Full references and summaries where available
(in alphabetical order of first author name by site):

REVIEWS/SYNTHESES

Jordan, C.F. (1985) Nutrient Cycling in Tropical Forest Ecosystems. John Wiley and Sons, Chichester. 190 pp.

Sanford, R.L. and E. Cuevas (1996) Root growth and rhizosphere interactions in tropical forests. In: Tropical Forest Plant Ecophysiology. (S.S. Mulkey, R.L. Chazdon and A.P. Smith, eds.), pp. 115-122. Chapman and Hall, New York.

Vitousek, P.M. (1984) Litterfall, nutrient cycling, and nutrient limitation in tropical forests. Ecology 65, 285-298.

Summary

Patterns of nutrient cycling (nitrogen - N, phosphorus - P and calcium) through litterfall were evaluated based upon published information from 62 tropical forests. Lowland tropical forests generally have more N and lower dry mass/N ratios in litterfall than most temperate forests, while N return in montane tropical forests is comparable to temperate forests. Many tropical forests have little P return and very high dry matter/P ratios in litterfall compared to most temperate forests - P appears to be cycled highly efficiently. Fine litterfall was predicted from climate, and the residuals of this regression were positively correlated with P but not N concentration in litterfall. Fine litterfall (uncorrected for climate) was also significantly correlated with P concentration in moist and wet lowland tropical forests. This suggests that P but not N availability limits litterfall in a substantial subset of intact tropical forests.

ATHERTON

Stocker, G.C., W.A. Thompson, A.K. Irvine, J.D. Fitzsimon and P.R. Thomas (1995) Annual patterns of litterfall in a lowland and tableland rainforest in tropical Australia. Biotropica 27, 412-420.

Summary

Over a 5 year period, fine litterfall (mostly leaves, twigs up to 1 cm diameter, and reproductive parts) was collected weekly from 30 traps randomly arranged in each of two 0.5 ha plots in tropical rainforests at two contrasting sites (lowland and tableland) in North Queensland, and sorted by species and components. Fine litterfall (±95% confidence limits) was 800 ± 36 g/m2/year at the lowland site and 1103 ± 47 g/m2/year at the tableland site. The range over 5 years of fine litterfall was not great (704-874 g/m2/year at the lowland site; 1002-1364 g/m2/year on the tableland), but reproductive material varied substantially, both in absolute amount (85-186 and 141-474 g/m2) and as a percentage of total litterfall for any year (12-21% and 14-35%) for lowland and tableland sites respectively. The old leaf component showed a seasonal maximum (October/November-hot dry season), whereas fruits and flowers were more irregularly spread through the year. The mean ratio of annual litterfall mass of reproductive material to leaves was 0.32. The high value of this ratio may be attributed to our shorter sampling interval (7 days) compared to longer intervals used in most other tropical rainforest litterfall studies. In a comparison of our results with other Australian studies, we estimated that fruit and flower mass in litter traps in tropical rainforest declines 50 percent every 10 days relative to leaf litter mass.

Spain, A.V. and R.P. le Feuvre (1987) Breakdown of four litters of contrasting quality in a tropical Australian rainforest. Journal of Applied Ecology 24, 279-288.

Summary

Rates of litter breakdown of Pinus caribaea, Araucaria cunninghamii, and Eucalyptus alba in northeastern Queensland were assessed using litter bags and compared with that of a mixed-species lowland tropical rainforest. Litter was exposed during the early part of the summer wet season and its breakdown studied for 253 days, during which time more than 1660 mm of rain fell (annual precipitation being 3609 mm). Rates of litter breakdown decreased in the order: E. alba > (mixed species rain forests, A. cunninghamii) > P. caribaea. Excluding arthropods from coarse and fine-mesh bags demonstrated that the litter of the mixed-species rainforest and E. alba were attractive to arthropods while that of P. caribaea was not; A. cunninghamii litter was excluded from the comparison. For litter of all species, breakdown rates were not simply related to the initial contents of elements, neutral detergent fibre or acid-detergent lignin. Single and double exponential regression models provided satisfactory fits to the data from all except the resistant litter of P. caribaea, where an asymptotic model proved appropriate.

Spain, A.V. (1984) Litterfall and the standing crop of litter in three tropical Australian rainforests. Journal of Ecology 72, 947-961.

Summary

Annual litterfall and the standing crop of litter were determined for three contrasting rainforest sites on similar soils but with different climatic regimes in northeastern Queensland. Litterfall varied between sites and ranged from 728 to 1053 g/m2/year for all sites over a period of 3 years. Litterfall is strongly seasonal and the heaviest falls occurred in the latter part of the dry season and the early part of the wet season. Between-year variation in the total litterfall was low and 3-year coefficients of variation within sites ranged from 4.5% to 10.0%. The proportions of leaf, fine woody material, and of flowers, fruits and seeds were assessed for 14 months and related to the characteristics of the forests. Seasonal, annual and between-site variation in the standing crops of litter was marked. The minimum standing crop at the most mesophytic sites was approximately 300 g/m2; the maximum recorded was in excess of 1050 g/m2. Over 14 months, the relative proportions of leaf, wood, and of flowers, fruits and seeds in the standing crop of litter varied seasonally and between sites.

Brasell, H.M. and D.F. Sinclair (1983) Elements returned to forest floor in two rainforest and three plantation plots in tropical Australia. Journal of Ecology 71, 367-378.

Summary

Potassium, calcium, magnesium and sodium returns to the forest floor in rainfall, throughfall, litterfall and branchfall were compared for a tropical rainforest and an adjacent plantation of Araucaria cunninghamii at two sites with contrasting rainfall and soil fertility. At one site a plantation of Flindersia brayleyana was also compared. The input of potassium was highest in the rainforest plots at each site. The addition of sodium was higher at the wetter site, and was mostly derived from rainfall. Estimates of the loss of dry weight and elements from the litter layer, based on the relationship between litterfall and the standing crop of litter on the forest floor, were greater in the rainforest plots than in the Araucaria plantations. The annual rate of litter disappearance (k, the quotient of the annual litterfall to the mean amount of litter on the forest floor) ranged from 0.69 for the Araucaria plot to 1.25 for the rainforest plot at the same site.

Brasell, H.M., G.L. Unwin and G.C. Stocker (1980) The quantity, temporal distribution and mineral element content of litterfall in two forest types at two sites in tropical Australia. Journal of Ecology 68, 123-139.

Summary

We compared litterfall from two plots, one on a plantation of Araucaria cunninghamii and the other on an adjacent rain forest at two sites in northeastern Australia over 3 and 4 years respectively, for quantity, temporal distribution, and the content of nitrogen, phosphorus, sodium, potassium, calcium and magnesium. The average litterfall for the four plots or two sites was 925 g/m2/year, comparable to values from similar studies on other tropical forests. No consistently significant differences were found in the quantity of litterfall between forest types or sites, or between years on the rain forest plots. Litter from the rain forest plots at both sites had significantly higher concentrations of nitrogen and potassium than litter from the Araucaria plots. Litter from both forest plots at the site where the soil was more fertile had significantly higher concentrations of nitrogen, phosphorus, potassium and calcium than did the litter from the less fertile site. For nitrogen, however, the differences between plots in the two forest types were greater than the differences between sites. The calcium content of Araucaria litter during the period of heavy seed production in December-January of the second study year was lower than at all other times. The conversion of rain forest to Araucaria plantation at each site appears to have been little effect on the annual accession to the soil of litter and the associated mineral elements; differences between sites in properties such as soil fertility and rainfall also had little effect.

