance. Fourth, the interaction of fire intensity and selective elk browsing resulted in four arthropod community types where the overall mosaic produced the greatest diversity. Our study demonstrates that patterns can completely reverse depending on the factors involved. This argues against a reductionist perspective and argues for studies incorporating greater complexity. At the very least, we need to be aware of such biases and consider how they may alter important decisions that affect basic ecological theory and management practices.
Abstract: Banksia woodland is a seasonally arid and fire-prone environment. Although a seemingly inhospitable environment for frogs, seven species were recorded in pitfall-trapping carried out in six areas of Banksia woodland. These areas had different fire histories, ranging from recently burned to unburned for 23 years. One of the areas was burned during the course of this study. Three species made up 95% of captures; Helleioporus eyrei, Limnodynastes dorsalis, and Myobatrachus gouldi. Annual numbers of captures of H. eyrei were not generally affected by fire or increasing time after fire. L. dorsalis, and to a lesser extent, M. gouldii were caught in higher numbers in long-unburnt areas than in recently burnt areas. Variation in the abundance of L. dorsalis and M. gouldii with time after fire did not appear to be related to changes in leaf litter and vegetation density, or to the abundance of invertebrates as potential prey.
Abstract: Fire influences the presence and distribution of plants, and their associated plant diseases in natural ecosystems. Plots at a Long Term Ecological Research facility in Cedar Creek Minnesota, were utilized to investigate the effects of fire on the annual changes in rust infection in this natural prairie. Infection by P. andropogonis was measured on both it's hosts, comandra (C), and big bluestem (BBS), over a four year period in two fields, one burned every fourth year, and one without burns. Fire reduced aecia on C by over 96 percent compared to years previous and following the fire, but there was no change in the overall average uredinal infection levels in BBS plots within or between fields of that year. This is likely due to the efficiency of uredinal spore dispersal. However, variation in rust levels on individual BBS plots between years was affected by fire. Simple regression of rust levels in pairs of years gave R2=0.06, regressing the year following the burn to the year of the burn, compared to R2=0.37 for the non-burned field, supporting that fire can disrupt perennial disease cycles. Field differences in R2 values hold true for all year by year comparisons.
Abstract: Acacia erioloba woodlands provide important forage and shade for wildlife in northern Botswana. Mortality of mature trees caused by browsing elephants has been well documented but the lack of regeneration of new trees had received little attention. Annual growth of new shoots and changes in height were measured to determine the influence of elephants and small ungulate browsers, rainfall and fire on the growth and survival of established A. erioloba seedlings from 1995 to 1997 in the Savuti area of Chobe National Park. All above-ground vegetation was removed from 40% of established seedlings in 1995 and 28% in 1997 by browsing elephants, and the mean height of remaining seedlings decreased from >550 mm to <300 mm. When seedlings browsed by kudu, impala and steenbok but not elephants are considered, mean seedling height increased <50 mm per year, even though mean new shoot growth remaining at the end of the dry season was 100-200 mm. Fires burned portions of the study area in 1993 and 1997, killing above-ground vegetation, but most established A. erioloba seedlings survived, producing coppice growth from roots. While elephants and fire caused the greatest reduction in established seedling height and number, small browsers suppressed growth, keeping seedlings vulnerable to fire and delaying growth to reproductive maturity.
Abstract: Little is known of the effects of fire on lesser prairie-chicken (Tympanuchus pallidicinctus) habitat in shinnery oak (Quercus havardii) communities. Our objective was to determine the influence of seasonal prescribed fire, at 1 and 2 years post-treatment, on the quality of nesting habitat, foraging and brooding habitat, and thermal and escape cover. In each of 3 study sites in western Oklahoma, 12 60X30-m plots were seasonally burned, annually burned, or left unburned, and an array of habitat variables were measured at 1 and 2 years post-fire. During both periods, canopy coverage of shrubs decreased (Pltoreq0.01) with fall and spring fire. Nesting grass cover decreased (P=0.007) with fall and spring burning at 1 year post-fire. Visual obstruction in May and January decreased (Pltoreq0.001) with burning in all seasons. Burning in all seasons increased warm- (gtoreq100% increase, P<0.001) and cool- (gtoreq200% increase, P=0.026) season forb coverage in year 1 and grasshopper density (Pltoreq0.1 00) in both years. Shinnery oak mast, leaf bud, and catkin production failed at 1 year post-fire At 2 years post-fire, cool-season forb cover increased (P=0.014) with fall and spring burning and winter (January) forb frequency increased (P=0.047) 190% with burning in all seasons. Prescribed fire appears to be an effective tool to increase abundance of growing-season forbs and sedges, winter forbs, and grasshoppers associated with quality Foraging and brooding habitat. Nesting habitat and thermal and escape cover are impacted negatively by fire, particularly spring fire, due to a reduction in overhead and horizontal cover and reduced abundance of important nesting grasses. Our data suggest a 2- to 3-year recovery period for nesting habitat following burning. Negative impacts of fire on nesting habitat and thermal and escape cover can be reduced by burning in seasons other than spring, decreasing burn size, and interspersing burned and unburned areas.
Abstract: Surprisingly little research has been done to partition the contribution of catastrophic disturbance from that of small-scale individualistic mortality events on riparian large woody debris (LWD) recruitment. This study compared the impact of both processes on recruitment through simulation of several catastrophic disturbances (a spruce beetle outbreak, a moderately intense fire, and a clearcut) and undisturbed (individualistic mortality only) old growth for a small headwater stream in the Intermountain West of the United States. All scenarios progressed through a two-stage process, with the Forest Vegetation Simulator growth and yield model controlling forest dynamics and a postprocessor (CWD, version 1.2) predicting riparian LWD recruitment. Projections indicate that individualistic-only conditions delivered 2.5 m3 LWDcntdot100 m reach-1cntdot10-yr cycle-1; while the spruce beetle-, fire-, and clearcut-affected stands averaged 2.9, 3.2, and 1.5 m3 LWDcntdot100 m reach-1cntdotcycle-1, respectively. Stands impacted by natural catastrophic disturbance significantly (P < 0.05) increased cumulative (300 yr) LWD recruitment over the individualistic-only scenario, whereas clear-cutting significantly decreased total delivery. In-stream LWD loads, relatively stable in undisturbed riparian zones, fluctuated sharply under catastrophic disturbance. Peak channel loads associated with natural perturbation occurred apprx30 yr after the event while debris volumes under clear-cutting immediately declined. The postevent recruitment and in-stream LWD stocks of all disturbance scenarios eventually fell below undisturbed conditions, requiring decades to recover historical volumes. Catastrophic disturbances induced such steep oscillations in riparian LWD load that the systems experiencing frequent large-scale perturbations never achieved a long-term steady state, as some have postulated. Because of the inflation in cumulative LWD delivery, it may prove advantageous to encourage (or imitate) some catastrophic disturbance in forests along streams noticeably depauperate of LWD.
Abstract: A quantitative analysis of the effect of fire regime on the abundance of common lizard species and genera and the species richness of two lizard groups in Kakadu National Park (12 degrees S) is presented. A surprising range of relationships between species abundance and components of fire regimes was revealed. Carlia amax, Heteronotia binoei and Carlia gracilis appear to be fire-sensitive, Diporiphora bilineata and Carlia triacantha are favoured by early hot fires, Cryptoblepharus plagiocephalus seems relatively unaffected, Carlia foliorum seems very tolerant of fires, while Ctenotus and Sphenomorphus spp. are favoured by low intensity, patchy fires with high intensity spots.
Lizard species experiencing the high-frequency fire regimes of the savannas and dry forests of the Australian wet-dry tropics are not able to select habitat at different stages of regeneration after fire but select habitat produced by fires of different types. The implication for management is that no one fire regime is optimal for the fauna as a whole. A range of fire regimes within a park should be maintained in order to retain the whole fauna.
Abstract: Densities of gopher tortoises were compared with habitat characteristics in scrub and in flatwood habitats on the Kennedy Space Center, Florida. Tortoises were distributed widely among habitat types and did not have higher densities in well-drained (oak-palmetto) than in poorly-drained (saw palmetto) habitats. Fall densities of tortoises ranged from a mean of 2.7 individuals/ha in disturbed habitat to 0.0 individuals/ha in saw palmetto habitat. Spring densities of tortoises ranged from a mean of 2.5 individuals/ha in saw palmetto habitat to 0.7 individuals/ha in oak-palmetto habitat. Densities of tortoises were correlated positively with the percent herbaceous cover, an indicator of food resources. Plots were divided into three burn classes; these were areas burned within three years, burned four to seven years, and unburned for more than seven years prior to the study. Relationships between densities of tortoises and time-since-fire classes were inconsistent.
Abstract: Fire-prone savanna ecosystems in southern African conservation areas are managed by prescribed burning in order to conserve biodiversity. A prescribed burning system designed to maximise the benefits of a diverse fire regime in savanna conservation areas is described. The area burnt per year is a function of the grass fuel load, and the number of fires per year is a function of the percentage area burnt. Fires are point-ignited, under a range of fuel and weather conditions, and allowed to burn out by themselves. The seasonal distribution of planned fires over a year is dependent on the number of fires. Early dry season fires (May-June) tend to be small because fuels have not yet fully cured, while late season fires (August-November) are larger. More fires are ignited in the early dry season, with fewer in the late dry season. The seasonality, area burnt, and fire intensity are spatially and temporally varied across a landscape. This should result in the creation of mosaics, which should vary in extent and existence in time. Envelopes for the accumulated percentage to be burnt per month, over the specified fire season, together with upper and lower buffers to the target area are proposed. The system was formalised after 8 years of development and testing in Pilanesberg National Park, South Africa. The spatial heterogeneity of fire patterns increased over the latter years of implementation. This fire management system is recommended for savanna conservation areas of >20 000 ha in size.
Abstract: Prior to Anglo-European settlement, fire was a major ecological process influencing the structure, composition and productivity of shortgrass prairie ecosystems on the Great Plains. However during the past 125 years, the frequency and extent of grassland fire has dramatically declined as a result of the systematic heavy grazing by large herds of domestic cattle and sheep which reduced the available levels of fine fuel and organized fire suppression efforts that succeeded in altering the natural fire regime. The greatly diminished role of recurrent fire in these ecosystems is thought to be responsible for ecologically adverse shifts in the composition, structure and diversity of these grasslands, leading specifically to the rise of ruderal species and invasion by less fire-tolerant species. The purpose of this study was to evaluate the ecological effects of fire season and frequency on the shortgrass prairie and to determine the means by which prescribed fire can best be restored in this ecosystem to provide the greatest benefit for numerous resource values. Plant cover, diversity, biomass and nutrient status, litter cover and soil chemistry were measured prior to and following fire treatments on a buffalograss-blue grama shortgrass prairie in northeastern New Mexico. Dormant-season fire was followed by increases in grass cover, forb cover, species richness and concentrations of foliar P, K, Ca, Mg and Mn. Growing-season fire produced declines in the cover of buffalograss, graminoids and forbs and increases in litter cover and levels of foliar P, K, Ca and Mn. Although no changes in soil chemistry were observed, both fire treatments caused decreases in herbaceous production, with standing biomass resulting from growing-season fire similar to600kg/ha and dormant-season fire similar to1200kg/ha, compared with controls similar to1800kg/ha. The initial findings of this long-term experiment suggest that dormant-season burning may be the preferable method for restoring fire in shortgrass prairie ecosystems where fire has been excluded for a prolonged time period.
Abstract: We used the computer program RAMAS to explore the sensitivity of an extinction-risk model for the Gila trout (Oncorhynchus gilae) to management of wildfires and number of populations of the species. The Gila trout is an endangered salmonid presently restricted to very few headwaters of the Gila and San Francisco river tributaries in southwestern New Mexico. Life history data for 10 extant populations were used to examine sensitivity of the species' viability to changes in a variety of factors including population size, fecundity, life stage structure, number of populations, severity and probability of forest fires, and a regulated fishery. The probability and severity of forest fires and number of populations had the greatest effect on viability. Results indicate that successful conservation of Gila trout requires establishment of additional populations and reduction of the severity of forest fires through a program incorporating more frequent, but less severe, fires.
Abstract: In western North America, major wildfires often now result in stand-replacement events and natural resource losses for many decades post-burn. Fire severity has been exacerbated by past fire suppression that has allowed large fuel load accumulations. To reduce woody debris and restore the ecological integrity of western forests, prescribed burning is increasingly used as a regional management tool. However, we do not understand the effects of either wildfire or prescribed fires on amphibians in stream, riparian and terrestrial habitats in western forests. Terrestrial amphibians, macroinvertebrates and other animals are surface active during periods of rainfall or high moisture. Wildland fire usually starts in the hot, dry summers typical of the more acrid Western and Mediterranean climates and may have less effect on resident biota than prescribed fires often conducted during the late fall to spring rainy season, when there is sufficient moisture to prevent crown fires. Still, intense wildfires may result in increased erosion and sediment or changes in soil chemistry impacting downstream aquatic environments. To our knowledge, no published reports exist on effects of fire on the aquatic herpetofauna of the Pacific Northwest. Research efforts now underway include new studies of wildland fires in Oregon and Idaho on aquatic amphibians, and studies on the effects of prescribed fire on terrestrial salamanders and associated forests in the Klamath Province along the Oregon-California border. These will help evaluate the cumulative effects of fuels reduction on amphibian population and habitat structure, and provide guidelines to better manage for wildlife species characteristic of western forests. In the Pacific Northwest, investigations of fire effect son wildlife are severely lacking relative to the vast acreage, economic value, and biodiversity of its forest ecosystems. Given the increasing prominence of wildfire and prescribed burning in many western forest systems, we suggest more resources will be devoted to such research endeavors, and that hey include other sensitive groups of wildlife such as mollusks.
Abstract: Few intensive studies have been conducted on reptile populations of the tallgrass prairie. In addition, the effects of fire on these populations are also largely unknown. I established drift fence arrays connected to funnel traps to study the community composition and seasonal activity of reptiles found on the Konza Prairie Research Natural Area located near Manhattan, Kansas. This design also gave me the opportunity to examine the response of reptile populations to a spring wildfire. A total of 657 individuals representing 12 species were captured from 1994-1996. The results suggest that one species, Coluber constrictor, may respond negatively to recent fire.
Abstract: Natural ecosystems globally are often subject to multiple human disturbances that are difficult to restore. A restoration experiment was done in an urban fragment of native coastal sage scrub vegetation in Riverside, California that has been subject to frequent fire, high anthropogenic nitrogen deposition, and invasion by Mediterranean annual weeds. Hand cultivation and grass-specific herbicide were both successful in controlling exotic annual grasses and promoting establishment of seeded coastal sage scrub vegetation. There was no native seedbank left at this site after some 30 years of conversion to annual grassland, and the only native plants that germinated were the seeded shrubs, with the exception of one native summer annual. The city green-waste mulch used in this study (C:N of 39:1) caused short-term N immobilization but did not result in decreased grass density or increased native shrub establishment. Seeding native shrubs was successful in a wet year in this Mediterranean-type climate but was unsuccessful in a dry year. An accidental spring fire did not burn first-year shrubs, although adjacent plots dominated by annual grass did burn. The shrubs continued to exclude exotic grasses into the second growing season, suggesting that successful shrub establishment may reduce the frequency of the fire return interval.
Abstract: Stand restoration of low-quality, mixed pine-hardwood ecosystems containing a Kalmia latiforilia L. dominated understory, through cutting, buring, and planting of Pinus strobus L., is common on xeric souther Appalachian forest sites. WE examined the effects of this tratment on early vegetation composition and diversity. Four 13-year-old stands were examined. Two of the four stands were mechanically released at age 6. Density and basala area were estimated for understory and overstory components, and density and percent cover for the herb component. Species diversity (Shannon-Wiener index) was estimated and comparisons were made with an untreated reference stand that was typical of stands receiving site preparation burning in the southern Appalachians. Overstory and herb diversity estimates were significantly lower for the reference stand that for the 13-year-old stands.
Abstract: Changes in aboveground and forest floor mass, carbon (C), and nitrogen (N) pools were quantified on three sites in the southern Appalachians 2 yr after felling and burning, Before fel ling and burning, stands were characterized by sparse overstories and dense Kalmia latifolia L. understories, Two years after burning, foliar C and N pools had reached 25% and 29% of pretreatment levels, respectively. Foliar N concentrations were not different from pretreatment values, Standing wood C and N pools were 1% and 2%, respectively, of pretreatment values, Wood N concentrations were significantly higher on two sites, likely related to differences in fire intensity, Forest floor N content 2 yr after burning was 90% of pretreatment levels, most contained in unconsumed large woody material. Forest floor mass was significantly lower in the Oi layer and unchanged in the Oe+Oa layers. Forest floor N concentrations were generally lower after treatment. The site with the least intense fire and the lowest mass loss from the forest floor had the highest forest floor, foliage, and wood N concentrations 2 yr after burning. Site recovery after felling and burning was a function of five severity and the capacity for site-nutrient retention through plant uptake.
Abstract: We sampled amphibians on 3 red alder (Alnus rubra) sites 1 year before and 1 and 2 years after the following treatments were applied to each site: (1) control (uncut), (2) clearcut and broadcast burned, and (3) clearcut, broadcast burned, and then sprayed with the herbicide glyphosate. All sites included uncut riparian buffer strips. For 3 of the 6 species with greater than or equal to 20 captures in pitfall traps, we did not detect changes in capture rates after clearcutting. Capture rates of ensatinas (Ensatina eschscholtzii) and Pacific giant salamanders (Dicamptodon tenebrosus) decreased after logging. Capture rates of western redback salamanders (Plethodon vehiculum) increased the first year after logging, probably because the salamanders sheltered in pitfalls, but effects on populations were unclear. Logging did not significantly alter capture rates of rough-skin newts (Taricha granulosa), Dunn's salamanders (P. dunni), and red-legged frogs (Rana aurora). Planning the location and timing of clearcuts or other silvicultural practices over a landscape and retaining riparian buffer strips may be necessary to ensure long-term persistence of Pacific giant salamanders. We did not detect any effects of herbicide spraying on capture rates. Capture rates for rough-skin newts and red-legged frogs were higher in uncut red alder stands than in Douglas-fir (Pseudotsuga menziesii) stands sampled in other studies, an indication that, when red alder stands are converted to Douglas-fir, some alders should be left adjacent to streams to provide habitat for these species and other hardwood associates.
