A climate model, based on effects of water availability and temperature, was recently proposed to explain global variation in bat species richness along altitudinal gradients. Yet such studies are sparse in the tropics and near-absent in Africa. Here we present results from an altitudinal study of bat diversity from Mount Mulanje, Malawi. Using ground nets, canopy nets and harp traps, we sampled eight sites across three habitat zones from 630 m to 2010 m asl. We assessed the influence of climatic, geographic and biotic variables on measures of estimated species richness, Fisher's α, and an unbiased index of compositional turnover. We recorded 723 individuals and 30 species along the gradient, revealing a ‘low plateau’ pattern in estimated species richness, peaking at 1220 m, which is congruent with the global climate model. Measures of local habitat structure significantly explained a large degree of variation in species richness and compositional turnover between sites. Fisher's α was further significantly correlated to mean annual relative humidity, suggesting a background climatic influence.

We studied the spatial and temporal habitat use of impala in Botswana's Okavango Delta at landscape level with the aid of satellite imagery, with minimal fieldwork. We related remotely sensed vegetation to impala habitat preferences, by first distinguishing three vegetation types through a multi-temporal classification, and dividing these into subclasses on the basis of their Normalized Difference Vegetation Index (NDVI). This indicator for abundance and greenness of biomass was assessed for wet and dry season separately. Similarly, habitat use was assessed for both seasons by allocating vegetation classes to bimonthly impala observations. Impala distribution patterns coincided with NDVI-based subclasses of the landscape, nested within broad vegetation types, to which impala did not show a marked seasonal response. We suggest that this methodology, using limited field data, offers a functional habitat classification for sedentary herbivores, which appears particularly valuable for application in extensive areas with high spatial variability, but with restricted access.

Recent studies have shown that western lowland gorillas (Gorilla gorilla gorilla Savage & Wyman) are highly frugivorous and expel in their dung viable seeds of many fruit species they consume. As part of a wider study of their role as seed dispersers in tropical rain forest, the importance of gorillas as consumers of three species of tropical tree was investigated. The species studied were Ganophyllum giganteum (Sapindaceae), Cola lizae (Sterculiaceae) and Uapaca guineensis (Euphorbiaceae). Gorillas swallowed large quantites of seeds of these species whenever they were available, and removed a considerable proportion of the crop from trees they visited. The differences in abundance and distribution of these trees, and their varied dispersal strategies influenced the quantity of seeds that was removed by gorillas. Uapaca can be seen as having a generalist fruiting strategy, with a wide range of consumers, whereas the other species are more specialist, gorillas being the principal dispersers. Compared to other consumers, this study showed that gorillas provided potentially high quality dispersal because: (i) they were reliable visitors to trees of these species; (ii) they swallowed and dispersed large numbers of seeds; (iii) they treated seeds benignly and often deposited them in sites favourable for establishment.

Studies of seed dispersal and fruit production often use fruit traps. Different trap designs may give dissimilar estimates; however, prior to this study there has been no tropical forest field comparison of trap designs. Likewise, there are no recommendations about the number of traps required to assess ecological parameters, such as fruit production, mass and number of seeds dispersed, and number of plant species producing fruits. We compared the effectiveness of five trap designs in terms of fruit/seed bouncing out of traps, wind effects, area effects and seed removal by predators. These studies took place in Colombia in two tropical rain forests and in laboratory conditions. We found that 300 traps (0.085 m2 each) were not enough to obtain stable estimates in two out of four parameters (number of species and dispersed seeds). All estimates were highly variable when using fewer than 100 traps. All trap designs evaluated (mesh on PVC frame, hanging mesh, basin and funnel traps) prevent seed removal by predators, in sharp contrast with removal from the ground. Mesh traps were less affected by bouncing effects than plastic traps, and this factor was a large source of bias among estimates from different traps. Since up to 68% of dry mass may bounce out, it is important to consider adequate trap designs and to be careful when comparing studies using different methodologies. Small traps received fewer seeds per area, however area affects were not evident when bouncing effects were controlled for. We recommend the use of mesh traps on PVC frames, although hanging mesh traps are a good option in tropical forests without strong winds.

