Conversion to permanent agriculture is rapidly occurring over vast areas of the 1.8 million km2; Brazilian Cerrado; a region that is naturally a mosaic of grasslands, savannas and evergreen tropical woodlands. Yet, few studies have quantified total biomass of plant communities in this ecosystem, particularly the belowground component; a C pool of potential global significance. Total biomass (aboveground and belowground), and the quantity of biomass consumed by fires were measured in four plant communities comprising a vegetation gradient from pure grassland (campo limpo) to a woodland with a closed canopy of tall shrubs and scattered trees (cerrado denso) near Brasilia, DF, Brazil. Total aboveground biomass (TAGB) increased along this gradient from 5.5 Mg ha-1 in campo limpo to 29.4 Mg ha-1 in cerrado denso. Vegetation structure varied among communities; trees were nonexistent in campo limpo, but were at a density of 1000 ha-1 and a biomass of 12.9 Mg ha-1 in cerrado denso. Fires consumed 92 and 84% of the TAGB in campo limpo (pure grassland) and campo sujo (savanna), respectively. In cerrado aberto and cerrado denso, trees and tall shrubs were little affected by fire. Combustion factors of the TAGB in these communities was 54 and 33%, respectively. The total biomass consumed by fire ranged from 5.0 Mg ha-1 in campo limpo to 13.5 Mg ha-1 in cerrado aberto. Compared to other widespread Brazilian ecosystems (tropical dry forest and evergreen forest), the Cerrado has a lower aboveground biomass. The TAGB of cerrado denso is > 9% of that of Amazonian tropical evergreen forest. The total quantity of biomass consumed by fire, and hence emissions to the atmosphere is lower in intact Cerrado communities compared to fires in slashed tropical forest.

The ant fauna of a rain forest in Sabah, Malaysia was sampled by using different collecting methods in three strata. In total, 524 morphospecies of ants could be distinguished. They belong to seven subfamilies and 73 genera. So far, the ant community described is the most species rich published for a primary tropical rain forest. Regarding the stratification in the forest, the leaf litter community comprised as many ant species as the lower vegetation or canopy. Furthermore the litter stratum had the highest generic diversity. The stratification of ants in rain forests seems to be a very strict one with the majority of species (75%) being related to only one stratum. This is in contrast to findings on the stratification of beetles in rain forests. The stratification and a radiation of some groups into vegetation and canopy, where a broad spectrum of permanent habitats exist, is responsible for the high diversity of ants in tropical rain forests.

Information on the feeding habits of the the lesser dog-faced friut bat, Cynopterus brachyotis, was obtained by the collection of food remains directly beneath daytime and feeding roosts. The bats were found to feed on the fruits of 54 plant species, the leaves of 14 species and the flower parts of four species. The seasonal phenological differences among congeneric plant species led to steady production of fruit throughout the year and the data suggets that Ficus spp. are a key component in the diet. Judging from its wide selection of fruits, C. brachyotis, is considered to be an important seed disperser. Folivory in C. brachyotis appears to be more common than previously thought. Of the leaves consumed by the bats, seven species belonged to the family Leguminosae, followed by Myrtaccae, Moraccae, Rhizophoacae and Euphorbiaccae. Friuts in general, provide an energy rich diet for phytophagous bats but most are low in protein. In contrast, leaves consumed by bats have a relatively high protein content. We suggest that folivory (by leaf fractionation) should be energetically more advantageous than the ingestion of large amounts of low protein friut or the active pursuit of mobile insects.

New leaf production in seasonal tropical forests may result from changes in water or light availability. In this study, the relationship between leaf flushing, photosynthetically active radiation (PAR) and rainfall was examined for understorey saplings in a moist tropical forest over one year. During the wet season, weeks with greater PAR were correlated with a greater proportion of saplings flushing new leaves during subsequent weeks in nine out of ten species. Rainfall was negatively correlated with subsequent leafing during the wet season for six of ten species. However, during the dry season, rainfall was positively correlated with leafing during the following weeks for six species, but the relationship was much weaker. PAR in the dry season was negatively correlated with flushing in eight species. These results support the hypothesis that under well-watered conditions, light limits leaf production, and peaks in insolation result in greater leaf production.

