We examined the consequences of habitat fragmentation on the assemblage of floral visitors and pollinators to male- and female-phase inflorescences of the understorey dominant palm Astrocaryum mexicanum at the Los Tuxtlas tropical rain forest. In six forest fragments ranging from 2 to 700 ha, we collected all floral visitors, pollinators and non-pollinators, to male- and female-phase inflorescences at the time of their greatest activity. We used multivariate and mixed-effects models to explore differences in guild composition between sexual phases of inflorescences and the effects of forest fragment size on several metrics of the assemblages of floral visitors. We detected 228 786 floral visitors, grouped into 57 species, across the six forest fragments. On average, abundance and species richness of floral visitors to female-phase inflorescences were higher than to male-phase ones. Forest fragmentation had no effect on species richness but negatively affected Shannon's diversity index. Overall, the most abundant species of floral visitors were predominantly found in inflorescences of plants from the large fragments. In contrast, most of the less common species were more abundant in the smallest fragments. The abundance of pollinators (those found on inflorescences of both phases and dusted with pollen that was carried to flower stigmas), and the ratio of pollinators to other floral visitors, increased with fragment size in both sexual phases of the inflorescences but these effects were significantly stronger on male-phase inflorescences than on female-phase inflorescences. These results show that tropical forest fragmentation correlates with changes in the composition of flower visitors to a dominant palm, with a reduction in the abundance of pollinators, but that such changes co-vary with the sexual phase of the plants.

Based on niche theory, closely related and morphologically similar species are not predicted to coexist due to overlap in resource and habitat use. Local assemblages of bats often contain cryptic taxa, which co-occur despite notable similarities in morphology and ecology. We measured in two different habitat types on Madagascar levels of stable carbon and nitrogen isotopes in hair (n = 103) and faeces (n = 57) of cryptic Vespertilionidae taxa to indirectly examine whether fine-grained trophic niche differentiation explains their coexistence. In the dry deciduous forest (Kirindy), six sympatric species ranged over 6.0‰ in δ15N, i.e. two trophic levels, and 4.2‰ in δ13C with a community mean of 11.3‰ in δ15N and −21.0‰ in δ13C. In the mesic forest (Antsahabe), three sympatric species ranged over one trophic level (δ15N: 2.4‰, δ13C: 1.0‰) with a community mean of 8.0‰ δ15N and −21.7‰ in δ13C. Multivariate analyses and residual permutation of Euclidian distances in δ13C–δ15N bi-plots revealed in both communities distinct stable isotope signatures and species separation for the hair samples among coexisting Vespertilionidae. Intraspecific variation in faecal and hair stable isotopes did not indicate that seasonal migration might relax competition and thereby facilitate the local co-occurrence of sympatric taxa.

Squirrels (Order Rodentia; Family Sciuridae) are among the group of small mammals that have high species diversity in the Malaysian tropical rain forests (Corbet & Hill 1992). In Peninsular Malaysia alone a total of 14 diurnal and 11 nocturnal species has been recorded (Medway 1983). In Peninsular Malaysia, several studies on squirrels have been done which emphasized vertical stratification (Harrison 1962, Lim et al. 1977, MacKinnon 1978, Saiful et al. 2001a), diversity (Zubaid & Ariffin 1997), home range sizes (Tamura 1993, Saiful et al. 2001b), social behaviour (Tamura & Yong 1993) and impact of human disturbance on habitat (Johns 1987). These studies were conducted in lowland and hill forests that have been logged. There are, however, few studies on squirrel abundance in terms of their density in Peninsular Malaysia especially in primary ill forests. Therefore, the purpose of the present study is to provide baseline data and information on squirrel richness, diversity and abundance in the Malaysian primary hill forest.

Spatial and temporal variation of tropical insect communities has rarely been studied, although such variation influences estimates of global species richness. Therefore, we compared spatial and temporal variation of herbivorous insect communities on Neoboutonia macrocalyx trees among seven sites over 1 y in a primary tropical rain forest in Kibale National Park, Uganda. The distance between the study sites varied from 4.8 to 31.2 km and altitudinal differences ranged from 20 to 242 m. Permutational multivariate analysis of variance (PERMANOVA) revealed significant spatial changes in community composition of the herbivorous insects and study sites differed also in insect abundance (6.9–26.2 individuals m−2 of leaf area). This is likely to be caused by differences in vegetation, altitude and microclimate among the study sites. The similarity of insect species composition was negatively correlated with geographic and altitudinal distances among sites and positively correlated with the similarity of tree community composition. Species richness varied significantly between sampling dates, ranging from 33 to 41 species. Also community compositions changed between sampling dates, which likely follows from marked seasonal changes in climate and the phenology of other host plants used by the generalist insect species also living on Neoboutonia macrocalyx. In general our study supports the idea of high variability of herbivorous insect communities in primary rain forests even at a small spatial scale. This should be considered when estimations of insect biodiversity are made.

