Patterns of fruit production were monitored over a 1-year period, from June 1990–May 1991, by counting the numbers of freshly fallen ripe and unripe fruits on five 5-km line transects located within 35 km of one another, in lowland tropical rainforest in the Lopé Reserve, central Gabon. A total of 195 species of fruit were found, representing at least 45 taxonomic families. The majority of fruits came from trees. Fruits were assigned to one of six categories which reflected their dispersal syndrome: succulent, arillate, dehiscent, fleshy pods, wind-dispersed, others. About three-quarters of all species had fruits characteristic of those dispersed by animals. There was a marked seasonal pattern to fruit production, with both the diversity and number of ripe fruits available peaking in January, and lowest immediately before and during the major dry season. The only climatic variable that showed a significant statistical correlation with fruit production was insolation. Candidates for the role of keystone fruit species were identified from species which fruited during the major dry season, and patterns of fruit production compared with other areas.

Effects of tree species heterogeneity on leaf fall were studied in a primary (4 ha) and in a selectively logged forest plot (2.5 ha) in the Ulu Segama Forest Reserve, Sabah, Malaysia, from April 1988 to December 1989. Leaf fall was collected at 30 sampling points in each plot, and identified to species.

Dipterocarpaceae, Euphorbiaceae, Lauraceae, Fagaceae and Meliaceae are important tree families in both plots with regard to their contribution to total basal area, tree density and annual leaf fall. The total number of tree species was higher in the primary forest plot (267) than in the logged forest plot (218), although the number of climber species was higher in the logged forest (44) than in the primary forest plot (33). The overlap in species composition between the two forest plots was relatively small (49%) compared with that in family composition (88%).

In the primary forest plot, the Dipterocarpaceae contributed 29% of the total basal area and 34% of the annual leaf fall. In the logged forest plot these contributions were much lower, 11% and 15%. The contribution to annual leaf fall made by climbers and pioneer trees was higher in the logged forest plot (34%) than in the primary forest plot (8%).

In the primary forest plot, leaf fall was dominated My large emergent and main canopy trees, mainly dipterocarps, and occurred as regular large peaks. In the logged forest leaf fall was dominated by climbers and many, relatively small trees of pioneer species, such as Macaranga hypoleuca, and was more evenly distributed in time.

A 100-ha quadrat of primary rainforest in French Guiana was ccnsused over two consecutive years by the mapping method, and a 24-ha core area was intensively mistnetted at the same time. More extensive surveys were conducted in successively larger areas including up to a large part of the forested interior of the country. From a total of 441 resident species found in the rainforest zone, 248 were regularly recorded within the 100-ha plot, 157 of which had mean densities of more than 1 pair km-2. The total estimated density of birds was at least 829 pairs km-2. Only two dominant species exceeded 20 pairs km-2, while 52% of all the species were represented by less than 2 pairs km-2. The distribution of body masses and niche characteristics among the bird community is given as well as the sample bias of the mistnet captures.

Rare species were a key component of this primary rainforest community. Several patterns of rarity were described and no marked and constant relationships were found between rarity and body size, habitat, diet, foraging behaviour or social system. Among a wide set of environmental constraints, the population of each species may be limited by a different combination of factors. Habitat heterogeneity, low, irregular and seasonal food availability, interspecific competition or heavy predation pressure were prominent and likely causes of the low density of most species which in turn facilitated the high species richness.

Leaf litter invertebrates were sampled at eight sites, approximately 250 m apart in elevation, along an altitudinal transect extending from primary lowland rainforest to cloud forest in western Panama. The study focused on several diverse and numerically important litter invertebrate taxa (e.g., ants, spiders, and beetles) that were effectively sampled using a combination of litter sifting and test tube pitfall traps. The mean altitudinal range of species was around 500 m (standard deviation 370 m) and approximately 50% of the species characteristic of a given elevation dropped out after a 500 m change in elevation in either direction. There was no evidence for distinct altitudinal zonation in leaf litter assemblages. Both species richness and number of individuals of most taxa showed a pronounced decline in the vicinity of the upward transition to cloud forests. The data also suggest a broad mid-elevation peak in sample species richness for the litter invertebrate fauna. The implications of the results for biodiversity conservation are discussed.

Growth in diameter and the relationship between age and size are analysed for 22 tree species in Amazonian Ecuador using growth simulation by a stochastic technique that projects the diameter-age relationships of a species. Maximum diameter growth rates varied from 1.2 mm y–1 (Grias neuberthii) to 20.0 mm y–1 (Cecropia sciadophylla). Minimum growth rates ranged from almost zero in Neea divaricata to 2.4 mm y–1 in Mollia lepidota. Median growth rates ranged between c. 0.5 mm y–1 (Grias neuberthii, Neea divaricata) and 11.6 mm y–1 (Cecropia sciadophylla). The maximum simulated life-span spent between a DBH of 10 cm and the largest DBH of a species varied from 54 y (Cecropia sciadophylla) to 529 y (Neea divaricata). Fast growing species and species that potentially can grow old showed a convex survivorship curve, whereas slower growing species and species that do not grow very old showed sigmoid, linear and convex survivorship curves. The species were grouped according to their DBH-height relationship and according to their maximum age, maximum growth rate, and maximum DBH. The groups probably reflect different light requirements. A negative correlation was found between maximum age and mortality rate. Growth rates vary within species, thus the largest tree is not necessarily the oldest.