BARRO COLORADO

Chave, J., R. Condit, S. Lao, J. P. Caspersen, R. B. Foster, and S. P. Hubbell (2003) Spatial and temporal variation of biomass in a tropical forest: results from a large census plot in Panama. 91, 240-252.

Summary

We estimated the dry, living, above-ground biomass (AGB) standing stock and its turnover in a 50-hectare forest plot located in moist tropical forest on Barro Colorado Island, Panama. The estimates were obtained using inventory data collected every 5 years from 1985 to 2000, including measurements of all trees = 1 cm diameter.

Condit, R., S.P. Hubbell and R.B. Foster (1995) Mortality rates of 205 neotropical tree and shrub species and the impact of a severe drought. Ecological Monographs 65, 419-439.

Summary

We estimated mortality rates of 205 tree and shrub species during two intervals, 1982-1985 and 1985-1990, in two size classes, 1-10 and > 10 cm in diameter, in a 50-ha census plot in tropical moist forest on Barro Colorado Island in Panama. The severe dry season of 1983 was the focus of the study, since prior observations had demonstrated that it caused mortality in the forest. Results show that forest-wide mortality was c. 3%/yr during the drought interval but only 2%/yr during the period afterwards, and that excess mortality during the first interval amounted to 2% of stems in the larger size class and 1% in the smaller. Our conclusions emphasize diversity as well as pattern. Every trend we illustrated had well-documented exceptions (i.e., large trees with lower mortality during the drought period). Clearly, predicting how tropical forests will respond to climatic perturbations will require much detailed information from many species.

Cornejo, F.H., A. Varela and S.J. Wright (1994) Tropical forest litter decomposition under seasonal drought - nutrient release, fungi and bacteria. Oikos 70, 183-190.

Summary

The consequences of seasonal drought for nutrient release and bacterial and fungal numbers during dry season litter decomposition were studied using irrigation, in a tropical forest on Barro Colorado Island, Panama. Litter bags containing a single species of leaves were placed beneath conspecific trees at the onset of the dry season in December 1987 and collected at one-month intervals until the onset of the wet season in May 1988. Serial dilutions were used to quantify densities of fungi and bacteria. Nutrient concentrations in recalcitrant litter fractions showed rapid declines in the first month of exposure (K,P) followed by bioaccumulation (N) or no significant changes over the next four months (P, K, Mg and most Ca). Irrigation depressed K concentrations and enhanced N and Mg concentrations, possibly as a consequence of leaching and bioaccumulation, respectively.

Leigh, E.G., Jr (1999) Tropical Forest Ecology: A View from Barro Colorado Island. Oxford University Press, New York.

Leigh, E.G., A.S. Rand, D.M. Windsor, eds. (1982) The Ecology of a Tropical Forest: seasonal rhythms and long-term changes. Smithsonian Institution, Washington DC. 468 pp.

Wright, S.J. and F.H. Cornejo (1990) Seasonal drought and leaf fall in a tropical forest. Ecology 71, 1165-1175.

Summary

Peak rates of leaf fall almost always occur during dry seasons in low-latitude, low-elevation tropical forests. We tested the hypothesis that plant water stress is the proximal cue for leaf fall by augmenting water supplies during the 4-mo dry season over two 2.25-ha plots of tropical moist forest on Barro Colorado Island (BCI), Panama. Our manipulation maintained soil water potentials at or above field capacity throughout the dry season, but did not affect atmospheric conditions in the canopy (i.e., relative humidity, temperature, windspeed, incident radiation). We ameliorated plant water status as measured by dry-season leaf water potentials compared with wet-season values. Leaf fall was delayed for 2 of 9 tree species for which quantitative data are available, but the timing of leaf fall was indistinguishable between manipulated and control plots for the remaining 25 species. It appears that neither plant water status (nor perhaps any single factor) is the proximal cue for leaf fall on BCI..

CHAMELA

Campo, J., J.M. Maass, V.J. Jarammillo, and A. Martínez-Yrízar (2000) Calcium, potassium and magnesium cycling in a Mexican tropical dry forest ecosystem. Biogeochemistry 49, 21-36.

Campo, J., J.M. Maass, V.J. Jarammillo, A. Martínez-Yrízar and J. Sarukhán (accepted) Phosphorus cycling in a Mexican tropical dry forest ecosystem. Biogeochemistry

Castellanos, J., M. Maass and J. Kummerow (1991) Root biomass of a dry deciduous tropical forest in Mexico. Plant and Soil 131, 225-228.

Filip, V., R. Dirzo, J.M. Maass and J. Sarukhán (1995) Within- and among-year variation in the levels of herbivory on the foliage of trees from a Mexican tropical deciduous forest. Biotropica 27, 78-86.

Kummerow, J., J. Castellanos, J.M. Maass and A. Larigauderie (1990) Production and seasonality of fine-root growth in a Mexican deciduous dry forest. Vegetatio 90, 73-80.

Maass, J.M., J.M. Vose, W.T. Swank and A. Martínez-Yrízar (1995) Seasonal changes of leaf area index (LAI) in a tropical deciduous forest in west Mexico. Forest Ecology and Management 74, 171-180.

Martínez-Yrizar, J. Sarukhán, A. Pérez-Jiménez, E. Rincón, J.M. Maass, A. Solís-Magallanes, and L. Cervantes (1992) Above-ground phytomass of a tropical deciduous forest on the coast of Jalisco, Mexico. Journal of Tropical Ecology 8, 87-96.

Martínez-Yrízar, A., J.M. Maass, L.A. Pérez-Jiménez and J. Sarukhán (1996) Net primary productivity of a tropical deciduous forest ecosystem in western Mexico. Journal of Tropical Ecology 12, 169-175.

CINNAMON BAY

Weaver, P.L. (1996) Forest productivity in the Cinnamon Bay Watershed, St. John, U.S. Virgin Islands. Caribbean Journal of Science 32, 89-98.

Summary

Above-ground NPP averaged 1064 g/m2/year and was estimated by summing litterfall (897 g/m2/year), herbivory rate (250 g/m2/year) and the above-ground biomass change (142 g/m2/year). Standing herbivory averaged 4.5% of the leaves and the herbivory rate was estimated at 4.6% per year. Standing crop of litter was 933 g/m2 with a turnover rate of 0.96 times per year. Recovering from past agricultural uses, the secondary forest in Cinnamon Bay watershed is maintained in a state of flux due to tree mortality caused by frequent disturbances such as hurricanes and periods of drought.

DARIEN

Golley, F.B., et al. (1975) Mineral Cycling in a Tropical Moist Forest Ecosystem. University of Georgia Press, Athens. 248 pp.

GUNUNG MULU

Proctor, J., J.M. Anderson, P. Chai and H.W. Vallack (1983) Ecological studies in four contrasting lowland rain forests in Gunung Mulu National Park, Sarawak. I. Forest environment, structure and floristics. Journal of Ecology 71, 237-260.