Abstract: Prescribed burning is a common method to eliminate sagebrush (Artemisia spp.) and has been suggested as a tool to enhance the habitat of sage grouse (Centrocercus urophasianus). Effects of this practice on sage grouse have not been evaluated rigorously. We studied effects of prescribed fire on lek (traditional breeding display areas) attendance by male sage grouse occupying low-precipitation (<26 cm) sagebrush habitats in southeastern Idaho from 1986 through 1994. During the preburn period (1986-89), average declines for male attendance were 48% and 46% for treatment and control leks, respectively. Lek counts were similar for treatment and control leks during the preburn years (G-test, 0.25>P>0.10). During the postburn period (1990-94), male attendance at treatment leks declined 90% and control leks declined 63%. Although declines were similar between treatment and control leks during the preburn period, postburn declines were greater for treatment than control leks (0.05<P<0.10). We rejected the null hypothesis that for the 2 largest leks in both the treatment and control areas, counts were independent of years for preburn (0.05<P<0.10) and postburn (Pltorsim0.05) periods and concluded that breeding population declines became more severe in years following fire. Prescribed burning negatively affected sage grouse in southeastern Idaho and should not be used in low-precipitation sagebrush habitats occupied by breeding sage grouse.
Abstract: Ecosystem management is a theoretical framework in which land managers attempt to approximate natural disturbance with harvesting practices. In the mixedwood boreal forest of northeastern Alberta, Alberta-Pacific Forest Industries Inc. alters cutblock size, structure, and distribution over the landscape to simulate fires, the dominant disturbance type. In 1997 and 1998, we sampled for Rana sylvatica (Le Conte) and Pseudacris triseriata maculata (Wied-Neuwied) near Owl River and Mariana Lake, Alberta, in undisturbed, harvested, and naturally burned landscapes. We compared patterns of distribution and relative abundance using transects, time-constrained lake margin searches, and opportunistic detections. In 1998, we characterized the understory, shrub layer, and canopy layer on each transect. We used stepwise logistic regression to describe microhabitat use by each species. We did not detect consistent differences between burned and logged areas. This may reflect pre-treatment variation in regional habitat. Our data suggest that the presence of R. sylvatica is related to deciduous leaf litter, and that both species may require extensive ground cover and moist soil conditions. Although the microhabitat descriptions we present can be used to plan future harvests, further work is required to determine the effectiveness of ecosystem management in the boreal forest.
Abstract: Restoration of many terrestrial plant communities involves the reintroduction of fire. However, there have been few studies of the effects of fire on the avifauna during the restoration process. To study the effects of oak savanna restoration on avian communities, breeding birds were censused and the vegetation structure documented in seven experimental burn units (8-18 ha) that had experienced different frequencies of controlled burns during the past 31 years (0-26 burns). Data were analyzed with both direct and indirect gradient analyses using multivariate techniques. The results showed that, as savanna restoration proceeded, there was a general decline in predominantly insectivorous species, particularly those that feed in the upper canopy region (leaves and air space), and a general increase in omnivorous species, particularly those that feed on the ground and in the lower canopy. Insectivorous bark gleaners (woodpeckers) also increased during restoration and were correlated with the increase in standing dead trees resulting from the fires. Overall, savanna restoration resulted in increases in the abundance of many open country bird species, including many species that have been declining in central and eastern North America, including red-headed woodpecker, Baltimore oriole, eastern kingbird, vesper sparrow, field sparrow, lark sparrow, brown thrasher, American goldfinch, and brown-headed cowbird. The shifts in species and guilds were correlated with changes in burn frequency and the macro vegetation structure-tree and shrub density, leaf area index, and relative proportion of standing dead trees. The findings show that savanna restoration can increase bird diversity and provide important habitat for uncommon or declining bird species. These birds are most likely attracted to one or more of the distinctive habitat features of the restored savanna environments, including scattered mature trees, standing dead trees and snags, and presence of both shrubby and grassland vegetation. The findings also suggest that restoration ecologists and wildlife biologists will need to work together to achieve desired goals, since different types of savanna restoration efforts may produce different effects on the breeding bird community.
Abstract: The application of fire as a management tool is often used to change the species composition of the vegetation and its cover to maintain plant communities in a specific successional stage. This study investigates the influence of two fire treatments (a head and a back fire) on the plateau grassland communities in the Mountain Zebra National Park (MZNP). The production of herbage yield on grazed areas and areas protected from grazing which were subjected to two fire treatments, were compared with that of an unburnt control area subjected to grazing in the same homogenous grassland over two growing seasons. No differences were found in herbage production between the two fire treatment areas. After the burn the grazing exclosures achieved the same herbage yield as the control area within two growing seasons. In comparison, the grazed areas could after the burn only achieve a herbage yield equal to 55.7% of that of the control area. The results indicate that fire stimulates active vegetation growth on the plateau grasslands in MZNP leading to a higher production rate and better utilisation by game.
Abstract: The Florida panther (Puma concolor coryi) is one of the most endangered mammals in the world, with only 30-50 adults surviving in and around Florida Panther National Wildlife Refuge and the adjacent Big Cypress National Preserve, hlanagers at these areas conduct annual prescribed burns in pine (Pinus sp.) as a cost-effective method of managing wildlife habitat. Our objectives were to determine if temporal and spatial relationships existed between prescribed fire and panther use of pine. To accomplish this, we paired fire-event data from the Refuge and the Preserve with panther radiolocations collected between 1989 and 1998, determined the time that had elapsed since burning had occurred in management units associated with the radiolocations, and generated a frequency distribution based on those times. We then generated an expected frequency distribution, based on random use relative to time since burning. This analysis revealed that panther use of burned pine habitats was greatest during the first year after a management unit was burned. Also, compositional analysis indicated that panthers were more likely to position their home ranges in areas that contained pine. We conclude that prescribed burning is important to panther ecology. We suggest that panthers were attracted to <1-year-old burns because of white-tailed deer (Odocoileus virginianus) and other prey responses to vegetation and structural changes caused by the prescribed fires. The strong selection for stands burned within 1 year is a persuasive indication that it is the bunting in pine, rather than the pine per se, that most influenced habitat use. Before burning rotation lengths are reduced, however, we suggest managers determine effects of shorter burning intervals on vegetation composition and evaluate the landscape-scale changes that would result.
Abstract: The four frog species in the Geocrinia rosea complex occur in state forest in southwest Western Australia. Fire management of these forests involves fuel-reduction burning with an average rotation of five to nine years. In this study we examined the impact of fire on Geocrinia lutea by counting calling males in six pairs of burned and control sites from 1992 to 1994. The immediate impact of the fire on G. lutea adults, and the survival of G. lutea eggs and larvae after the fire, were also addressed. We found that fuel-reduction burning in spring was associated with a significant decline in the number of calling males. The populations had not recovered two years after the fire. Up to 29% of the calling males may have been killed in the fire. Egg and larval survival was not significantly different between treatments. However, the treatments did differ in the cause of death, with higher in-situ egg death and lower predation at burned sites. The short-term impact of spring fuel-reduction burns may pose a serious threat of extinction for very small populations. The endangered species Geocrinia alba has many small, isolated populations and frequent fire may therefore be inimical to their survival. However, we do not know if there is a long-term effect. Populations may or may not have time to recover between fires.
Abstract: We describe our experience as biologists/resource advisors working with firefighting personnel to reduce the risk of impacts and disturbances to desert tortoises and their habitats. Pre-fire season planning is essential preparation for risk assessment and identifying sensitive areas of habitat between biologists/resource advisors and fire managers. Having resource advisors present at the onset of fire operations can prevent potentially destructive activities related to the logistics of having vehicles in habitat and providing for the needs of groups of fire suppression personnel. Rehabilitation of road heads in tortoise habitat is a useful means of deterring further long-term degredation of habitat in some cases. We provide two appendices for use in the field: 1) an outline of fire management activities to be used by fire managers, and 2) an outline of a shift briefing used to educate firefighters at the scene of a fire. These prescriptions for action and education were developed for use in the northeast Mojave Desert of Utah and Arizona. These procedures are not universal in application and should be tailored to local needs and consideration of other resource values than tortoises. THe Sonoran Desert of Arizona differs substantially in physiography, and plant species composition and fuel loads. THerefore, we should consider habitat characteristics and habitat use by tortoises in the Sonoran Desert of Arizona specifically to assess the possible effects of fire suppression activities and to minimize adverse impacts to desert tortoises and their habitats. This approach could be useful for protecting other sensitive species and habitats in a variety of areas.
Abstract: Stratigraphic and geomorphic evidence indicate floods that occur soon after forest fires have been intermittent but common events in many mountainous areas during the past several thousand years. The magnitude and recurrence of these post-fire flood events reflects the joint probability between the recurrence of fires and the recurrence of subsequent rainfall events of varying magnitude and intensity. Following the May 1996 Buffalo Creek, Colorado, forest fire, precipitation amounts and intensities that generated very little surface runoff outside of the burned area resulted in severe hillslope erosion, floods, and streambed sediment entrainment in the rugged, severely burned, 48 km(2) area. These floods added sediment to many existing alluvial fans, while simultaneously incising other fans and alluvial deposits. Incision of older fans revealed multiple sequences of fluvially transported sandy gravel that grade upward into charcoal-rich, loamy horizons. We interpret these sequences to represent periods of high sediment transport and aggradation during floods, followed by intervals of quiescence and relative stability in the watershed until a subsequent fire occurred.
An alluvial sequence near the mouth of a tributary draining a 0-82 km(2) area indicated several previous post-fire flood cycles in the watershed. Dendrochronologic and radiocarbon ages of material in this deposit span approximately 2900 years, and define three aggradational periods. The three general aggradational periods are separated by intervals of approximately nine to ten centuries and reflect a 'millennium-scale' geomorphic response to a closely timed sequence of events: severe and intense, watershed-scale, stand-replacing fires and subsequent rainstorms and flooding. Millennium-scale aggradational units at the study site may have resulted from a scenario in which the initial runoff from the burned watershed transported and deposited large volumes of sediment on downstream alluvial surfaces and tributary fans. Subsequent storm runoff may have produced localized incision and channelization. preventing additional vertical aggradation on the sampled alluvial deposit for several centuries. Two of the millennium-scale aggradational periods at the study site consist of multiple gravel and loam sequences with similar radiocarbon ages. These closely dated sequences may reflect a 'multidecade-scale' geomorphic response to more frequent. but aerially limited and less severe fires, followed by rainstorms of relatively common recurrence.
Abstract: In April 1995, the USDA Forest Service conducted a prescribed burn along with a south-facing slope of southern Appalachian watershed, Nantahala National Forest, western NC. Fire had been excluded for over 70 years and the purpose of the burn was to create a mosaic of fire intensities to restore a degraded pine/hardwood community and to stimulate forage production and promote oak regeneration along a hillslope gradient. Permanent plots were sampled at three locations along a gradient from 1500 to 1700 m. Plot locations corresponded to three community types: mesic, near-riparian cove (low slope); dry, mixed-oak (mid slope); and xeric, pine/hardwood (ridge). Before burning (1994-1995) and post-burn (summer, 1995 and summer, 1996) vegetation measurements were used to determine the effects of fire on the mortality and regeneration of overstory trees, understory shrubs, and herbaceous species. After the burn, mortality was highest (31%) at the ridge location, substantially reducing overstory (from 26.84 pre-bum to 19.05 m(2) ha(-1) post-burn) and understory shrub (from 6.52 pre-burn to 0.37 m(2) ha(-1) post-bum) basal area. At the mid-slope position, mortality was only 3%, and no mortality occurred at the low slope. Not surprisingly, percent mortality corresponded to the level of fire intensity. Basal area of Kalmia latifolia, Gaylussacia baccata, and Vaccinium spp. were substantially reduced after the fire, but density increased due to prolific sprouting. The prescribed fire had varying effects on species richness and diversity across the hillslope gradient. On the ridge, diversity was significantly increased in the understory and herb-layer, but decreased in the overstory. On the mid slope, no change was observed in the overstory, but diversity significantly decreased in the understory. On the low slope, no change was observed in the overstory or understory. (C) 1999 Elsevier Science B.V. All rights reserved.
Abstract: The Florida box turtle, Terrapene carolina bauri, ranges over most of central and eastern peninsular Florida and the Keys. Over the range of T. c. bauri, the pine flatwoods habitat with which it is best associated is subject to periodic burning. The authors look at the extent to which the Florida box turtle is adversely affected by such events by examining a series of T. c. bauri in the collections of the United States National Museum of Natural History, Smithsonian Institution, and George Mason University. Their observations indicate that fire may play a critical role in the ecology of Florida box turtle populations. Unfortunately, so little has been published on the life history of this animal that it is difficult to assess its ecological and behavioral requirements with any degree of certainty.
Abstract: Evidence of direct mortality to vertebrates was gathered following controlled spring burns in a reestablished prairie in eastern Nebraska. During 3 years (1974-1976) in which observations were made, several species were killed by fires, including: cottontail rabbits (Sylvilagus floridanus), western harvest mice (Reithrodontomys megalotis), voles (Microtus pennsylvanicus and M. ochrogaster), bull snakes ( Pituophis melanoleucas), plains garter snakes (Thamnophis radix) and red-sided garter snakes (T. sirtalis). Young harvest mice pups were partially susceptible to spring prairie fires; morrtality to these on a 22.8-ha section burned 26 April 1976 was estimated at between 208 and 522 individuals. Many eggs of ground-nesting birds were destroyed by the fires; species included were ring-necked pheasant (Phasianus colchicus), bobwhite quail (Colinus virginianus), mallard duck (Anas platyrhynchus) and meadowlark (Sturnella neglecta).
Abstract: The effects of habitat manipulations on Texas horned lizards (Phyrnosoma cornutum) and their main prey, harvester ants (Pogonomyrmex spp.) were studied in South Texas. The relative abundance of lizards, their scat, and active harvester ant mounds was assessed on 1-ha plots that were manipulated with either prescribed burning, disking, burning and disking combination, grazing, or land in the Conservation Reserve Program (CRP). We determined differential habitat use or avoidance using Chi-square analysis and Bonferroni Z-statistics to control the experiment-wise error probability at 10%. Lizards used burned plots disproportionately more, were neutral in their use of the disked and grazed plots, and under-utilized the burned and disked combination and CRP plots. Analysis of scat led to similar conclusions in relation to burned, grazed, and CRP plots, but scats were distributed on combination plots pro rata to availability and were underrepresented on the disked plots. No difference was detected in the relative abundance of active ant mounds among the 5 land management practices. Even though Texas horned lizards preferentially used areas that were recently burned, the process of burning may harm them due to the shallow depths in which they hibernate.
Abstract: Federal land managers in the western United States are interested in the potential of prescribed fire as a tool to decrease fuel loads, increase vegetational heterogeneity, and increase faunal diversity in various ecosystems. I tested whether implementation of a prescribed fire program by the US Forest Service in a watershed in the central Great Basin had significant effects on butterfly species richness and composition. I monitored butterfly communities during the first two years after implementation in five to seven burn units and controls in the watershed. To estimate baseline spatial and temporal variation in butterfly communities in the greater ecosystem, I also monitored butterflies in five untreated canyons outside the project area. Butterfly species richness and butterfly species composition (measured as community similarity) did not differ significantly between burn units and controls. Geographic location had statistically significant effects on species richness. Butterfly species composition of individual locations varied over time, as did the magnitude of that variation. These results emphasize that standardized, repeatable monitoring protocols are vital for evaluating the effects of experimental management treatments and for predicting and assessing the effects of future management strategies and environmental changes.
Abstract: Ponderosa pine (Pinus ponderosa), Jeffrey pine (P. jeffreyi), longleaf pine (P. palustris), and south Florida slash pine (P. elliotti var. densa) are fire resisters. Trees of these species are able to survive the direct effects of wildfires. Monterey pine (P. radiata), knobcone pine (P. attenuata), sand pine (P. clausa), and jack pine (P. banksiana) are fire evaders. Trees of these species are killed by wildfire, but species survive on the postfire site via seed germination. Needles were burned in a 2x2 factorial experiment to compare these eight species, all of which are prominent in fire-related communities. The experiment tested two factors-fire adaptive strategy (resisters vs. evaders), geographic region (western vs. eastern United States)-and interactions between those two factors. Flame height, flame time, ember time, burn time, percent fuel combusted, and mean rate of weight loss were measured. Longleaf pine, ponderosa pine, and south Florida slash pine had the highest values for flame height, percent fuel combusted, and mean rate of weight loss. Knobcone pine and Monterey pine had the longest ember time and burn time. Sand pine and jack pine had the longest flame time. Resisters tested highest in flame height, percent fuel combusted, and mean rate of weight loss. Evaders had greater flame and burn times. Western pines were significantly greater than eastern pines in all burning characteristics except flame time and mean rate of weight loss. Significant interactions between fire adaptive strategy and geographic region existed for all burning characteristics except mean rate of weight loss. The interaction was accounted for primarily by differences between western evaders, which had some of the highest values for each characteristic, and eastern evaders, which had some of the lowest values.