In a study carried out to find out if inselbergs enrich their surroundings with nutrients via drainage, amounts of total nitrogen, nitrate-nitrogen and potassium in rainfall, drainage from bare rock patches and vegetation mats on an inselberg in south-western Nigeria were measured over one year. 43.3 kg ha−1 total nitrogen, 4.8 kg ha−1 nitrate-nitrogen and 10.7 kg ha−1 potassium were recorded in rainfall for the year of study. The amount of total nitrogen in drainage from bare rock was 79% of that in rainfall whilst that in drainage from vegetation mats was 29% of the rainfall amount. The respective values for nitrate-nitrogen were 57% and 13%; for potassium they were 90% and 38%.

It was assumed that the loss of nutrients as water drains through vegetation mats and over bare patches was due to absorption by plants and soil in the mats and lichens in the bare patches. It was therefore concluded that there was no net enrichment of rainwater with nutrrients as it flows over inselberg slopes. There is, however, a funelling of water along with contained nutrients from the inselberg to the surrounding areas. This funnelling is additional to the nutrients and rainfall incident on these surrounding areas and may account for the vegetation around inselbergs being more lush than vegetation in the same area but further away from the inselbergs.

A simple modelling approach was used to assess potential nutrient outflow from inselbergs. The model shows that discharge of nutrients from the edges of inselbergs increases linearly with inselberg diameter. The model further shows that if nutrient funnelling only affects an area near to the edge of the inselberg then nutrient addition is several times higher than would be expected from rainfall deposition alone.

Various aspects of the reproductive biology of a montane population of Colostethus trinitatus were quantified during the transition from a prolonged dry season to a wet season with abnormally low rainfall. One-third to three-quarters of the females collected in the dry period (March to June) had mature ovarian follicles. The proportion of ovigerous females did not increase in July or August when the number of rainy days was greater. However, breed-ing and egg laying were only observed in the latter season. The principal environmental change that stimulated oviposition was frequent daily rain which increased humidity in the terrestrial nest sites.

Pair formation, nests, and males carrying larvae are reliable criteria that indicate the breeding period of Colostethus trinitatus. The average number of mature ovules (>2 mm) was greater in the wet season (=13.1) than during the dry months (= 11.3). Female standard length and the number of yolked follicles was positively correlated. Five nests contained an average of 13.6 eggs, and males carried only slightly fewer larvae (= 11.5). One female and one individual of unknown sex were found with eggs at two different nests. Five nests were unattended.

The survival, height and leaf production of seedlings and juveniles of Aspidosperma fendleri and Richena grandis were measured monthly for three years after germination. During the first year, some seedlings and juveniles of Aspidosperma fendleri were collected and the number of rootlets, the primary root length and the shoot: root ratio were determined.

Both species show periodicity in growth but their relative growth rate differs between species. For Aspidosperma fendleri, the highest relative growth rate (0.313 y-1) was found for individuals grown under greenhouse conditions followed by individuals growing in an old forest gap (0.143 y-1) and finally individuals under the forest canopy (0.137 y-1). For Richeria grandis, the relative growth rate under the forest canopy was 0.261 y-1. Leaf production for Aspidosperma fendleri in the forest (natural conditions) was 4.39 total mean leaf number for five years and 5.46 total mean leaf number under greenhouse conditions. For Richeria grandis it was 5.34 mean leaf production for four years. The root: shoot ratio for Aspidosperma fendleri was constant during the observation year. Aspidosperma fendleri showed a lower number of rootlets than did Richeria grandis. There was an inverse relationship between growth and survival during the dry season. During this period, mortality was higher and the highest mortality occurred during the first year when the total relative growth rate was highest.

Slow growth is evident in both species. This mechanism may represent an adaptive advantage to remain dormant until there is an opening in the forest canopy. Since the seeds of Aspidosperma fendleri and Richeria grandis are highly vulnerable to predators and pathogens, slow growth as seedlings and juveniles allows them to survive, and contributes to regeneration in cloud forest.

