Management Recommendations
for
Bensoniella (Bensoniella oregana (Abrams & Bacigal.) C. Morton)

v. 2.0

by

L. Hoover and R. Holmes

December 1998

TABLE OF CONTENTS

EXECUTIVE SUMMARY

Species: Bensoniella oregana (Abrams & Bacigal.) C. Morton

Taxonomic Group: Vascular Plants

ROD Components: 1, 2 (for California only)

Other Management Status: Region 5 and 6 Regional Forester's Sensitive Species Lists, Former U.S. Fish & Wildlife Federal Candidate Category 2, Washington/Oregon Bureau of Land Management Bureau Sensitive, State of Oregon Candidate, State of California Rare, California Native Plant Society Database rare, threatened, or endangered in California and Elsewhere, Oregon Heritage Program Endangered Throughout Range.

Range: Bensoniella is limited to the Klamath Mountain Province and Coast Range of southwest Oregon and northwest California. There are approximately 86 Bensoniella occurrences in Oregon and 6 occurrences in California. The California occurrences are geographically isolated from the Oregon sites by approximately 176 kilometers (110 miles). All 6 California sites occur within a 10 kilometer (6 mile) radius of Snow Camp Mountain in central Humboldt County. There are 4 occurrences on private land and 2 in the Six Rivers National Forest with less than 1000 plants occurring on federal land (Imper 1989; Seevers and Lang 1987). One of the Six Rivers National Forest sites is an experimentally introduced population established in 1980. A potential still exists to discover additional sites in the Coast Range and Klamath Mountain Province of Oregon and California.

Specific Habitat: California and Oregon populations of Bensoniella typically occur along the periphery of meadows adjacent to seeps and small streams in the true fir zone. Elevation ranges between 600 and 1500 meters (2000 and 5000 feet) in Oregon and 900 and 1400 meters (3000 and 4600 feet) in California (Lang 1988). Prolonged moisture, edge habitat along streams and meadows providing partial canopy cover, and soils derived from ancient sedimentary rock are key habitat components (Copeland 1980; Lang 1988). Populations are most often found on north aspects. Bensoniella is most commonly associated with Senecio triangularis (arrowleaf groundsel), Mitella ovalis (oval-leaved mitrewort), Viola glabella (stream violet), and Asarum caudatum (wild ginger) (Lang 1988). It appears to tolerate some disturbance if subsurface drainage and other critical factors are not altered (USDA, Forest Service and USDI, BLM 1994; Lang 1988).

Threats: The viability of Bensoniella in California is a concern due to the small size of populations, limited genetic variability, isolation from Oregon populations, poor seed dispersal, habitat specificity, limited number of known sites, and the lack of protection on private land. Alterations to hydrology, reductions in cover, erosion, grazing, and recreation, are priority concerns for California populations.

Management Recommendations:

For known sites and selected experimental populations (populations artificially established in potential but previously unoccupied habitat):

1. Manage timber adjacent to known sites and selected experimental populations in a manner that will minimize blowdown potential.
2. Design, construct, and maintain roads to avoid hydrologic impacts at known sites. Redesign or decommission existing roads when it is necessary to restore hydrologic processes.
3. Maintain partial shade and edge habitat. Avoid logging prescriptions, firewood cutting, or other management activities that would result in direct sunlight to occupied habitat for extended periods.
4. Maintain coarse woody debris to provide microsite shading and to retain soil moisture.
5. Manage livestock to avoid consumption of plants, trampling of plants, soil compaction, increased soil erosion, and the introduction of nonnative vegetation.
6. Manage recreation to avoid trampling of plants, removal of coarse woody debris, soil compaction, and increased soil erosion.
7. Control exotic vegetation, noxious weeds, and encroaching native vegetation competitive with Bensoniella.

