From the saprotrophs that decay plant material to the pathogens and mutualists that shape plant demography at local and regional scales, fungi are major drivers of tropical forest dynamics. Although endophytic fungi are abundant and diverse in many biomes, they reach their greatest diversity in tropical forests, where they can influence plant physiology, performance and survival. The number of quantitative studies regarding endophytes has increased dramatically in the past two decades, but general rules have not yet emerged regarding the biogeography, host affiliations, local or regional distributions, or phylogenetic diversity of endophytes in most tropical settings. Here, endophytic fungal communities associated with 18 species of eupolypod fern were compared among forest reserves in Panama, Costa Rica and Mexico. Molecular sequence data for >2000 isolates were used to determine the relationships of host taxonomy, forest (site), and environmental dissimilarity to endophyte community composition. Communities in related ferns differed significantly among forests, reflecting the interplay of geographic distance and environmental dissimilarity. Although the same phyla and classes of fungi were prevalent at each site, they differed in relative abundance. All sites were dominated by the same order (Xylariales), but sites differed in the phylogenetic clustering vs. evenness of their endophyte communities. By addressing the relationship of endophyte communities to host taxonomy, geographic distance and environmental factors, this study complements previous work on angiosperms and contributes to a growing perspective on the factors shaping communities of ecologically important fungi in tropical forests.

The identification of seed dispersers and predators is essential to understand the effect of anthropogenic disturbances, and the associated defaunation process, on tropical forest dynamics in Central Africa. In this study, the animals involved in seed predation and dispersal of Dacryodes normandii (Burseraceae), an endozoochorously dispersed tree species endemic to Gabonese forests, were identified in a site in south-east Gabon using two complementary methods: direct observation and camera-trap monitoring of fruit piles. The combined sampling effort (172 h of direct observations and 796 d of camera trapping) led to the identification of six disperser and eight predator species of D. normandii seeds. With high frequency of consumption (88% and 57% of their visits, respectively) and long visit duration (83 and 23 min, respectively), the western lowland gorilla and central chimpanzee were identified as the main dispersers of this species. Seeds passed through the gorilla gut exhibited high germination success (68%). Rodents were identified as predators of D. normandii seeds, potentially displaying rare secondary dispersal through scatter-hoarding. The results of this study highlight the importance of great apes in the seed dispersal of this tree species.

Two main types of hollow tree are frequently found in savannas: trees with external splits (externally damaged trees), and trees with no or little visible external damage, but with their entire core removed (internally damaged or ‘piped’ trees). As this may affect trunk mechanical resistance and tree survivorship, we studied the incidence of these two types of cavity in relation to two possible causal agents, fire and termites, in a West African savanna. Overall, the proportion of damaged adult trees (height >2 m) reached 36%, and up to 84% for Crossopteryx febrifuga. In this species, almost all (93%) damaged individuals showed signs of digging by fungus-grower and wood-feeder termites. External damage was more frequent in the more fire-prone shrubby savanna, suggesting that while termites are responsible for the piping, fire is responsible for the later opening of the trunk. Trees growing in the more fire-prone savanna tended to reach significantly smaller sizes, both in height and basal diameter, than in the less intensely burnt woody savanna. There was also evidence that piped trees were taller than externally damaged trees. This strongly suggests that fire causes an increased mortality of adult trees through lateral opening of the trunks causing later breakage.

During 5 y, we monitored reproductive activity and seed production of Carapa guianensis in two forest types to test the hypothesis that seed production is influenced by multiple factors across scales (regional climatic cues, local habitat heterogeneity and individual tree attributes). Variability in seed production was moderate at the population (CVp = 1.25) and individual level (xCVi = 1.24). A mixed model with a Poisson regression revealed that seed production was explained by variables at all scales. Total seed production was significantly higher in occasionally inundated forests. Diameter at breast height, dbh2, crown cross-sectional area, liana load, density, dry-season rainfall and mean maximum temperature were also significant in explaining seed production variation. Seed production increased with dbh until 40–50 cm, then decreased. Liana load demonstrated a negative relationship with seed production, but only in terra firme forests. Climatic cues (rainfall and temperature parameters) were central to setting overall patterns in reproductive activity and seemed to best explain why years with high seed production were consistent across the two forest types (habitats) examined. Dry-season rainfall was positively correlated with seed production.