We examined quantity and quality components of primary seed dispersal for an assemblage of sigmodontine rodents in a high-elevation montane tropical forest in Peru. We collected faecal samples from 134 individuals belonging to seven rodent species from the subfamily Sigmodontinae (Cricetidae) over a 2-y period. We conducted seed viability tests for seeds found in faecal samples. We identified seeds from eight plant families (Bromeliaceae, Annonaceae, Brassicaceae, Ericaceae, Melastomatacae, Myrtaceae, Rosaceae, Solanaceae), nine genera and 13 morphospecies. The most abundant seeds belonged to Gaultheria sp. 1 (46% of total) and Miconia sp. 1 (31% of total), while the most viable seeds belonged to Greigia sp. (84% viability) and Guatteria sp. (80% viability). We utilized relative rodent abundance, seed species diversity, seed abundance and seed viability per rodent species to calculate an index of rodent disperser effectiveness, and found that Thomasomys kalinowskii was the most effective disperser, followed by Akodon torques, Calomys sorellus, Thomasomys oreas, Oligoryzomys andinus and Microryzomys minutus. Plant genera dispersed by sigmodontine rodents overlapped more with bird- and terrestrial-mammal-dispersed plants than with bat-dispersed plants. Future neotropical seed dispersal studies should consider small rodents as potential seed-dispersers, especially in tropical habitats where small-seeded, berry-forming shrubs and trees are present.

The process by which solitary animals evolve to live in groups is a central question in biology. Conspecifics that compete for patchy resources may evolve incipient social behaviours such as group formation and conspecific tolerance when persistent aggressive interactions reduce resource access. In this investigation, a facultative group living species of whip spider was studied to understand the microhabitat resources that support group formation. Although most species of whip spider are solitary and oftentimes cannibalistic, Heterophrynus batesii sometimes aggregate in small groups at the bases of tree trunks. Twenty-five groups of whip spiders and associated tree buttress microhabitats were surveyed at Tiputini Biodiversity Station bordering Yasuní National Park in Eastern Amazonian Ecuador. Tree buttress complexity, surface area and other microhabitat variables were recorded. Heterophrynus batesii aggregated in groups of 2–8 animals and used large, buttressing, complex trees with more leaf litter relative to those available in the environment. This study showed that large groups of whip spiders require more complex microhabitats than smaller groups that were associated with more variable microhabitat parameters. These microhabitats act as patches of limited resources important for the species, and may have led to the evolution of tolerance and facultative group living.

The response of vascular epiphyte communities following natural or human disturbance has been little studied. Over 5 y, we evaluated the post-stripping recolonization of vascular epiphytes in cloud forest. Vascular epiphytes were experimentally removed from branch and trunk plots (1 m in length) on five trees in two secondary cloud forest fragments in southern Mexico. Similarity between colonizer and established communities was compared in each fragment using a further five trees with no stripping. All seedlings were recorded yearly. Non-vascular epiphyte cover was estimated in each plot. The recolonization rate was very high; after 5 y, epiphyte density of the colonizer community (27.4 ± 6.8 individuals per segment) reached similar values to those of the established community (26.7 ± 3.3) in nearby trees. While similarity (composition and abundance) between the colonizer community and established community was high (81%), diversity accumulation curves indicated that the colonizer community presents a lower diversity of epiphytes (5.5 equivalent species) than the established community (11.4). Colonization of xerophytic bromeliads was high, while pteridophytes and orchids presented reduced recovery. The immediately surrounding source of propagules had a strong influence on recolonization. In both the colonizer and established communities, dominance rank was bromeliads > peperomias > pteridophytes. The results show that the recovery capacity of epiphytic vegetation in secondary forest is high, if propagule sources are close by. However, at 5 y after disturbance, it is unclear whether the colonizer community would present the same species composition as the established community or if it would give rise to a different community.

The ant assemblages in two common tree species in primary lowland forest of New Guinea were explored using direct canopy access and tuna bait traps. The 19 trees investigated were occupied by 21 ant species of which 18 were canopy inhabitants. On average only 3.6 ant species per tree and 3 species per bait were found. Height of bait position was positively related to ant species richness, with the upper parts of the canopy being occupied by the highest number of species. On the other hand, tree species and study site did not have any effect on ant species richness nor on structure of the ant assemblages. Ant species appeared to be distributed randomly and we did not detect any effect of distance on similarity of ant assemblage occurring on the trees. The dominant species (Crematogaster polita) had certain negative effects on the presence of some species at food sources co-occurring at the same tree, but it did co-occur with the other ants to some extent as well. The majority of species found in the canopy were generalist omnivores (depending mainly on trophobionts or plant exudates).