Plots of 1.25 and 11.25 ha were enumerated for trees and lianes ≥10 cm and trees ≥70 cm dbh respectively along a line transect in the Lopé Reserve, Gabon. In the small plot 511 trees and lianes of 116 species were found, and 175 trees of 48 species were present in the large plot. The plots were then subject to commercial mechanised logging and the enumerations were repeated once logging had been completed. The extraction rate was two trees ha−1 and in the large plot a total of 31 (17.7%) trees representing 20.6% of the total original basal area died. Incidental damage in the small plot resulted in the loss of 10.8% of trees and lianes present, and 12.9% of the original basal area. Canopy cover was reduced by 10%. Damage levels were low compared with figures from most other tropical regions. The relevance of these figures to forest management in Gabon are discussed.

The diet of capuchin monkeys, Cebus apella, in a 250 ha semideciduous forest in south-east Brazil was studied for 44 consecutive months. Based on 367 feeding bouts the diet of capuchins was 53.9% fruit pulp, 16.0% seeds, 11.1% flowers, 6.3% leaves and new shoots, 1.5% roots and 13.9% corn from plantations surrounding the forest. Seventy-one plant species were consumed by capuchins. Food availability was markedly seasonal. During the dry season the fleshy fruit availability decreased, and at that time the capuchins became seed predators and flowereaters. Several fruits eaten by capuchins in the dry season were not consumed by other frugivorous vertebrates, such as howler monkeys, parrots or squirrels, allowing capuchins to avoid competition with other arboreal frugivores. In semideciduous forests where fleshy fruits are less abundant than in the wet forests capuchins are important seed predators.

Dysoxylum gaudichaudianum is an important canopy tree on the Krakatau Islands, and its ecology is of significance to an understanding of successional dynamics. It is abundant on Panjang and Sertung, but only locally common on Rakata. A study was undertaken of three aspects of its seed ecology in July/August 1992. The chief dispersers of D. gaudichaudianum are suggested here to be birds, with two species of pigeon and a bulbul prominent as fruit feeders over a short observation period. Bird activity dislodges large numbers of fruits and seeds which fall to the ground where they form a resource available to other animals. It was observed that seeds of D. gaudichaudianum suffer varying levels of attrition on the forest floor, with 40% of the total sample lost over a 12-day period, compared with 23% which had germinated. When mature, opening fruits develop a fishy aroma, which is attractive to insects. They hasten the decay process and release the seeds. The soft, rotting tissues of fallen fruits support a small, short-lived successional insect community. After about five days on the forest floor only the seeds and the outer fruit coat remain. Despite the abundance of fruit of this species during the dry season and its obvious attraction tó frugivorous birds, D. gaudichaudianum has still colonized only a small fraction of the near-coastal lowlands of Rakata.

The relationships between soil properties, topography and tree species distribution were analysed in a tropical riverine forest at the margins of the Rio Grande, in Bom Sucesso, state of Minas Gerais, south-eastern Brazil. The forest was sampled by three 0.18 ha plots, with each plot made up of eight contiguous 15 m X 15 m quadrats, four of which were placed at the river margin and the remaining four in the forest interior. A canonical correspondence analysis indicated that the species' density distribution was significantly correlated with some soil chemical characteristics and topographical features. The soils of the three sample plots showed statistically significant differences for the levels of Ca, Mg, K and pH, with the fertility (expressed by the cation exchange capacity) increasing from Plot I to Plot III. These variations were mainly explained by the first canonical axis while the second was strongly correlated with topographical variables, separating the quadrats into two groups: those of the higher and steeper sites from those of the lower sites. The only soil property that was significantly different in lower and upper sites was the concentration of phosphorus. No significant difference in tree species distribution was found between river margin and interior quadrats, certainly because this forest sector lies on the outer side of a curve of the river where erosion is currently building high and steep river banks and forcing the forest to retreat. A tentative ecological classification of the 30 most abundant species according to their habitat preference in terms of soil fertility and topographical sites, and to their growth strategy in the forest dynamics, is presented. It is suggested that these factors play an important role in promoting the coexistence of tree species in this type of forest.

Patterns of bird species diversity within three vegetation types were investigated by the line transect method on Mundanthurai Plateau, South India. Minimum numbers of species and individuals were seen in the study area during July and August. Such seasonal variation was more pronounced in riverine and dry deciduous forest than in the secondary vegetation which was avoided by most of the winter migrants. There was a greater species overlap between riverine and dry deciduous forest than between riverine and secondary vegetation.

No relationship could be established between bird species diversity and tree species/foliage height diversity. The secondary vegetation had fewer specialized forest species and more generalists. Larger birds (>200 g) were rare but smaller ones (<50 g) were more common. The paper emphasizes that the conservation status of avifauna in managed forests in India needs to be assessed and monitored.