Landscape-scale studies of community traits such as species richness and community composition are sorely needed to explore the impact of large-scale disturbance events such as ENSO (El Niño Southern Oscillation)-induced burning and habitat isolation on rain-forest communities. Here we assess butterflies in continuous forest, in unburned isolates surrounded by burned forest and in burned forest, in addition to areas sampled before the most recent (1997/98) large-scale burn event in Borneo. Overall levels of species richness were significantly higher pre-ENSO and in continuous forest than in unburned isolates and burned forest. There was, however, some variation among butterfly families in these patterns, with no significant differences among habitats (continuous forest, isolates and burned forest) for the Hesperiidae and significant differences for the other butterfly families. Patterns of community composition showed that similarity was greater between distant continuous forest and isolates than between either of these and burned forest. Since the unburned isolates were surrounded by the burned forest this indicates that the habitat (burned or unburned) overrides geographical differences. Dominant species that contributed substantially to differences among habitats were often completely absent from either burned or unburned forest. The combined patterns of species richness and community structure suggest that burning affects forest ecosystems by a replacement of dominant species while habitat isolation may affect areas by leading to the local extinction of rare species.

Phenology is a key ecosystem process that reflects climate–vegetation functioning, and is an indicator of global environmental changes. Recently, it has been suggested that land-use change and timber extraction promote differences in forest phenology. We use remote-sensing data to describe regional leaf phenological patterns in combination with field data from 131 plots in old-growth and disturbed forests distributed over subtropical forests of Argentina (54–65°W). We assessed how climate is related to phenological patterns, and analysed how changes in forest structural characteristics such as stock of above-ground biomass relate to the observed phenological signals across the gradient. We found that the first three axes of a principal component analysis explained 85% of the variation in phenological metrics across subtropical forests, ordering plots mainly along indicators of seasonality and productivity. At the regional scale, the relative importance of forest biomass in explaining variation in phenological patterns was about 15%. Climate showed the highest relative importance, with temperature and rainfall explaining Enhanced Vegetation Index metrics related to seasonality and productivity patterns (27% and 47%, respectively). Within forest types, climate explains the major fraction of variation in phenological patterns, suggesting that forest function may be particularly sensitive to climate change. We found that forest biomass contributed to explaining a proportion of leaf phenological variation within three of the five forest types studied, and this may be related to changes in species composition, probably as a result of forest use.

Seedlings in tropical forests are ultimately the source of canopy trees, thus factors controlling their composition and growth potentially influence the composition of the forest. Seedlings are primarily limited by above-ground competition with trees, but below-ground competition is potentially also important. Over 4 y we experimentally reduced below-ground competition by trenching to 50 cm and reduced drought stress by irrigating in the dry seasons (6 cm every 2 d) in the understorey of a semi-evergreen rain forest in Panama. There were four irrigated plots and four unirrigated, in each plot there were eight subplots (four trenched, four untrenched); 32 seedlings (two per subplot) of each of four tree species were equally allocated to the four treaments; the four species were: Aspidosperma cruenta; Gustavia superba; Simarouba amara and Tachigali versicolor. Over all species together, trenching increased seedling height by 41% and leaf area by 140% over 4 y. The cause was likely to be increased nutrient supply, because the amounts of N, K and Ca were higher in trenched plants, though concentrations were not higher. Irrigation had no significant effect on growth. Irrigation, but not trenching, reduced seedling mortality. We conclude that below-ground competition was a major limitation for seedling growth for at least some common species (Gustavia and Tachigali in this experiment). More experiments are necessary to determine whether below-ground competition is also important in other tropical rain forests on fairly fertile soils.