Biopedturbation, or animal-caused soil disturbance, may be important for development and maintenance of small-scale heterogeneity in ecosystems with the potential to alter seed mortality and recruitment. However, its role in tropical forests has been largely ignored. This study explored effects of vertebrate biopedturbation on seed (1) microsite heterogeneity, (2) predation and (3) germination in a West African rain forest. Exclosure experiments were used to study how biopedturbation altered burial and movements of seeds of four common canopy species. Effect of seed burial on removal by seed predators was also examined. Germination of the dominant canopy species (Raphia palma-pinus) in swamp forest was tested within artificial disturbances mimicking that of a locally common but endangered mammal, the Liberian mongoose (Liberiictis kuhni), which was estimated to turn over the entire forest floor in this habitat in c. 8 mo. Seed exposure to biopedturbation for 20 d (n = 80) led to an overall 6.5-fold increase in small-scale horizontal movement and increased probability of burial (6–52% higher), varying by species. Burial effectively eliminated seed removal for all four species (n = 160) by seed predators over 20 d. Germination of Raphia palma-pinus seeds (n = 100) was enhanced by 17.5% on average over 4 mo in simulated disturbances. Results suggest biopedturbation may be important for seedling recruitment and that loss of species with this functional role could have underappreciated yet important impacts on tropical plant communities.

The dioecious character (sex ratios and stand structures, conspecific neighbour relationships, inflorescence numbers and structure) and reproductive process (phenology, anthesis, flower visitors and fruit production) of a miombo woodland species, Uapaca kirkiana were investigated in natural populations in Malawi. The sex ratio of reproductive individuals ≥ 10 cm diameter at breast height was about 1:1 and departures from this ratio mostly resulted from a higher proportion of the males. Spatially, the sexes were randomly distributed but generally within 10 m of each other with no obvious gender differences in size. Throughout Malawi, male and female reproductive individuals flower synchronously between October–April (with a peak period in February–March). A 6 : 1 male to female inflorescence sex ratio was common. Anthesis in female inflorescences lasts almost twice as long as in male inflorescences and only the latter have any odour. On male trees, inflorescences are in fascicles, whereas on female trees, they are solitary. In both cases, the inflorescences are generally similar in size except for the peduncles of the male inflorescences which are longer than the female's. A range of insects visits U. kirkiana flowers but the most likely pollinators are bees (Apis mellifera), and beetles (Dothera bennigseni, Chelomenes lunata, Alcidodes denticulatus and Mitracamenta sp.). Apart from pollen from the male inflorescences, female flowers do not offer any obvious reward for flower visitors. Pollination studies revealed that assisted pollination did not significantly improve fruit production or seed quality over unpollinated or naturally pollinated inflorescences. Facultative agamospermy (apomixis) is suspected as a phenomenon requiring further attention in U. kirkiana.

We report on a 2009 survey of Acacia woodlands in the Seronera area of central Serengeti, Tanzania, and compare the results to previous surveys from the 1970s–1980s. We document a substantial change in woodland structure and composition. From 1978 to 2009, woody plant density (mean ± SD) declined from 255 ± 35 trees ha−1 to 147 ± 14 trees ha−1. Canopy cover declined from 15.1 ± 1.9% to 5.7 ± 0.6%. Canopy volume declined from 1810 ± 207 m3 ha−1 to 1410 ± 121 m3 ha−1. A 19% increase in the relative canopy volume of Acacia robusta, a species avoided by the giraffe, represents a sharp decline in the quality of the giraffe's food supply, which was last comprehensively assessed in 1978. We examine these changes in the context of Pellew's 1983 woodland dynamics model describing the impacts of elephant, giraffe and fire on an Acacia tortilis tree population and determine that our data are qualitatively consistent with this model. We hypothesize that selective elephant and giraffe browsing has contributed to an increase in the relative dominance of unpalatable species, consistent with Pellew's predictions.

Species showing mast seeding synchronously produce large amounts of fruits during some scattered years. This massive crop has been hypothesized to improve dispersal effectiveness by a satiation of seed predators, but the consequences for seed dispersers have barely been studied in the tropics. We tested the hypothesis that masting resulted in satiation of frugivorous dispersers using the study case of two Manilkara species growing in an Amazonian forest in French Guiana. Seed dispersal was estimated by means of seed traps in two forest types during a 10-y monitoring. Manilkara huberi and M. bidentata showed three fruiting events in a time span of 10 y (in 2001, 2006 and 2010). Estimates of seed dispersal from 2001 and 2010 showed that satiation of frugivores only occurred in the year with the largest crop of Manilkara (2010) and in the habitat where the diversity of primate-dispersed species retrieved in seed traps was the highest (Grand Plateau, with clay soils), while fruit consumers did not seem to be satiated in other instances. Spatio-temporal variability of seed production and the community-crop context are therefore affecting satiation of frugivores during masting events.