Summary

Gunung Mulu National Park, Sarawak, extends over an area of 544 km2 and elevations from 50 to 2376 m, and has a wide range of rain forest formations on several soil types. It receives about 5000 mm of annual rainfall. Sites of one hectare were established in each of four contrasting types of primary lowland rain forest: alluvial forest (AF); dipterocarp forest (DF); heath forest (HF) and forest over limestone (LF). All trees (>10 cm dbh) were measured for dbh and height, except for the LF where height was calculated using a regression equation based on height and diameter measurements of a sample of 34 trees. Estimates of numbers or biomass or both of small trees (<10 cm dbh), lianes, ground herbs and ferns, and epiphytes (including ferns) <3m from the ground were also made. Epiphytes >3 m from the ground and bryophytes were not ennumerated. The total above-ground forest biomass (g/m2 dry weight) for AF, DF, HF and LF was calculated as 25,000, 65,000, 47,000, and 38,000, respectively. Leaf and branch material were collected from each tree and, as far as possible, identified by species.

Proctor, J., J.M. Anderson, S.C.L. Fogden and H.W. Vallack (1983) Ecological studies in four contrasting lowland rain forests in Gunung Mulu National Park, Sarawak. II. Litterfall, litter standing crop and preliminary observations on herbivory. Journal of Ecology 71, 261-283.

Summary

We compared small litterfall (leaves, wood <2 cm diameter, reproductive parts, and trash) on sites of 1 ha in each of four types of lowland forest in Gunung Mulu National Park, Sarawak, for quantity, seasonal distribution and the concentrations of nitrogen, phosphorus, potassium, sodium, calcium, magnesium and total phenols. An alluvial forest (AF), a dipterocarp forest (DF) and a heath forest (HF) were sampled for 50 weeks and a forest over limestone was sampled for 42 weeks. The total small litterfall (g/m2/year ±95% confidence limits) was 1150 ±190, 880 ±60, 920 ±120, and 1200 ±130 for the AF, DF, HF, and LF, respectively. Litterfall peaked at all four sites during a May-June period of high rainfall before the driest time of the year. The element concentrations in the litterfall differed greatly between each forest type. Large-wood litterfall was measured over a shorter period than the small litterfall. Litterfall for the >2cm--<10 cm diameter wood ranked AF > HF > LF > DF and virtually no wood over 10 cm in diameter fell in the collection quadrats. Small-litter standing crop showed some changes with season and differences between the forests. The lowest value was 470 g/m2 in the AF in March 1978 and the highest was 750 g/m2 in the LF in February 1978. Large-wood (>10 cm diameter) standing crop values (g/m2/year ±95% confidence limits) were 2030 ±1760, 5270 ±2700, 2270 ±1660, and 5230 ±3810, for the AF, DF, HF and LF, respectively. Levels of herbivory, judged from the proportions of areas of leaves in litterfall eaten by invertebrates, were at least as high as reported values in other tropical forests, and were ranked AF > HF > DF >LF.

Anderson, J.M., J. Proctor and H.W. Vallack (1983) Ecological studies in four contrasting lowland rain forests in Gunung Mulu National Park, Sarawak. III. Decomposition processes and nutrient losses from leaf litter. Journal of Ecology 71, 503-527.

Summary

We measured soil respiration, leaf litter decomposition and litterfall-standing crop quotients during one year in three rain forest types in Gunung Mulu National Park, Sarawak: alluvial forest (AF), dipterocarp forest (DF) and heath forest (HF). Comparative studies were also made in forest over limestone (LF) over a 6-month period. Soil respiration at the three main sites exhibited considerable variation which was not attributable to changes in soil temperature or moisture. For the four sites, mean annual soil temperatures in the litter layers ranged from 24.3-25.6 C and mean values for sampling occasions varied <1 C over the year. No single group of variables can be identified which accounts for differences between sites in litter decomposition and accumulation of organic matter in the soil nor the slow decay rates at these sites in general. Decomposition and nutrient cycling processes in humid tropical areas appear to be are more complex and variable than is typically indicated in the literature.

JOHN CROW RIDGE

Tanner, E.V.J. (1977) Four montane rain forests of Jamaica: a quantitative characterization of the floristics, the soils and the foliar mineral levels, and a discussion of the interrelations. Journal of Ecology 65, 883-918.

Summary

The tree flora is described for 38 plots, 10 x 10 m, in four forest types at c. 1550 m altitude on the ridge between John Crow Peak and Morce's Gap in the Blue Mountains in Jamaica. The four forest types (Mor Ridge, Mull Ridge, Wet Slope and Gap) can be assigned to three associations: the Chaetocarpus globosus-Clusia cf. havetioides-Lyonia cf. octandra association (Mor Ridge), the Dendropanax pendulus-Hedyosmum arborescens-Podocarpus urbanii association (Mull Ridge and Wet Slope) and the Cyathea pubescens-Meriania purpurea-Solanum punctulatum association (Gap). The two Ridge forests have a higher basal area and more individuals per unit area than the Gap and Wet Slope forests and the distributions of individuals in girth size-classes show that most species are regenerating. Competitively, the forests appear to line up with the Gap > Mull Ridge > Mor Ridge and the Gap forest also seems to be more competitive than the Wet Slope forest. The organic matter quantity in the soil decreases in the series Mor Ridge > Mull Ridge > Gap > Wet Slope. It is tentatively suggested that the Mor Ridge forest is limited primarily by the extremely low soil pH (2.8-3.5), that the Mull Ridge forest is limited relative to the Gap forest by a slower circulation of nutrients, and that the Wet Slope forest is limited relative to Mull Ridge forest by the lack of support provided in the very shallow soil (<30 cm deep) and the difficulty of establishment on a 30 degree slope. In comparison to the soils of Lower Montane Rain forests in Puerto Rico and New Guinea, the Jamaican forest soils are low in total carbon (except for Mor Ridge soil), total nitrogen and instantaneously exchangeable bases.

Tanner, E.V.J. (1980) Studies on the biomass and productivity in a series of montane rain forests of Jamaica. Journal of Ecology 68, 573-588.

Summary

Standing crop biomass was estimated in five Upper Montane forest types in Jamaica for 42 plots, 10 x 10 m. Two plots were destructively sampled, one in the Mor Ridge forest and one in the well-developed Mull Ridge forest. The total above-ground biomass (g/m2) of each forest type was estimated from regression equations derived from the total above-ground tree biomass on tree area at breast height: 22900 in Mor Ridge forest, 31200 in Mull Ridge forest, 40700 in well-developed Mull Ridge forest, 23000 in Wet Slope forest and 23800 in Gap forest. Regression equations derived for tree leaf biomass on tree area at breast height were not used to predict tree leaf biomass because of the large amount of variability in the data. Below-ground biomass was determined only in Mor Ridge forest. The biomass of roots and underground stems was estimated to be 5400 g/m2 in an excavated area of 3.5 x 5.0 m. The biomass of seedlings and saplings, tree ferns, herbs, climbers, epiphytes, hemi-parasites and standing dead trees was also determined. The total leaf area index was 5.5 in the Mor Ridge forest and 5.7 in the well-developed Mull Ridge forest. First estimates of standing crop, live biomass increase (g/m2/yr), using dendrometers, were: c. 50 in Mor Ridge forest, c. 100 in Mull Ridge forest, c. 200 in Wet Slope forest and c. 350 in Gap forest. Loss estimates of live, standing crop, above-ground biomass (g/m2/yr) were: c. 200 in Mull Ridge forest, c. 270 in Wet Slope forest and c. 60 in Gap forest. Comparison of the Jamaican montane forests with other tropical forests shows that with increasing elevation, there is a proportionately greater reduction in forest canopy height than in total above-ground biomass. However, leaf biomass is not less in forests at higher altitudes.