Most ecological studies of fungi associated with tropical plants have focused on the rhizosphere or phyllosphere of seedlings, saplings and adult trees (Augspurger 1983, 1984; Bell et al. 2006, Gilbert 2002, Gilbert et al. 2002, Husband et al. 2002, Kiers et al. 2000, Mangan et al. 2004). However, fungi also infect the seeds of tropical trees, reducing seed survival and potentially affecting adult distributions (Gallery et al. 2007a, b). Fungicide experiments have shown that fungal and oomyceteous pathogens are the major cause of seed mortality in the soil for a variety of tropical pioneers (Dalling et al. 1998, Gallery et al. 2007b, Murray & Garcia 2002), which depend on recruitment from seed banks to colonize gaps and other disturbances in mature forest (Alvarez-Buylla & Martinez-Ramos 1990, Dalling et al. 1997, Hall & Swaine 1980). Persistence in the soil prolongs exposure of seeds to infection by soil-borne fungi and is especially problematic for small-seeded species with thin fruit or seed walls (Baskin & Baskin 1998, Blaney & Kotanen 2002, Crist & Friese 1993). At present little is known about the host affinity of fungi associated with seeds of tropical trees, and consequently, whether seed-infecting fungi influence plant species coexistence through differential infection of, or effects on, potential hosts.

Windthrow was assessed following a convective storm in a stand of tropical savanna in Kakadu National Park, northern Australia. Over an area of 3 ha, 79 out of 810 trees (9.8%) were damaged; 27 of them were either uprooted or snapped off at the trunk. Logistic regression showed that both species and tree height were significant determinants of the probability of wind damage. Branch loss and either uprooting or trunk snapping was highest in the canopy sub-dominant Eucalyptus porrecta. Damage was lowest in the sub-dominant trees Erythrophleum chlorostachys, a species which is relatively resistant to termite damage, and Terminalia ferdinandiana, a deciduous species which is generally shorter than the main canopy dominants. Damage was intermediate in the two most common canopy dominants, Eucalyptus tetrodonta and E. miniata. Wind damage was greatest in trees taller than 9 m and relatively minor in trees below this height. Wind disturbs savanna trees in a manner opposite to that of fire, because wind damage is greatest in taller trees, whereas fire damage is greatest in smaller trees. This, coupled with significant within-patch variability in the extent of wind damage, may act to increase small-scale environmental heterogeneity in savannas.

Two kinkajous (Potos flavus) were equipped with radio-transmitters and tracked during a 14- and a 7-day period in a primary forest of French Guiana. Both individuals were strictly nocturnal. They moved between food patches (flowering or fruiting trees) during c. 65% of the night, visited food trees during c. 20%, while the remaining time was devoted to rest. Rest time tended to peak in the middle of the night, whereas distances travelled peaked at the beginning and the end of the night. Minimum and maximum home range areas, estimated from minimum area and minimum convex polygon methods respectively, reached 15.7 and 17.6 ha in the female, 26.6 and 39.5 ha in the male. Mean daily activity area amounted to 5.5 ha in the female, 11.3 ha in the male. Distances travelled in a night averaged 1495 m for the female, 2540 m for the male. In contrast to the female, the male used the periphery more intensively than the centre of its home range. Both individuals occupied several roosts located in the canopy, but one far more frequently than the others. The male's roosts were all situated in the periphery of the home range.

Kinkajous were observed feeding on flowers or fruits of 15 plant species. Among the 10 species exploited for fruits, at least seven were dispersed. Dispersal distances averaged 200 ± 75 m (13 seed dispersal occurrences for 16 defecations), while seed transit time varied from 45 min to 3 h 35 min. P. flavus appears to be nocturnal, solitary, a generalist fruit and flower-eater and an important seed dispersal agent.