Information Needs:

• What are current population trends?
• How effective are habitat management and restoration efforts?
• What are the ecological requirements for Bensoniella?
• What is the impact of native herbivory on Bensoniella, and what species are involved?
• Are mycorrhizal associations necessary for germination and survival?
• What are the current population demographics at Rooster Rock and Grove's Prairie?
• What are the critical stages of Bensoniella development?
• Does apogamy occur in Bensoniella?
• Does Bensoniella exclusively self-pollinate?
• Are insects involved in pollination and, if so, which ones?
• What are the seed germination requirements for Bensoniella?
• What are the seed dispersal mechanisms?
• Is inbreeding depression occurring?
• How does Bensoniella respond to management treatments?

I. NATURAL HISTORY

A. Taxonomic/Nomenclatural History

Bensoniella was first described by Abrams and Bacigalupi in 1929 from a specimen collected by J. W. Thompson from Snow Camp in the Siskiyou Mountains of Curry County, Oregon in 1916 (Lang 1988). The authors originally named the species Bensonia oregana and the name was used by regional floras until it was realized that the genus Bensonia had been previously used to describe fossil plants in 1845. C. V. Morton from the U. S. National Herbarium renamed the species Bensoniella oregana in accordance with the rules of the International Code of Botanical Nomenclature in 1965. Over the years, bensonia, bensoniella, and coalscoop have been used as common names.

B. Species Description (Abrams and Bacigalupi 1929; Abrams and Ferris 1944; Peck 1961; Morton 1965; Munz 1973; Hickman 1993)

1. Morphology

Bensoniella is a rhizomatous perennial herb that resembles several other species in the Saxifragaceae that grow in similar habitats (Figure 1). Look-a-likes with which Bensoniella may be confused include youth-on-age (Tolmiea menziesii), foamflower (Tiarella unifoliata), leafy-stemmed mitrewort (Mitella caulescens), and large fringe-cup (Tellima grandiflora). Floral and vegetative characteristics permits the identification of Bensoniella at any time during the year.

Flowers are borne on a 20-40 cm spike-like glandular inflorescence. Pedicels are less than 1 mm long. The hypanthium is approximately 2 mm wide and saucer shaped with 5 cream-white sepals each 2 mm long. There are 5 nearly filiform petals. Stamens are 5 in number, opposite the sepals, exerted and approximately 3 mm in length. Anthers are bright salmon-pink when flowers are in full bloom. Carpels are 2 in number and the styles are nearly as long as the stamens. The capsule splits into broadly spreading valves prior to maturity exposing seeds that turn coal-black as they mature.

Leaves are all basal, 5-9 lobed, 3-7 cm long, and deeply cordate at the base. The upper leaf surface is light green and glabrous or sparsely hairy. The lower leaf surface has shaggy hairs along the veins. The petiole is entirely light green without any purple pigment toward the base and has long curly shaggy white hairs that often turn brown with age. Leaves are persistent year round

Key characteristics to look for during field surveys are salmon-pink anthers when plants are in flower, open long styled capsules with many ovules or shiny black seeds when plants are in fruit, and deeply lobed leaves with light green petioles covered with long shaggy white hairs (possibly brown hairs if older) when plants are vegetative.

Figure 1. Bensoniella oregana

From Abrams, L. and R. S. Ferris, 1944, Illustrated Flora of the Pacific States, vol II.
Reprinted with permission of Stanford University Press

2. Reproductive Biology

Vegetative growth of Bensoniella begins in early June (Copeland 1980). The inflorescence of plants become visible in mid June and mature by early July. Capsules begin to dehisce by mid July, and mature seeds are shed in mid August. Lang (1988) reports that seeds in many plants are retained until late August and probably later.

Pollination mechanisms have not been established. Copeland (1980) observed very few insects and none seemed to be interested in visiting Bensoniella flowers. Lang (1988) reported not seeing any pollinators visiting flowers during his studies even though flies, beetles, bees, wasps, and butterflies were visiting flowers of other species in the vicinity. Copeland (1980) suggests that plants self-pollinate, and Lang (1988) suggests that some apogamous mechanism may be involved. There is no genetic exchange between individuals with either of these mechanisms.