Tanner, E.V.J. (1980) Litterfall in montane rain forests of Jamaica and its relation to climate. Journal of Ecology 68, 833-848.

Summary

Litterfall was studied at four sites in an impoverished Montane Rain forest at c. 1550 m in the Blue Mountains of Jamaica, during two separate periods—January 1974 to March 1975 and March 1977 to April 1978. Temperature, rainfall, throughfall, relative humidity, litterfall and water content of the trapped litter were studied for varying lengths of time. The ranges of mean monthly maximum and minimum temperatures were 18.5-20.5 C and 11.0-12.0 C, respectively. Rainfall in the area was c. 2500 mm/yr. Relative humidity in the forest was usually above 90% due to persistent low cloud and fog. Rainfall was markedly seasonal; 5 months (four consecutive) each had less than 200 mm, but the effects were mollified by the high humidity. Total litterfall (g/m2/yr) in the Mor Ridge, Mull Ridge, Wet Slope, and Gap forests was 660, 550, 560, and 650, respectively and leaf litterfall was 490, 530, 440, and 550, respectively. During the drier period, January to August, the litterfall rate was twice that during the wet period for all forests. Mean leaf life was estimated as c. 18 months in the Mor Ridge forest and c. 13 months in the well-developed Mull Ridge forest. Although leaf biomass and leaf litterfall quantity in the upper Montane Rain forests were similar to published values for the Lower Montane and Lowland forests, above-ground net primary production was lower in Upper Montane Rain forests than in Lowland Rain forests (c. 700 compared to c. 1600 g/m2/yr).

Tanner, E.V.J. (1981) The decomposition of leaf litter in Jamaican montane rain forests. Journal of Ecology 69, 263-275.

Summary

Litter accumulation and decomposition were studied over two separate years in four montane rain forests (Mor Ridge, Mull Ridge, Wet Slope, and Gap forests) located at an elevation of c. 1550 m in Jamaica. Mean standing crop of leaf litter ranged from 810 to 1170 g/m2. Mean decomposition rates for leaf litter standing crop at the three sites on level ground were 68%/yr, 45%/yr, and 44%/yr for the Gap, Mull Ridge, and Mor Ridge forests, respectively. Decomposition of freshly fallen leaves varied from 27% to >96%/yr between species (15 studied); was not affected by site of collection, but was affected by site of decomposition in one year (of two); was slower in drier periods; was positively correlated with the nitrogen and phosphorus concentrations of mature leaves; and was not significantly correlated with various anatomical features of the leaves. A comparison of data for a range of tropical rain forests suggests that leaf litter decay rates parallel the net primary productivity and stature of the forest, irrespective of elevation.

KADE

Greenland, D.J. and J.M.L. Kowal (1960) Nutrient content of the tropical moist forest of Ghana. Plant and Soil 12, 154-174.

Summary

We determined the total weight of vegetation on a one-acre (0.4 hectare) area of old secondary forest in the moist forest zone of Ghana to be 144 imperial tons per acre dry weight (365.5 tonnes per hectare). Nutrient content of each component of the vegetation was also estimated, showing that the amounts of major nutrients immobilised were as follows in pounds per acre (g/m2): N, 1800 (202); P 120 (13.5); K 800 (89.7); Ca 2400 (269); Mg 350 (39.2). The corresponding amounts of nutrients in the top 12 inches (30.5 cm) of soil were in pounds per acre (g/m2): total N, 4100 (460); available P, 11 (1.23); exchangeable K, 580 (65.0); exchangeable Ca, 2300 (258); exchangeable Mg, 330 (37.0). About half the nutrients stored in vegetation were in readily combustible material, and except for N would be released to the soil in the case of clearing and burning for cultivation. The quantity of roots and amount of nutrients they contained would not make an important addition to soil nutrients during cultivation, although 85.5% of roots were within 12 inches (30.5 cm) of the soil surface.

John, D.M. (1973) Accumulation and decay of litter and net production of forest in tropical West Africa. Oikos 24, 430-435.

Summary

Monthly fall of small litter in traps was measured over 26 months, and wood litter once over 6 months, for a moist semi-deciduous forest in Ghana. Dry weight of ground litter and its rate of disappearance were also measured. Litterfall was greatest from January to early March, with a small peak in leaf fall also from September to early December; the major peak corresponded to the driest part of the year. About 77% of the total annual fall of 966 g/m2 was leaf material. No significant differences were found between forest growing on two different soil types, and little difference between the two years. Litter decay times ranged between 0.25 and 9.0 years, with leaf litter disappearing nearly three times as fast as twigs. Net dry matter production was estimated roughly as 2200-2500 g/m2/yr.

Lawson G.W., Armstrong-Mensah, K.O., and Hall, J.B. (1970) A catena in tropical moist deciduous forest near Kade, Ghana. Journal of Ecology 58, 371-398.

Summary

The variation in structure and composition of vegetation was investigated along a catena in moist semi-deciduous forest near Kade, Ghana, and correlations with soil types and microclimate attempted. Microclimatic observations showed there was little difference in the diurnal ranges of air and soil temperatures, relative humidity and evaporation of the top, middle and bottom slopes of the catena under forest conditions, though much larger differences were found where the canopy had been removed. In upper (Bekwai series) and middle (Nzima series) slope soils, over 80% of the root mass occurred in the top 10 cm as against only 50% in the alluvial soil in the valley bottom. The standing crop of trees on the middle slope, measured by basal area, was somewhat greater than that of the upper slope.

Nye, P.H. (1960) Organic matter and nutrient cycles under moist tropical forest. Plant and Soil 13, 333-346.

Summary

The amount and composition of litter and rain falling beneath a tropical high forest in Ghana were measured continuously throughout the year. Litter was considerably richer in N than temperate forest litter. On the forest floor it decomposed very rapidly at an average rate of 1.3% per day. 16% of annual rainfall was intercepted by the canopy and evaporated before it reached the ground. Compared with the amount falling as litter, very large amounts of K and significant amounts of P and Mg, but only a little N and Ca were washed out of the canopy by rain, with HCO3- as the anion. Little Na, Cl or SO4 leached as leaf drips. Amounts of nutrients in litter fall, rain wash and estimated amounts in timber fall were added together to give the rate of nutrient cycling.

KHAO CHONG

Kira, T., H. Ogawa, K. Yoda and K. Ogino (1964) Primary production by a tropical rain forest of Southern Thailand. Botanical Magazine Tokyo 77, 428-429.

Kira, T., H. Ogawa, K. Yoda and K. Ogino (1964) Comparative ecological studies on three main types of forest vegetation in Thailand. IV. Dry matter production, with special reference to the Khao Chong rain forest. In: Nature and Life in Southeast Asia Vol. V (T. Kira and K. Iwata, eds.) pp. 149-174.

Summary

The principle, procedures and results are presented of a trial to estimate primary organic production by a tropical rain forest in Khao Chong Forest Reserve, Trang Province, southern Thailand. Empirical formulae relating diameter at breast height (DBH) to tree biomass were combined with DBH increments of all trees over 4.5 cm DBH on a 40 a 40 m plot. Tree live biomass increment averaged 656 g/m2/year, whilst tree mortality was 122 g/m2/year. Daily litterfall was estimated using plastic net stretched over the ground for a period of 1.5 months. By extrapolation, annual litterfall would be 2330 g/m2/year, of which 51% was leaves. Net primary production was estimated at 2860 g/m2/year, excluding heterotrophic consumption and fine root turnover. Adding the estimated annual respiratory consumption gives gross primary production of 12,320 g/m2/year. High respiratory turnover and low net biomass increase are suggested as characteristic of a climax forest.

