Epiphytic orchids are very diverse in montane forests, but fragmentation modifies this diversity. Twenty fragments were quantified to evaluate the effects of fragmentation on the alpha and beta diversities of epiphytic orchids in a montane forest located in southern Mexico. The following factors were evaluated: area, core area, shape, edge density, Euclidean nearest-neighbour distance fragment and contrast index. In each fragment, two transects of 2 × 50 m were drawn, and the trees with a diameter at breast height ≥ 20 cm were recorded. In each tree, the orchid species present were identified and quantified. Twenty-three species of epiphytic orchid in 234 phorophytes corresponding to 20 species were recorded. The epiphytic orchid richness per tree and species turnover was different between the phorophytes. The edge density and the contrast index had significant effects on the alpha diversity, while the isolation of the fragments significantly affected the beta diversity. The edge density positively affected the alpha diversity of the epiphytic orchids, likely through microclimatic changes caused by fragmentation. Drought-tolerant species were common on the edges of the fragments, and shade-tolerant species established on the core area of the fragments. This pattern most likely depends on the ecological range of the taxa, which is crucial to their development and persistence in fragmented habitats.

To understand the variation in community dynamics of tropical montane forests along gradients of soil fertility, death, recruitment and growth of trees (≥5 cm diameter) were monitored over 14 y (1997–2011) in nine plots placed in a matrix of three geological substrate types (Quaternary sediments, Tertiary sedimentary rocks and ultrabasic rocks) and three topographical units (ridge, middle and lower slopes) on Mount Kinabalu, Borneo. The plot area was 0.05 ha for ridge, 0.1 ha for middle slope and 0.2 ha (on ultrabasic rocks) and 1 ha (on the other substrates) for lower slope. Recruitment rates did not show a consistent pattern across geological substrates or topographies. Mortality rates were relatively high in almost all plots during the 1997–1999 period, including the El Niño drought, and in three plots on ultrabasic rocks during 2001–2005. Binomial logistic regression analyses showed that mortality during 1997–1999 increased with soil fertility (soluble phosphorus). Background mortality, excluding these periods, did not differ across geological substrates or topographies. The average growth rate during 1997–2011 was higher on more fertile soils and positively correlated with mortality during 1997–1999. We suggest that a high mortality rate during the drought period was related to high species diversity on more fertile soils, whereas a lower growth rate was related to stunted structures on poorer soils.

South-East Asian tropical rain forests experience sporadic, but profuse, seed production after general flowering, leading to the synchronous emergence of various seedlings and subsequent seedling dynamics, which play a crucial role in determining species distribution and coexistence. We examined the relative importance of both biotic (initial height, conspecific seedling density) and abiotic (canopy openness, per cent sand, soil water content) drivers using survival data for 1842 seedlings of 12 dipterocarp species for 1.5 y following mast fruiting in an old-growth Bornean tropical rain forest. More than 30% of all dipterocarp seedlings survived 1.5 y after mast fruiting. When all species were analysed together, we found that initial seedling height, canopy openness and conspecific seedling density affected dipterocarp seedling survival. Negative density dependence indicated that predators were not satiated, but dipterocarp seedlings rather suffered from host-specific natural enemies or intraspecific competition. Species-level analyses of seven dipterocarp species showed large variation in response to biotic and abiotic factors. These results suggest that interspecific differences in the relative importance of biotic and abiotic effects on seedling survival might contribute to species coexistence.

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.

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.

For endozoochorous seed dispersal systems, the extant dung beetle assemblage at seed deposition sites may influence site suitability as burial activity may change the probability that seeds germinate and seedlings establish. This study tested if the different conditions of the two main seed-deposition habitats of a western lowland gorilla population of south-east Cameroon (sleeping sites and old secondary forest) influenced dung beetle assemblages and consequently the seed relocation patterns. In March 2012, in both habitats, burial patterns (proportion and depth) were described in eight stations based on two 300-g experimental faeces with known number of Uapaca spp. seeds (N = 75) left for 48 h, and beetle assemblages were described based on one 48h-dung-baited pitfall trapping session in five of these stations. To assess the impact of burial pattern on seedling emergence, Uapaca seedling emergence trials were performed in a nursery (75 seeds per depth treatment). Assemblage at sleeping sites had a higher species richness (non-significant) and was significantly more abundant than in old secondary forests. Conversely, significantly more seeds were buried in old secondary forests than sleeping sites and at significantly greater depths (mean: 14.9 cm vs. 8.7 cm). As trials suggested that burial depth ≥7 cm prevented Uapaca seedling emergence, dung beetles are assumed to induce seed loss more strongly in old secondary forests than sleeping sites (20.5% vs. 6.7% of initial seed crop). The demonstration that dung beetles may exert a negative influence on seed fate overall, and that the degree to which this occurs may vary depending on habitat, highlights the complexity in determining the suitability of deposition sites for recruitment.