Abstract: As part of the Wine Spring Creek ecosystem management project on the Natahala National forest, North Carolina, we assessed the effects of a community restoration fire on small mammals and herpetofauna in the upper slope pitch pine (Pinus rigida) stands, neighboring mid-slope oak (Quercus spp.) stands and rhododendron (Rhododendron maximum) dominated riparian areas during 1995 and 1996. Using drift-fence arrays with pitfalls and snap-trapping, we collected these small mammals: masked shrew (Sorex cinereus), smoky shrew (S. fumeus), water shrew (S. palustris), pygmy shrew (S. hoyi), northern short-tailed shrew (Blarina brevicauda), deer mouse (peromyscus maniculatus), white-footed mouse (P. leucopus), golden mouse (Ochrotomys nuttalli), southern red-backed vole (Clethrionomys gapperi), pine vole (Microtus pinetorum) and woodland jumping mouse (Napaeozapus insignis). Herpetofauna collected fom drift-fence arrays and time-constrained searches included: eastern newt (Notophtalmus viridescens), seepage salamander (Desmognathus aeneus), mountain dusky salamander (D. ochrophaeus), Blue Ridge two-lined salamander (Eurycea wilderae), spring salamander (Gyrinophilus porphyriticus), Jordan's salamander (Plethodon jordani), wood frog (Rana sylvatica), five-lined skink (Eumeces fasciatus), eastern garter snake (Thamnophis sirtalis), and northern ringneck snake (Diadophis punctatus). Prior to the prescribed community restoration fire in the spring of 1995, there were no significant differences in small mammal or herpetofauna collections between burned and control areas. Slope position accounted for more variation among the species of greatest abundance than did burning. Concern for the effects of prescribed fire as a management tool on small mammals and herpetofauna in the southern Appalachians seems unwarranted.
Abstract: We review and compare well-studied examples of five large, infrequent disturbances (LIDs)-fire, hurricanes, tornadoes, volcanic eruptions, and floods-in terms of the physical processes involved, the damage patterns they create in forested landscapes, and the potential impacts of those patterns on subsequent forest development. Our examples include the 1988 Yellowstone fires, the 1938 New England hurricane, the 1985 Tionesta tornado, the 1980 eruption of Mount St. Helens, and the 1993 Mississippi floods. The resulting landscape patterns are strongly controlled by interactions between the specific disturbance, the abiotic environment (especially topography), and the composition and structure of the vegetation at the time of the disturbance. The very different natures of these interactions yield distinctive temporal and spatial patterns and demand that ecologists increase their knowledge of the physical characteristics of disturbance processes. Floods and fires can occur over a long period, whereas volcanic eruptions and wind-driven events often last for no more than a few hours or days. Tornadoes and floods produce linear patterns with sharp edges, but fires, volcanic eruptions, and hurricanes can affect broader areas, often with gradual transitions of disturbance intensity. In all cases, the evidence suggests that LIDs produce enduring legacies of physical and biological structure that influence ecosystem processes for decades or centuries.
Abstract: Logging and wildfire are significant anthropogenic disturbance agents in tropical forests. We compared the abundance and species richness of selected terrestrial wildlife taxa including small mammals, amphibians, reptiles, and terrestrial invertebrates in areas burned by wildfire and then logged and in adjacent undisturbed areas of a tropical humid forest in Bolivia. Disturbed areas had 24% less canopy cover than undisturbed areas but had 2.6 times the cover of large woody debris. Understory cover did not differ between disturbed and undisturbed areas. Small mammal abundance and species richness in disturbed areas were 43 and 70% higher, respectively, than in adjacent undisturbed areas. Herpetofaunal abundance did not differ significantly among disturbed and undisturbed areas, but trends for higher abundance were observed for both reptiles and amphibians in disturbed areas. Herpetofaunal species richness was significantly higher in disturbed compared to undisturbed areas. Total terrestrial invertebrate abundance, as estimated by pitfall traps, was significantly higher in undisturbed compared to disturbed areas mostly due to higher abundances of Formicidae and Blattidae. However, two invertebrate groups, Orthoptera and Lepidoptera (larvae) were more abundant in disturbed areas. Wildlife conservation strategies for areas where logging or wildfire occur should take into account species- or guild-specific responses to these disturbance agents.
Abstract: The short- and long-term post-fire response patterns of small mammals, reptiles and amphibians inhabiting mallee woodlands and heathlands in temperate Australia are reviewed with respect to species' life history parameters in a search for unifying trends. Pyric response patterns of small mammal species are closely tied to their shelter, food and breeding requirements. There is a trend of increased specificity and reduced flexibility in life history traits concomitant with increased impact of fire and later post-fire recolonization. For reptiles there appears to be a strong relationship between the shelter and foraging requirements of species and their abundance in various successional states. The high incidence of burrowing in mallee/heath amphibian fauna imparts considerable resilience to fire, and most species' abundance and distribution patterns seem more closely related to moisture regimes than to fire perse.
The high degree of consistency between species' post-fire response patterns and their life history parameters points to the feasibility of developing a model to predict the impact of fire on small vertebrates. Such a model is currently being developed.
Abstract: Louisiana Seaside Sparrows (Ammodramus maritimus fisheri) breed and winter exclusively in brackish and saline marshes along the northern Gulf of Mexico. Many Gulf Coast marshes, particularly in the Chenier Plain of southwestern Louisiana and southeastern Texas, are burned intentionally in fall or winter as part of waterfowl management programs. Fire reportedly has negatively affected two Seaside Sparrow Subspecies (A. m. nigrescens and A. m. mirabilis) in Florida, but there is no published information regarding effects of fire on A. m. fisheri. We compared abundance of territorial male Louisiana Seaside Sparrows, number of nesting activity indicators, and vegetation structure in paired burned and unburned plots in Chenier Plain marshes in southwestern Louisiana during the 1996 breeding season (April-July) before experimental winter burns (January 1997) and again during two breeding seasons post-burn (1997-1998). We found that abundance of male sparrows decreased in burned plots during the first breeding season post-burn, but was higher than that of unburned plots during the second breeding season post-burn. Indicators of nesting activity showed a similar but non-significant pattern in response to burning. Sparrow abundance and nesting activity seemingly are linked to dead vegetation cover, which was lower in burned plots during the first breeding season post-burn, but did not differ from that in unburned plots during the second breeding season post-burn. We recommend that marsh management plans in the Gulf Coast Chenier Plain integrate waterfowl and Seaside Sparrow management by maintaining a mosaic of burned and unburned marshes and allowing vegetation to recover for at least two growing seasons before reburning a marsh.
Abstract: We examined the effects of chaparral wildfire on stream-breeding California newts (Taricha torosa) in a 750-m stretch of a perennial Santa Monica Mountain stream (Los Angeles County). Detailed field surveys of 1992 and 1993 established the composition (run, riffle, pool) of this habitat and determined oviposition sites of newts. We also quantified California newt egg mass density and estimated density of newt adults. A chaparral wildfire burned the entire study site on 2 November 1993. Using the same methods, we collected field survey data in 1994 and 1996. Erosion following the 1993 wildfire produced major changes in stream morphology and composition. Pools and runs represented approximately 40-50% of pre-fire stream area. In the spring following the fire, the stream consisted of less than 20% run and pool. Pools that did remain were often smaller and shallower. The average density of adult California newts did not differ among years. The total number of newt egg masses in the spring after the fire was approximately one-third of egg mass counts from pre-fire surveys. Most California newt egg masses were laid in pools and runs; California newts prefer deeper slow-moving water. We conclude that fire-induced landslides and siltation have eliminated pools and runs, thus reducing the amount of habitat suitable for oviposition. Habitat alterations caused by fire likely account for the observed reduction of egg masses at the stream.
Abstract: We studied litter-dwelling beetles (Coleoptera: Carabidae and Staphylinidae) in residual patches of unburned forests (fire residuals) left by two natural wildfires in high-elevation coniferous forests in western Alberta, Canada. Fire residuals were wet, late-successional patches of fir and spruce stands, and served as refugia for populations of forest-dwelling beetle species. The largest fire residuals contained older living trees than the mature forest surrounding the burnt areas. Pterostichus empetricola, a glacial relict beetle species, was associated only with habitats provided by the fire residuals. Although there was no relationship between the size of fire residuals and beetle diversity or activity-abundance, more Nebria crassicornis were collected per trap in larger residuals, suggesting dependence of this species on late-seral attributes present within the largest residuals. Conservation of habitats-equivalent to fire residuals in managed forests will likely contribute to landscape continuity and preservation of faunal elements common in wildfire-origin landscapes.
Abstract: Trees may be retained on logged sites in eucalypt forests for a number of reasons, such as to provide wildlife habitat, for future wood production, for aesthetic reasons, to mitigate erosion, or to provide seed for regeneration. These trees may be required to survive for a considerable period to meet these objectives. Logged sites in eucalypt forests are routinely treated with a post-logging slash-burn to reduce fuel loads and facilitate regeneration. We compared rates of mortality and collapse among trees retained on logged sites that were routinely treated with a high-intensity slash-burn with logged sites routinely treated with a low-intensity slash-burn. All observations were made 2-5 years after logging. The proportion of all retained trees that were killed after logging was 37% on sites treated with a high-intensity slash-burn and 14% on sites treated with a low-intensity slash-burn. The rate of collapse among retained trees over the same period was 1.5 and 0.5%, respectively. Results of logistic regression models indicated that trees retained on logged sites were more likely to die and collapse if the site was treated with a high-intensity slash-burn; however, trees were also more likely to die if the basal area of trees retained on the site was relatively low and the site had a northerly aspect. Mortality was similar among all diameter classes on sites treated with a high-intensity slash-burn. Some of the objectives of retaining trees on logged sites, such as perpetuating hollow-bearing trees for wildlife, may be compromised where high-intensity post-logging slash-burns are employed.
Abstract: Because of increasing concern over the constancy of intervals between prescribed fires within a vegetation type, we examine various sources of evidence that can be used to determine variation appropriate to the conservation of biodiversity while minimizing the chances of economically destructive fires. Primary juvenile periods of plants (especially of 'serotinous seeders') and non-breeding periods of birds (especially poorly dispersed species) suggest extreme lower limits for fire intervals whereas longevity of plant species which usually only reproduce after fire, set the extreme upper li:mits. Modelling of the behaviour of selected plant and animal species may be used to set 'optimal' mean intervals. Historical fire-interval data might seem a useful way to determine the variation about the mean fire-interval but data are scarce and interpretations are controversial. The Weibull distribution and its special case, the negative exponential distribution, have been the most supported in North American studies of unplanned fires. It has been argued that fire-interval distributions, before European settlement at least, were largely the result of large fires during, or following, extreme weather events (dry in forests, wet in the arid zone). Long weather records are most beneficial when they can be related to the areas burned each year. Practical solutions to the question 'what range of fire intervals should be used at any one site' may be achieved using highly simplified skewed distributions, constructed on the basis of land-management objectives.
Abstract: This paper reports on the results of a 3-year field study of the effects of spring/summer burning and cattle grazing on wintering sparrows in the grasslands of southeastern Arizona. The effects of fire were studied with 1 year of pre-burn data and 1 year of post-burn data from 1 fire, plus limited sampling from a second fire at Buenos Aires National Wildlife Refuge in Pima County, Ariz, The effects of grazing were studied by comparing study plots at a site that has not been grazed by cattle since 1968 with a nearby grazed pasture in Santa Cruz County, Ar;iz. Sparrow abundance was measured as the number of captures from flushnetting sessions conducted by groups of 13- 30 volunteers. Vesper (Pocecetes gramineus (Gmelin)) and Savannah (Passerculus sandwichensis (Gmelin)) Sparrows responded positively to fire, while Cassin's Sparrows (Aimophila cassinhi (Woodhouse)) responded negatively. The ecologically and geographically restricted Baird's (Ammodramus baridil (Audubon)) and Grasshopper (A. savannarum (Gmelin)) Sparrows utilized burned areas during the first post-burn winter and did not significantly respond to fire. Both Ammodramus sparrows also utilized the grazed pasture; they were more abundant there than in the ungrazed study area in 1 year. While field observations and a prior study suggest that heavy grazing can have a strong detrimental effect on Ammodramus sparrows, the results of this study suggest that moderate cattle grazing may be compatible with the conservation of these species.
Abstract: Fire has an important role in the sensory ecology of many animals. Using acoustic cues to detect approaching fires may give slow-moving animals a head start when fleeing from fires. We report that aestivating juvenile reed frogs (Hyperolius nitidulus) respond to playbacks of the sound of fire by fleeing in the direction of protective cover, where they are safe. This is a novel response to fire not known to occur in other animals. Moreover, we identify the rapid rise-time of the crackling sound of fire as the probable cue used. These results suggest that amphibian hearing not only has evolved through sexual selection, but also must be viewed in a broader context.
Abstract: We tested whether the herpetofaunal response to clearcutting followed by site preparation was similar to high-intensity wildfire followed by salvage-logging in sand-pine scrub. Herpetofaunal communities were compared in three replicated 5- to 7-year post-disturbance treatments and mature sand-pine forest. The three disturbance treatments were (1) high-intensity wildfire, salvage-logging, and natural regeneration; (2) clearcutting, roller-chopping, and broadcast-seeding; and (3) clearcutting and bracke-seeding. Animals were trapped over a 14-month period using pitfall traps with drift-fences. Micro-habitat features were measured along line transects. Because amphibian (frog) occurrence appeared to be unaffected by treatment, this paper focuses only on reptile communities. Six species of lizards and one snake species were numerically dominant. Reptile species richness, diversity, and evenness did not differ among treatments or mature forest. Species composition differed markedly, however, between mature forest and disturbance treatments. Typical open scrub species such as Cnemidophorus sexlineaus, Sceloporus woodi, and Eumeces egregius, were dominant in high-intensity burn, roller-chopped, and bracke-seeded stands but scarce in mature forests, and they were positively correlated with bare sand and other micro-habitat features typical of open scrub. Conversely, Eumeces inexpectatus was most abundant in mature forests and was correlated with ground litter and other features typical of mature forest. With respect to the species sampled, especially the lizards (including endemic species) of open scrub, clearcutting appeared to mimmic high-intensity wildfire followed by salvage-logging by creating microhabitat features such as bare sand. In a mirror image of the usual concept, forest maturation historically served as the fragmenting agent of an extensive open-scrub landscape matrix that was maintained by high-intensity wildfire. Hence, the patchwork of age classes created by current clearcutting patterns could serve as a barrier to lizard dispersal and impede meta-population dynamics. The absence of a true control (unsalvaged burns) suggests caution in interpreting the results of this study.
Abstract: A population of frillneck lizards, Chlamydosarus kingii, was monitored by radio telemetry and mark-recapture techniques between April 1991 and April 1994, as part of a landscape-scale fire experiment, in Kakadu National Park, Northern Territory. The study aimed to investigate both the short- and longer-term effects of fire on a lizard species in a tropical savanna where fires are frequent and often annual. Frillneck lizards are able to survive fires that occur in the first few months of the dry season by remaining perched in trees. A high level of mortality (29%) occurred during late dry-season fires, along with changes in their behavioural response to fire; sheltering in either larger trees or hollow termite mounds. Food is more accessible after fires due to the removal of ground vegetation. This is reflected in greater volume and diversity of prey in stomach contents after fires. This increase is more pronounced after late dry-season fires, possibly due to increased accessibility of prey caused by more complete vegetation removal. Frillneck lizards show an overall preference for trees with a dense canopy cover located in an area with a low density of grass. Fire has an effect on this relationship. Frillneck lizards in habitat unburnt for a number of years tend to perch in trees with a smaller canopy. Volume and composition of lizard stomach contents was broadly similar among fire treatments over a 2-year period, although termites were more predominant in stomach contents of lizards in unburnt habitat. Wet-season body condition is lower in lizards from unburnt habitat, although the reason for this is unclear. These results demonstrate the importance of different fire intensities and regimes on the ecology of a lizard species in a tropical savanna.
Abstract: The impact of fire and mechanical habitat destruction on a population of the tortoise Testudo hermanni in northern Greece varied with vegetation type and season. A major fire in summer 1980 caused low (< 5%) mortality of sexable tortoises (> 10 cm) in coastal heath, highest (about 50%) mortality in grassland, and intermediate levels in dry heath. Mechanical habitat destruction caused about 50% mortality in affected areas. Mortality of juveniles was greater than that of sexable animals. Overall, the 1980 catastrophe was more damaging than previously thought, causing a 64% decrease in the total size of the Alyki main heath population. A localized summer fire in 1986 caused a similar level and pattern of mortality to that of 1980, but a spring fire in 1988 had little effect on the tortoise population. A fire and mechanical habitat destruction in winter 1989/90 caused only a 14% decrease in population size; mortality was again concentrated in grassland areas, but affected juveniles and sexable animals equally. Variation of mortality with season suggests that any burning needed for habitat management at tortoise sites should occur in winter or early spring. Juveniles were undersampled by 3-4 times compared to sexable animals; their number increased greatly by 1990, reaching the same proportion as in the original population. There was, however, no recovery in the number of sexable tortoises in the decade after the 1980 catastrophe.
Abstract: Five tetra- to hexabrominated diphenyl ether (BDE) congeners (BDE-47, -99, -100, -153 and -154) are the most frequently reported in wildlife and humans. The commercial penta-BDE product, used predominantly to flame-retard polyurethane foam, consists primarily of these same congeners. In 1999, North American demand accounted for 98% of the total global penta-market of 8500 metric tons. Frogs, housed with flame retardant-treated polyurethane foam as a dry substrate, accumulated 10,100 mug/kg (wet weight) of the above BDEs. Crickets kept therein as food contained 14,400 mug/kg. The crickets are believed to have browsed directly on the foam and, in turn, were consumed by the frogs. BDE congener composition in all three matrices matched that of the penta-commercial product. Similar congeners were also observed in soil and stream sediments collected near a polyurethane foam manufacturing plant. Summed concentrations of BDE-47, -99 and -100, the dominant congeners observed in these samples, ranged from <1 to 132 mug/kg (dry weight basis). Sunfish fillets obtained from a nearby, off-site pond contained a total of 624 mug/kg (lipid basis). Sewage treatment plant (STP) sludge exhibited these same congeners at 1370 mug/kg (dry weight). BDE-209, the fully brominated congener predominant in the commercial deca-BDE product, was also present at 1470 mug/kg. While no known polyurethane foam manufacturers discharged to this plant, the distribution pattern of the low brominated congeners in the sludge matched that of the penta-product. After four weeks of exposure to ambient outdoor conditions, the surface of flame-retarded polyurethane foam became brittle and began to disintegrate. Subsequent dispersal of these penta-containing foam fragments may be one mechanism by which these BDEs reach the environment.
