Data on the laxonomic composition of the arboreal arthropod fauna of 10 Bornean lowland rain forest trees are presented, based on samples obtained using insecticide fogging. Combined samples from all trees comprised 23,874 individuals of at least 3000 species. The mean number of species on each tree was 616.7 with one tree sample containing more than 1007 species. The relative rank of the major orders of arthropods in terms of both species and individuals was remarkably constant across the trees. Hymenoptera, Coleoptera, Diptera and Hemiptcra were the orders with the most species and individuals. Formicidae, though not particularly species rich, was the most abundant family in terms of individuals and the commonest species in six of the 10 trees was an ant. Refogging of one of the trees 10 days after initial sampling showed that the arthropod fauna had not completely recovered. What many arthropods are doing in the canopy is discussed.

The frails of Cola lizae, an endemic tree with a limited geographical distribution, have been a major food source for lowland gorillas in the Lopé Reserve during part of each year over a six-year period. Faecal analysis indicated that 11,000-18,000 Cola seeds km-2 were deposited by gorillas during the 4-month season in 1989. Gorillas are the only important dispersers of this species: other primates consume the succulent mesocarp, but do not swallow the large seed; elephants do not eat Cola fruits. Observations of Cola seeds in gorilla faeces showed a very high germination rate and, despite initial high mortality, 18% of seedlings still survived six months after deposition. Survival of seedlings was significantly better in faeces left at nest-sites than in other areas of the forest: 40% of seedlings were viable at nest-sites six months after deposition. This suggests that the open areas of forest, preferred by gorillas as nest-sites, are advantageous to the propagation of this species.

Leaf litter production by lianes (=lianas) and trees was compared in an evergreen rain forest in subtropical Australia. Several successional stages were represented at the main site. Lianes contributed 2.2% of total basal area (69.6 m2 ha-1) of this site, but 24% of leaf litterfall (5.9–6.5 tha-1 y-2 over two years. Minor year-to-year variation in litterfall was attributed to incidence of severe storms, and drought. Lianes were responsible for about 17% of leaf litterfall in spring, 21% in the summerpeak, and 40% in autumn, more lianes than trees being deciduous. Leaf litter production by 23 individual species of liane, in relation to their basal area within the main site, was, on average, 15 times as great as that by 34 tree species, but declined more steeply between the species-groups of early and later succession. Tendrillar lianes, unlike twiners and scramblers, were confined to the ‘early’ successional group, and their foliage was spread across canopy surfaces, maximizing light interception. It was concluded that this contributed to greater production of leaf litter, per unit basal area, by tendrillar than by other climbers, and to the successional decline in leaf litterfall from lianes.

Soil nutrient concentrations under Acacia albida and Kigelia africana trees growing in Zambezi riverine woodlands were compared with soils in the open, beyond tree canopies. Concentrations of N, C, P and K were higher under tree canopies. Concentrations of Ca and Mg were unchanged. Soils were slightly more acid under A. albida trees relative to open soil, but were less acid under K. africana. Soil P concentration was higher under K. africana than under A. albida. Otherwise, the two species had similar effects on soil fertility. Despite previous claims, A. albida is probably no more efficient at increasing soil fertility than other savanna trees.

Some aspects of the ecology of bagrid catfishes in River Ase, southern Nigeria were studied for a period of two years. Nine species of Bagridae were recorded and these accounted for 15.0% of the number and 24.4% of the weight of all fish captured. Chrysichthys nigrodigitatus and Chrysichthys auratus longifilis were the principal species. C. nigrodigitatus was a rainy season species, while C. auratus longifilis was abundant in both dry and rainy seasons. Both species showed a major peak in catches between 0600 and 0900 h. C. nigrodigitatus exhibited a minor peak in catches between 1500 and 2100h, while C. auratus longifilis showed a minor peak between 1500 and 1800h. The spatial distribution of C. nigrodigitatus and C. auratus longifilis populations was heterogeneous. Bagrid fishes were an important component in the fish yield of the study river and its species composition has been compared with those of other Nigerian waters. The distribution and abundance of C. nigrodigitatus and C. auratus longifilis are discussed in detail.

Mean annual quantities of solar radiation absorbed during various stages of regeneration of a tropical rain forest in the upper Rio Negro valley of Colombia and Venezuela were estimated for the consecutive intervals between clear-cut and 1,3, 10, 20, 35, 60, 80 and 200 years of growth. Forest phytomass and litter fall data from each of these stages were used to calculate the mean annual net dry matter production per unit of absorbed photosynthelically active radiation (PAR), the PAR conversion efficiency. The quantities of PAR absorbed by the forest stands were calculated from the leaf area index values with an extinction coefficient for PAR of 0.74, a PAR albedo of 0.04, and an annual mean incoming PAR of 2.86GJ m-2y-1. Efficiency decreased with increase in successional stage. During the first 10 years of regrowth, the efficiency of conversion of PAR into above-ground phylomass averaged 0.23 g MJ-1, decreasing to 0.07 g MJ-1 over the following 50 years. Inclusion of annual root production in the calculations resulted in a small increase in PAR conversion efficiency; however, efficiency was more than doubled for some periods when the annual leaf and twig lillerfall were included. Efficiency values for above-ground production were much lower than PAR conversion efficiency values estimated for above-ground production of temperate forests.

The frugivorous phyllostomid bat Carollia perspicillata is closely associated with specific fruits which are found and picked in flight, then eaten at a feeding roost. Each fruit eaten corresponds to a single flight. An apparatus designed for this study permits the simultancous tracking of 10 bats equipped with double rhythm transmitters (slow rate corresponding to resting position and rapid rate to flying bouts). (1) The number of flights, (2) the percentage time spent flying and (3) the range of activity were recorded for different categories of animals during two periods of fruit production. Heavier males displayed high activity, while other males, non-breeding females and females in early pregnancy displayed a similar pattern of flying behaviour. Full-term pregnant females and lactating females performed almost as many flying bouts as non-reproductive females, but these flights were much shorter. This unexpected feeding strategy can be interpreted as a means of shifting energy to reproductive effort from exploratory behaviour (non-breeding females performed longer flights which combine the survey of environment and the fruit collection). This strategy, based upon the optimization of flying bouts, is in contrast to those of non-flying mammals and probably is only compatible with periods of high food production.

The competitive interactions between two species of characins (Astyanax fasciatus and Astyanax bimaculatus) were investigated by studying their horizontal distribution, relative abundance and feeding habits in littoral and limnetic zones of Americana Reservoir, southern Brazil.

Differences in horizontal distribution of the species mainly as adults led to their partial habitat segregation. Most adult A. bimaculatus were littoral dwellers, whereas A. fasciatus adults were distributed from inshore to offshore waters, but with most in the latter region.

Both are facultative zooplanktivores in the reservoir, feeding mostly on planktonic crustaceans, insects (chiefly chironomids), some higher plant material, detritus and even fish scales (A. bimaculatus). Food overlap coefficients, considering adult and juvenile stages of both species are large in dry as well as wet seasons, although in the dry season the overlaps are significantly reduced for juveniles of both species and for juveniles of A. bimaculatus versus adults of A. fasciatus. Both species prey more on cladocerans than on cyclopoid copepods, and the adults selectively take larger forms (Daphnia gessneri and Moina micrura) in the reservoir (as in previously reported enclosure experiments). Juveniles prey heavily on Bosmina longirostris.

These two formerly riverine species may reduce competition, in the reservoir, by partial habitat segregation in older stages, a mechanism to avoid competition, which may have existed in their previous interactive history in rivers.