LA SELVA

Clark, D.B. and D.A. Clark (2000) Landscape-scale variation in forest structure and biomass in a tropical rain forest. Forest Ecology and Management 137, 185-198.

Summary

We used three data sets to estimate stem number, basal area, and above-ground (AG) biomass over a 600-hectare old-growth tropical rain forest landscape (La Selva, N.E. Costa Rica). We analyzed the effects of soil type, slope angle, topographic position, and different sample designs and measurement techniques on these estimates. All three data sets were for woody stems greater than or equal to 10 cm in diameter. Basal area, estimated AG biomass and the contributions of major life forms were similar among studies, in spite of the differences in sampling design and measurement techniques. The methods used to measure buttressed trees had a large impact. Plot sizes of 0.35-0.5 ha were sufficient to achieve coefficients of variation of <12% for basal area with only six replicates in a given edaphic type. AG biomass estimates ranged from 161 to 186 Mg/ha. These low values appear to be mainly due to the Tropical Wet Forest allometry equation used. This in turn may be indicative of a real and substantially lower ratio of biomass/basal area in Tropical Wet Forest than in Tropical Moist Forest.

Lieberman, D., M. Lieberman, G. Hartshorn and R. Peralta (1985) Mortality patterns and stand turnover rates in a wet tropical forest in Costa Rica. Journal of Ecology 73, 915-924.

Summary

We determined mortality over a 13-year period for all stems (>10 cm dbh) on 12.4 ha of primary lowland tropical forest at La Selva. Altogether, 23.3% of 5623 trees and lianas present in the initial inventory had died by the time of the subsequent inventory. Mortality was independent of size and presence of buttresses. 26% of the dead trees were standing, 31% has fallen, 7% were found buried and 37% had decomposed entirely. Mortality was nearly balanced by recruitment; there was a net loss of 1.7% of stems in 13 years. With an annual loss of stems of 2.03% and a consequent stand half-life of 34 years, La Selva appears to be among the most dynamic of tropical forests studied to date.

Lieberman, D. and M. Lieberman (1987) Forest tree growth and dynamics at La Selva, Costa Rica (1969-1982). Journal of Tropical Ecology 3, 347-358.

Summary

All stems >= 10 cm dbh were tagged and measured in 1969 in permanent plots totalling 12.4 ha at La Selva. The plots were again censured in 1982 and all live trees re-measured. Mortality over 13 years was 23.2%, or 2.03% per year based on a logarithmic mortality model, suggesting a stand half-life of 34 years. Mortality was independent of size class in trees >= 10 cm dbh, and recruitment was equal to mortality....

McDade, L.A., K.S. Bawa, H.A. Hespenheide and G.S. Hartshorn, eds. (1994) La Selva: ecology and natural history of a neotropical rain forest. University of Chicago Press. 486 pp.

Vitousek, P.M. and J.S. Denslow (1986) Nitrogen and phosphorus availability in treefall gaps of a lowland tropical rainforest. Journal of Ecology 74, 1167-1178.

Summary

We report extremely high nitrogen availability (net N mineralisation) for a lowland rainforest on volacanic soil at La Selva, Costa Rica, averaging 50-80 micrograms/gram/month (822 kg/ha/year). Available phosphorus concentrations were relatively low (2.5 micrograms/gram). N mineralisation did not increase in the crown-fall zone of treefall gaps, although the possibility of a short-lived increase immediately after treefall could not be ruled out. P concentrations increased non-significantly (3.3 micrograms/gram). N mineralisation and P concentrations were significantly lower in the root-throw zone of treefall gaps compared with the crown-fall zone or the zone along the fallen trunk, factors which could select for colonising species in the root-throw zone distinct from those establishing in other zones of treefall gaps.

LUQUILLO

Cuevas, E., S. Brown and A.E. Lugo (1991) Above and below-ground organic matter storage and production in a tropical pine plantation and a paired broadleaf secondary forest. Plant and Soil 135, 257-268.

Summary

We measured the distribution of tree biomass and the allocation of organic matter production in an 11-yr-old Pinus caribaea plantation and a paired broadleaf secondary forest growing under the same climatic conditions. The pine plantation had significantly more mass aboveground than the secondary forest (94.9 vs 35.6 t/ha for biomass and 10.5 vs 5.0 t/ha for litter), whereas the secondary forest had significantly more fine roots (less-than-or-equal-to 2 mm diameter) than the pine plantation (10.5 and 1.0 t/ha, respectively). Standing stock of dead fine roots was higher than aboveground litter in the secondary forest. In contrast, aboveground litter in pine was more than ten times higher than the dead root fraction. Both pine and secondary forests had similar total organic matter productions (19.2 and 19.4 t/ha/yr, respectively) but structural allocation of that production was significantly different between the two forests; 44% of total production was allocated belowground in the secondary forest, whereas 94% was allocated aboveground in pine.

Frangi, J.L. and A.E. Lugo (1985) Ecosystem dynamics of a subtropical floodplain forest. Ecological Monographs 55, 351-369.

Frangi, J.L. and A.E. Lugo (1990) Hurricane damage to a flood plain forest in the Luquillo mountains of Puerto Rico. Biotropica 23, 324-335.

Jordan, C.F. (1971) Productivity of a tropical forest and its relation to a world pattern of energy storage. Journal of Ecology 59, 127-142.

Summary

A young secondary successional plant comunity and an older mature stand were studied with respect to net primary productivity (NPP) in the tropical forest of the Luquillo Mountains of Puerto Rico. NPP of both communities was relatively low, probably because of limited solar energy input into the forest. Comparisons were made between rates of wood production, and rates of leaf and litter production of plant communities throughout the world. Annuals have the highest rate of leaf and litter production, and often the highest rate of total production. Leaf and litter production is relatively uniform in perennial herb and grass, and tree communities. Rates of wood production by trees is similar throughout the world, but efficiency of wood production is higher in northern latitudes.

Lugo, A.E. (1992) Comparison of tropical tree plantations with secondary forests of similar age. Ecological Monographs 62, 1-41.

Summary

The structure and dynamics of small plantations of pine (Pinus caribaea; 4 and 18.5 yr old in 1980) and mahogany (Swietenia macrophylla; 17 and 49 yr old in 1980) were compared with those of paired secondary forest stands of similar age and growing adjacent to each other under similar edaphic and climatic conditions. The study was conducted in the Luquillo Experimental Forest between 1980 and 1984. Comparisons included a variety of demographic, production, and nutrient cycling characteristics of stands. Plantations had higher aboveground biomass and net aboveground biomass production than paired secondary forests. Higher root densities and biomass were found in secondary forests as were greater depth of root penetration, higher nutrient concentration in roots, and more microsites where roots grow, than paired plantations.

Scatena, F.N., W. Silver, T. Siccama, A. Johnson and M.J. Sanchez (1993) Biomass and nutrient content of the Bisley Experimental Watersheds, Luquillo Experimental Forest, Puerto Rico, before and after Hurricane Hugo, 1989. Biotropica 25, 15-27.