Abstract: We assessed the relative contributions of in situ survival and recolonization to overall recovery of arthropod populations following prescribed fire by monitoring arthropod morphospecies richness and abundance in enclosed and open plots in adjacent burned and unburned units within two remnant Illinois prairies. Vacuum sampling of arthropods at semimonthly intervals following spring burns at each site indicated that fire strongly depressed arthropod abundance initially, but that abundance and species richness tended to recover toward the end of the summer, mostly due to recolonization from adjacent unburned refuges. Nevertheless, arthropod groups (taxa or guilds) were affected differently by fire, and differences in arthropod species composition among burned and unburned plots persisted. Sampled arthropod groups significantly reduced by fire at one or both study sites included springtails (Collembola), deltocephaline leafhoppers (Homoptera: Cicadellidae: Deltocephalinae), aphids (Homoptera: Aphididae), delphacid planthoppers (Homoptera: Delphacidae), parasitoid wasps (Hymenoptera), and spiders (Araneae). Only one group, typhlocybine leafhoppers (Homoptera: Cicadellidae: Typhlocybinae), exhibited a significant positive response to fire. These results indicate that in situ populations of many arthropod species are substantially reduced by prescribed fire. Thus, to preserve native arthropod faunas, land managers should ensure that unburned refuges are maintained and that the intervals between burns are sufficient to allow recolonization of burned areas to occur.
Abstract: The effects of post-fire changes in vegetation and habitat quality on the developmental stability of individual birds have not been assessed to date. Here we compare fluctuating asymmetry in tail feathers of Sardinian Warblers Sylvia melanocephala inhabiting two shrubby zones, the first burned in both 1982 and 1994 and the second only in 1982. Juveniles with unmoulted rectrices showed significantly higher levels of tail feather asymmetry in the zone burned in 1994. This result is consistent with the hypothesis that recently burned shrublands offer lower quality habitats for this species. Because feather asymmetry was positively and significantly related to the abundance of low shrubs up to 50 cm tall, we suggest that juvenile assessment of habitat quality is primarily based on the structure of the shrub layer.
Abstract: A current paradigm in conservation biology is that forest harvest practices that better approximate natural disturbance processes are more likely to conserve biodiversity. We contrasted bird communities in three replicate stands in each of 1, 13-15, and 22-28 yr old forests following wildfire and harvest in north-central Alberta, Canada. Stands were chosen from old (>120 yr) boreal mixedwood forests having greater than or equal to 95% of the canopy trees killed during fire, and harvested sites retaining an average of 6% of the pre-harvest canopy trees. For all age classes, postharvest sites tended to have greater bird abundance. Species composition also differed between these treatment types. Two-Way Indicator Species Analysis (TWINSPAN) identified five major ecological groupings of species that differed between wildfire and harvest, and among stand ages. Correspondence analysis (CA) identified similar bird communities. Greatest differences between bird communities occurred immediately following disturbance, and gradual convergence of communities occurred throughout the first 28 yr after disturbance. Species associated with open shrub and grassland or riparian habitats were associated primarily with I-yr postharvest stands. Three-toed Woodpeckers (Picoides tridactyla) and Black-backed Woodpeckers (P. arcticus), together with other species that use snags for foraging or nesting, occurred primarily in 1-yr postwildfire stands. Convergence in avian communities was correlated with the loss of standing snags on postwildfire sites. However, differences in bird communities were apparent up to 28 yr following disturbance, and this lack of complete convergence has important consequences for sustainable forestry practices designed to maintain biodiversity in the boreal mixedwood forest. Notably, Connecticut Warbler (Oporornis agilis), Brown Creeper (Certhia americana), Winter Wren (Troglodytes troglodytes), and American Robin (Turdus migratorius) had higher densities on postwildfire than on postharvest stands. Lincoln's Sparrow (Melospiza georgiana), Alder Flycatcher (Empidonax alnorum), Tennessee Warbler (Vermivora peregrina), Black-and-white Warbler (Mniotilta varia), American Redstart (Setophaga rutticilla), Mourning Warbler (Oporornis philadelphia), Rose-breasted Grosbeak (Pheucticus ludoviciana), Canada Warbler (Wilsonia canadensis), and Pine Siskin (Carduelis pinus) had higher densities on postharvest stands, possibly due to the greater abundance, after harvest, of larger live residual trees and a taller and more dense shrub layer. Harvest designed to approximate stand-replacing fires may require the retention of more snags than is currently practiced. New approaches to fire salvage logging are also required to ensure adequate retention of standing dead trees on the landscape.
Abstract: Information on wildlife survival of prescribed (controlled) brushland fires was obtained by three methods: (1) 37 rodents and snakes in cages with temperature recording devices were placed in different habitat situations, and the area was control burned; (2) the number of birds and mammals drinking from a spring was counted both before and after the area was burned; and (3) the behavior of wild animals was observed from an observation point within the fire.
The cage temperature lethal to rodents was somewhere between 138o and 145o F. Results indicate that there was little chance of wild vertebrate animals getting caught in a situation that would lead to their death during such fires. Most species of vertebrates benefit from control burns, because the habitat then becomes more favorable.
Abstract: Effects of fire, forest insects and diseases, grazing, and forest health treatments on fish populations and habitat are reviewed. Fire, insects, and disease affect fish habitat by their influence on the rate and volume of woody debris recruitment to streams, canopy cover and water temperature, stream flow, channel erosion, sedimentation, nutrients, and residual vegetation. Physical effects from fire vary greatly depending on fire severity and extent, geology, soil, topography, and orientation of the site, and subsequent precipitation. Most effects moderate within a decade. Post-fire erosion and wood recruitment are also influenced by fire lines, road construction, and timber harvest. Although some disturbances, such as severe fire and subsequent floods, appear catastrophic, and effects may last decades or centuries, natural disturbances help create and maintain diverse, productive aquatic habitats. Recolonization of fish populations following wildfires can be rapid and is related to occurrence of local refugia, life history patterns, access for migratory forms, and distribution of the species. In most livestock studies, grazing negatively affected fish habitat and populations, but results may vary depending on sites and specific grazing management. Effective approaches to grazing management similarly depend on the specific application and the commitment of operators and managers. Restoration of the structure, function, and processes of watersheds more similar to those with which native species evolved may favor those species; however, there is little documentation of the aquatic effects of those activities. Risk from vegetative treatments may be minimized by experimenting outside of critical areas (i.e., conserving key habitats and populations, focusing intensive treatments on upland sites). Use of more benign techniques (e.g., lower-impact logging systems) and pulsed treatments consistent with characteristics of natural disturbance regimes are other considerations for achieving both terrestrial and aquatic objectives.
Abstract: Fire-induced soil hydrophobicity is presumed to be a primary cause of the observed post-fire increases in runoff and erosion from forested watersheds in the Colorado Front Range, but the presence and persistence of hydrophobic conditions has not been rigorously evaluated. Hence the goals of this study were to: (1) assess natural and fire-induced soil hydrophobicity in the Colorado Front Range, and (2) determine the effect of burn severity, soil texture, vegetation type, soil moisture, and time since burning on soil hydrophobicity.
Five wild and prescribed fires ranging in age from 0 to 22 months were studied. Each fire had four study sites in ponderosa pine forest, that had been burned at high, moderate, or low severity, and three sites were in unburned areas. Additional sites were established in lodgepole pine stands and an area with unusually coarse-textured soils. At each site the soil hydrophobicity was assessed in two pits using the water drop penetration time (WDPT) and the critical surface tension (CST). Measurements were made at the mineral soil surface and depths of 3, 6, 9, 12, 15, and 18 cm.
In sites burned at moderate or high severity the soils were often strongly hydrophobic at 0. 3, and 6 cm. Unburned sites or sites burned at low severity were typically hydrophobic only at the surface. Although soil hydrophobicity generally strengthened with increasing burn severity, statistically significant differences in soil hydrophobicity were difficult to detect because of the high variability within and between sites. Hydrophobicity also increased with increasing percent sand and was not present when soil moistures exceeded 12-25%. There were no significant differences in soil hydrophobicity between ponderosa and lodgepole pine stands, regardless of burn severity.
Repeat measurements on one fire suggest a weakening of fire-induced soil hydrophobicity after 3 months. Comparisons between fires suggest that fire-induced soil hydrophobicity persists for at least 22 months. Overall, CST values were more consistent and more highly correlated with the independent variables than the WDPT, and the CST is recommended for assessing soil hydrophobicity rather than the more commonly used WDPT.
Abstract: During the two breeding seasons immediately following the numerous and widespread fires of 1988, I estimated bird community composition in each of 34 burned-forest sites in western Montana and northern Wyoming. I detected an average of 45 species per site and a total of 87 species in the sites combined.
Abstract: Previous to this study, the Pine Barrens treefrog, Hyla andersonii, was known to occur at ten localities within Conecuh National Forest. During this study, the status of this frog species in the Forest was assessed from June through September 1991. Location of the frogs was accomplished by searching for suitable habitats by day, revisiting the sites at night, and listening for the distinct call of males or eliciting them to call by vocally imitating their call. Thirteen new localities were discovered and six previous localities maintained calling males. At four previously known localities males were never heard, indicating that they no longer support Hyla andersonii. Lack of fire at these four localities is suspected to be the reason the frog populations have disappeared.
Abstract: The Boreal Mixedwood Ecosystem Study near Thunder Bay, Ontario is a multi-disciplinary investigation of the impacts of harvesting and fire on the structure and function of a boreal mixedwood ecosystem. The fire component comprises a set of treatments in which fire severity was manipulated by adjusting fuel loadings through a variety of harvesting techniques, and also included fire in standing timber. Intensive fuel sampling before and after the fire enabled detailed determinations of fuel consumption, heat output and forest floor reduction. Nutrient concentrations in ash, soil, and plant tissue following the fire were compared with fire severity in order to quantify potential nutrient inputs and their relationship to the amount of biomass consumed during the fire. Forest floor and woody fuel consumption varied significantly among treatments, with the most important factor being whether or not the stand had been harvested previous to the fire. The pH was highest and P concentrations among the lowest in the ash of unharvested blocks. Nutrient concentrations of the remaining forest floor and upper mineral soil were weakly related to the treatments. Forest floor P concentrations were highest on whole-tree harvested and lowest on uncut blocks. Whole-tree harvested blocks also had the highest pH values in forest floor and mineral soil. Concentrations of N, P, and Mg in the foliage of Populus tremuloides Michx. and Rubus idaeus L. were higher on unharvested burned than cut and burned plots, and were negatively correlated with the depth of forest floor reduction. These results indicate that fire severity plays a role in determining the extent of nutrient enrichment following fire, and may be important in influencing long-term site productivity.
Abstract: We examined how native herpetofauna of the Cross Timbers in Oklahoma, USA, were influenced by vegetation types derived from combinations of herbicide applications and prescribed burning. Brush management treatments consisted of tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiazol-2-y-1]-N,N'-dimethylurea)-only, tebuthiuron + fire, and untreated pastures of mature hardwood forest (no herbicide or fire). A total of 292 individuals representing 30 species was captured in 1994 and 1995 using time-constrained searching and drift-fence arrays on 3 replicates of the 3 treatments. Relative total abundance and species richness of herpetofauna mere similar on all 3 treatment types. However, differences were apparent by taxonomic group. In general, amphibians were most abundant in untreated and tebuthiuron-only pastures, lizards mere most abundant on the untreated pastures, and snakes were most abundant on pastures treated with tebuthiuron + fire, Maintenance of a mosaic of habitats in the Cross Timbers may enhance diversity of the native herpetofauna.
Abstract: Within the context of studying the ecological impacts of wildland fires in the boreal forest, a spatial analysis of a major wildfire was conducted. The fire covered nearly 500 km2 in the north-western part of Quebec's boreal forest in the summer of 1995. The spatial distribution of different fire impacts on the forest canopy was obtained using timber damage assessment maps. Fire impacts varied throughout the burned area, ranging from areas where trees had completely burned crowns (43%) to remaining patches of trees with green foliage (3%). The effects of local stand and site factors on crown fire, as assessed by the fire impacts, were evaluated using geographic information systems. Despite the large extent and high intensity of the wildfire created by extreme fire weather conditions, stepwise logistic regression and analysis by log-linear models indicated that variations in surface material, stand composition, and estimated stand age played a role in the presence or absence of crowning at the stand level. However, it appears that height and density of stand, as well as topography, did not have a significant influence. Our study presents the variability of fire impacts and its implications, and it provides a better understanding of the relationships between landscape components and fire crowning.
Abstract: This study reports on the changes in the soil invertebrate community on ridges on the Cumberland Plateau of Kentucky, USA, one year after a prescribed fire. There was a significant 36% reduction in the total dry mass of soil invertebrates as a result of the fire. Approximately 95% of the total loss of mass was due to significant reductions in mass of invertebrates in the forest floor, and approximately 60% was due to reductions in the mass of beetle (Coleoptera) larvae. In addition, burning resulted in declines in the number of invertebrate orders and in the frequency of occurrence of mesofaunal ants and of macrofaunal beetle larvae and adults. Beetles were ubiquitous in soils on these ridges and were the single most important order, accounting for 38% of the total dry mass of invertebrates. Given the importance of this group, managers need to consider the possibility that prescribed fire, especially if used repeatedly and at short intervals, may result in substantial and possibly long-lasting reductions in beetle populations. One possible approach to preventing this is to strive for spatial and temporal heterogeneity on multiple scales, leading to increased complexity after burning and increased probability that all biotic and abiotic components will survive within the postfire ecosystem.
Abstract: In order to find out which factors influenced the forest dynamics in northern Italy during the Holocene, a palaeoecological approach involving pollen analysis was combined with ecosystem modelling. The dynamic and distribution based forest model DisCForm was run with different input scenarios for climate, species immigration, fire, and human impact and the similarity of the simulations with the original pollen record was assessed. From the comparisons of the model output and the pollen core, it appears that immigration was most important in the first part of the Holocene, and that fire and human activity had a major influence in the second half. Species not well represented in the simulation outputs are species with a higher abundance in the past than today (Corylus), with their habitat in riparian forests (Alnus) or with a strong response to human impact (Castanea).
Abstract: A 1993 wildfire and subsequent landslides modified many streams in the Santa Monica Mountains of southern California (USA). Prior to the fire at Cold Creek Canyon, adult California newts (Taricha torosa) frequently preyed on conspecific eggs and larvae. Post-fire landslides increased the number of stream pools containing terrestrial earthworms. Earthworms were more common in adult newt diets after the fire, and conspecifics were absent. More earthworms and fewer conspecifics were present in the stomachs of adult newts in streams at burned sites than at unburned sites. In laboratory experiments, newt larvae used refuges significantly less in the presence of combined chemical cues from both newt adults and earthworms as compared to adult-newt cues alone. These data suggest that cannibalism is reduced in the presence of increased alternative prey items and that larvae can detect this reduced predation risk.
Abstract: The impact of fire on small mammals and amphibians was investigated in an Oak (Quercus spp.)-dominated forest in S-central Pennsylvania. Sampling with Y-shaped arrays of pitfalls and drift fences was conducted for 78 days between 31 March and 13 November 1992 following a fire in November 1991. Shrews, rodents and total small mammals were significantly less abundant in burned than in unburned forest: however, significant differences in habitats were recorded only for the first 3 sampling periods (April, June, July) for rodents and total small mammals. Eight species of small mammals were captured in unburned forest compared to six species in burned areas. The two species not taken in the burned forest were both arvicoline rodents, the meadow vole (microtus pennslvanicus) and southern red-backed vole (Clethrionomys gapperi). A significant corrrelation was found between the rank order of species of small mammals taken in burned and unburned habitats. The two most abundant species in both habitats were the white-footed mouse (Peromyscus leucopus) and Maryland shrew (Sorex fontinalis), which combined comprised 78.1% of the small mammals taken in the unburned forest and 72.4% of the sample from the burned site. In contrast to small mammals, significantly more amphibians were captured in the burned forest. The American toad (Bufo americanus) was the most abundant amphibian, comprising 70.8% of the amphibians captured: this species was largely responsible for the greater numbers of amphibians captured in the burned forest.
Abstract: We examined short-term trends in relative abundance and species richness of breeding and wintering grassland birds before (1996) and after (1997, 1998) a prescribed burn in a mesquite-invaded, desert grassland at Buenos Aires National Wildlife Refuge, Arizona. We surveyed birds and sampled vegetation along 1-km line transects bisecting 14 (7 control, 7 burn) 25-ha plots located randomly within a burn and adjacent control unit. Following a spring burn that was moderate in intensity and patchy in areal extent, we observed that ground cover was affected more strongly by burning than mesquite (Prosopis) cover, smaller mesquite were affected more strongly by burning than larger mesquite, and mortality of mesquite was low. No change in total abundance of birds was detected on the burn unit following fire for either wintering or breeding birds; however, species richness of breeding birds decreased in the first year post-burn. During the breeding season, mourning doves (Zenaida macroura) increased, whereas Botteri's sparrows (Aimophila botterii), Cassin's sparrows (Aimophila cassinii), and cactus wrens (Campylorhynchus brunneicapillus) decreased in relative abundance following fire. During the wintering season, ladder-backed woodpeckers (Picoides scalaris) and vesper sparrows (Pooecetes gramineus) increased and cactus wrens decreased in relative abundance following fire. Beyond species-level trends, we found stronger evidence of trends and greater magnitudes of relative change for breeding species associated with open grasslands compared to those associated with shrubs. The use of spring burns on the Refuge will likely improve conditions for open-grassland species that were historically more abundant by killing smaller mesquite and reducing mesquite recruitment. However, more intense and extensive fires will be required to reduce the presence of larger mesquite. Such fires would likely have a greater impact on birds associated with shrubs, and consequently, a greater impact on the avian community as a whole.