Knight (1987) reported an average of 39 ovules or seeds per capsule that would translate to a minimum of 600 seeds for each mature flowering plant. Levine (1995) estimated that Bensoniella was capable of producing as many as 100,000 seeds per square meter. Once dispersed, seeds persist on the soil surface and germinate after a long stratification period (Ganio 1982). Seedlings have been observed on sites of small disturbance such as game trails, collapsed mole tracks, gopher mounds, and streambanks. It appears that seedling survival is dependent on continuous surface moisture.

Seeds of flowering plants may be disseminated by either abiotic or biotic factors. The primary abiotic factors are gravity, water, and wind. Biotic factors include the consumption of seeds or fruits by animals and by seeds or fruits clinging externally to the feet of animals. The role of animals in seed dispersal is poorly understood and needs further study. Abiotic factors appear to be the primary mechanisms by which seeds are dispersed.

Vegetative reproduction occurs primarily through a well developed system of branching rhizomes just below the soil surface. Rhizomes will branch and then the older portions will die back producing 2 plants from one section of rhizome. Extensive branching produces patches of plants that are genetically identical.

Self-pollination, apogamy, and asexual reproduction have resulted in populations with very little genetic variation. Soltis et al. (1992) conducted enzyme analyses of material collected from Oregon and found the plants he collected to be indistinguishable. A similar study was conducted with plants collected from Rooster Rock in California by Mesler (1993). Mesler concluded that within population variability was completely absent and the variability between Oregon and California was minimal.

3. Ecology

Bensoniella oregana is typically found in edge habitat adjacent to meadows and streams. Ecological conditions most important to the survival of Bensoniella include partial shade, moist soils derived from ancient sedimentary rock, high rain fall (approximately 100 to 140 inches per year), and summer fog (Copeland 1980; Lang 1988). Other factors, such as slope and aspect are much more variable and do not appear to be as critical in defining suitable habitat. Mycorrhizal associations, though not known at this time, may be important. A more detailed account on the ecology of known sites is provided in Section I D, "Habitat Characteristics and Species Abundance."

C. Range, Known Sites

Bensoniella is limited to the Klamath Mountain Province and Coast Range of southwest Oregon and northwest California. There are approximately 86 Bensoniella occurrences in Oregon and 6 occurrences in California. The California occurrences are geographically isolated from the Oregon sites by approximately 176 kilometers (110 miles). All 6 California sites occur within a 10 kilometer (6-mile) radius of Snow Camp Mountain in central Humboldt County (Table 1). There are 4 occurrences on private land and 2 in the Six Rivers National Forest. One of the Six Rivers National Forest sites is an experimental population established in 1980. A potential still exists to discover additional sites in the Coast Range and Klamath Mountain Province of Oregon and California.

The Rooster Rock population is the only natural occurring population known to occur on federal land in California. It is located approximately 32 kilometers (20 miles) due east of Eureka within an out-holding of land in the Six Rivers National Forest. The parcel is surrounded by private land and is accessed by gated roads that are not owned by the Forest Service. The Six Rivers National Forest has been granted right-of-way.

The second known location on federal land in California occurs at Grove's Prairie in the Six Rivers National Forest. This is an experimental population established in October 1980 from plants collected at Rooster Rock that were threatened by a failing culvert. The prairie is located 32 kilometers (20 miles) northeast of Rooster Rock and 51 kilometers (32 miles) inland from the ocean at 1260 meters (4130 feet) elevation.

Table 1. Known locations of Bensoniella oregana in California.

D. Habitat Characteristics and Species Abundance

Typically, Bensoniella occurs in moist edge habitats along streams and meadows in the true fir zone of California and Oregon. Populations in both California and Oregon are all within the coastal summer fog belt. Bensoniella appears to require intermediate conditions of both sunlight and moisture. Soils are derived from ancient sedimentary rock. Bensoniella is believed to occupy only a small fraction of its potential habitat in California. The Rooster Rock site in California is located in a saddle that extends along the entire west branch of Snow Camp Creek. The narrow bottom land in the saddle contains small meadows dominated by late seral stage Douglas-fir, white fir, and incense cedar.