Summary

We estimated biomass and nutrient content of two steepland watersheds using allometric equations and nutrient concentrations derived from a subsample of the vegetation. Prior to the passage of Hurricane Hugo in September 1989, the watersheds had a total vegetative biomass of 301 tons/ha, 75 percent of which was aboveground. The total nutrient content of this vegetation was 907, 49, 644, 653, and 192 kg/ha for N, P, K, Ca, and Mg, respectively, and varied with topographic setting. Concentrations per unit dry weight of P (0.16), K (2.49), Ca (2.13), and Mg (0.62) in aboveground vegetation were similar to other steepland tropical forests, while the concentration of N (2.9) was greater. Following the passage of Hurricane Hugo, the standing aboveground biomass was reduced to 113 t/ha and the aboveground nutrient content of the forest was reduced 45 to 48 percent.

Weaver, P.L., E. Medina, D. Pool, K. Dugger, J. Gonzales-Liboy and E. Cuevas (1986) Ecological observations in the dwarf cloud forest of the Luquillo mountains of Puerto Rico. Biotropica 18, 79-85.

Summary

In the dwarf cloud forest of the Luquillo Mountains in Puerto Rico, 5 species accounted for 95% of the stems of at least 10 cm DBH on three plots totaling 0.22 ha. Mean density for stems of at least 10 cm DBH was 3671 +/- 516 stems/ha, and mean basal area was 49.1 +/- 8.2 m2/ha. The aboveground woody biomass on two small plots of 0.0036 ha, one located on a ridge and the other 100 m to the leeward, was 48 and 110 t/ha, respectively. Leaf area index on the ridge was 1.99 m2/m2, leaf biomass was 288 g/m2, and specific leaf weight was 14.5 mg/cm2. Mean annual litterfall rates averaged only 0.85 g/m2/day (3.10 t/ha/year), of which 79% was leaf litter, 9% wood litter and 12% miscellaneous material. The rate at which nutrients returned to the soil (kg/ha/year) averaged 23.9 for N, 0.7 for P, 4.3 for K, 16.3 for Ca and 7.6 for Mg. The annual increment in tree diameter was low, averaging only 0.03 +/- 0.01 cm/year. For trees at least 2.5 cm in diameter, aboveground biomass accumulated at an average rate of 45 g/m2/year, and NPP was 384 g/m2/year.

Weaver, P.L. and P.G. Murphy (1990) Forest structure and productivity in Puerto Rico's Luquillo mountains. Biotropica 22, 69-82.

MAGDALENA VALLEY

Foelster, H., G. de las Salas and P. Khanna (1976) A tropical evergreen forest site with perched water table, Magdalena valley, Colombia: biomass and bioelement inventory of primary and secondary vegetation. Oecologia Plantarum 11, 297-320.

Summary

We studied a primary forest stand of tropical seasonal evergreen type and three regrowth stages of 2, 5 and 16 years on the terraces of the Magdalena valley, Colombia. The above-ground biomass and the bioelement store of the above-ground vegetation was estimated by means of sample trees and allometric regressions. The primary stand is a simple-structured low forest, rich in palms, with a low biomass (180 t/ha); the secondary regrowth is a community of two dominant species, reaching 200 t/ha within 16 years. The plateau site of the terraces for which these stands are typical, is characterised by soils of low bioelement status, by long phases of water saturation, enforced concentration of roots on the surface of the mineral soil and the associated accumulation of an organic layer, and by irregular phases of drought. It is believed that frequent wind-throw and drought impact result in high mortality and the maintenance of young trees in the primary forest, and strengthen the competitive position of palms.

MANAUS

Fittkau, E.J. and H. Klinge (1973) On biomass and trophic structure of the central Amazonian rain forest ecosystem. Biotropica 5, 2-14.

Franken, M., U. Irmler and H. Klinge (1979) Litterfall in inundation, riverine and terra firme forests of Central Amazonia. Tropical Ecology 20, 225-235.

Summary

We studied three forest types along a hydrological gradient in the area of Manaus, Amazonas, as follows: (1) dry land (terra firme); (2) riverine; (3) seasonally inundated forest. Production of fine litter was studied for at least one year, with the following results: (1) 780 and 800 g/m2/year (78% and 84% leaves); (2) 640 g/m2/year (67% leaves); (3) 670 g/m2/year (79% leaves). These data are consistent with those reported for comparable forests from the Amazon region. Litterfall was seasonal, with significantly less shed in the rainy season compared with the dry season. The amount of leaf litter produced was positively correlated with its nutrient content.

Klinge, H., and Rodrigues, W.A. (1968) Litter production in an area of Amazonian terra firme forest. Part I. Litterfall, organic carbon and total nitrogen contents of litter. Amazoniana 1, 287-302.

Klinge, H., and Rodrigues, W.A. (1968) Litter production in an area of Amazonian terra firme forest. Part II. Mineral nutrient content of the litter. Amazoniana 1, 303-310.

Klinge, H., Rodrigues, W.A., Brunig, E., and Fittkau, E.J. (1975) Biomass and structure in a central Amazonian rainforest. In: Tropical Ecological Systems. Trends in Terrestrial and Aquatic Research (F.B. Golley and E. Medina, eds.), pp. 115-122. Springer-Verlag, Berlin.

Luizao, F.J. and H.O.R. Schubart (1987) Litter production and decomposition in a terra-firme forest of Central Amazonia. Experientia 43, 259-264.

McWilliam, A-L.C., Roberts, J.M., Cabral, O.M.R., Leitao, M.V.B.R., de Costa, A.C.L. Maitelli, G.T. and Zamparoni, C.A.G.P. (1993) Leaf area index and above-ground biomass of terra firme rain forest and adjacent clearings in Amazonia. Functional Ecology 7, 310-317.

Summary

We determined leaf area index (LAI) and above-ground biomass by destructive sampling for 0.04 ha of terra firme amazonian rain forest and for an adjacent clearing. In the forest, LAI varied considerably with height for four 0.01 ha subplots, but cumulative LAI was similar (mean = 5.7). Total above-ground biomass was 27130 g/m2. Specific leaf area varied linearly from 65 cm2/g at the top of the canopy to 114 cm2/g at 5 m height (average 90 cm2/g).

MARAFUNGA

Edwards, P.J. and P.J. Grubb (1977) Studies of mineral cycling in a montane rain forest in New Guinea. I. The distribution of organic matter in the vegetation and soil. Journal of Ecology 65, 943-969.

Summary

We estimated organic matter content in a Lower Montane Rain forest (6 degrees S), located at an elevation of c. 2500 m in New Guinea, prior to studies on mineral cycling. Detailed, destructive sampling took place on a 20 x 20 m plot. Biomass estimates were derived for other plots using a regression of dry weight on the square of trunk diameter at breast height. A total biomass of 35000 g/m2 was estimated for a 2400 m2 plot, considered representative of the forest at large. Of this total, roots, above-ground tree parts (gbh >30 cm), climbers and scramblers, epiphytes, plants in the 0-1 m layer, and other plants contributed c. 4000, 29500, 400, 200, 200, and 700 g/m2, respectively. Specific leaf area was determined for seventeen tree species (range 37-127 cm2/g, mean 58 cm2/g), four common climbers (45-81 cm2/g), and a scrambling bamboo (216 cm2/g). The leaf area index for the 20 x 20 m plot was estimated as c. 5.5 m2/m2. The ash contents of 140 representative plant samples were determined; they ranged from 2% in the trunks to c. 10% in the 0-1 m layer. The organic matter content of the soil (based on dry weight), considered to be twice the organic carbon content, was c. 19% in the 0-2 cm layer, c. 13% in the 2-10 cm layer and fell to c. 9% at the 100 cm depth. The organic matter content of the plants and the soil on the 0.24 ha plot was estimated to be c. 34000 g/m2 and c. 120000 g/m2, respectively. About 100 g/m2 of soil (4% ash) had accumulated in the crowns of the larger trees, formed largely from the remains of epiphytes.

