Although the potential contribution to tropical tree species coexistence of niche differentiation along light gradients has received much attention, the degree to which species perform differentially along soil resource gradients remains unclear. To examine differential growth response to soil resources, we grew seedlings of nine tropical tree species at 6.0% of full sun for 12 mo in a factorial design of two soil types (clay and white sand), two phosphate fertilization treatments (control and addition of 100 mg P kg−1) and two watering treatments (field capacity and water limitation to one-third field capacity). Species differed markedly in biomass growth rate, but this hierarchy was almost completely conserved across all eight treatments. All species grew more slowly in sand than clay soils, and no species grew faster with phosphate additions. Only Eperua grandiflora and E. falcata showed significant growth increases in the absence of water limitation. Faster-growing species were characterized by high specific leaf area, high leaf allocation and high net assimilation rate but not lower root allocation. Slower-growing species exhibited greater plasticity in net assimilation rate, suggesting that tolerance of edaphic stress in these species is related more to stomatal control than to whole-plant carbon allocation. Although relative growth rate for biomass was correlated with both its physiological and morphological components, interspecific differences were best explained by differences in net assimilation rate across six of the eight treatments. A suite of traits including high assimilation and high specific leaf area maintains rapid growth rate of faster-growing species across a wide gradient of soil resources, but the lack of plasticity they exhibit may compromise their survival in the poorest soil environments.

Tree recruitment is determined in part by the survivorship and growth of seedlings. Two seedling cohorts of the three most abundant caesalpiniaceous species forming groves at Korup, Cameroon, were followed from 1995/1997 to 2002, to investigate why Microberlinia bisulcata, the most abundant species, currently has very few recruits compared with Tetraberlinia korupensis and T. bifoliolata. Numbers of seedlings dying, and the heights and leaf numbers of survivors, were recorded on 30 occasions. Survivorship after 2.5 y was 30% for M. bisulcata and 59% for the similar Tetraberlinia spp. together. After 7 y the corresponding values were 4 and 21%. Growth of all species was slow for the first 4 y; but survivors of T. korupensis became 63% taller, as the other species stagnated, by 7 y. The poor recruitment of M. bisulcata was the result of its very low seedling survival. Within species, the tallest seedlings of M. bisulcata and T. bifoliolata, but medium-height ones of T. korupensis, survived longest. This was likely due to higher root allocation in T. korupensis. Seedling dynamics of M. bisulcata and T. korupensis over 7 y accorded well with relative abundances of adult trees; T. bifoliolata is predicted to recruit later.

Seedlings of five species in the Dipterocarpaceae were grown in experimental plots in Sabah, Malaysia. These were sited both in gaps and understorey and on alluvial and sandstone soils. Half of all seedlings were provided with a complete fertilizer. Herbivore damage levels were recorded on over 25 000 individual leaves in four surveys over the course of 2 y. Rates of herbivory were lower on mature leaves (0.07–0.8% leaf area mo−1 among species) than new leaves (2.1–4.4% leaf area mo−1). There were no overall effects of light conditions, soil type, fertilizer treatment or time on rates of herbivory. The only consistent source of variation was that between species, with the three alluvial-specialist species suffering higher rates of damage than the two sandstone-specialists. Mature leaves of alluvial species received greater damage in sandstone soils, whereas sandstone species were damaged at equivalent rates on both soil types. New leaves were more damaged on their native soil type. Published herbivory rates vary in the timescales and methods of measurement. Nevertheless, the few comparable studies confirm that herbivory rates on seedlings in tropical rain forests are remarkably constant over time and across experimental treatments.

We used tree-rings to reconstruct long-term patterns of suppression, release and growth among five sympatric canopy tree species representing the full range of shade tolerance in a seasonal tropical forest in western Thailand. We expected that the frequency and duration of suppression and release events would be positively correlated with shade tolerance. All five species showed evidence of major and moderate growth releases. As expected, Melia azederach, an extreme heliophile, had the fewest releases. However, among the other species the number of major releases was consistent across the range of shade tolerance. The most significant difference among the species was the number of moderate releases recorded. There was a general positive correlation between the number of moderate releases and shade tolerance; however, Chukrasia tabularis, a relatively shade-intolerant species, had an anomalously high number of moderate releases. The study species also showed considerable variation in canopy accession strategies. The least common canopy accession strategy was establishment in the understorey and growth into the canopy in the absence of any gaps. However, with the exception of Melia, all four study species had one or more individuals that successfully reached the canopy using each of the four canopy accession strategies. These results highlight the importance of periodic or episodic bouts of gap formation on canopy tree recruitment and the utility of tree-rings for reconstructing long-term growth patterns in tropical trees.