The fact that certain climatic variables are similar in high-latitude temperate zones and at high-altitude sites in the tropics, has led to assumptions about ecologically equivalent situations. The altitudinal differences between two data sets obtained in forests in temperate Denmark at sea level and in tropical Ecuador at 3000–3350 m above sea level provided a comparison suitable for examining whether high-altitude Andean forests are temperate or tropical from the standpoint of avian richness, abundance and trophic organization. Sampling methods at the two locations were similar. The Ecuadorian high-altitude sites were found to be significantly more species-rich than Danish temperate sites at all spatial scales studied (from point census to 10 km2). Additionally, species–area curves from the two countries displayed positive correlations, as expected, but with different rates of increase. The high-altitude Andean curve demonstrated a higher rate of increase causing the two curves to separate widely as more area was added. This means that when increasing areas are considered, proportionately more species squeeze into the Ecuadorian high-altitude forest landscape than do into the temperate Danish forest landscape. Corresponding to the data on richness, bird abundance was significantly higher at the Ecuadorian sites than at the Danish ones. The analysis of rank–abundance plots from Denmark and Ecuador throws light on the organization of bird species and abundance. The majority of communities in both countries fitted both the log-series and the log-normal models, making statistical distinction impossible. However, a visual inspection of the rank-ordered abundance distributions demonstrated that the Danish communities, in contrast to the Ecuadorian ones, had dominant species with relatively higher abundance, had more species with intermediate abundance, and had fewer species ‘rare by abundance’. Some major food resources (especially fruit and nectar) exploited in high-altitude sites of Ecuador were not reliably available in temperate Denmark leading also to differences in the distribution of bird species within six major trophic categories. In conclusion, the ecological characteristics of birds of the high Andes apparently are similar to those of the tropical and tropical lower montane sites (increased richness and abundance, similar organization of richness and abundance, similar additional trophic categories, similar clutch sizes), and not to those of the high- and low-latitude temperate sites.

Drying floodplains that were not inundated for more than 10 y were investigated to relate plant species and vegetation structure to time-since-fire for the southern Okavango Delta wetland in Botswana. The aims of the research were to study post-fire succession on savanna habitats in the Okavango Delta and to investigate the mechanisms behind vegetation changes with time-since-fire. We hypothesize that vegetation structure rather than species occurrence is affected by the fire event and that the driving forces of post-fire succession change from fire-driven to competition-driven with increasing time-since-fire. A total number of 153 study sites were investigated, representing areas of 2–12 y without a fire. Both woody and herbaceous plant species were recorded and cover/abundance values were measured. The vegetation changes with time-since-fire could be assigned to three different successional stages: (1) the post-fire conditions shortly after fire, supporting high species numbers due to open space and little competition; (2) the dominance of competitive perennial grass species (e.g. Urochloa mosambicensis) after 6–8 y; and (3) the enhanced establishment of woody species after about 10 y, creating new habitats in their vicinity. High species numbers were found after short and long fire-free periods, and different species occurred shortly after the fire event and at late stages of the post-fire succession. A variety of different inter-fire intervals is therefore expected to be responsible for sustaining plant species richness and habitat diversity in the study area. Post-fire succession could be described as not only being driven by the life history of the species, but also by seedbank dynamics and plant mobility in early successional stages and by competition and niche differentiation in late-successional stages.

Not much is known about the nitrogen (N) uptake capacity and N-form preference of tropical trees. In a replicated labelling experiment with 15N-ammonium, 15N-nitrate and dual-labelled glycine applied to saplings of six tree species from southern Ecuadorian montane forests, we tested the hypotheses that (1) the saplings of tropical trees are capable of using organic N even though they are forming arbuscular mycorrhizas, and (2) with increasing altitude, tree saplings increasingly prefer ammonium and glycine over nitrate due to reduced nitrification and growing humus accumulation. Three- to 5-y-old saplings of two species each from 1000, 2000 and 3000 m asl were grown in pots inside the forest at their origin and labelled with non-fertilizing amounts of the three N forms; 15N enrichment was detected 5 days after labelling in fine roots, coarse roots, shoots and leaves. The six species differed with respect to their N-form preference, but neither the abundance of ammonium and nitrate in the soil nor altitude (1000–3000 m asl) seemed to influence the preference. Two species (those with highest growth rate) preferred NH4+ over NO3−, while the other four species took up NO3− and NH4+ at similar rates when both N forms were equally available. After 13C-glycine addition, 13C was significantly accumulated in the biomass of three species (all species with exclusively AM symbionts) but a convincing proof of the uptake of intact glycine molecules by these tropical montane forest trees was not obtained.