Edwards, P.J. (1977) Studies of mineral cycling in a montane rain forest in New Guinea. II. The production and disappearance of litter. Journal of Ecology 65, 971-992.

Summary

We monitored litter production and quantity of litter remaining on the ground for a 12-month period in an undisturbed Lower Montane Rain forest located at an elevation of c. 2400-2500 m in the Eastern Highlands of New Guinea. Sampling took place in 20 x 10 m plots at four contrasting sites; one site (on a ridge) was a natural gap caused by the fall of a large tree, and the other three sites (on a broad ridge, on a steep slope and in a valley bottom) were of well-developed, mature or late-building phase trees. Litter fall was measured at each site using 16 traps 1 x 1 m. The average litter production for the four sites was 755 ± 27 (s.e.m.) g/m2/yr with 635 ± 20 g/m2/yr in non-woody material. There were no significant differences among the sites. An estimated 10% of the dry leaf weight reduction is due to phytophagous insect grazing and another 10% reduction is due to nutrient withdrawal by the trees before leaf shedding. Density measurements made on healthy twigs and on twigs in the litter fall suggests that considerable decomposition occurs before the twigs are shed. Based on the relationship between the standing litter crop on the ground and the annual litter production, estimates of the annual rate of litter disappearance range from 1.04 to 1.55 for the Ridge and Valley sites, respectively. Leaf litter decomposition of six tree species (Dacrycarpus cinctus, Elaeocarpus ptilanthus, Litsea sp. 65, Macaranga albescens, Planchonell firma and Schizomeria sp. 203) and a widespread bamboo species (Nastus productus) was studied over 325 days at the Ridge and Valley sites by enclosing the litter in plastic mesh. There were no significant differences between the two sites. After 325 days, only 15% of the original dry leaf weight of the Elaeocarpus ptilanthus remained. Leaf disappearance in the other tree species was slower with 56% and 57-74% of the dry leaf weight remaining for bamboo and the other tree species. The average rate of disappearance for the seven species, equivalent to 47-48% in the first year, is much less than the rate calculated from the standing litter crop and the annual litter production (100-148% for non-woody litter), which along with other evidence suggests that the time-course of disappearance is linear rather than exponential.

Grubb, P.J. and P.J. Edwards (1982) Studies of mineral cycling in a montane rain forest in New Guinea. III. The distribution of mineral elements in the above-ground material. Journal of Ecology 70, 623-648.

Summary

Nitrogen, P, K, Na, Ca and Mg concentrations in various above-ground components have been estimated for a lower montane rain forest located at an elevation of about 2500 m in New Guinea. Approximately 2300 analyses were applied to nineteen forest and/or plant components in a 20 x 20 m plot on a single ridge-top; trees of gbh >30 cm (trunk wood, trunk bark, branches, twigs (stems, leaves), plants <1 m tall (seedlings, climbers and scramblers, herbs), climbers and scramblers >1 m tall (stems, leaves), epiphytes (stems, leaves), epiphytic soil, litter and dead trunks and branches. Generally, N, Ca and Mg concentrations increased toward the centre of the trunks of large trees, while that of P decreased and that of K and Na were variable. The N, P and Mg concentrations in the wood tended to increase with height, and there were no significant trends in the bark. Intraspecific differences were considerable, and interspecific differences were large. Generally, mean concentrations of N, P, K and Mg increased according to the pattern: trunk wood < branches < trunk bark < twigs < leaves. Calcium increased according to the pattern: trunk wood < branches < leaves < twigs < trunk bark. Leaf N, P and K concentrations decreased with increasing age, but that of Ca increased and those of Na and Mg were variable. Nitrogen, P, K and Na concentrations were not consistently different in saplings and trees of the same species, but Ca and Mg concentrations were higher in sapling leaves. All six elemental concentrations in small trees, saplings, seedlings and climbers varied greatly between species, but the mean values for leaves, or for stems of similar girth, were similar in all vegetation types. The vascular epiphytes differed in their consistently low foliar concentrations of N. The elemental concentrations in the epiphytic bryophytes and lichens were similar to those in epiphytic soil derived largely from them, and the N concentration was not as low as that in the vascular epiphytes. Based on the elemental concentration calculations of above-ground biomass components for the 20 x 20 m plot, the N, P, K, Na, Ca and Mg concentrations were estimated for the whole forest to be 85, 4.9, 70, 3.1, 150, and 21 g/m2, respectively. The distribution in four major fractions was similar for N and P, and for Ca and Mg. The comparative importance of the dead and epiphytic matter relative to their N and P concentrations was much greater than is suggested by their dry weight contributions. The correlations among particular elemental concentrations in different parts of the tree, and correlations among different elemental concentrations within each part of the tree for eighteen species are presented and discussed. Nitrogen, P or K concentrations in leaves were not significantly correlated to those in the trunk wood or bark.

Edwards, P.J. and P.J. Grubb (1982) Studies of mineral cycling in a montane rain forest in New Guinea. IV. Soil characteristics and the division of mineral elements between the vegetation and soil. Journal of Ecology 70, 649-666.

Summary

Soil attributes and the elemental contents of the vegetation and soil were studied in a lower montane rain forest of exceptional stature (33-37 m) located in an isolated basin at an elevation of about 2500 m in New Guinea. The major soil parent material was alluvium, and most slopes were less than 20 degrees. Very similar deep profiles were found on ridge-crests, gentle slopes and in valleys, but shallower, more stony profiles were found on a few very steep slopes. Generally, the A horizon, extending 50-70 cm deep, was a well-drained humic clay loam, with organic C and total N content ranges of 8.5-21.6% and 0.8-1.7% (based on dry weight), respectively. The B horizon, extending 30-50 cm deep, was more clayey, but still rich in organic matter as organic C and total N contents were about 9% and 0.6-0.9%, respectively, at 100 cm depth. The C horizon was 1-5 m deep, and varied greatly in detail. The humus was a well-defined crumb mull, as reflected by the density of earthworms in the top 100 cm, 68-120 earthworms/m2. Highly hydrated amorphous iron oxides dominated the inorganic fraction. The soils were categorized as humic brown clay. The soil pH in H2O was 5.6-6.6 and the cation exchange capacity was 61-78 mequiv./100 g. The exchangeable K, Ca and Mg were concentrated in the top 10 cm, where the base-saturation was about 20-80% (cf. 4-5% at 60 cm). The total PO4-P concentration was high, increasing from 1500-2100 ppm at the surface to 2800-4000 ppm at 100 cm. The fluoride-extractable PO4-P concentration declined from 37-41 ppm at the surface to 6-10 ppm at 10 cm, and 2.5-5.5 ppm in the 25-100 cm layer. Estimates of total N and P, extractable P and exchangeable K, Na, Ca and Mg in the top 25, 30 and 100 cm are given for three sites. Estimates of N, P, K, Na, Ca and Mg contents in the roots to a depth of 25 cm are presented for two areas. In conclusion, the soils possessed several features that could, together, partially explain the exceptional stature of the forest. The proportional distribution of mineral nutrient capital among living plants, dead plant matter, and soil is discussed. Lower montane rain forests are similar to lowland rain forests in this respect for P, K, Ca and Mg, but they generally differ for N and the possible importance of this for the growth of the lower montane forests is emphasized.