Copeland (1980) identified geology, soils, elevation, aspect, slope, climate, and associated species as key variables in defining the habitat of Bensoniella.

Geology and Soils - Populations in Oregon are found on soils derived from the Jurassic Dothan Formation and Jurassic Colebrooke Schists (Meyer and Amaranthus 1979). Populations in California occur on soils derived from Triassic metasedimentary bedrock of the Franciscan Formation (Copeland 1980; Levine 1995). Most soils appear to be of recent colluvial origin and tend to show little soil development. Populations throughout the species' range appear to be associated with surface or subsurface seepage. The surface soil tends to remain moist late into the summer when fruit development is well underway but is never excessively wet or saturated. Down logs and residual snow pack may be important in retaining soil moisture. The maintenance of moisture into the summer months may be a critical factor affecting seedling survival. Soils that are derived from granites, serpentine, peridotite, or are sandy are either too wet or too dry or have a nutrient balance that is not suitable for Bensoniella (Copeland 1980). The transplants at Grove's Prairie have survived since 1980 on parent material that is primarily dioritic. Numbers of individual plants have remained relatively constant; however, the number of rosettes have increased since the time of transplanting.

Elevation and Aspect - Bensoniella has been located at elevations between 600 and 1500 meters (2000 and 5000 feet) in Oregon and 900 and 1400 meters ( 3000 and 4600 feet) in California. The majority of sites throughout the species' range occur between 1070 and 1370 meters (3500 and 4500 feet) (Seevers and Lang 1987; Lang 1988). There appears to be no trend toward higher elevations in California. The absence of Bensoniella at higher sites in California could be due to the proximity of sites to the ocean and the consequent cooling effect. A cold stratification requirement for seed germination (Levine 1995) may be a factor setting the lower elevation limit. Populations are most often found on north aspects.

Slope - Oregon populations occur on slopes that range between 1 and 40 percent with an average of 12 percent (Lang 1988). California populations occur on gentle slopes (Copeland 1980). Most populations occur on ridgetops, saddles, flat pockets on upper slopes, or are associated with wet meadows at the heads of drainages where subsurface water flow fans out and is not channelized (Lang 1988).

Climate - The Klamath Mountain Province of southwest Oregon and northwest California has wet mild winters and dry warm summers. Populations are limited to the coastal summer fog belt where precipitation ranges between 254 and 356 centimeters (100 and 140 inches) per year (Meyer and Amaranthus 1979; Lang 1988).

Associated Species - Bensoniella has been observed in meadow, shrub, and forest habitats. A single population may have plants in all 3 habitats. Copeland (1980) determined that 80-90 percent of Bensoniella plants occur in meadows, 10-20 percent in riparian shrub communities, and 1-2 percent in communities with a shrub overstory. Occurrences tend to be restricted to sites receiving no more than a couple hours of direct sunlight a day (Levine 1995). Plants are commonly exposed to indirect or peripheral sunlight and are rarely found in deep shade. Lang (1988) describes the associated species occurring in these habitats.

The most common and striking associate of Bensoniella is Senecio triangularis (spear-headed senecio); others include Viola glabella (stream violet), Asarum caudatum (wild ginger), Elymus glaucus (western rye-grass), a group of related and easily confused saxifrages: Tiarella unifoliata (foamflower), Mitella ovalis (oval-leaved mitrewort), Tellima grandiflora (large fringe-cup), Tolmiea menziesii (youth-on-age); and Lotus pinnatus (bog lotus).

In addition, the Six Rivers National Forest reports Mimulus moschatus (musk-flower) and Circaea alpina (enchanter's night-shade) as typical associates and have documented the following rare species from one or more of the California sites: Sanguisorba officinalis (great burnet), Veratrum insolitum (Siskiyou false Hellebore), Pleuropogon refractus (nodding semaphore grass), Pityopus californicus (California pinefoot), Collomia tracyi (Tracy's collomia), and Juncus tenuis (rush).