A survey of the diurnal raptor community (46 resident species) at five altitudinal levels from 100 to 4600 m was made in Venezuela using 106 1-km2 sample quadrats and then compared with similar censuses (211 plots) in southwestern Colombia and eastern Ecuador. Six habitat types were defined and habitat preferences were measured from every encountered birds and from the association between individual abundances and the coverage of habitat types on plots. The overall species richness steeply declined with elevation in all three countries. The raptor community consisted mostly of tropical species that rapidly decreased in both abundance and frequency of occurrence with elevation. A small set of subtropical-temperate forest specialists partly replaced them at mid-elevation and only two species occurred in the paramo of Venezuela, against 5–7 in the other countries. Although originally the gradients were probably almost completely covered with forest, a large part of the raptor community is now composed of grassland species, three of them extending from the lowlands to the tree line. The relative impoverishment of the Venezuelan community, especially at upper levels, is attributed to a peninsular effect at the narrow extreme northern tip of the Andes and perhaps also to former forest fragmentation. Within some species, different subspecies had discrete altitudinal distributions and interspecific competition may explain differences in the range extension of some species between countries. Today, however, accelerating deforestation may result in a severe decline of forest-interior species and a probable reduction in the altitudinal range of at least some of them. Species naturally associated with forest gaps or edges usually tolerate a high degree of forest fragmentation and degradation but only one of them may become abundant in heavily human-altered woodlands. Few grassland specialists have become more widely distributed in the increasingly deforested landscapes.

Tropical rain forests are evergreen and experience a climate suitable for plant growth year round (Whitmore 1998). However, most tropical rain-forest trees display periodic shoot growth (Borchert 1991) and show synchronous leaf flushing at the community level (Itioka & Yamauti in press, Medway 1972, Ng 1981). Synchronous leaf flushing may have a great impact on animal population such as herbivores, because young leaves are suitable food resources for many herbivores (Aide 1988, 1992; Coley 1983, Itioka & Yamauti 2004, Lowman 1985).

The Neotropics house two guilds of large arboreal vertebrate seed predators: parrots and the pitheciin primates. Both have diets dominated by immature fruits. The possibility of members of the Pitheciinae (genera Cacajao, Chiropotes and Pithecia) acting as occasional seed dispersers has been mooted, but not experimentally shown. We combined primate behavioural data and seed germination data from three separate field studies in the Brazilian states of Amazonas and Pará to analyse patterns of post-consumption seed survivorship for seeds discarded by three pitheciin species (Cacajao melanocephalus ouakary, Chiropotes chiropotes and Chiropotes albinasus). We then calculated the frequency of dispersal events for four species eaten by C. m. ouakary. All three primate species dropped intact seeds while feeding, and 30.7% of 674 dropped seeds germinated ex situ. Undamaged seeds from unripe and ripe samples germinated (29.3% and 42.7%, respectively), and all three primate species carried some fruits up to 20 m from the parent tree before consuming them. Potential seed-dispersal events varied from 1 (Macrolobium acaciifolium) per fruiting cycle to more than 6500 (Duroia velutina), suggesting that there are differences in dispersal potential. In summary, although they are highly specialized seed predators, these primates may also act as important dispersers for some plant species, and effective dispersal is not restricted to ripe fruits, as immature fruits removed from a tree may continue to mature and the seeds later germinate, a much-neglected aspect of dispersal ecology. The possibility that similar events occur in parrots should be experimentally investigated.