The direct removal of adult trees by logging affects tree recruitment in tropical rain forests. However, secondary effects of logging, such as loss of vertebrate seed dispersers may also affect tree recruitment. We studied the recruitment and spatial distribution of five tree species namely Balanites wilsoniana, Celtis zenkeri, Chrysophyllum albidum, Cordia millenii and Ricinodendron heudelotii in Kibale, Budongo and Mabira Forests in Uganda. These forests have been subjected to varying degrees of disturbance leading to changes in their vertebrate seed dispersers. Vertebrate frugivores of the five tree species were identified. Three 1-ha plots were established around adult trees of the same five species in each forest and the distance from the juveniles to the nearest adult conspecific was measured to generate a recruitment curve. Frugivore visitation rates were high in the less disturbed Budongo and Kibale (2.2 and 1.6 individuals h−1 respectively) compared with the highly disturbed Mabira (0.9 individuals h−1). In the frugivore-impoverished forest, 70–90% of juveniles established beneath adult conspecifics, whereas in the less-disturbed forests juveniles were established up to 80 m from adult conspecifics. Shade-tolerant species capable of recruiting beneath adult conspecifics appeared to maintain their populations without dispersal. Consequently, disturbances leading to significant loss of vertebrates may alter tree recruitment and spatial distribution with consequences for long-term population viability of shade-intolerant tropical trees.

I investigated the extent to which adult butterflies with different wing colours display preferences for flying heights within a lowland tropical forest. Observations on eight colour groups, some of which comprised putative aposematic models and mimics while others contained nonaposematic species, were made from the forest floor and from a scaffold tower that reached above the canopy. Two groups (yellow pierids and papilionids and orange heliconiines) were most frequently observed in or above the canopy, and other groups were most frequently observed in or below the canopy. The evidence suggests that significant differences exist between some groups, but stratification does not occur among all colour groups. In particular, flight distributions of some mimicry rings overlap considerably. The light environments of different forest layers are variable, and the role that butterfly wing colours play in signalling or avoiding prcdation is little understood. However, the general lack of fine stratification of colour groups suggests that flight preferences do not occur because wing colours and patterns are especially cryptic against the background of particular forest layers.

The production and predictability of nectar resources in a population of Stachytarpheta glabra (Verbenaceae) and their use by insects and hummingbirds on ironstone outcrops in south-east Brazil were investigated. The phenology, density, nectar production, reproductive biology and floral visitors were studied, as well as territory size and daily nectar consumption by its main pollinator, Colibri serrirostris. The plant is abundant in the area, aggregated, and has a long flowering period, with very variable daily flower output. Although it can self-fertilize, it requires a pollen vector. Insect visitors totalled 21 species of bees and lepidopterans, including both pollinators and nectar robbers. Individuals of C. serrirostris defend their territories against other hummingbirds and large insects. Nectar production per hummingbird territory (mean size c. 462 m2) was estimated as 68.6–104 mL d−1 in dense areas at the flowering peak, an amount well above the estimated daily consumption of 13 mL by territory holders. Still, defence of large areas seems necessary to reduce nectar theft and cope with spatial resource unpredictability. Phenological characteristics, high density, and the fact that plants are perennial make S. glabra an attractive resource for nectar-feeders in general, and the main long-lasting nectar source for hummingbirds in the area.

The wet tropical forests in Madagascar have endemic dung beetles that have radiated for tens of millions of years using a limited range of resources produced by the species-poor mammalian fauna. Beetles were trapped in two wet-forest localities over 4 years (6407 trap nights, 18,869 individuals). More limited data for six other local communities were used to check the generality of the results. Local communities are relatively species poor (around 30 species) in comparison with wet-forest-inhabiting dung beetle communities elsewhere in the tropics (typically 50 or more species). The species belong to only two tribes, Canthonini and Helictopleurina (Oniticellini), which have evolved, exceptionally for dung beetle tribes, completely nocturnal versus diurnal diel activities, respectively. Patterns in the elevational occurrence, body size and resource use suggest that interspecific competition restricts the numbers of locally coexisting species exploiting the limited range of resources that are available. On the other hand, regional turnover in the species composition is exceptionally high due to a large number of species with small geographical ranges, yielding a very large total fauna of dung beetles in Madagascar (>250 species). Apart from exceptionally low local (alpha) diversity and high beta diversity, the Malagasy dung beetle communities are ecologically distinctive from comparable communities in other tropical regions in having high numerical dominance of the most abundant species, small average body size and low degree of resource specialization.