Abundance - Habitat in Oregon supports many more plants than in California. Lang (1988) reported approximately 30,000 plants across the species range, most of which occurred in Oregon. Jimerson (1981) estimated between 3,560 and 6,810 plants in California. Less than 1000 plants are believed to occur on federal land in California (Seevers and Lang 1987). Imper (1989) estimated only 600 plants based on a count of inflorescences. Problems have been reported in estimating population sizes. The rhizomatous habit of the species makes it difficult to identify separate individuals and population estimates by different investigators have varied considerably. Population numbers should be considered rough estimates until counting methods are standardized.

The experimental population at Groves Prairie was established when 52 plants were moved from the gully at Rooster Rock and planted at 3 sites along a stream running along the east side of the prairie. The 3 sites include an alder dominated stream edge, a coniferous dominated stream edge, and a meadow. Annual monitoring was conducted for the years 1980 to 1985 and then again in 1990. The population has remained relatively constant with an average population size of 48; however, the number of rosettes has increased over 5 years of monitoring from 45 to 226 (Jimerson 1980-1985).

II. CURRENT SPECIES SITUATION

A. Why Species is Listed Under Survey and Manage Standards and Guidelines

Bensoniella was rated separately in Oregon and California because of the distinct differences in population viability between the 2 States. Viability analysis during development of the Northwest Forest Plan determined that Bensoniella was expected to remain stable in Oregon (91% chance of remaining stable and no risk of extirpation) but to be at high risk in California (0% chance of remaining stable and a 50% chance of extirpation). Viability of Bensoniella in California is a concern because of the small size of populations, limited genetic variability (jeopardizing adaptive ability of individual known sites), isolation from Oregon populations, poor seed dispersal, habitat specificity, limited number of known sites (6 total with 2 on federal land), and the lack of protection on private land.

B. Major Habitat and Viability Considerations

1. The viability of known sites in California will be dependent primarily on the maintenance and restoration of habitat. Specific factors relating to Bensoniella and its habitat that need to be considered for population viability include:
2. Most soils are of recent colluvial origin with little soil development.
3. Soils tend to remain moist late into the summer but are never excessively wet or saturated. Down logs and residual snow may play an important role in retaining soil moisture.
4. Populations occur within the coastal summer fog belt between 600 and 1500 meters (2000 and 5000 feet) elevation.
5. Most plants (80-90%) are located in meadows on gentle slopes (12% average).
6. Most plants are exposed to indirect sunlight for most of the day, rarely in direct light for long periods, or in deep shade.
7. Natural propagation of the species is accomplished through self-pollination, asexual reproduction, and possibly apogamy resulting in little genetic variation between populations and virtually no genetic variation within populations.
8. Ecological succession alters the structure and composition of habitat and may be detrimental to Bensoniella.
9. Structural diversity enhances the quality of the habitat. Understory canopies filter light, overstory canopies provide peripheral shade, and down logs provide shade and act as reservoirs for moisture.

C. Threats to the Species

Impacts to Oregon populations of Bensoniella have been documented from timber harvesting, grazing, road construction, and road maintenance (Copeland 1980). Additional impacts have been documented in California from recreation and catastrophic natural events. Alterations to hydrology, such as reductions in cover, erosion, grazing, and recreation, are priority concerns for California populations.

Erosion and Alteration of Hydrology - As a result of road intercepted run-off and factors related to an existing road, a large gully has developed at the Rooster Rock site that now runs along the current edge of the largest patch of Bensoniella. The gully is approximately 61 meters (200 feet) long, 4.6 meters (15 feet) deep, and 4.6-5.5 meters (15-18 feet) wide at the top. It has resulted in the loss of habitat and has altered soil moisture by lowering the water table. There is no way to know the extent of Bensoniella at Rooster Rock prior to the construction of the road and formation of the gully but it is assumed that Bensoniella occupied a larger area because of the sudden break that now exists in the population along the gully.