Secondary succession in a 19-y old tropical rainforest of French Guiana was investigated through the distribution pattern of primary forest species. The experimental plot of 25 ha was logged to simulate conditions of a paper pulp cut. Enumeration of all plants of height ≥ 50 cm in 52 subplots 10 m × 10 m indicated the number of species and individuals in five species categories; short-lived pioneer species, pioneer species that persist in mature forest, primary forest species capable of germinating in shade, primary forest species that indicate a preference for clearings (small gaps) in mature forest and understorey primary forest species. Change in proportion of the most abundant species (≥ 1 cm dbh) over the last 15 y indicated a decrease in short-lived pioneer species and an increase in pioneers that can persist in the mature forest. Proportion of species categories per height class indicated that primary forest species were mainly found in the lower height class in this forest which is largely dominated by secondary forest tree species forming a canopy that rarely exceeds 20 m. Individuals of primary forest species were encountered on ARBOCEL as sprouts from large stumps, sprouts from juveniles or as untraumatised saplings or juveniles. The distribution pattern in a 4-ha area of 11 selected primary forest canopy tree species revealed an overall trend in recolonisation of this species category in the secondary forest. Considered individually, the clustered distribution of stems of Eperua grandiflora showed the importance of regeneration through sprouting or remaining individuals. The gradient distribution, oriented from the edge to the centre of the studied plot, and displayed by the stem densities of Virola michelii, suggested a recent progressive dispersal of seeds. A more dynamic recolonisation front was observed for the primary forest understorey species Cassipourea guianensis and was probably linked to both the initial logging conditions and the fact that this species fruits when relatively young.

Patterns of buttress formation in tropical trees vary greatly within and among species. In Kibale National Park, Uganda, some form of a buttres was found on 23% of the 78 species (1785 trees) sampled from a variety of distantly related families. Large differences in buttress formation were documented within a single family and even within the same genus. Previous studies have suggested that buttresses are mechanical adaptations to counter asymmetric loads experienced during brief critical phases in a tree’s development and these persist after the need for a mechanical support has disappeared. As a tree grows from the understorey, up to the canopy, or emerges from the canopy, the potential number of occasions that a tree will experience directional stress increases. Many canopy level trees will probably have been in the vicinity of a treefall gap during their development, while emergent trees may experience gap exposure in addition to wind stresses associated with canopy emergence. Therefore, it is predicted that understorey trees should have fewer and less developed buttresses (after correcting for overall tree size) than canopy trees, which should have fewer and less developed buttresses than emergent trees. Detailed measurements of buttresses from 194 trees of eight species support this prediction. There was no evidence that trees thought to have experienced directional stress associated with selective logging almost 30 y ago had increased the number or size of existing buttresses. The pattern of buttressing in Kibale generally supports the idea that buttresses are mechanical adaptations to counter episodic asymmetric loads, and that buttresses persist after the need for a mechanical support has disappeared.

Seed dispersal is a process critical to the maintenance of tropical forests, yet little is known about the interactions of most dispersers with their communities. In the Dja Reserve, Cameroon, seed dispersal by the hornbills Certaogymna atrata, C. cylindricus and C. fistulator (Aves: Bucerotidae) was evaluated with respect to the taxonomic breadth of plants dispersed, location of seed deposition and effects on seed germination. Collectively, the three hornbill species consumed fruits from 59 tree and liana species, and likely provided dispersal for 56 of them. Hornbill-dispersed tree species composed 22% of the known tree flora of the site. Hornbill visit lengths, visit frequencies, and seed passage times indicated that few seeds were deposited beneath parent trees; in five hornbill/tree species pairings studied, 69–100% of the seeds ingested were deposited away from the parent trees. Germination trials showed that hornbill gut passage is gentle on seeds. Of 24 tree species tested, 23 germinated after passage by hornbills; of 17 planted with controls taken directly from trees, only four species showed evidence of inhibition of germination rate, while seven experienced unchanged germinated rates and six experienced enhanced germination rates. Results suggested that Certaogymna hornbill rank among the most important seed dispersers found in Afrotropical forests, and they deserve increased conservation attention. Ceratogymna hornbills are likely to become increasingly important in forest regeneration as populations of larger mammalian seed dispersers (such as forest elephants and primates) diminish.

Although two studies (Loubry 1994, Sabatier 1985) have been conducted on the phenology of primary forest tree species in French Guiana, there exists little synthetic information on the phenology of a forest dominated by pioneer species. Charles-Dominique (1986) conducted zoological observations at ARBOCEL between 1981 and 1985, where he indicated the fruiting periods of certain species. However, stands of early pioneer plants such as Solanum spp. and Cecropia obtusa Trécul 9Cecropiaceae) have reduced in number or have completely disappeared from the study area since then (Larpin 1989, Toriola et al. 1998).

Soluble carbohydrates are the major nutritional reward in the pulp of most vertebrate dispersed fruits (Corlett 1996, Herrera 1987, Johnson et al. 1985, Jordano 1995). However, although detailed analyses have been made of the carbohydrate content of many cumtivated fruits (e.g. Nagy et al. 1990, Widdowson & McCance 1935), most studies of wild fruits have only quantified total soluble carbohydrates (e.g. Conklin & Wrangham 1994, Corlett 1996, Foster & McDiarmid 1983, Herrera 1987, Izhaki 1992). This is unfortunate because relatively minor differences in the chemical structure of nutrients can have profound implications for frugivorous animals (Martinez del Rio & Restrepo 1993), and the fruit choices of these animals in turn, may have major implications for the abundance and distribution of the plant species.