High-nutrient patches are important for regulating the structure and physiognomy of dystrophic habitats. Leaf-cutting ants create these rich patches in many neotropical habitats. Burning, however, could diminish or even annul the effects of ant nests on soil properties. To test this hypothesis, we compared the nutrient concentrations at various depths in soil samples near three nests of the leaf-cutting ant Atta laevigata and three non-nest soils, located in 10-ha plots subjected to burning or with fire-protection within a Brazilian cerrado. Root density in ant-nest soil was greater than in non-nest soil in both unburned and burned plots. Besides, the concentration of Ca, Mg, K and P increased 2–50-fold in ant nests from the unburned area compared to non-nest soils. In contrast, nutrient concentrations and pH in burned ant nests were similar to or lower than non-nest soils, but the nests maintained higher values of organic matter and cation exchange capacity. The positive effect of leaf-cutting ant nests as high-nutrient patches may be strongly reduced in habitats with frequent burning. In this case, the negative effects of leaf-cutter herbivory on a plant community could surpass the benefits of local nutrient enrichment by their nests.

Resumo: Sauveiros modificam as propriedades físicas e químicas do solo, alterando a estrutura e fisionomia local. Entretanto, queimadas podem reduzir os efeitos dos formigueiros nesses ambientes como, por exemplo, pela diminuição do forrageamento das formigas e, conseqüentemente, pela baixa incorporação de material orgânico ao solo. Este estudo testou o efeito do fogo sobre a concentração de nutrientes no solo de colônias de Atta laevigata em área de cerrado. A densidade de raízes foi maior nas colônias do que áreas controle, independentemente da presença do fogo. Na ausência de queimadas, as concentrações de nutrientes foram até 50 vezes superiores nos sauveiros. Contudo, queimadas reduzem a concentração de nutrientes e pH nas colônias. Possivelmente, essa baixa concentração seja atribuída à maior demanda pela vegetação remanescente, em resposta à perturbação provocada pelo fogo. Nesse caso, os efeitos negativos da herbivoria podem superar os benefícios causados por meio da disponibilização de nutrientes pelos sauveiros.

Results of a 3-y study on the populations of three evergreen woody species (Byrsonima crassifolia, Palicourea rigida and Bowdichia virgilioides), from a regularly burnt savanna, in Venezuela, are reported. Tree density, size structure, fruit-seed production per tree of different size classes and soil seed bank were estimated. Viable seed production was one order of magnitude higher in B. crassifolia, which was also the only species with a permanent soil seed bank. Seeds of B. virgilioides germinated readily after dispersal, whilst seeds of P. rigida showed an innate dormancy synchronously released after a year. Both of the latter species seemed to maximize the first growth season by germinating at the beginning of the favourable season. In B. crassifolia, germination proceeds with an early small burst of germination, possibly followed by a second peak at the beginning of the next rainy season and little or no germination thereafter. The results showed that despite the high fire frequency, the studied species produce a substantial number of viable propagules, and have the capacity to germinate in field conditions (readiness depending on the species). Sexual reproduction is expected, therefore, to play an important role, as suggested by their reproductive investment, in long-term population maintenance.

Spiders from 10 rainforest tree canopies in Borneo were sampled by knockdown insecticide fogging. Spider density ranged from 2.0 to 10.1 m−2 on different trees, and species numbers ranged from 16 to 62; species diversity, as measured by William's α, ranged from 26 to 92. Similarity of the spider assemblages on individual trees was low, whether measured by the number of shared species or the Morisita-Horn index of similarity.