Six Vochysia species occurring in cerrado vegetation or gallery forest in central Brazil were studied for their pollination biology and breeding system. The species showed rather different flowering phenologies, but presented a relatively uniform floral morphology and attracted a mostly similar spectrum of visitors. Principal pollinators were large Anthophoridae bees, but three species were also visited by sphingid moths while hummingbirds were opportunistic visitors to all species. Some observations indicated that the slight differences in flower size or habitat between species may have influenced the relative importance of bees versus hummingbirds or sphingids as effective pollinators. All six species were found to be self-incompatible with self-pollen tube rejection, usually accompanied by callose deposition, occurring in the mid-style.

This paper examines the floristic changes that occur following human disturbance in mid-montane forest in the Wau area in Papua New Guinea. The study was restricted to a 1600–2400 m altitudinal range on Mt Kaindi, with disturbed forest, and Mt Missim, with undisturbed forest. Special attention was given to the status of Nothofagus pullei which is locally dominant on Mt Kaindi.

A major change in floristic composition was observed between 1800 and 2000 m. The abundance and species composition of ferns and mosses above 2000 m characterizes the floristic differences. Nothofagus pullei was found to be a pioneer species with a long life-span, one which does not regenerate under its own cover. There were no other important floristic differences between Notho-fagus-dominated forest and mixed mid-montane forest. Nothofagus pullei locally dominates the canopy and thereby suppresses the growth of other trees.

The wet evergreen forest of Nelliampathy in the Western Ghats of Kerala in India is a mixed forest with a high species diversity and basal cover. In this relatively undisturbed ecosystem, canopy gaps are largely formed through single tree fall, but gaps through branch fall, crown fall, standing dead trees or multiple tree fall also occur. Canopy gap formation is more (over 82% of the total gaps created) during the monsoon season. The mean number of gaps formed in this forest is 1.13 ha−1 y−1 and the turnover rate is 83 years. The majority of the gaps created (over 70%) are of smaller size (≥ 100 m2). In this forest, while some top canopy tree species (those capable of exceeding 25 m in height at maturity) such as Palaquium ellipticum and Mesua nagassarium are well represented in seedling, sapling and mature tree stages, others like Aglaia exstipulata and Mastixia arborea are observed only as saplings and/or mature trees with no seedling populations. The possible reasons for these two types of regeneration behaviour by top canopy tree species in the context of canopy gap size and seasonality in gap formation are discussed.

Reproduction of the African murid genus Mastomys, multimammate rats, is seasonal, starting after the rains and extending well into the dry season. During a two-year study in Tanzania, we tested three hypotheses to investigate the proximal causes of this seasonality. Food availability was no limiting factor since food supply could not induce continuous breeding. Temperature was always high and thus not a restrictive climatic factor. Diet was probably always sufficiently varied and protein-rich to allow reproduction. This contradicts earlier hypotheses that consider Mastomys as an opportunistic breeder in which reproduction is seasonally limited by poor conditions; environmental predictors were believed not to be involved since the animals live in an unpredictably unstable environment. However, although the occurrence of rain may be unpredictable, it is highly predictable that heavy rainfall will be followed by good conditions. Laboratory experiments show that sprouting grass has a stimulatory effect on reproduction, suggesting that breeding is triggered by new vegetation.

Mistnets were set at ground level and 11–30 m above ground in lowland rainforest at Kuala Lompat in peninsular Malaysia, and Sepilok in Sabah, to compare the abundance of fruit bats in the subcanopy and at ground level. Capture rates in the subcanopy were up to 100 times greater than at ground level, averaging 3–7 bats per net-night. Species diversity was higher in the subcanopy than forest understorey. Two species that were frequently captured in the subcanopy, Megaerops wetmorei and Dyacopterus spadiceus, were previously thought to be rare. The abundance of Old World fruit bats in the subcanopy indicates that their roles in pollination and seed dispersal of Malaysian forest trees may be greater than previously recognized. Further research on foraging ranges, food selection and roosting habits is required to determine the overall importance of fruit bats in forest regeneration through seed dispersal, and the adequacy of existing reserves for their conservation.

The fate of mature Acacia tortilis pods on the tree and ground and A. nilotica pods on the ground were investigated at a site in South Africa. Pods on Acacia trees were browsed only by giraffe whereas pods on the ground were browsed by kudu, impala, steenbok and duiker. In the absence of giraffe most A. tortilis pods fell from the tree to the ground. When giraffe were present they consumed most A. tortilis pods at tree level. Bruchids infested 21.6–54.0% of seeds within pods on the tree. Once fallen, in the absence of browsing ungulates, A. tortilis and A. nilotica pod and seed disappearance could be attributed to burial by termites and ants, seed consumption by rodents and to decomposition; when browsing ungulates were present they consumed most pods on the ground. Between 20.0–47.6% of A. tortilis and 31.0–58.0% of A. nilotica seeds on the ground were infested by bruchids. Ungulate browsing had no effect on bruchid infestation of seeds. This study exemplifies the importance of browsing ungulates as consumers of Acacia pods. Although survival of A. tortilis and A. nilotica seeds was greatest in the absence of browsing ungulates the survival of seeds following pod consumption by ungulates is unknown.