Does competition prevail in large size classes of trees in tropical forests? This question is fundamental to our understanding of the demography and dynamics occurring in rain forests. We investigated this question based on an undisturbed late-secondary forest on a 1-ha plot in central Cameroon. Trees were stem-mapped and classified into three size classes: understorey, midstorey and overstorey. The diameter at breast height and yearly biomass increment were determined as measures of plant growth and performance. Spatial statistics such as pair- and mark-correlation functions were used to detect scale-dependent patterns that could be caused by competition within and between the three size classes. The results revealed a random pattern and spatially uncorrelated measures of plant growth of overstorey trees. This suggests that competitive effects are of minor importance in the large size class of overstorey trees. Likewise, only weak evidence for competition between trees was found within the two lower size classes. However, negative distance correlations were found between the different size classes. We suggest that competition within height classes was relatively low due to the diversity of species with their variable niche differentiations and phenotypic plasticity that may compensate for competitive effects.

The keystone plant resources (KPR) concept describes certain plant species in tropical forests as vital to community stability and diversity because they provide food resources to vertebrate consumers during the season of scarcity. Here, we use an 8-y, continuous record of fruit fall from a 1.44-ha mature forest stand to identify potential KPRs in a lowland western Amazonian rain forest. KPRs were identified based on four criteria: temporal non-redundancy; year-to-year reliability; abundance of reproductive-size individuals and inferred fruit crop size; and the variety of vertebrate consumers utilizing their fruit. Overall, seven species were considered excellent KPRs: two of these belong to the genus Ficus, confirming that this taxon is a KPR as previously suggested. Celtis iguanaea (Cannabaceae) – a canopy liana – has also been previously classified as a KPR; in addition, Pseudomalmea diclina (Annonaceae), Cissus ulmifolia (Vitaceae), Allophylus glabratus (Sapindaceae) and Trichilia elegans (Meliaceae) are newly identified KPRs. Our results confirm that a very small fraction (<5%) of the plant community consistently provides fruit for a broad set of consumers during the period of resource scarcity, which has significant implications for the conservation and management of Amazonian forests.

Germination success of Chlorocardium rodiei is low in large gaps. High light levels, however are beneficial for the survival of seedlings. (Partial) removal of cotyledons has a large negative impact on survival especially under low light conditions. Seedlings from large gaps are larger but not taller than those from the understorey, due to differential internode growth. Although growth of seedlings is improved by higher light levels caused for example by logging, great care should be taken with logging intensity, which may increase seed mortality.

Many areas of rain forest now exist as habitat fragments, and understanding the impacts of fragmentation is important for determining the viability of populations within forest remnants. We investigated impacts of forest fragmentation on genetic diversity in the butterfly Mycalesis orseis (Satyrinae) in Sabah (Malaysian Borneo). We investigated mtDNA diversity in 90 individuals from ten forest sites typical of the sizes of forest remnants that currently exist in the region. Nucleotide diversity declined with increasing isolation of remnants, but there was no effect of remnant size or population size, and haplotype diversity was similar among sites. Thus, approximately 50 y after forest fragmentation, few changes in genetic diversity were apparent and remnants apparently supported genetically viable populations of this butterfly. Many studies have shown that responses of species to habitat fragmentation usually follow a time delay, and so we developed a Monte Carlo simulation model to investigate changes in genetic diversity over time in small remnants. Model output indicated a substantial time delay (> 100 y) between fragmentation and genetic erosion, suggesting that, in the smallest study remnants, an increased risk of extinction from reduced genetic diversity is likely in the longer term.

Species interactions have been recently depicted as networks, in which each species is connected to one or more other species in binary interaction matrices. Forty networks of epiphytic orchid and host tree species were assessed in Brazilian gallery forests. The nestedness of the networks was estimated with the NODF index and the significance was tested with null models. The phylogenetic structure of the network was also assessed, by searching for phylogenetic signals in the number of interactions and in the similarity of interacting species. In total, 105 orchid species and 132 host tree species were sampled. A nested pattern in all orchid–host tree networks was found. However, phylogenetic signals were not observed. The results support that the host specificity of orchids is small and most of the interactions occur among generalist orchids and generalist host trees. While the concept of species-specificity can thus be rejected, the extreme alternative – that interacting orchids and host trees are not a random subset of the regional species pool – can be dismissed as well. However, factors other than phylogenetic history may structure interaction networks of epiphytic orchids and host trees.