Abstract: We compared 5 zones in shrubsteppe habitats of southwestern Idaho to determine the effect of differing disturbance combinations on landscapes that once shared historically similar disturbance regimes. The primary consequence of agriculture, wildfires, and extensive fires ignited by the military during training activities was loss of native shrubs from the landscape. Agriculture created large square blocks on the landscape, and the landscape contained fewer small patches and more large shrub patches than non-agricultural areas. In contrast, fires left a more fragmented landscape. Repeated fires did not change the distribution of patch sizes, but decreased the total area of remaining shrublands and increased the distance between remaining shrub patches that provide seed sources. Military training with tracked vehicles was associated with a landscape characterized by small, closely spaced, shrub patches.
Our results support the general model hypothesized for conversion of shrublands to annual grasslands by disturbance. Larger shrub patches in our region, historically resistant to fire spread and large-scale fires because of a perennial bunchgrass understory, were more fragmented than small patches. Presence of cheatgrass (Bromus tectorum), an exotic annual, was positively related to landscape patchiness and negatively related to number of shrub cells. Thus, cheatgrass dominance can contribute to further fragmentation and loss of the shrub patch by facilitating spread of subsequent fires, carried by continuous fuels, through the patch. The synergistic processes of fragmentation of shrub patches by disturbance, invasion and subsequent dominance by exotic annuals, and fire are converting shrubsteppe in southwestern Idaho to a new state dominated by exotic annual grasslands and high fire frequencies.
Abstract: The objective of this report is to organize literature on the effects of fire on wildlife into a publication for resource managers, particularly in the Southwest. Fire effects on wildlife habitat, wildlife fire response classifications, and detailed fire effects for classes and species of vertebrates are given.
Abstract: Successful fire exclusion since the 1940s has contributed to shifts in understory species composition in oak-pine forest communities in the Cumberland Plateau of Kentucky, USA, exemplified by a lack of oak (Quercus L.) regeneration and an increase in regeneration of fire-sensitive species. On ridgetop sites in Daniel Boone National Forest, the U.S. Forest Service is using prescribed fire to maintain oak-pine communities, a management practice that could also affect understory species composition and richness. We examined the four-year effects of a single, late-winter prescribed fire on understory vegetation and tree regeneration. There was a nonsignificant trend of increased species richness in burned areas, mostly due to an elevated number of herbaceous species. There were no significant effects of fire on herb and shrub cover. Higher densities of oak, yellow-poplar (Liriodendron tulipifera L.) and red maple (Acer rubrum L.) seedlings in burned areas occurred only in the second growing season after fire. Total sprouting, especially of red maple and flowering dogwood (Cornus florida L.), was higher for two growing seasons following fire. Fire promoted regeneration by fire-tolerant and fire-intolerant species alike, The use of prescribed fire to maintain density of fire-tolerant tree species and reduce proliferation of fire-intolerant tree species will probably require more frequent fires, higher intensity fires, or both.
Abstract: This investigation focused on the role of terrain variables in fire-related mortality. The study area was the location of a 1991 wildfire, the Warner Creek Burn, on the Willamette National Forest in western Oregon.
Forest survival at the Warner Creek Burn was interpreted from aerial photography. Terrain data were generated from digital elevation models (DEM), and from digitized stream, ridge, and vegetation layers, which were input into a geographic information system (GIS). We randomly sampled all layers, and investigated the relationship of vegetation and terrain to mortality using regression analyses.
Vegetation and terrain variables accounted for more Variation in forest survival within individual physiographic areas (5.4-61.9%) than across the entire study area (3.7-24.4%). Moreover, the significant topographic variables differed among individual physiographic areas, and included ridgeline proximity, elevation, stand age, and aspect.
Factors such as fire fighting, fuel loading, weather conditions, and neighborhood effects probably affected forest survival at Warner Creek along with terrain. Observational studies such as this one could identify the topographic variables meaningful for inclusion in probabilistic models of wildfire behavior.
Abstract: Spatial and temporal variations in fire frequency in the boreal forest of Wood Buffalo National Park (WBNP) were assessed using forest stand age, fire scar and historical data. I test the hypotheses that (1) fire frequency is higher in jack pine forests and aspen forests than in black spruce forests and white spruce forests, (2) these variations in fire frequency can be related to the mean waterbreak distance (MWD) around a site and (3) fire frequency has changed over the past 300 years.
The fire cycles (the time required to burn an area equal in size to the entire study area) in jack pine forests (39 years) and in aspen forests (39 years) were significantly shorter than those in black spruce forests (78 years) and in white spruce forests (96 years). The length of the fire cycle varies inversely with the MWD around a site, and the MWD was significantly higher in jack pine and aspen forests than in black or white spruce forests. It is suggested that covariations between soil type and the MWD influence, respectively, variations in forest dominant and fire frequency.
A change in fire frequency at 1860 was apparent in the fire history for all of WBNP, the black spruce dominated stands, and the near and medium MWD classes. The fire cycle estimates for these classes were all significantly shorter during the period 1750 to 1859 (fire cycles=25-49 years) than they were in the period 1860 to 1989 (fire cycles=59-89 years). The possible roles of changes in climate and aboriginal burning practices in causing the temporal change in fire frequency are discussed.
Abstract: Chaparrel fire brings decided changes in the species composition and density of both plant and animal populations in the Sierra Nevada foothills. Some species decrease whereas others increase following a burn, but no species is totally eliminated, nor is there any apparent diminution of total life on a burn after plant growth resumes.
These conclusions were reached in the course of a 4-year study of adjoining burned and unburned areas near Glennville, Kern County, California. Field work began in 1953 at which time study plots were selected and plant and vertebrate population were censused. A year later part of the study area was burned, and ensuing investigation compared populations on the burned and check areas for a period of 3 years, terminating in 1957.
At the time of the fire, temperatures were recorded in the sites both above and below ground, and the actions of animals were observed. There was very little evidence of direct mortality among any of the vertebrates, most of them escaping the heat in one way or another. The woodrat was perhaps the most vulnerable species because of its dependence on houses made of dry twigs. However, in the bare ash after the fire many species were severely exposed to predation, and populations of most small mammals and some brush-dwelling birds decreased rapidly. Predatory birds and mammals increased, as did some seed-eating birds that found good foraging on the exposed earth.
When the rains stimulated new plant growth, a very different habitat developed in the area of burned chaparrel. Most of the original trees sustained little damage, although the pitchy digger pines were largely eliminated. However, the extensive brush stands were reduced by almost 90%, and there was a corresponding increase in the invading grasses and forbs.
Birds and mammals that normally exhibit a strong preference for chaparrel habitat were sustantially reduced in numbers in the years following the burn. Conversely, some of the birds that normally prefer grassland or oak woodland increased in number. The fire resulted in an overall increase in densities of nesting birds. None of the small mammals increased in numbers but some of the larger predators, such as coyote and badger, moved into the burn during the months following the fire.
Abstract: A wettable surface layer overlying a water-repellent layer is commonly observed following a fire on a watershed. High surface temperatures 'burn' off organic materials and create vapours that move downward in response to a temperature gradient and then condense on soil particles causing them to become water repellent. Water-repellent soils have a positive water entry pressure h(p) that must be exceeded or all the water will runoff. Water ponding depths h(o) that exceeds h(p) will cause infiltration. but the profile is not completely wetted. Infiltration rate and soil wetting increase as the value of h(o)/h(p), increases. The consequence is very high runoff, which also contributes to high erosion on fire-induced water-repellent soils during rain storms. Grass establishment is impaired by seeds being eroded and lack of soil water for seeds that do remain and germinate. Extrapolation of these general findings to catchment or watershed scales is difficult because of the very high temporal and spatial variabilities that occur in the field.
Abstract: The preference of Sceloporus occidentalis for perching on dark or light colored branches was studied in the field and in the laboratory. Lizards perched preferentially on dark branches and tended to avoid those which were light in color. In southern California chaparral active S. occidentalis perch selectively on blackened stalks of burned shrubs for at least several years following a fire. The lizards are cryptically colored on the black stalks and match reflectance within a few percent over the visible spectrum. However, as the char on the outer surfaces of the stalks wears off, the lizards are no longer color-matched, are seen less frequently on the stalks, and appear to center activities on rock outcrops. The association and color match between lizards and shrubs coincides with postfire conditions of reduced cover and increased predator abundance.
Abstract: In the old growth forests of New York City parks, fires contributed to black cherry (Prunus serotina Ehrh.), sassafras (Sassafras albidum Nutt.), and oaks (Quercus spp.L.) having large increases in tree density over the past half-century and attaining dominance among saplings and seedlings. An old growth urban forest in Cleveland, which showed no evidence of fire, had little change in tree density since 1935. Urban forest management practice would benefit from including fire related activities such as planting fire tolerant species in locations that direct travel within the urban forests and increasing public interest in protecting the forests from fire.
Abstract: The effects of logging on three species of common skinks were estimated from censuses in four age classes of forest: unlogged, just logged, 1-year logged and 10-15 year regrowth. The effects of topography (ridge and gully) were examined in each age class. A fire in November 1980 occurred just after the initial census was completed. ANother census was taken in December 1980 to assess its immediate effects. Further censuses were carried out each December from 1981 to 1984. An intense drought overlapped from 1980 to 1983 with the census period. Lampropholis guichenoti occurred in about equal numbers in unlogged and recently logged forests, but its numbers were reduced in the 10-15 year regrowth forest. This was attributed to changes in the amount and pattern of sunlight reaching the ground. A similar pattern of response was found for Lampropholis delicata. The numbers of Eulamprus heatwolei, a gully species requiring partial shade, were lowest in the exposed, recently logged forest, but had increased in the 10-15 year regrowth class to about equal their numbers in unlogged forest. Fire reduced the numbers of L. guichenoti on ridges but had no immediate impact on numbers of the other species, while drought markedly depressed numbers of all species. Lampropholis guichenoti recovered more quickly from the drought than did L. delicata, but the numbers of E. heatwolei were still declining 19 months after the drought broke. The drought also revealed a habitat (ridge/gully) difference between the two Lampropholis species. The management of these species in commercial forests requires that some areas, particularly gullies, be reserved and the logging sequence modified to prevent the creation of widespread stands of uniform regrowth.
Abstract: To more effectively manage remaining native grasslands and declining populations of prairie passerine birds, linkages between disturbance regimes, vegetation, and bird abundance need to be more fully understood. Therefore, we examined bird- habitat relationships on mixed-grass prairie at Lostwood National Wildlife Refuge (NWR) in northwestern North Dakota, where prescribed fire has been used as a habitat management tool since the 1970s. We sampled bird abundance on upland prairie at 310 point count locations during 1993 and 1994 breeding seasons. We also measured vegetation structure and composition at each location. Complete fire histories were available for each point, with over 80% having been burned one to four times in the previous 15 years. Post-fire succession generally transformed vegetation structure from short, sparse, and grassy with few forbs and low litter immediately after fire, to increasing and moderate:amounts of forbs, litter, and shrubs two to eight years postfire, to tall, dense, shrubby prairie with little forb, grass, or litter understory when fire was absent (>80 years). Most grassland birds (six of nine species examined) at Lostwood NWR were absent from prairie untreated with fire. Species richness and abundances of Baird's Sparrows (Ammodramus bairdii), Bobolinks (Dolichonyx oryzivorus), Grasshopper Sparrows (A. savannarum), Le Conte's Sparrows (A. leconteii), Sprague's Pipits (Anthus spragueii), and Western Meadowlarks (Sturnella neglecta) were positively related to an index of amount of fire, and these species were absent from unburned units. In contrast, Common Yellowthroats (Geothlypis trichas) and Clay-colored Sparrows (Spizella pallida) both reached highest abundance on unburned prairie. To provide maximum grassland bird diversity, managers of mesic, mixed-grass prairie generally should provide areas with short (2-4 year), moderate (5-7 year), and long (8-10 year, or more) fire return intervals. Because long-term rest may create habitat unfavorable for most species of grassland passerines in mesic, northern mixed prairie, periodic defoliations by disturbances such as fire should be considered essential to restore and maintain native biodiversity.
Abstract: We conducted an experiment using infrared-triggered camera traps to document relative abundance of wildlife in pine flatwoods habitat at different stages of post-fire recovery at the Florida Panther National Wildlife Refuge in southwest Florida. Total wildlife, which for the purposes of this study was defined as records of wild turkey (Meleagris gallopavo) and all mammals captured on film, used pine flatwoods habitat in a fire management unit (FMU) with a post-fire recovery history of 24 months significantly more than adjacent pine flatwoods in an FMU with a post-fire recovery history of 48 months (P=0.04). Data suggested that the relative abundance of white-tailed deer (Odocoileus virginianus) was also higher in the 24-month post-fire FMU (P=0.12) compared to the 48-month FMU. To evaluate response of wildlife to prescribed fire, we burned the 48-month FMU and, after approximately 8 weeks, repeated the camera-trap surveys in the newly burned (<6-month) FMU and the adjacent FMU, now at approximately 30-months post-fire recovery. We documented a significant increase in use of the recently burned (<6-month) FMU compared to previous levels of use (48-month FMU) by total wildlife (P=0.04) and white-tailed deer (P=0.02). Use of the <6-month FMU by wild turkey also appeared to increase (P=0.13). No difference was detected between the <6-month and the adjacent 30-month FMU in use by total wildlife (P=0.52), white-tailed deer (P=0.43), Florida panther (P=0.23), or wild turkey (P=0.14), although data suggested that wild turkey may have preferred the newly burned area. More importantly, our data suggested that wildlife did not avoid pine flatwoods habitat at up to 30-month post-fire recovery. Wildlife use of pine flatwoods habitat, therefore, was observed to increase in areas recently burned (<6 months post-fire), was similar between FMUs with post-fire recovery of <6 and up to 30 months, and was lowest in habitat that had not been burned for 48 months. Maintaining a prescribed-fire rotation of ltoreq48 months, therefore, appears to improve habitat quality of pine flatwoods for white-tailed deer, wild turkey, and other wildlife in southwest Florida.
Abstract: Despite the many complexities concerning their initiation and propagation, forest fires exhibit power-law frequency-area statistics over many orders of magnitude. A simple forest fire model, which is an example of self-organized criticality, exhibits similar behavior. One practical implication of this result is that the frequency-area distribution of small and medium fires can be used to quantify the risk of Large fires, as is routinely done for earthquakes.
Abstract: The distribution and abundance of amphibians and reptiles in forest stands subjected to salvage cutting and prescribed burning were compared with their unmanaged counterparts. The study was conducted on the Atlantic coastal plain at Chesapeake Farms near Chestertown, Maryland. Three herpetofaunal trapping arrays were systematically located in each of four forest stand types: hardwood (Hardwood), cut-over hardwood (Cut), mixed pine-hardwood (Pine) and prescribed burn pine (Burn). A total of 3931 individuals representing 29 species were captured in 30,540 trap nights during the spring and summer 1992 and 1993. Felling of hardwoods and prescribed burning of pine resulted in similar responses from the herpetological communities; Hardwood had the most distinctive herpetofaunal community of the four stands. Adults and young-of-the-year (YOY) of six amphibian species were significantly more abundant in Hardwood than Cut. Only one amphibian species, Pseudacris triseriata, was less abundant in Hardwood than Cut. Total ranid captures did not differ between Hardwood and Cut. Snake and total reptile captures, and Elaphe obsoleta and Eumeces faciatus abundances were significantly less in Hardwood than Cut. Hardwood also had fewer small mammals than Cut, particularly Microtus pennsylvanicus and Zapus hudsonius, that might serve as large prey for snakes. Adults of four amphibian species, YOY of five amphibian species, and three reptile species (Carphophis amoenus, Storeria dekayi, and Thamnophis sirtalis) were significantly more abundant in Pine than Burn; two reptile species (Coluber constrictor and Lampropeltis getula) were significantly less abundant. Potential small mammal prey of the latter two snakes were not significantly different between Pine and Burn; however, Zapus hudsonius was less abundant in Pine than Burn. More amphibians were captured in Hardwood and Pine stands than in their respective logged and burned counterparts. The trend for reptiles tended to depend on the mix of species present and their habitat preferences. Greater canopy cover and depth of leaf litter in Hardwood and Pine stands likely had a moderating effect on temperature and helped to maintain a moist microenvironment for mesophilic species. Disturbance of a small patch of forest could locally decrease herpetofaunal diversity, but diversity on a much larger scale would likely increase.
Abstract: In late December 1996, the South Fork Payette River basin in west-central Idaho experienced a prolonged storm that culminated on January 1. 1997, with intense rain on melting snow that triggered slide failures, producing debris flows and sediment-charged floods. Failures occurred in saturated, cohesionless. grussy colluvium derived from Weathered Idaho batholith granitic rocks. Many failures along the South Fork Payette River originated in ponderosa pine forests burned in the 1989 stand-replacing Lowman fire. An example is the 0.49 km(2) 'Jughead' Creek basin. where a single large colluvial failure produced almost 40% of the total volume eroded from the basin and generated a massive and rapid debris flow. Failures also occurred in steep, unburned. and unforested drainages such as Hopkins Creek. In this south-facing 0.58 km(2) basin, 15 colluvial hollows failed. but no single failure produced more than 10% of the total eroded volume. Sediment transport in Hopkins Creek occurred by prolonged sediment-charged sheetflooding. Despite vegetation differences, sediment yields from the geomorphically similar Hopkins Creek (similar to 42 000 Mg km(-2)) and Jughead Creek (similar to 44 000 Mg km(-2)) basins were quite similar. These 1997 erosion events are equivalent to several thousand years of sediment yield at low rates (2.7-30 Mg km(2) year(-1)) measured by short-term sediment trapping and gauging in Idaho batholith watersheds. If similar large events were solely responsible for sediment export. recurrence intervals (Rls) of several hundred years would account for higher sediment yields averaged over similar to 10(4) year from Idaho batholith watersheds. Dating of small fire-induced sheetflooding events in an early Holocene tributary junction fan of Jughead Creek indicates that frequent small sedimentation events (RI approximate to 33-80 year) occurred between 7400 and 6600 cal year BP. with an average yield not greatly exceeding 16 Mg km(-2) year(-1). Compared with the Holocene average, erosion rates during that 800 year period were unusually low, suggesting that sediment yields have not been constant over time, and that climatic variations and related fire regime changes may exert a strong influence on the probability of major erosional events.