It is thought that the gully may be the result of the 1964 flood that caused water courses throughout northwest California to exceed their banks. It is speculated that the culvert at the population site was unable to handle the amount and intensity of the water and the excess flow bypassed the culvert and created the gully. In 1982 a stone gabion was placed at the mouth of the culvert to dissipate the energy of the water and to stabilize the banks at the culvert opening. Neither the road nor the gully appear in aerial photos taken prior to 1964.

Although the gully does not appear to be cutting any deeper, bank erosion is causing the gully to widen due to road intercepted run-off. The road passing through the site concentrates water along the in-slope ditch. During storm events, the ditch is not able to accommodate all of the water. The water cuts across the road and flows into the gully causing more erosion. The amount of erosion is not the same on both sides of the gully. Most of the erosion and bare soil is on the north side of the gully (Bensoniella is on the south side). Scattered bare patches of soil occur on the south side beyond the occurrence of Bensoniella. The gully walls, along which Bensoniella is situated, are relatively well vegetated and do not show any signs of erosion to date. Bensoniella seedlings have been observed growing on the vegetated gully walls (Hoover 1991).

The formation of the gully has created a concern for the long-term viability of the Rooster Rock population. Terry Spreiter, geologist for the Redwood National Forest, has concluded that the next 50 or 100-year flood event could expand the width of the gully by an additional 4.6 to 6.1 meters (15 to 20 feet). The loss of this much habitat would nearly eliminate all of the Bensoniella at Rooster Rock.

Another impact resulting from the gully is a lower water table. The lower water table may be causing the meadow to become drier, thereby influencing ecological succession. Currently, there is considerable encroachment of incense cedar into the meadow. Although the cedar may provide some shade, which could be beneficial, it could in time occupy the site to the exclusion of Bensoniella and further reduce available moisture. The drier soil conditions may also be detrimental to seedling establishment.

Reduction of Cover - Reduced cover from logging, wind-throw, and firewood cutting, or the removal of peripheral vegetation and coarse woody debris can lead to increased exposure to sunlight and accelerated drying of the surface soil. Coarse woody debris appears to provide micro-site shading and retention of moisture (Hoover 1990; Lang 1988). Cover in the form of logs or shrubs also serve as mechanical barriers to people and livestock.

In 1980, 32 hectares (80 acres) of the Rooster Rock parcel were exchanged with Simpson Timber Company. The 32 hectares (80 acres) were clear-cut in 1989. Blowdown commenced on the exposed forest edge along the boundary of the Six Rivers National Forest. Approximately 15-20 white fir in excess of 0.9 meters (3 feet) diameter fell during the spring following logging. This is a concern since Rooster Rock is the only natural occurring population in California. Scattered patches of Bensoniella were within the area of greatest wind-throw. Wind-throw has increased exposure to sunlight and the potential progression of wind-throw to the east would continue to adversely alter Bensoniella habitat.

In addition to the alteration of overstory cover, the blow-down has attracted firewood cutters. Between 6 and 10 logs have been completely removed. This activity has not only reduced cover and decreased soil moisture but has resulted in direct mechanical impact to individual plants. Hunters who seasonally use a primitive campsite near the Bensoniella population have also removed woody material for building campfires.

Grazing - Cattle have been observed to graze Bensoniella plants and degrade habitat by compacting soil, increasing soil erosion along streambanks, and introducing nonnative vegetation. Cattle have been observed moving in from private land onto Rooster Rock in late summer. Monitoring conducted by the Six Rivers National Forest in 1990 and 1991 documented that cattle consumed more than 85 percent of the leaf material of Bensoniella and consumed flowering stems before seeds were disseminated.

Recreation - Impacts from recreation are primarily associated with a primitive campsite located at Rooster Rock. The campsite is used primarily by hunters and receives little management attention from the Forest Service other than occasional signing. Impacts have occurred from vehicles, the collection of firewood for campfires, and the use of the creek as a source of water. These activities have damaged or destroyed plants, compacted soil, and increased erosion.