The contribution of five descriptor variables of tree taxonomy and structure to the similarity of the spider assemblages on different trees was assessed using stepwise multiple regression. No variable made a significant contribution to the variation in similarity indices for the spider assemblages and it was concluded that either other factors were important in determining similarity or that the measurement of these variables was too imprecise. In particular, there was no evidence that taxonomic similarity between tree species influenced the similarity of spider assemblages.

Results were compared with similar data from tropical and sub-tropical rainforests in Sulawesi and Australia. Species densities in Borneo and Sulawesi were similar but lower than in Australia. Species richness and diversity were markedly higher in the Bornean rainforest than in Sulawesi or Australia.

In Ethiopia, plantation forestry for soil conservation and wood supply is mainly based on exotic tree species harvested at 12–25-y rotation age. To evaluate if these forests truly represent ecological rehabilitation of degraded areas through the build-up of soil organic matter before harvest, relative abundances of C3 vs. C4 carbon in soils under a 25-y-old forest on Mt. Yegof have been studied based on changes in soil δ13C values due to vegetation cover changes by afforestation. At Yegof, shrub and tree leaves had δ13C value of −28.7 ± 0.4‰. The grasses showed a value of −30.7 ± 0.6‰ at 2700–3000 m asl (typical C3) and of −13.6 ± 0.3‰ at 2520 m asl (typical C4). Soil δ13C values were −21.7 ± 0.9‰ in soil at 0–5 cm and −20.7 ± 0.6‰ in soil at 30–50 cm indicating a long history of C4-dominated grass or cropland over the elevations sampled. The shifts towards lower δ13C values in soil at 0–5 cm coincide with 25 y of C3 vegetation. Carbon content in topsoil was 3.4–9.2% and in tree leaves was 45–56%. However, an estimate of new C3 carbon (54%) in 0–5 cm soil was low as compared with tropical rain-forest and savanna ecosystems suggesting a slow rate of carbon turnover at Yegof. The results suggest that degraded sites at Yegof may need further duration of forest cover longer than current rotation times of the forests to improve soil conditions and restore soil organic matter and carbon, which have been lost during the past land use. It is encouraging from the perspectives of ecological rehabilitation and soil conservation that a shift in the dominance from C4 vegetation types of agricultural and grassland ecosystems to C3 forest ecosystems could be established in less than 25 y on these highly degraded slopes of Mt. Yegof.

The abundance and distribution of reptiles and amphibians inhabiting tropical monsoonal wetlands in Kakadu National Park, northern Australia, were monitored between late 1979 and 1982. Seasonal trends in species richness, and the influence of various environmental attributes (including those caused by feral ungulates) on species distribution patterns were also examined.

These wetlands support a high proportion of the amphibian species known from the Park, but are of less importance to reptiles. Within the wetlands, the structurally more complex forested ‘margins’ support many more species than the treeless floodplains. Amphibian species distributions seem to be influenced primarily by elevation, through its effects on soil moisture and flooding levels, while reptile distribution patterns reflect a more complex set of environmental factors, with structural attributes (e.g. vegetation height structure and cover, refuge abundance, leaf litter cover and depth, extent of flooding) being of prime importance.

Feral buffalo and pigs, through their grazing, trampling and wallowing, may considerably influence such structural attributes and change the duration and extent of water lie, and thus indirectly affect species distribution patterns. Current buffalo culling programmes provide an opportunity to monitor vegetation and faunal changes, and quantify feral animal impact post facto.

The Auchenorrhyncha community within the understorey of a montane monsoon rain forest in Vietnam is described. It was highly diverse, with 328 morphospecies in a sample of 1611 specimens. The community was variable in species composition with respect to space (between sites 1–5 km distant) and time (between early and late wet seasons). Differences in species composition attributable to spatial heterogeneity and to seasonal variation were of a comparable magnitude when examined by the CCA ordination. Auchenorrhyncha density, estimated by sweeping, was generally low, at 1 to 2 individuals m−3 of vegetation. There was a negative correlation between the species' population size in the early and the late wet seasons.