Abstract: The Mortar Creek Fire burned 26 000 ha of mixed-conifer Rocky Mountain forest in July-August 1979. Changes in burn stream conditions were examined relative to reference streams for various ecological factors on two to six occasions, from October 1979 to August 1980. Factors included major ions and nutrients, suspended and benthic particulate matter, periphyton (algae), and macroinvertebrates. Elevated levels of most dissolved chemicals in the burn streams were evident soon after the fire and again during spring runoff. However, there were no major disruptions in the relative composition of cations (and presumably of anions also) in the burn streams during the study. Concentration (mg/L) and load (g/s) of some constituents were higher (e.g. NO3-N) and of others (e.g. Ca) were lower in the burn than in the reference streams during spring runoff, depending on whether they were normally under biological or geological control, respectively. Suspended sediment and particulate organic matter generally were higher in burn streams, especially during snow-melt runoff or following heavy rain storms. Benthic organic matter was higher in burn streams and was mainly charcoal, compared to the usual leaf litter found in the reference streams. Fine sediments increased and periphyton decreased in the burn streams. The fire increased the sensitivity of the burn streams to more routine smaller-scale disturbances, such as rainstorms, which had major impacts on the burn streams but not on the reference streams. The macro invertebrate assemblage showed little direct effect from the fire but was severely altered in composition and abundance by the subsequent runoff, scouring, and channel alteration initiated by spring runoff. The burn streams showed considerable individuality in their response to fire depending on the particular set of conditions to which they were exposed.
Abstract: The effects of wildfire on benthic macroinvertebrate assemblages of streams in mixed-conifer forest were examined for 10 successive years following the Mortar Creek Fire of 1979. Changes in burned-catchment streams were evaluated relative to a paired set of reference-catchment streams. Taxa richness and total abundance tended to be lower in burn than in reference streams but to converge near the end of the study; increases in the final years in both burn and reference streams were associated with reduced flows due to drought. Total biomass and that of the scraper, filterer, and minor functional groups usually were greater in the burn streams. Lack of a strong relationship of macroinvertebrate metrics with weather conditions showed that factors specific to each stream also were influencing the biotic community. Mean among-year Jaccard similarity was lower for burn than for reference streams. Specific taxa responded differently to the effects of fire. Densities of disturbance-adapted forms (e.g. Chironomidae, Bactis) increased after the fire but not during the drought period of more stable flows at the end of the study; many other taxa showed the opposite response. Adverse effects of wildfire on the biotic community were largely the result of physical changes in habitat due to increased runoff. Timing and magnitude of effects differed widely among streams as a result of differences in stream size, burn severity, and specific storm or snowmelt events. Though major effects of the fire on the macroinvertebrates dissipated within 7 years, adjustment in the habitat and biotic conditions still were taking place at the end of 10 year and normal recovery patterns may have been obscured by the drought.
Abstract: Wildfire alters the hydrologic response of watersheds, including the peak discharges resulting from subsequent rainfall, Improving predictions of the magnitude of flooding that follows wildfire is needed because of the increase in human population at risk in the wildland-urban interface. Because this wildland-urban interface is typically in mountainous terrain, we investigated rainfall-runoff relations by measuring the maximum 30 min rainfall intensity and the unit-area peak discharge (peak discharge divided by the area burned) in three mountainous watersheds (17-26.8 km(2)) after a wildfire.
We found rainfall-runoff relations that relate the unit-area peak discharges to the maximum 30 min rainfall intensities by a power law. These rainfall-runoff relations appear to have a threshold value for the maximum 30 min rainfall intensity (around 10 mm h(-1)) such that, above this threshold, the magnitude of the flood peaks increases more rapidly with increases in intensity. This rainfall intensity could be used to set threshold limits in rain gauges that are part of an early-warning flood system after wildfire. The maximum unit-area peak discharges from these three burned watersheds ranged from 3.2 to 50 m(3) s(-1) km(-2). These values could provide initial estimates of the upper limits of runoff that can be used to predict floods after wildfires in mountainous terrain.
Abstract: A system of drift fences and pitfall traps was used over a 2-yr period to monitor the herpetofaunal community on four plots of land (1 ha each) maintained on different burn schedules. Experimental plots were burned every year (1E), every 2 yr (2E), or every 7 yr (7E); the control plot (CE) has not burned for 20 yr. A total of 1236 amphibians and reptiles of 27 species were captured during 1983 and 1984. Severe cold in December 1983 may have caused a large decline in herpetofauna in 1984; over two-thirds of the animals were captured in the first year of the study. Both Shannon-Weiner and Simpson's diversity indexes indicated that plot 2E had the lowest diversity each year. THe greatest diversity was found on 1E or 7E. The 2-yr fire periodicity produced a dense layer of grasses and herbaceous plants that was not readily occupied by sandhill herpetofauna.
The most abundant reptile was the six-lined racerunner, Cnemidophorous sexlineatus, which comprised about 33% of all captures. The highest density of racerunners was found on 1E, while lizards on 7E showed the greatest philopatric tendencies (especially in 1983, the year 7E was burned). The results indicated that burning increased diversity and abundance of amphibians and reptiles over control plots, and some fire periodicities were better than others for maintaining high diversity.
Abstract: The southeastern five-lined skink, Eumeces inexpectatus, occurs in a wide range of habitats throughout Florida, but it is most abundant in scrub and sandhill (high pine) habitats. Both the scrub and sandhill habitats are fire maintained, and resident animals respond to the frequency of burning. During 7 yr of study, adult males were trapped most often in March and April and adult females most often after nesting and hatching of young, from late June to mid-July. As judged by the number of individuals captured, [the author] determined that plots of sandhill protected from fire for about two decades or burned on 5 or 7 yr cycles support more individuals than plots burned on either 1 or 2 yr cycles. Differences in the number of skinks found in plots subjected to the three burn frequencies likely reflect the structure of the habitat. Frequent burning reduces the amount of litter and tree canopy, produces patches of open ground, and promotes the growth of herbaceous plants. Plots protected from fire have thick layers of litter which provide shelter and foraging habitat for southeastern five-lined skinks. Plots burned on 5 or 7 yr cycles have sufficient time to accumulate litter between fires to provide good quality habitat for this species.
Abstract: To determine the importance of different fire variables in promoting ant diversity in Pilanesberg National Park, South Africa, ants were studied in savanna grassland patches of different post-fire fuel age, and fire frequency. Pitfall traps were set in six grassland sites representing three fire regimes (1: young (<24 months post-fire) and frequently burned; 2: young and infrequently burned; 3: old (4 and 6 years post-fire) and infrequently burned). Species richness declined with decreasing fire influence, being greatest on young and frequently burned plots, and lowest on old and infrequently burned plots. There was pronounced dominance by a few species on young and infrequently burned plots, and greater equitability at other sites. Ant diversity appears to be influenced more by post-fire fuel age than frequency of burning, although there is a need for a wider range of fire frequencies and greater replication to explore this further. Species richness was inversely correlated with the proportion of foliage biomass at ground level. Southern African ant communities may be quite resilient to differences in fire regime, and only a limited amount of fire diversity (young vs old patches) may be necessary to maintain ant diversity.
Abstract: The density of a population of common skinks, Leiolopisma nigriplantare maccanni, in tussock grassland was measured before and after the vegetation was burnt. Population density declined 28% from 1 lizard per 24 m2 before the fire, to 1 lizard per 33 m2 after the fire. Skink survival is attributed to the low heat of the fire and to the possible use of crevaces for shelter.
Abstract: Information on amphibian responses to fire and fuel reduction practices is
critically needed due to potential declines of species and the prevalence of new, more
intensive fire management practices in North American forests. The goals of this review
are to summarize the known and potential effects of fire and fuels management on
amphibians and their aquatic habitats, and to identify information gaps to help direct
future scientific research. Amphibians as a group are taxonomically and ecologically
diverse; in turn, responses to fire and associated habitat alteration are expected to vary
widely among species and among geographic regions. Available data suggest that
amphibian responses to fire are spatially and temporally variable and incompletely
understood. Much of the limited research has addressed short-term (1-3 yr) effects of
prescribed fire on terrestrial life stages of amphibians in the southeastern United States.
Information on the long-term negative effects of fire on amphibians and the importance
of fire for maintaining amphibian communities is sparse for the high number of taxa in
North America. Given the size and severity of recent wildland fires and the national
effort to reduce fuels on federal lands, future studies are particularly needed to examine
the effects of these landscape disturbances on amphibians. We encourage studies to
address population-level responses of amphibians to fire by examining how different life
stages are affected by changes in aquatic, riparian, and upland habitats. Research designs
need to be rigorous and credible, yet provide information that is relevant for fire
managers and those responsible for assessing the potential effects of various fuels
reduction alternatives on rare, sensitive, and endangered amphibian species.
Abstract: Mac Arthur's "Q-Minimization" theory of competition-mediated community structure suggests a protocol for predicting species abundances from knowledge of the availabilities and species utilizations of critical resources. Using this protocol, we compared predicted changes in rodent abundances with those observed over the two and one-half years following a fire in a topographically uniform area of California coastal sage scrub vegetation. Approximately half of our permanent census grid covered an area burned in 1979, and half covered an adjacent unburned area. A separate trapping survey at a nearby unburned site showed that the five rodent species common to the permanent grid had distinct capture frequencies in four structural microhabitats. We used these microhabitat-specific capture frequencies as resource-utilization functions for each species, because structural microhabitats appear to be related to underlying resources that limit rodent populations. Resource-availability functions were derived from censuses of vegetation and other structural features on burned and unburned sides of the permanent grid. Predictions from Mac Arthur's theory were upheld in that (1) abundances of each species on one side of the grid relative to the other correlated significantly with relative K values on the two sides of the grid (K values were calculated as the overlap between microhabitat utilization and availability functions); (2) relative abundances of the five rodent species on the burned side of the grid were correlated with those predicted from relative K values; and (3) the total microhabitat utilization of the rodent community on each side of the grid matched overall microhabitat availability on that side well and matched availability on the other side poorly. These results provide support for a potentially powerful protocol for predicting identities and relative abundances of coexisting species. Although this protocol should provide results similar to those from a more inductive one relying on empirical foreknowledge of spatial correlations between resource and consumer abundances, it differs in important respects.
Abstract: Reversing decades of fire exclusion by hardwood midstory reduction is now used to recover populations of the federally endangered Red-cockaded Woodpecker (Picoides borealis) in longleaf pine (Pinus palustris) forest ecosystems. The effects of Red-cockaded Woodpecker management on winter birds in longleaf pine sandhill forests are largely unknown. Examining habitat use of winter migrants, some of which are declining, may influence the selection of habitat management techniques used for Red-cockaded Woodpeckers to benefit overwintering migrants. During the winters (December-February) of 1997-1998 and 1998-1999, we tested experimentally the effects of hardwood reduction treatments applied in 1995 on winter birds at Eglin Air Force Base in fire-excluded northwest Florida longleaf pine sandhills. Treatments were (1) prescribed spring burning, (2) herbicide application, (3) mechanical felling and girdling, and (4) a control where decades of fire exclusion was maintained. We also sampled winter bird flocks in frequently burned, nonexperimental reference plots to measure management success. Hardwood reduction techniques had no effect on flock species richness, which averaged 7.9 and 7.2, respectively, during 1997-1998 and 1998-1999. Larger flocks in felling and girdling and in herbicide plots were primarily due to significantly higher numbers of overwintering Chipping Sparrows (Spizella passerina), as well as resident Red-cockaded Woodpeckers and an influx of temperate migrant Pine Warblers (Dendroica pinus). In contrast, flocks in control plots were smaller (flock size and species composition in spring burn plots were intermediate) and composed of hardwood-associated species, such as Tufted Titmouse (Baeolophus bicolor) and Carolina Chickadee (Poecile carolinensis). The relative uses of longleaf pines and hardwoods by Red-cockaded Woodpeckers, Pine Warblers, and Brown-headed Nuthatches (Sitta pusilla) during both winters best explained that winter birds present in herbicide, felling and girdling, and reference plots were more likely to forage on the same tree species and substrates than birds in spring-burned plots, and least likely to forage on the same species and substrates as birds in the control plots. Those differences corresponded to the following increasing order of hardwood stem mortality among treatments: control, spring burn (41%), felling and girdling (62%), and herbicide (92%). Repeated burning is recommended to restore the reference foraging condition because it was eight times less expensive than other techniques, which favored mostly Chipping Sparrows.
Abstract: Both redbilled oxpeckers (Buphagus erythrorhynchus) and yellowbilled oxpeckers (Buphagus africanus) have experienced recent population decreases in southern Africa largely as a result of cattle dipping against ticks, their primary source of food. In Namibia, oxpeckers are confined largely to the Caprivi region in the north-east and the yellowbilled oxpecker is classified as a Namibian Red Data species. Counts in 1983-1984 estimated populations of 2285-3780 redbilled oxpeckers and 2062-2613 yellowbilled oxpeckers on cattle in East Caprivi. In this study, three counts of oxpeckers were made in 1997-1998. Bird numbers had not increased in proportion with cattle numbers, the primary host which had increased three-fold in the last 15 years. Current redbilled oxpecker numbers (3627-4902) were similar to those in the 1980s. Too few yellowbilled oxpeckers were observed to derive robust population estimates, but our counts suggest a decline to about 330 birds. There have been no official cattle dipping programmes in Caprivi, and private tick control is virtually non-existent. We suggest that the current dry conditions, in combination with the increasingly widespread and more frequent practice of veld burning are having a substantial, differential effect on some of the tick species favoured by the two species of oxpeckers. We hypothesise that these two factors act as a control mechanism on ticks favoured by yellowbilled oxpeckers, so precipitating the dramatic decline of this species. If current trends continue, yellowbilled oxpecker will soon disappear from Caprivi.
Abstract: The effects of fire in plant communities in the western South Texas Plains are not clearly understood. Our objective was to compare forb density, cover, frequency, and diversity on prescribed-burned rangelands and untreated rangelands under controlled conditions, and with the influence of livestock grazing during the first growing season after treatment. Four rangeland sites that were burned during winter 1997, and four sites of untreated rangeland were selected on the Chaparral Wildlife Management Area, Dimmit Co., Texas. Two burned and two untreated sites were subjected to grazing by cattle. Herbaceous canopy cover and forb density were estimated with 20- by 50-cm quadrats during late spring 1997. Forb diversity was similar between treatments. Forb coverage was greater on burned than nonburned sites. Important seed-producing annuals, such as prairie sunflower (Helianthus petiolaris) and croton (Croton), were more prevalent on burned sites. Day flower (Commelina erecta), a beneficial perennial, also increased following burning. Grazing did not appear to influence the presence of forbs on burned sites; however, grazing reduced density and cover values of desirable species such as prairie sunflower.
Abstract: Lewis's Woodpecker (Melanerpes lewis) has been characterized as a "burn specialist" because of its preference for nesting within burned pine forests. No prior study, however, has demonstrated the relative importance of crown-burned forests to this woodpecker species by examining its reproductive success in different forest types. We studied breeding Lewis's Woodpeckers in cottonwood (Populus fremontii) riparian forest patches of Colorado and crown-burned ponderosa pine (Pinus ponderosa) forests of Idaho to compare their reproductive success, productivity, and potential source-sink status in the two forest types. Daily nest survival rates were significantly lower in cottonwood compared to burned pine forests. Nesting success was 46% (n=5) in cottonwood forests and 78% (n=283) in burned pine forests. Proportion of nests destroyed by predators was significantly higher in cottonwood forests (34%) compared to burned pine forests (16%). We consistently found crown-burned forests to be potential source habitat, whereas cottonwood riparian sites were more often concluded to be potential sink habitat. Cottonwood riparian forests were surrounded primarily by an agricultural landscape where the composition and abundance of nest predators was likely very different than the predator assemblage occupying a large-scale burn in a relatively natural landscape. Conversion of riparian and adjacent grassland landscapes to agriculture and prevention of wildfire in ponderosa pine forests have likely reduced nesting habitat for this species. Prescribed understory fire is the prevailing management tool for restoring ponderosa pine ecosystems. Conditions created by crown fire may be equally important in maintaining ponderosa pine systems and conserving nesting habitat for the Lewis's Woodpecker.
Keywords: ground radiometer measurements/ african savanna trees/ southern africa/ satellite/ reflectance/ calibration/ botswana/ model/ index
Abstract: Estimates of biomass production are important in a wildlife reserve such as Etosha National Park, Namibia, for assessment of fire risk and subsequent selection of sites for controlled burning. We present methodology for using locally acquired NOAA-AVHRR images to make estimates of biomass in near-to-real-time. To this end, techniques for rapid measurement of the biomass of herbaceous and woody vegetation were developed using a rising disc pasture meter and individual plant dimensions. A field sampling methodology is presented to make biomass estimates which were compatible with the scale of AVHRR spatial resolution and sufficiently close to the time of satellite overpasses to enable correlation with the NDVI from single images. Initial results show high correlations of biomass with NDVI for individual vegetation cover classes, which appear to be temporally stable. There seem to be different regression equations for the different savanna vegetation types although more field observations are needed to confirm this. The results were exploited to illustrate the potential application of this work for fire management. The combination of rapid field methods and real time image acquisition developed in this work provides a sound basis for biomass monitoring at local level.
Abstract: Rodent populations were sampled at sites in California chaparral and coastal sage scrub six months after wildfire. Sites adjacent to unburned brush were compared with sites in the center of large burned areas. Eight species of rodents were captured. Species of Peromyscus were the most abundant, 40.2% of individuals captured; followed by Neotoma (32.4%), Chaetodipus (20.3%), and Dipodomys (7.0%). Peromyscus maniculatus accounted for 32.8% of all individuals and was captured most frequently at sites in the center of large burns. Neotoma lepida which accounted for 31.3% of individuals captured, was trapped most commonly at the periphery of burns. Several species showed contrasting distribution patterns in coastal sage scrub and in chaparral. Coastal sage scrub sites had the highest estimates of rodent populations. Species diversity varied widely among sites.