Gut transit times and dispersal distances of seeds ingested by Callicebus coimbrai at two localities were estimated by tracing seeds found in faeces to feeding sites. Feeding events and faecal samples were recorded/collected and mapped by GPS between April and July, 2012. Junco group fed almost exclusively on fruit, whereas Trapsa group fed on fruit and leaves/flowers in similar proportions. A much higher proportion of faecal samples from Junco contained seeds (47.9%, n = 244, vs. 33.6%, n = 177), and contained more seeds, on average (3.0 ± 2.8 vs. 2.1 ± 2.1) than those from Trapsa. However, gut transit times were absolutely longer at Trapsa (mean = 4.87 ± 1.48 h, n = 6, vs. 2.85 ± 0.53 h, n = 13 daytime events), and dispersal distances were significantly longer (200 ± 81.0 m vs. 126 ± 53.4 m). The evidence indicates that, while the more folivorous diet at Trapsa was reflected in a much lower faecal seed count, it was also associated with longer gut transit times, and significantly longer dispersal distances, i.e. while dispersing approximately half the seeds dispersed by Junco group, Trapsa group dispersed these seeds over almost twice the distance.

Apes are important long-distance dispersers of large seeds in African tropical forests. Seed size and shape are likely to affect the ease of swallowing for an animal species. If an endozoochorous seed is larger than the digestive tract of an animal, the seed cannot be swallowed, and a round seed is more difficult to swallow than an elongated seed of the same length. In order to test if such a correlation exists between the seed size and its shape, we investigated the length and width of chimpanzee-dispersed seeds at the Mahale Mountains National Park, Tanzania. Among the 14 species of seeds, longer seeds had significantly narrower relative widths, and thus, they were more ovoid. Since the chimpanzee is the largest arboreal frugivore at Mahale, their food selection might have influenced the shape of larger seeds. The chimpanzee's selective consumption of such fruits with longer, elongated seeds may have facilitated the selective dispersal of such plant species in that area.

For birds, we tested the efficacy of a technique used to obtain faecal samples and their seed content from bats by placing plastic sheets below mist nets. This method was compared with that of collecting faecal samples using cotton bags. Plastic sheets were placed below each of eight mist nets to obtain faecal samples from birds caught in cloud forest remnants. Each bird was then placed separately in a cotton bag to catch any other seeds excreted. There were 84 faecal samples in total: 64 with no seeds and 20 with seeds; of the latter 65% were obtained from the plastic sheets. A total of 407 seeds were collected, 317 from 11 plant species were collected on the plastic sheets and 90 belonging to six plant species in the bags. Seed richness and abundance were significantly greater for samples obtained using the plastic sheets than with the cotton bags. Although the number of bird faecal samples obtained did not differ between methods (13 vs 7), with the plastic sheets the number of faecal samples with seeds increased. Thus, to obtain more representative faecal samples from frugivorous birds, we strongly recommend the use of plastic sheets as part of the technique.

The Winkler extractor is widely used for collecting both micro- and macrofauna from large samples of forest litter, but the long period of extraction that it demands and that allows continuous feeding and reproduction of target organisms is a serious drawback when samples are collected for subsequent stable isotope analysis. This problem is exacerbated in a humid tropical climate. In this study, we assessed the effectiveness of the modified Winkler apparatus equipped with heating plates placed inside each mesh bag. The study was performed at the end of the wet season in a mature forest and young forest plantation at Cat Tien National Park, southern Vietnam. The heating plates increased the temperature within the extractors by about 8ºC and accelerated the desiccation of litter in the mesh bags. The extraction speed of macrofauna from the forest litter was strongly increased and the number of mites collected nearly doubled in the modified extractors, though the extraction rates of collembolans were not affected significantly. Overall, our results suggest that the application of heating plates accelerates the extraction process while yielding large quantities of litter-dwelling animals.

Plant facilitation can improve the diversity of plant communities in several ecosystems, especially in stressful environments. The establishment of tree species on rocky outcrops can be limited by several biotic and abiotic factors. The richness and abundance of forest trees species on rocky outcrops surrounded by a large forest remnant in south Brazil were correlated with the cover of Bromelia balansae, a spiny stoloniferous species commonly occurring at forest–grassland transitions. Sixty plots were established on three flat rocky outcrops (20 in each). In each plot the coverage of bromeliads was estimated into three classes (0%, 1–50% and 51–100%) and all seedlings (individuals 10–30 cm in height) were counted and identified. ANOVAs with randomization tests were performed to establish the effect of different bromeliad cover classes on the richness and abundance of seedlings. The cover of bromeliads was positively related to the richness and abundance of young pioneer tree species. Evidence suggests that B. balansae can act as a nurse plant for tree seedlings, but manipulative experiments are needed to confirm this.