Lack of Protection on Private Land - Four of the 6 populations known in California occur on private land. The landowner for one of the sites on private land has agreed to protect the site through participation in The Nature Conservancy's Landowner Contract Program. Without similar conservation agreements with the landowners of the other 3 private parcels, a potential exists for Bensoniella to be eliminated from these sites.

D. Distribution Relative to Land Allocations

Bensoniella is currently known at 6 different locations in California. Four of these occur on private land. One of the federal locations is a naturally occurring known site, the other is an experimental population established in 1980. The known site is located in the Matrix land allocation and is designated General Forest Management under the Six Rivers National Forest Land and Resource Management Plan. The experimental population is located within a Late-Successional Reserve land allocation and is within a Tier 1 Key Watershed (Horse Linto Creek).

III. MANAGEMENT GOALS AND OBJECTIVES

A. Management Goal for the Taxon

The management goal for Bensoniella orgegana is to assist in maintaining species viability within the range of the northern spotted owl in California.

B. Specific Objectives

Maintain or restore ecological conditions favorable to the survival of Bensoniella at known sites.

Prevent disruption of soil except where it is considered necessary for habitat restoration, maintain coarse woody debris, and prevent introduction of exotic species.

Minimize impacts from livestock grazing and recreation where they are a current or potential threat.

IV. HABITAT MANAGEMENT

A. Lessons from History

Past management, research, and monitoring have provided the following lessons on the management of Bensoniella habitat.

1. Clear-cutting timber adjacent to Bensoniella habitat can result in blow-down and threaten populations.
2. Road design, construction, and maintenance have significantly affected hydrology and threatened populations.
3. Reduced cover from logging, wind-throw, firewood cutting, and other management activities can lead to increased exposure to sunlight and accelerated drying of surface soil.
4. Coarse woody debris creates favorable habitat by providing micro-site shading and retention of moisture.
5. Livestock grazing can impact populations and degrade habitat by consumption and trampling of Bensoniella plants, compacting soil, increasing soil erosion, and introducing nonnative vegetation.
6. Recreational camping and other forms of public use (e.g., firewood cutting, collection of special forest products) can impact Bensoniella and its habitat by damaging or destroying plants, removing coarse woody debris, compacting soil, and increasing soil erosion.
7. Bensoniella has survived limited disturbance at reduced levels when soil moisture and other critical factors have remained adequate.
8. Suitable habitat exists and additional populations could be located in California.
9. Bensoniella has survived transplanting into previously unoccupied similar habitat.

B. Identification of Habitat Areas for Management

Management will be applied to all known sites and any established experimental site that is considered to be important to the viability of Bensoniella in California. Decisions on the management of experimental populations will be made by the individual field office responsible for the management of that population.

C. Management Within Habitat Areas

Management goals and objectives can be achieved through habitat maintenance and restoration. Current habitat conditions should be maintained in habitat areas identified for management that do not have any identifiable threats. Habitat areas identified for management that do have identifiable threats should be managed in such a way so as to eliminate threats and restore favorable habitat conditions. Sites that have been chosen for management should include an area that is large enough to maintain the habitat and associated microclimate of the population. The size of the area should be determined by a field visit and consider factors such as landscape context, slope, topographic position, aspect, and forest structure and composition (Chen et al. 1995; Harris 1984).

Specific management recommendations for known sites and selected experimental populations are listed below.

1. Manage timber adjacent to known sites and selected experimental populations in a manner that will minimize blowdown potential.
2. Design, construct, and maintain roads to avoid hydrologic impacts at known sites. Redesign or decommission existing roads when it is necessary to restore hydrologic processes.
3. Maintain partial shade and edge habitat. Avoid logging prescriptions, firewood cutting or other management activities that would result in direct sunlight to occupied habitat for extended periods.
4. Maintain coarse woody debris to provide micro-site shading and to retain soil moisture.
5. Manage livestock to avoid consumption of plants, trampling of plants, soil compaction, increased soil erosion, and the introduction of nonnative vegetation.
6. Manage recreation to avoid trampling of plants, removal of coarse woody debris, soil compaction, and increased soil erosion.
7. Control exotic vegetation, noxious weeds, and encroaching native vegetation competitive with Bensoniella.