This paper addresses the effects of habitat fragmentation on the phyllostomid bats of the Atlantic rain forest in Brazil, by comparing community structure (species richness and capture frequency) and the frequency of three bat species sampled along 36 transects encompassing six habitat categories: interiors and edges of large (>1000 ha) and small fragments (<100 ha), and the surrounding matrix of second-growth forests and areas of shade cocoa plantation. Species composition, richness and total captures were not directly affected by forest size per se, although the frequency of one dominant forest species (Artibeus obscurus) was significantly lower in small fragments compared with larger ones. The high connectivity among forest patches in the study area and the ability of some species to use the surrounding matrix of secondary forests and shade cocoa plantations possibly precludes the insularization effect. Qualitative habitat changes induced by fragmentation, such as edge formation and forest regrowth affected bat community structure; both modified habitats comprised a limited subset of the species assemblage found in the interiors of mature forests. The results presented here provide evidence of impoverished bat assemblages in man-modified habitats linked with deforestation and overall disturbances related with forest fragmentation.

Discrete humus layers are common on podzols under temperate coniferous and tropical heath forests, and patchy layers also occur under some temperate broadleaved forests on non-podzolic soils. We used multiple data sets to test the reported association of humus with oligotrophic but non-podzolic soils under non-heath dipterocarp forest at Lambir, Sarawak. We examined the distribution, morphology and nutrient dynamics of necromass on soils derived from sandstone and shale. Concentrations of the main mineral nutrients were lower in fresh litter on the very oligotrophic sandstone soils than on shale. The rates of litterfall were similar, so that annual litterfall fluxes of all nutrients were lower on sandstone. The lower nutrient concentrations and fluxes in the litter on sandstone resulted in slower decomposition, longer residence times and larger standing crops of forest-floor necromass, with lower concentrations of nutrients. The necromass on sandstone sequestered significantly more N, K and Mg but less Ca and Mn than on shale, with no significant difference for P. The variations in necromass nutrient dynamics were associated with morphological differences. There were mats of densely rooted humus under the litter on sandstone, whereas litter lay directly over the mineral topsoil on shale. Spatial associations with soil nutrients were weak for necromass thickness, but clear for humus. The proportions of nutrients in the litterfall and necromass reflected the stoichiometric profiles of the soils. We attribute the differences in necromass nutrient dynamics and their association with soil reserve nutrients to lower rates of nutrient replenishment from the weathering of sandstone than from shale. Necromass characteristics are robust field indicators of multivariate edaphic differences in these and other tropical forests on Acrisols/Ultisols derived from Tertiary clastic sediments.

The presence and density of two sympatric, large-sized vipers (the Gaboon viper, Bitis gabonica and the nose-horned viper, Bitis nasicornis) were studied along several transects, during both dry and wet seasons, and at different times of day, in southern Nigeria (West Africa). Three habitat types were found along the various transects (mature rain forest (MF), secondary rain forest (SF), swamp forest (SW)). The detection probabilities for these vipers were modelled with a set of competing models, and the various models were ordered by Akaike Information Criterion procedures. Two classes of models were used: the single-season model, and the multi-species model. The best models (single-season model) suggested that: for the Gaboon viper, habitat types SF and SW were particularly important in detecting this species, especially during the rainy season at 08h00–16h00. For nose-horned vipers, the best models had SW and MF as site-covariates. Application of the multi-species model revealed that there were different detection functions if both species are present at a site, with a ‘negative’ interaction of occupancy between the species. Females and males were similarly detectable in a logistic regression model, but feeding status and pregnancy slightly increased detection probability in a logistic regression model. Viper density was modelled by a DISTANCE sampling procedure. The density of one species tended to be inversely correlated to the density of the other, suggesting that (1) the rain-forest environment does not support abundant populations of both vipers when sympatric, and (2) the two Bitis species subtly partition the habitat resources.

The objective of this study was to analyse the factors explaining spatial variation in soil respiration over topographic transects in a tropical rain forest of French Guiana. The soil of 30 plots along six transects was characterized. The appearance of the ‘dry to the touch’ character at a depth of less than 1.2 m was used to discriminate soils exhibiting vertical drainage from soils exhibiting superficial lateral drainage and along with colour and texture, to define five classes from well-drained to strongly hydromorphic soils. Spatial variation in soil respiration was closely related to topographic position and soil type. Increasing soil water content and bulk density and decreasing root biomass and soil carbon content explained most of the decrease in soil respiration from the plateaux (vertically drained hypoferralic acrisol) to the bottomlands (haplic gleysol). These results will help to stratify further field experiments and to identify the underlying determinants of spatial variation in soil respiration to develop mechanistic models of soil respiration.