Abstract: Populations of Florida grasshopper (Ammodramus savannarum floridanus) and Bachman's sparrows (Aimophila aestivalis) are small and declining. Prescribed burning is the primary management tool used to maintain their grassland habitats, but the effects of this management practice on the breeding density and reproductive success of these populations are poorly understood. We conducted a 3-year spot-mapping study of 3 winter burn classes (0.5-yr, 1.5-yr, and 2.5-yr postfire) in native dry prairie on 2 sites in central Florida to determine the effects of fire management on breeding density and reproductive success of these 2 sparrows. Florida grasshopper sparrow densities were greater on recently burned plots (0.5 yr postburn: x = 4.1 +- 1 territories/10 ha (x +- SE); 1.5 yr postburn x = 3.4 +- 0.8 territories/10 ha) than on plots that had not been burned in 2.5 years (x = 1.8 +- 0.8 territories/10 ha). Grasshopper sparrow reproductive success was also higher in recently burned plots (0.5 yr postburn; x = 1.6 successful territories/plot) than in 2.5-year burn plots (x = 0.6 successful territories/plot). In contrast, Bachman sparrow breeding densities and reproductive success were not affected by fire management rotation. Our results indicate that a fire rotation of ltoreq3 years is necessary to maintain suitable breeding habitat for Florida grasshopper sparrows but does not appear to negatively affect breeding Bachman's sparrows.
Abstract: To test the assumption that forest harvesting can maintain wildlife through emulating natural disturbance, we compared small mammal abundance between seven post-fire and nine clearcut plots representing three ages since disturbance (4, 14 and 27 years). On each site, two Victor snap traps were placed at 100 stations on 10 x 10 grids spaced 20 m apart. Clethrionomys gapperi were more abundant in clearcut plots, likely due to abundant coarse woody debris. This difference decreased through time. No other species differed between disturbance types. In both burned and clearcut plots, the abundance of C. gapperi was lowest on 14-year-old sites while Microtus pennsylvaticus and Sorex cinereus peaked at 14 years. At the meso-scale (plot-level), grass, herbs, and coarse woody debris explained 53% of the variation in small mammal abundance. At the micro-scale (individual trapsite), several variables showed statistical significance, yet only 13% of the variation in small mammals was explained. This was reduced to 4% when the spatial component of ecological variation was controlled. This suggests that our small mammals are coarse- grained foragers and fine-scale vegetation descriptions have little ability to explain small mammal abundance. We conclude that the coarse-filter approach to forest management by emulating natural disturbances can maintain small mammal communities in central Labrador.
Abstract: I trapped rodents on and near adjacent desert areas for 13 months before and after fire burned one area. Dipodomys merriami colonized the burned area after fire, but abundance of Neotoma albigula, Perognathus amplus, and Chaetodipus baileyi declined on the burned area after fire. Neotoma albigula showed immediate and long-term changes to fire, whereas burrowing species showed mostly long-term changes. Much about fire can be inferred through the elimination of competing hypotheses, despite statistical limitations of studying single fires.
Abstract: Using radio-telemetry, we evaluate and discuss effects of a prescribed fire in a Madrean community on mortality, behavior, and habitat of 3 rattlesnake species. Eight snakes exposed to low intensity fire survived, whereas a snake exposed to intense fire died. Spatial descriptors of activity did not significantly differ before versus after the fire; however, individuals moved significantly less frequently and were found in subterranean retreats more frequently after the fire than before the fire. Wooded canyons and wooded steep slopes burned intensely because of high fuel accumulation, resulting in habitat loss for Crotalus willardi obscurus. Reintroduction of fire is essential in maintaining a mosaic of habitats and ecosystem function. Prior to reintroduction of large-scale summer fires, consideration should be given to reducing artificially high fuel loads to preserve C. w. obscurus habitat and reduce mortality.
Abstract: This literature review concerns insect responses to fire, compared to other feasible and appropriate conservation managements of open habitats. Many insect groups decline markedly immediately after fire, with the magnitude of reduction related to the degree of exposure to the flames and mobility of the insect. Niche diversity is lower in recently burned habitat, and the rate of insect increase following fire also relates to the species' ability to gain access to the regrowing vegetation. Postburn flora can be quite attractive to some recolonizing insects, possibly to some degree a result of fire-caused insect mortality which provides plants with short-term release from insect herbivory. Insect declines may follow immediately after mowing, but usually of lesser degree and shorter duration than after a fire of comparable timing and size. Season and scale of cutting may affect how much and which species showed positive or negative responses. Cut areas offer the vegetational structure and composition preferred by some insects, but cutting-or cutting at certain scales, seasons, or frequencies-may also be unfavorable for some species. Heavy grazing results in niche and assemblage simplification. Nonetheless, some invertebrates prefer the short turfs and bare ground resulting from heavier grazing. Other species vary in whether they peak in abundance and diversity in intermediate, light, or no grazing. In comparisons of mowing/haying and grazing regimes of similar compatibility with maintenance of the same habitat types, responses of particular species and species groups varied as to whether they had a preference for one or the other. Characteristics associated with insect responses to fire related to the degree of exposure to lethal temperature and stress experienced in the post-fire environment, suitability of post-treatment vegetation as habitat, and ability to rebuild numbers in the site (from survivors and/or colonizers). These factors appear equally useful for explicating insect responses to other managements such as haying, mowing, and grazing. By contrast, the assumption that the most habitat-restricted species will be most adapted to ecological forces believed to be prevalent in that ecosystem appears less efficacious for predicting insect management preferences.
Abstract: Applied historical ecology is the use of historical knowledge in the management of ecosystems. Historical perspectives increase our understanding of the dynamic nature of landscapes and provide a frame of reference for assessing modern patterns and processes. Historical records, however, are often too brief or fragmentary to be useful, or they are not obtainable for the process or structure of interest. Even where long historical time series can be assembled, selection of appropriate reference conditions may be complicated by the past influence of humans and the many potential reference conditions encompassed by nonequilibrium dynamics. These complications, however, do not lessen the value of history; rather they underscore the need for multiple, comparative histories from many locations for evaluating both cultural and natural causes of variability, as well as for characterizing the overall dynamical properties of ecosystems. Historical knowledge may not simplify the task of setting management goals and making decisions, but 20th century trends, such as increasingly severe wildfires, suggest that disregarding history can be perilous.
We describe examples from our research in the southwestern United States to illustrate some of the values and limitations of applied historical ecology. Paleoecological data from packrat middens and other natural archives have been useful for defining baseline conditions of vegetation communities, determining histories and rates of species range expansions and contractions, and discriminating between natural and cultural causes of environmental change. We describe a montane grassland restoration project in northern New Mexico that was justified and guided by an historical sequence of aerial photographs showing progressive tree invasion during the 20th century. Likewise, fire scar chronologies have been widely used to justify and guide fuel reduction and natural fire reintroduction in forests. A southwestern network of fire histories illustrates the power of aggregating historical time series across spatial scales. Regional fire patterns evident in these aggregations point to the key role of interannual lags in responses of fuels and fire regimes to the El Nino-Southern Oscillation (wet/dry cycles), with important implications for long-range fire hazard forecasting. These examples of applied historical ecology emphasize that detection and explanation of historical trends and variability are essential to informed management.
Abstract: The frequency, extent, and severity of fires strongly influence development patterns of forests dominated by Douglas-fir in the Pacific Northwest. Limited data on fire history and stand structure suggest that there is geographical variation in fire regimes and that this variation contributes to regional differences in stand and landscape structure. Managers need region-specific fire regime data to develop process-based management schemes to manage new late-successional reserves (LSR). This study quantifies fire regimes and stand structural patterns in a LSR in Douglas-fir-dominated forests in northern California. We analyzed tree species composition, structure (diameter, age), and fire scars from 75 plots in a 1570 ha area in the northern Klamath Mountains. Tree species composition varied with elevation and aspect, and median fire return intervals were similar (12-19 years) among species composition groups. However, median fire return intervals (FRI) were shorter on south- (8 years) and west-facing (13 years) slopes than on northern (15 years) or eastern (16.5 years) aspects. Fire return intervals also varied by historical period. Median FRIs were longer (21.8 years) during the suppression period (1905-1992) than in the settlement (1850-1904) (12.5 years) or presettlement (1627-1849) (14.5 years) period. The average burn area for a fire was 350 ha, and 16 fires larger than 500 ha burned between 1627 and 1992. Fire rotations varied by century from 15.5 to 25.5 years and were longest in the fire suppression period. Stand conditions were multi-aged, and Douglas-fir recruitment occurred after fire. Patterns of past fire severity, inferred from age-classes, indicate that upper slopes, ridgetops, and south- and west-facing slopes experienced more severe fires between 1850 and 1950 than lower slopes or east- and north-facing slopes. Implications are that lower slopes and north and east aspects are more likely than other topographic positions to sustain or promote long-term, late-successional conditions. Prescribed fire will likely be an integral component of management plans that successfully maintain natural processes and structures in newly established late-successional reserves in the Klamath Mountains.
Abstract: The effects of atmospheric fluoride pollution on the lizard fauna of the open forest of coastal dunes in New South Wales, Australia were examined. Lizards were pitfall-trapped at sites with background fluoride levels (<0.25 mumol F.g-1), or subject to low (1.85-3.4 mumol F.g-1) or high (8.00-13.2 mumol F.g-1) levels of fluoride pollution. Sites had been disturbed by fire or mineral sand-mining 4 or 8 years prior to the study. Fluoride pollution resulted in significant changes to canopy cover, understorey vegetation density and ground cover. Where fluoride levels were low in unmined forest, there was significantly higher species richness, total lizard abundance and abundance of the most common species, Lampropholis guichenoti and Lampropholis delicata (Scincidae), compared with areas of high or background fluoride levels. Both the present and previous studies show that fluoride pollution is significantly correlated with increased abundance of the most common lizard species in sand-mined areas, Ctenotus robustus, Ctenotus taeniolatus (Scincidae) and Amphibolurus muricatus (Agamidae). A discriminant function model of background-fluoride mined sites was used to predict lizard abundances based on vegetation density, leaf litter density and soil hardness. The model was verified by using it to predict similarities between background-fluoride sites and fluoride-affected sites. The sites within each predicted group were more similar in lizard species composition than when grouping of sites was done by time since mining or fire. With this analysis, a close relationship between vegetation variables and the lizard fauna, irrespective of the type of disturbance or time since disturbance, is demonstrated. Discriminant function analysis suggested that Ctenotus would be unlikely to use unmined forest sites that had been burned within 12 months previously. Thus it seems unlikely that the original open forest of these coastal dunes would have supported populations of either C. robustus or C. taeniolatus. In conclusion, the original source of Ctenotus that colonized sand-mined areas is more likely to have been the relatively small areas of heath vegetation in the area. Therefore, sand-mining and atmospheric fluoride pollution result in landscape-scale changes to the relative abundance of lizard species, with forest species becoming less common and lizard species from open areas becoming more common.
Abstract: Advanced forest succession and associated accumulations of forest biomass in the Blue Mountains of Oregon and Washington and Intermountain area have led to increased vulnerability of these forests to insects, diseases, and wildfire. One proposed solution is large-scale conversion of these forests to seral conditions that emulate those assumed to exist before European settlement: open-spaced stands (ca, 50 trees per ha), consisting primarily of ponderosa pine (Pinus ponderosa Laws.) and western larch (Larix occidentalis Nutt,), We question how well presettlement forest conditions are understood and the feasibility and desirability of conversion to a seral state that represents those conditions. Current and future expectations of forest outputs and values are far different from those at presettlement times. Emphasis on prescribed fire for achieving and maintaining this conversion raises questions about how well we understand fire effects on forest resources and values. We consider here potential effects of prescribed fire on two key aspects of forest management-productivity and wildlife. Use of large-scale prescribed fire presents complex problems with potential long-term effects on forest resources, Before implementing prescribed fire widely, we need to understand the range of its effects on all resources and values. Rather than attempting to convert forests to poorly described and understood presettlement seral conditions, it would seem prudent to examine present forest conditions and assess their potential to provide desired resource outputs and values, Once this is achieved, the full complement of forest management tools and strategies, including prescribed fire, should be used to accomplish the desired objectives. We suggest a more conservative approach until prescribed fire effects are better understood.
Abstract: A stand-replacement prescribed fire in an over-mature lodgepole pine (Pinus contorta Dougl. ex Loud.)-subalpine fir (Abies lasiocarpa (Hook.) Nutt.) stand (snag area) and in a mature lodgepole pine thicket (thicket area) resulted in lower plant diversity within the first year after burning, and as fire energy outputs increased, postburn plant cover and diversity decreased. There was no reestablishment of the original plant cover where total heat output exceeded 100 000 kcal/m2. Apparently, most plants in this habitat were not fire resistant. Postfire recovery appears to depend on immigration of seeds from adjacent unburned areas or on seeds and rhizomes that survive on unburned microsites (refugia) within the burn. After fire, temperatures increased in the forest floor fermentative layer (FL) (10 to 19 degreeC) and upper 10 cm of the soil layer (SL) (3 to 7 degreeC) on several dates in summer 1976. Increased pH levels in FL (about 2 units) and SL (about 0.5 unit) after burning provided an improved environment for bacterial development, and counts of total bacteria and proteolytic bacteria both increased. Both nitrogen fixation and nitrification were increased after burning. Despite the apparent increase in microbiological activity, microbial respiration declined after burning-apparently because of reduced forest floor organic carbon energy reservoir. Diversity of birds increased the year after burning. New species of birds included hairy woodpecker (Picoides villosus), black-backed woodpecker (Picoides arcticus), three-toed woodpecker (Picoides tridactylus), common flicker (Colaptes auratus), and mountain bluebird (Sialia currucoides). Numbers of needle-foraging species, such as Townsend's warbler (Dendroica townsendi), hermit thrush (Catharus guttatus), golden-crowned kinglet (Regulus satrapa), and western tanager (Piranga ludoviciana), declined or were absent after fire. Responses of small mammals to fire were not definitive, but there was a marked decline in Townsend's chipmunk (Tamias townsendii) after burning. In the first year after burning, forage for elk (Cervus elaphus) in the burned area was higher in crude protein than in unburned areas, but low productivity and distance from water diminished the value of the burned area for elk.
Abstract: The effects of three fire regimes-(1) burning early in the dry season (June), (2) burning late in the dry season (September) and (3) not burning (protected from wildfires)-on the water quality, water yield and export coefficients of three intermittent streams, which flow between December and June, have been examined in a tropical savanna in northern Australia. The study was conducted over a three year period in Kakadu National Park, and employed a comparative catchment approach though without any pre-treatment data. The canopy cover, density of riparian vegetation, litter- and ground-cover of the catchment burnt early in the dry season (catchment E, stream E) and the unburnt catchment (catchment U, stream U) were similar. Fires lit late in the dry season (catchment L, stream L) however resulted in tree mortalities, and a lower canopy cover (50% less), riparian tree density (80% less) and litter cover, and increased amounts of bare ground; thereby increasing catchment L's susceptibility to erosion. This resulted in episodic runoff events from catchment L in November and December, before continuous wet season flow. These events, absent in catchments E and U, featured high concentrations of total suspended sediment (TSS). volatile suspended sediment (VSS), N, P, Fe and Mn up to 10 times those measured later in the wet season. During continuous wet season flow between December and June, baseflow water quality of the three streams were similar. Storm runoff concentrations for N and P were also similar, however stream L storm runoff concentrations of TSS, VSS, Fe and Mn were 2-5 times higher than those measured in streams E and U. Despite this, only the export coefficients for TSS from catchment L (average 61 kg ha(-1)) were significantly higher (average 2.4 times) than catchment E and U coefficients. This was attributed to the overwhelming influence of stream volume, relative to concentration in determining stream load and hence catchment export coefficients (load/catchment area). The apparently negligible impact of the fire regimes on VSS, N, P, Fe and Mn export coefficients, and also the overall low sediment export coefficients for the three catchments which were up to 100 times less than that reported for other tropical environments, were ascribed to the low catchment slopes (average 0.5%), low soil fertility, maintenance of a protective surface gravel lag, the negligible impact of the fire regimes on water yield, and the sometimes lengthy (maximum 6 months) period between burning and runoff.
Abstract: A species-rich lizard community responded variably to a range of experimental fire regimes in a tropical savanna. Heteronotia binoei was the only lizard species that showed a short-term response to fire, decreasing in abundance directly after the early- and late-burns. H. binoei and Diporiphora bilineata were significantly more abundant in early-burn treatments. Carlia amax was more abundant in unburnt and early-burn treatments. C. munda was more abundant in unburnt and early-burn sites. Differences in the relative abundance of species between treatments is attributed to site differences in vegetation structure, and fire-induced changes to the structure of habitat. Early-burn sites were significantly richer in lizard species (P lt 0 .05); however, overall lizard abundance, Shannon-Wiener diversity and Detrended Correspondence Analysis (DCA) 1 and DCA 2 scores were not significantly different, suggesting that habitat partitioning has a stronger influence than the direct effects of fire. Many lizards were associated with a direct gradient of moisture availability, including a seepage assemblage, with Carlia gracilis and Sphenomorphus darwiniensis correlated with increased moisture, a well-developed canopy and abundant leaf litter. An assemblage associated with the drier end of the gradient included Carlia triacantha, Ctenotus kurnbudj, Diporiphora magna and D. bilineata. The lizard composition of most quadrats was intermediate along the moisture gradient and was associated with typical eucalypt savanna communities. Lizard species that largely are restricted to the moist seepage zones may be particularly sensitive to late dry-season fires which alter this habitat type.