PASOH

Gong, W.K. (1982) Leaf litter fall, decomposition and nutrient element release in a lowland dipterocarp forest. Malaysian Forester 45, 367-378.

Summary

Total leaf litter fall in a lowland dipterocarp forest was estimated at 920 g/m2/year, of which leaf litter constituted 680 g/m2/year (74%). Rate of loss of leaf material was very rapid - up to 98.5% in 5 weeks; this was affected by the nature of the leaf as well as by exposing or covering. Annual release of nutrients from leaf litter was estimated at 21.46 g/m2, of which nitrogen constituted about half.

Kira, T. (1978) Primary productivity of Pasoh Forest - a synthesis. Malaysian Nature Journal 30, 291-297.

Summary

The results of three methods of assessing productivity of the Pasoh Forest Reserve (harvest method, canopy photosynthesis method, micrometeorological method) did not agree closely, but they suggest a range of net primary productivity of 2500-5000 g/m2/year and that of gross primary productivity of 7000-10,000 g/m2/year. These ranges seem somehat lower than the peak net productivity known so far in Malaysian rubber and oil palm plantations, but they are not inconsistent with data on growth rates from Malaysian forests and tree plantations.

Ogawa, H. (1978) Litter production and carbon cycling in Pasoh forest. Malaysian Nature Journal 30, 367-373.

SAN CARLOS DE RIO NEGRO

Cuevas, E. and E. Medina (1986) Nutrient dynamics within amazonian forests. I. Nutrient flux in fine litter fall and efficiency of nutrient utilisation. Oecologia 68, 466-472.

Cuevas, E. and E. Medina (1988) Nutrient dynamics within amazonian forests. II. Fine root growth, nutrient availability and leaf litter decomposition. Oecologia 76, 222-235.

Jordan, C.F. and C. Uhl (1978) Biomass of a "tierra firme" forest of the Amazon basin. Oecologia Plantarum 13, 387-400.

Jordan, C.F., ed. (1989) An Amazonian Rain Forest: structure and function of a nutrient-stressed ecosystem and the impact of slash-and-burn agriculture. UNESCO-MAB/Parthenon, Carnforth, UK. 176 pp.

Jordan, C.F. and G. Escalante (1980) Root productivity in an Amazonian rain forest. Ecology 61, 14-18.

Summary

We determined the average rate of root biomass accumulation for the surface root mat of an Amazonian rain forest near San Carlos de Rio Negro, Venezuela, to be 117 g/m2, and total root biomass increment was 201 g/m2. Growth of roots was higher in the surface root mat when fresh litter was present, and the ratio of root growth rate to shoot growth was similar to that of a temperate forest near Oak Ridge, Tennessee, although root turnover was higher at San Carlos. High turnover results in a relatively large proportion of roots in smaller size classes, with a large surface area ratio for trapping nutrients. It appears that high efficiency of trapping nutrients is important in the San Carlos forest, which is poor in nutrients.

Klinge, H. and R. Herrera (1978) Biomass studies in amazon caatinga forest in southern Venezuela. I. Standing crop of composite root mass in selected stands. Tropical Ecology 19, 93-110.

Klinge, H. and R. Herrera (1983) Phytomass structure of natural plant communities on spodosols in southern Venezuela: the tall Amazon Caatinga forest. Vegetatio 53, 65-84.

Medina, E. and E. Cuevas (1989) Patterns of nutrient accumulation and release in Amazonian forests of the upper Rio Negro basin. In: Mineral Nutrients in Tropical Forest and Savanna Ecosystems. (J. Proctor, ed.) British Ecological Society Special Publication No. 9: Blackwell Scientific, Oxford. pp. 217-240.

Summary

Results of the San Carlos project on Amazonian rain forest are critically reviewed with emphasis on the functional properties of mature forests. Forest types are characterised by dominant species, soil and topographical position in the sequence: mixed forest on oxisols, yevaro and guaco forests on ultisols and Amazon caatinga forest complex (including tall and low caatinga) on spodosols. The first three types are generally non-flooded (terra firme forests) while the caatinga forests have a variety of flooding regimes depending on their topographical position. Terra firme forests are relatively depleted in P, K, Ca and Mg, but have relatively high N contents in both soil and vegetation. Tall caatinga and the tall bana unit of low caatinga accumulate relatively large amounts of P, and have N:P ratios comparable with those of forests at nutrient-rich sites. Root growth and decomposition appear to be limited by P, Ca and Mg in mixed forest, by N in tall caatinga, and by N and P in low caatinga. Endomycorrhizal roots generally occur in all forest types, and infection of adult trees and seedlings is often heavy. The efficiency of the nutrient trapping process appears to be correlated with the density of fine roots in the upper soil layers, or the root mat above the soil.

Stark, N. and M. Spratt (1977) Root biomass and nutrient storage in rain forest oxisols near San Carlos de Rio Negro. Tropical Ecology 18, 1-9.

Uhl, C. and C.F. Jordan (1984) Succession and nutrient dynamics following forest cutting and burning in Amazonia. Ecology 65, 1476-1490.

SAN EUSEBIO

Grimm, U. and H.W. Fassbender (1981) Ciclos bioquimicos en un ecosistema forestal de los Andes Occidentales de Venezuela. I. Inventario de las reservas organicas y minerales (N, P, K, Ca, Mg, Fe, Al, Na). Turrialba 31, 27-37.

Summary

Organic matter and stored elements (N, P, K, Ca, Mg, Fe, Al, and Na) were measured in 13 stands of a montane forest ecosystem in the Sierra de Merida, northwestern Venezuela. The soils of the studied area are very acid (pH in CaCl2 3.5-4.0) and rich in organic matter; the dominant exchangeable cation is Al. Mean values for organic matter were 404 t/ha of living biomass, 24 t/ha of dead trees, 38t/ha in the organic layer and 585 t/ha in the soil (0-120 cm). The forest contains high mineral stores, accumulated especially in the woody compartment. N and P values are very high in the soil compartment. The exchangeable K, Ca and Mg stores are low in comparison to the exchangeable Al store. Site variations are believed to be regulated by site-dependent water regime, and we present a corresponding site index classification.

Fassbender, H.W and U. Grimm (1981) Ciclos bioquimicos en un ecosistema forestal de los Andes Occidentales de Venezuela. II. Produccion y descomposicion de los residuos vegetales. Turrialba 31, 39-47.

Summary

We studied litter production (tree stands, each 12 collectors; sampling every two weeks) and litter decomposition (samples of leaves and branches exposed to environment; collection every two months) in a montane forest ecosystem of the Venezuelan Andes. Total litter production was 697 g/m2/yr, distributed as follows: leaves 338 (48%), branches 227 (33%), flowers and fruit 109 (16%), epiphytes 23 g/m2/yr (3%). The coefficients of variation of leaves, flowers and fruit were low (14% and 26%) and that for branches was high (64%). Annual renewal of leaf biomass was 73%. Litter production in the form of roots and dead wood was 1400 and 480 g/m2/yr. Transfer of chemical elements with litter depended on the specific soil conditions. For N, P and K, values of 69.4 and 33 g/m2 were recorded. The decomposition of litter is linear. Leaf litter was totally decomposed after 20 months exposure, but branches would require 12.5 years to disappear. We calculated a coefficient of organic matter transformation and compared this with other tropical forest ecosystems.