This study describes a pollination system in a species of Araceae that involves three species of beetle, one of which is also a fruit predator. In a tropical cloud forest in Colombia, inflorescences of Xanthosoma daguense opened at dusk, releasing a sweet scent and raising their temperature 1–3 °C. Soon after, two species of Scarabaeidae (Dynastinae; Cyclocephala gregaria and C. amblyopsis) and one species of Nitidulidae (Macrostola costulata) arrived with pollen. Cyclocephala beetles remained inside the inflorescence for 24 h. The next night, Cyclocephala beetles left the inflorescence after picking up the freshly shed pollen, almost always moving to the nearest inflorescence available. The probability of inflorescence abortion and number of fruits set after the visit of one individual was equivalent for both Cyclocephala species. However, C. gregaria was much more abundant than C. amblyopsis, so it was the most important pollinator. There was a positive relationship between the number of dynastine visits and the number of fruits produced. Besides carrying pollen to the inflorescences, nitidulid beetles had a negative effect on female reproductive success through fruit predation. Nitidulid larvae developed inside the infructescence and preyed on up to 64% of the fruits. However, 8% of inflorescences not visited by dynastines were probably pollinated by nitidulids, because hand-pollination experiments showed that self-pollination was unlikely. Inflorescences potentially pollinated by nitidulids comprised 25% of the fruit crop in the year of our study. This interaction with a fruit predator that is also a potential pollinator resembles brood-site pollination systems in which pollinators prey on part of the fruit set (e.g. Ficus, senita cacti, Yucca), making this system substantially more complex than previously described dynastine-pollinated systems in aroids.

The Hellshire Hills are an extensive area of tropical dry forest over limestone, located on the south coast of Jamaica. Despite being a protected area, they are subject to encroachment and clearance by charcoal burners, leaving a relatively pristine core within more disturbed areas of forest. Future management requires a consideration of the forest's resilience to such disturbance, and this study reports on seedling dynamics before and after different intensities of disturbance. The study was conducted within twelve 225-m2 plots comprising four blocks and three treatments. The treatments were removal of all trees (≥ 2 cm dbh), removal of 50% of stems (> 5 cm) and an uncut control plot. Seedling dynamics were monitored before and 3, 8, 13 and 20 mo after the application of treatments. The study indicates that regeneration by seed was not severely affected by this small-scale disturbance. However, the density of some species was affected by the environmental conditions created by partial and clear cutting, and seasonal effects were more pronounced after disturbance. Biomass recovery by seedlings was negligible in comparison with coppice regrowth which clearly offers considerable resilience to disturbance in this dry forest where successful regeneration by seed is highly susceptible to rainfall seasonality. This will likely affect long-term species diversity if the present rate of clearance continues.

In May and June of 1989 data on elephant (Loxodonta africana) dung density were collected in the main forested areas of the Central African Republic. A total of 147.0 km of line transects (N = 14 transects, = 10.50 km, SD = 3.79) was completed. Dung was recorded in 37.4% of the 294 sectors of 0.5 km each. The overall dung density was estimated to be 266 piles km-2 (= 382, SD = 383.7). The highest dung density was found in the proposed Dzanga-Sangha Reserve in the extreme south-west with 1166 piles km-2 (N = 12 sectors of 0.5 km). The south-eastern forests were found to have an intermediate dung density of 336 piles km-2 (N = 215 sectors of 0.5 km, = 419, SD = 308). In the eastern section of the south-western forests no dung was recorded along survey transects (N = 67 sectors of 0.5 km). These data indicate that elephant populations are still relatively high in the forests of south-western and south-eastern Central African Republic, while the population in the eastern section of the south-western forests has diminished to a very low level.