Abstract: The impact of time since fire after two consecutive wildfires 44 years apart (1939 and 1983) within the same area, and the distance from the fire boundary (< 100 m or 500- 2000 m), were investigated in relation to the distribution and abundance of arboreal marsupials in 1994. Arboreal marsupials were censused by stagwatching and spotlighting in two relatively young age classes of mountain ash (Eucalyptus regnans) dominated forest in the Central Highlands of Victoria. Five species of arboreal marsupial were detected, but only three were detected in sufficient numbers to determine habitat preferences. Petauroides volans (greater glider) was statistically more abundant in 1939 regrowth forests, while Trichosurus caninus (mountain brushtail possum) showed no significant preference for either age class of forest. All but one record of Gymnobelideus leadbeateri (Leadbeater's possum) came from young forest, though the effect of age-class was not statistically significant. Distance from fire boundary explained little or no variation in mammal distribution or abundance. While the actual number of hollow-bearing trees was similar in both age classes of forest, the long-term lifespan of hollow-bearing trees in more recently burnt forest is predicted to be lower than in unburnt or not recently burnt forest. Post-fire salvage logging following the 1983 wildfires appears to have reduced the number of hollow-bearing trees at sites burnt in 1983.
Abstract: Collecting unbiased monitoring data on fire effects is often problematic. Samples collected for assessing the effects of managed (prescribed) fires and wildfires are often "pseudoreplicated" because it is impossible to replicate the disturbance event. Furthermore, monitoring data for managed fires and wildfires may be confounded because it is difficult to randomize the effects of fires not under strict experimental control. It is not possible to replicate or randomize large-scale events such as wildfires and many prescribed fires, yet there are techniques that can account for some of the bias introduced by these problems. Since monitoring usually involves repeated observations, this paper discusses simple time-series analysis, along with two common modifications: impact/reference designs and before/after comparisons. While there are many possible monitoring strategies, most monitoring efforts are covered by these broad categories. In this paper we attempt to outline the assumptions, strengths, and limitations of these methods. We recommend four primary strategies to improve the confidence of findings when assessing fire effects: (1) acknowledge pseudoreplication in the data when it exists; (2) expand the use of managed fire and wildfire data for quantifying fire effects; (3) increase the use of unburned reference sites to improve the confidence of analyses of fire effects; and (4) in some instances, consider treating data taken from multiple fires as independent replicates. The concepts discussed in this paper are illustrated by examples taken from data sets for prescribed fire effects in Sequoia and Kings Canyon National Parks, California, USA.
Abstract: 1. Despite the importance of fire in many natural systems, knowledge of how fire affects the relationship between hypogeous fungi and mycophagous mammals in fire-prone environments is limited. Using experimental fires, we examined consumption of hypogeous ectomycorrhizal fruit-bodies by an endangered tropical mycophagist, the northern bettong Bettongia tropica Wakefield, in north-eastern Australia. 2. Fungus was the major dietary component (56%) throughout all seasons, both before and after fire. At least 35 hypogeous taxa were consumed. Number of taxa consumed during different seasons was similar, but was significantly higher on unburnt sites than on burnt sites. Similarly, diversity of taxa per faecal sample was significantly greater on unburnt sites, but also increased irrespective of fire from wet season to dry season. 3. Cluster and principal component analyses were used to examine patterns in consumption of fungal taxa. The greatest differences in dietary composition were between the period immediately after fire on burnt sites (early wet season) and all other season and treatment combinations. This difference was due to increased consumption of taxa in the fire-adapted family Mesophelliaceae and reduced consumption of the genus Elaphomyces. Principal component analysis revealed two major gradients in consumption. The first accounted for 32% of total variance and described change in consumption of taxa with season. The second accounted for 24% of total variance and described change in consumption of taxa before and after fire. 4. Despite taxon-specific changes in consumption of hypogeous fungi, the body condition of bettongs did not change significantly between seasons or in relation to fire, suggesting that bettongs were never compromised in their optimal fungal intake. 5. Our data show that the northern bettong has a flexible response to fire and could be best thought of as a fire-adapted marsupial. We therefore propose a precautionary approach to fire management of bettong habitat; at the present time this would include maintaining the recent fire regime of low to moderately intense fires every 3-4 years.
Abstract: An examination of movement paths, foraging patterns and habitat use of an endangered mycophagous marsupial, the northern bettong (Bettongia tropica), was undertaken in fire-prone forest in north-eastern Australia before and after experimentally induced fires. Fungal biomass remaining at bettong foraging points was similar across the study area prior to burning, but increased significantly on burnt ground during the period after fire. After burning, significantly more bettongs chose to forage in burnt habitat and those that did experienced higher probabilities of truffle recovery. Using data from spool-and-line tracking, observed movement patterns of bettongs were compared with those expected from a simple null model of animal movement (a correlated random walk). Analysis of mean-squared displacement revealed that 22% of observations fell beyond the model's 95% prediction interval. Further analysis revealed the reasons for the model's inadequacy: bettongs exhibited area-restricted search behaviour by taking significantly more frequent and more acute turns immediately prior to and following recovery of hypogeous fungi (truffles), and by taking significantly more frequent and more acute turns following any other foraging activity. In general ecological terms, the results indicate a flexible response by the northern bettong to habitat alteration and increased food availability brought about by low intensity fires.
Abstract: A total of 754 birds were recorded on a portion of a pond shore line during 63 visits for 4 months following a controlled burn, while 236 birds were observed on an adjacent and comparable, but unburned, shore line. Only 5 of the 35 bird species encountered were seen more often on the unburned site. Fire-induced bird and mammal injury or mortality was unobserved even though the burn resembled a wildfire. Birds showed no fear of the fire and some were attracted to the smoking landscape. Although some cold-blooded vertebrate mortality occurred, other herptiles survived, and alligators used the burned shore line almost exclusively. Mammal populations of burned and unburned areas appeared similar 4 months after the fire.
Animal responses are considered related to the fire removal of the heavy grass mat that otherwise covered the water and soils and foods contained therein, and physically impared new plant growth. Burning also produced an earlier, and far more productive growth of wet-prairie plants.
Abstract: Pine-hardwood ecosystems in the southern Appalachians are in serious decline due to fire exclusion and insect infestations. Fire has been advanced as a tool to restore these ecosystems, yet there are few studies evaluating overall ecosystem effects. Our objectives were to evaluate the effects of stand restoration burning on forest floor nitrogen (N) and carbon (C) pools, and soil and stream chemistry. We measured changes in forest floor (coarse woody debris, small wood, litter, and humus) mass, N, and C; changes in soil chemistry (calcium (Ca), potassium (K), magnesium (Mg), cation exchange capacity (CEC), pH, C, and N); and changes in stream nitrate (NO3). Results showed that significant reductions in mass, N, and C occurred only for litter and small wood on the ridge, where N losses were 52.9 kg ha-1 for litter and small wood combined. No significant effects were observed on the mid- or lower slope of the treatment watershed. Losses on the ridge are considerably lower than losses which occur with alternative burning treatments used in the region, such as the fell and burn treatment. Soil and stream chemistry showed no response to burning. Spatial heterogeneity in fire intensity (combustion temperatures ranged from < 52 - >800degree C) and severity associated with stand replacement burning results in a mosaic of fire effects and considerably less consumption and subsequent nutrient losses.
Abstract: Stand-replacement prescribed fire has been recommended to regenerate stands of table mountain Pine (Pinus pungens Lamb.) in the southern Appalachian mountains because the species has serotinous cones and is shade-intolerant. A 350 ha prescribed fire in northeast Georgia provided an opportunity to observe overstory mortality and regeneration of table mountain pine at various levels of fire intensity. Fire intensity for each of 60 study plots was classified by discriminant function analysis. Fires of low and medium-low intensity gave rise to abundant regeneration but may not have killed enough of the overstory to prevent shading. High-intensity fires killed almost all overstory trees but may have destroyed some of the seeds. Fires of medium-high intensity may have been the best choice; they killed overstory trees and allowed abundant regeneration. The forest floor remained thick after fires of all intensities, but roots of pine seedlings penetrated duff layers up to 7.5 cm thick to reach the mineral soil. In this study area, fire intensity levels did not have to reach extreme levels in order to successfully regenerate table mountain pine.
Abstract: Riparian habitats in eastern Oregon and Washington compose a small percentage of the landscape, and yet these habitats are essential for many species of vertebrates. Riparian areas are sensitive to disturbance agents, which can pose a formidable challenge to effective management of these habitats. Moreover, few studies have documented the effects of disturbance agents on riparian habitats and associated fauna. In general, disturbances from insects and disease likely have-strong effects on cavity nesters and insect feeders, and use of Bt (Bacillus thuringiensis) to control insect pests decreases the food supply for insectivores. Most fire effects on terrestrial vertebrates are through changes in habitat, food, and competitors, and responses to fire are variable and species specific. Salvage logging likely has negative effects for species that use dead and dying trees. Livestock grazing in riparian areas can eliminate nesting substrates, alter habitat structure and composition, compact soil, trample banks, encourage cowbird expansion, and increase exotic plants. The magnitude of these effects depends on the timing and intensity of grazing. There are almost no studies on how landscape-level vegetation patterns (including riparian corridors) contribute to the viability of wildlife populations. Managers have usually chosen to buffer riparian areas from harvest, spraying, and prescribed fire, but there are no decision-support tools or guidelines for management of riparian habitat for terrestrial vertebrates.
Abstract: Relationships between (1) degree of damage caused by the 1987 fires in northern California and (2) prior management activities, fuel-bed characteristics, and site/stand factors were studied on the Hayfork Ranger District of the Shasta-Trinity National Forests. Postfire aerial photography was used to assess scorch and consumption of tree crowns (the selected measure of fire damage), and other data were obtained from existing records. Data were collected and analyzed separately for (1) plantations and (2) uncut and partial-cut stands. Ordinal logistic regression was the primary analytical technique used. Factors significantly related to degree of fire damage in plantations were cover of grasses, cover of forbs, elevation, site preparation method, and level of damage in the adjacent stand. Damage to uncut and partial-cut stands depended on stand treatment, primary tree species, and aspect. The variables that most strongly influenced fire damage tended to be those most directly related to management activities-site preparation method and damage in adjacent stand for plantations, and stand treatment for uncut and partial-cut stands.
Abstract: Managing for the endangered Red-cockaded Woodpecker (Picoides borealis) on federal lands requires burning large tracts of mature pine forests every 3-5 yr. Many cavity trees that serve as potential nest sites for primary and secondary hole-nesting birds are destroyed by fire. We assessed the efficacy of a nest box program for the Great Crested Flycatcher (Myiarchus crinitus) at Carolina Sandhills National Wildlife Refuge, an area intensively managed for Red-cockaded Woodpeckers. During 1996-1998, we installed and monitored 330 (30 in each of 11 sites) nest boxes in mature (>60 yr) longleaf pine (Pinus palustris) tracts that were burned either in April-June (warm season) or December-March (cool season). Prescribed-burned, sites were nearly devoid of snags; we estimated only 0.8/ ha in cool-season burns and 1.7/ha in warm-season burns. Great Crested Flycatchers built nests in 20% of the boxes available to them. Clutch sizes were larger in warm-season burns than in cool-season burns, but fledging success (fledglings/nest hatching greater than or equal to 1 egg) was lower. Twenty-two of 59 Great Crested Flycatcher nests were depredated and the proportions in each burn class were similar. We recommend the installation of nest boxes for Great Crested Flycatchers in prescribed-burned pine forests, but additional research is needed in these habitats on nest depredation rates and causes.
Abstract: This study investigated the distribution, habitat and population dynamics of the swamp antechinus (Antechinus minimus maritimus) in the eastern Otway Ranges. The species has a restricted, disjunct distribution and has been recorded at 25 sites between 1969 and 1999. All sites were located within 7 km of the coast, occurred at altitudes up to 80 m above sea level and within 10 m of a gully. Analysis of landscape site variables identified sun index as being significant in determination of the probability of occurrence of A. minimus. The presence of A. minimus is negatively associated with sun index, occuring at sites that have a southerly aspect and gentle slope. A. minimus was located in a range of structural vegetation including Open Forest, Low Woodland, Shrubland and Hummock Grassland and a number of floristic groups, some characterised by high frequencies of sclerophyll shrubs, others by high frequencies of Pteridium esculentum, hummock grasses and herbaceous species. A. minimus occurs in fragmented, small populations with maximum population densities of 1.1-18 ha-1. Populations at inland sites became extinct after the 1983 wildfire which burnt 41 000 ha. These sites have not been recolonised since, while on the coast the species did not re-establish until 1993-97. One population that is restricted to a narrow coastal strip of habitat is characterised by high levels of transient animals. The species is subject to extinction in the region due to habitat fragmentation, coastal developments and fire. Management actions to secure the present populations and ensure long-term survival of the species in the area are required and include implementation of appropriate fire regimes, prevention of habitat fragmentation, revegetation of habitat, and establishment of corridor habitat.
Abstract: Temporal patterns of stem and needle production and total aboveground net primary production (ANPP) were studied at the tree and stand level along four chronosequences of Siberian Scots pine (Pinus sylvestris L.) forests differing in site quality (poor lichen type or the more fertile Vaccinium type) and in frequency of surface fires (unburned, moderately burned (fire return interval of apprx40 years), or heavily burned (fire return interval of apprx25 years)). The maximum range of variability in aboveground production was quantified for: (1) possible long-term changes in site quality; (2) stand age; (3) non-stand-replacing, recurring surface fires; and (4) inter-annual climate variability. For (1) and (2), total ANPP was low in the lichen-type chronosequence, reached a maximum of 170 g C m-2 year-1 after 100 years and decreased to 100 g C m-2 year-1 in older stands. Maximum ANPP in the Vaccinium-type chronosequence was 340 g C m-2 year-1 and occurred earlier in the 53-year-old stand than in the other stands. Along the lichen-type chronosequences, peak ANPP was paralleled by maximum carbon allocation to stem growth. (3) In mature trees, damage by recurrent surface fires decreased stem growth by 17 +- 19% over a 10-year period relative to pre-fire values. At longer timescales, ANPP was hardly affected by fire-related differences in mortality. (4) Needle- plus stem-NPP, reconstructed for a 3-year period, varied within a range of 15 g C m-2 year-1 in the lichen-type stands and 35 g C m-2 year-1 in the Vaccinium-type stands. For the same period, the coefficient of variance was higher for needle-NPP (20 +- 10%) than for stem-NPP (12 +- 7%). Needle- and stem-NPP did not covary in time. Most 30-year time series of stem-NPP at the tree level exhibited strong autocorrelation. In older trees, stem-NPP was positively correlated with growing season precipitation. Thus, the factors driving variability in ANPP ranked according to their maximum influence as: stand age (controlled by the frequency of stand-replacing fires) > site quality > growth depression because of surface fire damage apprxeq age-related reduction in ANPP > interannual variability apprxeq long-term effects of fire (stand density reduction). In lichen-type forests, we found that ANPP at the landscape level declined sharply when the interval between stand-replacing fires was less than 120 years, illustrating that fire strongly influences ANPP of boreal Scots pine forests.
Abstract: Wildfire usually promotes Hooding and accelerated erosion in upland watersheds. In the summer of 1999, a high-severity wildfire burned a series of mixed pine/oak headwater catchments in the San Jacinto Mountains of southern California. Log erosion barriers (LEBs) were constructed across much of the burned area as an erosion control measure. We built debris basins in two watersheds, each about I ha in area, one with LEBs, the other without, to measure post-fire hydrologic response and sediment yield and to evaluate the effectiveness of the LEBs. The watersheds are underlain by granitic bedrock, producing a loamy sand soil above large extents of weathered bedrock and exposed core stones (tors) on the surface. Measured soil water-repellency was similar over the two catchments. Rain gauges measured 348 mm of precipitation in the first post-fire year. The ephemeral stream channels experienced surface flow after major rainstorms. and the source of the water was throughflow exfiltration at the slope/channel interface. Post-fire overland flow produced some rilling, but hillslope erosion measured in silt fences away from any LEBs was minor, as was sediment accumulation behind the LEBs. Stream channels in the catchments exhibited minor net scour. Water yield was much greater in the LEB-treated watershed. This resulted in 14 times more sediment yield by weight than the untreated watershed. Average soil depths determined by augering were nearly double in the catchment without the LEBs compared with the treated watershed. This suggests that differences in water and sediment yield between the two catchments are due to the twofold difference in the estimated soil water-holding capacity in the untreated watershed. It appears that the deeper soils in the untreated watershed were able to retain most of the precipitation, releasing less Water to the channels and thereby reducing erosion and sediment yield. Thus, the test of LEB effectiveness was inconclusive in this study, because soil depth and soil water-holding capacity may have masked their performance.
Abstract: Birds and reptiles were censused at two sites of contrasting soil texture (clay, loam) on pastoral land in the Victoria River District, Northern Territory. Both sites comprised 16 plots (each of 2.6 ha) subjected to seven different experimental fire regimes (unburnt, burnt in the early dry season at 2, 4, and 6 year intervals, and burnt in the late dry season at 2, 4, and 6 year intervals) beginning five years before sampling (and thus, not all regimes had been operationally distinct between the onset of the experiment and this sampling). The regimes were deconstructed to four fire factors: the imposed regime, the time since last fire, the number of fires since the inception of the experiment, and the number of hot (=late dry season) fires. Of 30 species recorded from at least four plots, 12 were significantly associated with time since last fire. These responses were mostly to the extremes - some species were associated with the most recently burned areas, and others occurred mainly in the plots which had been unburnt the longest. longer-term responses to fire regimes were generally less clear-cut, possibly because the relatively short duration of the imposed experimental fire treatments had not yet brought about substantial environmental divergence.
Abstract: Following fire, changes in streamflow and bank stability in burned watersheds can mobilize coarse woody debris. In 1990 and 1991, I measured characteristics of coarse woody debris and standing riparian trees and snags in Jones Creek, a watershed burned in 1988, and in Crow Creek, an unburned watershed. The mean diameter of riparian trees along Jones Creek was less than that of trees along Crow Creek, but the coarse woody debris in Jones Creek was greater in mean diameter. Tagged debris in Jones Creek was three times as likely to move, and moved over four times as far as such debris in Crow Creek. In Jones Creek, the probability of movement was higher for tagged pieces that were in contact with the stream surface. Larger pieces tended to be more stable in both streams. It appears that increased flows and decreased bank stability following fire increased the transport of coarse woody debris in the burned watershed. Overall, debris transport in Rocky Mountain streams may be of greater significance than previously recognized.
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