D. Other Management Issues and Considerations

Two additional management issues could affect the viability of Bensoniella in California. First, sites in California are disjunct from those in southwest Oregon and are small in size, making them vulnerable to inbreeding depression. Secondly, 4 of the 6 sites known in California occur on private land. Preparation of Conservation Agreements with private landowners should be considered in order to offset any loss of individuals or alteration of habitat occurring at known sites as well as to reduce the isolation of known sites.

V. RESEARCH, INVENTORY, AND MONITORING NEEDS

The objective of this section is to identify opportunities for additional information which could contribute to more effective species management. The content of this section has not been prioritized or reviewed as to how important the particular items are for species management. While the inventory, research, and monitoring identified below are not required, these recommendations should be addressed by a regional coordinating body at the Northwest Forest Plan level.

A. Data Gaps and Information Needs

In 1980 Six Rivers National Forest contracted surveys of potential habitat along South Fork Mountain on the Mad River Ranger District and in selected stream and meadow habitat on the Lower Trinity and Gasquet Ranger Districts. Surveys were conducted in potential habitat proximal to the known populations by Forest Service botanists in 1981 and 1983. A significant amount of potential habitat remains to be surveyed and additional surveys need to be conducted. A better understanding of what constitutes potential habitat would be beneficial. Priority for surveys should be given to those areas where management treatments or projects are scheduled or proposed. Surveys should be conducted according to agency sensitive species survey protocols until survey and manage species' protocols are developed by the Regional Ecosystem Office.

B. Research Questions

Some examples of the types of questions that research could investigate to provide additional information for the effective management of Bensoniella in California are listed below.

Ecological Studies

What are the ecological requirements for Bensoniella to survive and reproduce?

What is the impact of native herbivory on Bensoniella, and what species are involved?

Are mycorrhizal associations necessary for germination and survival?

Demographic Studies

What are the current population demographics at Rooster Rock and Grove's Prairie?

What are the critical stages of Bensoniella development?

Reproductive Biology

Does apogamy occur in Bensoniella?

Does Bensoniella exclusively self-pollinate?

Are insects involved in pollination and, if so, which ones?

What are the seed germination requirements for Bensoniella?

What are the seed dispersal mechanisms?

Is inbreeding depression occurring?

Management Treatments

How does Bensoniella respond to management treatments?

C. Monitoring Needs and Recommendations

A monitoring plan has already been developed and implemented at the 2 sites located on federal land (Grove's Prairie and Rooster Rock). These monitoring efforts need to be continued to determine population trends and the effectiveness of habitat management and restoration. Similar efforts will need to be considered at known sites and selected experimental populations identified in the future to determine the viability of Bensoniella in California.

VI. REFERENCES

Abrams, L. and R. S. Ferris. 1944. An Illustrated Flora of the Pacific States, v. II. Stanford University Press, Stanford, California.

Abrams, L. and R. Bacigalupi. 1929. A new genus of the Saxifragaceae family. Contr Dudley Herb 1:95-96.

Chen, J., J. Franklin, and T. Spies. 1995. Growing season microclimatic gradients from clear-cut edges into old-growth Douglas-fir forests. Ecological Applications 5(1):74-86.

Copeland, W. 1980. Bensoniella oregana: Field study and status report, final summary. Six Rivers National Forest, Eureka, California.

Ganio, L. 1982. Seed Germination in Bensoniella oregana. Senior thesis, Dr. Meredith, Biol 125, Humboldt State University.

Harris, L. D. 1984. The Fragmented Forest. University of Chicago Press, Chicago.

Hickman, J. (Ed.). 1993. The Jepson Manual: Higher Plants of California. University of California Press, Berkeley, California.

Hoover, L. D. 1991. Personal observations. Six Rivers National Forest, Eureka, California.

Hoover, L. D. 1990. Personal observations. Six Rivers National Forest, Eureka, California.

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