We used regression models and information-theoretic model selection to assess the relative importance of environment, local dispersal and historical contingency as controls of the distributions of 26 common plant species in tropical forest on Barro Colorado Island (BCI), Panama. We censused eighty-eight 0.09-ha plots scattered across the landscape. Environmental control, local dispersal and historical contingency were represented by environmental variables (soil moisture, slope, soil type, distance to shore, old-forest presence), a spatial autoregressive parameter (ρ), and four spatial trend variables, respectively. We built regression models, representing all combinations of the three hypotheses, for each species. The probability that the best model included the environmental variables, spatial trend variables and ρ averaged 33%, 64% and 50% across the study species, respectively. The environmental variables, spatial trend variables, ρ, and a simple intercept model received the strongest support for 4, 15, 5 and 2 species, respectively. Comparing the model results to information on species traits showed that species with strong spatial trends produced few and heavy diaspores, while species with strong soil moisture relationships were particularly drought-sensitive. In conclusion, history and local dispersal appeared to be the dominant controls of the distributions of common plant species on BCI.

We investigate a hypothesis for explaining maintenance of forest canopy dominance: bamboo (Guadua weberbaueri and Guadua sarcocarpa) loads and crushes trees, resulting in a self-perpetuating disturbance cycle. Forest inventory data revealed a peculiar pattern of tree form and size class distribution in bamboo-dominated plots within the Tambopata River watershed, Madre de Dios, Peru. Bamboo disproportionately loaded trees 5–29 cm in diameter, and this size class had over seven times more canopy damage than trees in control plots without bamboo. These differences were accompanied by reduced tree basal area and tree density in the 5–29-cm-diameter size class in the presence of bamboo. Elevated tree canopy damage was not apparent for trees ≥30 cm dbh, which are beyond the reach of bamboo. Additional evidence for the impact of bamboo was revealed by an experiment using artificial metal trees. Artificial trees in bamboo-dominated forest plots had nine times higher frequency of physical damage and nine times more plant mass loading as compared with control plots. Our results support the hypothesis that bamboo loading causes elevated physical damage to trees and suppresses tree recruitment, particularly for trees 5–29 cm in diameter.

Leaf phenology and leaf traits of the fern Oleandra pistillaris were examined in relation to canopy cover (open and understorey) and seasonal reduction in rainfall in a wet tropical montane forest, Indonesia. Although the annual rainfall is high, rainfall is relatively less in June and July. Stomatal density and diameter were greater in the open than in the understorey (229 versus 167 mm−2 for stomatal density and 33 versus 29 μm for stomatal diameter). The stable carbon isotope ratio (δ13C) of leaves, positively correlated with water use efficiency, was higher in the open than in the understorey (mean δ13C −30 versus −33‰). Therefore, it is considered that leaves have high gas-exchange capacities per leaf area in the open where water availability would be limited, compared with the understorey. In contrast, leaf mass per area (LMA) was lower and leaf life span was longer in the understorey than in the open (25 versus 34 g m−2 for LMA and 2.1 and 1.6 y for leaf life span). These thin leaves with a long life span in the understorey would contribute to efficient light capture and photosynthetic production per leaf mass. The number of leaves per stem decreased during the period with less rainfall in both the open and understorey conditions, which should reduce the water loss from plants, but increased again after the period with less rainfall. Stem growth rate was higher in the open than in the understorey, and the seasonal reduction in rainfall hardly affected stem growth rate in either open or understorey conditions. This study concludes that O. pistillaris responds to canopy cover and seasonal reduction in rainfall by adjusting leaf traits and leaf phenology, respectively.

The lowland rain-forest ecosystem in Sundaland (Borneo, Sumatra, Java, the Malay Peninsula south of 10°N, and associated islands) has been recognized as a biodiversity hotspot (Myers et al. 2000). However, it is suffering from huge amounts of disturbance, and it is predicted that South-East Asia will lose three-quarters of its rain forest by the turn of next century (Sodhi et al. 2004).

Termites are dominant invertebrates in tropical soils (Wood & Sands 1978) and are important mediators of decomposition in terrestrial ecosystems (Abe & Matsumoto 1979, Lawton et al. 1996, Lee & Wood 1971, Matsumoto & Abe 1979, Wood & Sands 1978, Yamada et al. 2005). Furthermore, these processes, such as carbon mineralization and nitrogen fixation, are dependent on the species assemblage structure of the termite community (Lawton et al. 1996, Yamada et al. 2005, 2006). Feeding habits of termites reflect their metabolic processes. The three major isopteran groups – wood-feeders, fungus-growers (fungus-growing wood/litter feeders), soil-feeders – appear to play very different roles in the decomposition process (Tayasu et al. 1997, Wood 1976, Wood & Sands 1978, Yamada et al. 2005). Consequently, the relative abundance of each feeding group provides useful information on the function of the termite assemblage in an ecosystem.