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opencc-zeroDec 2015View details →

Data from: Barriers to dispersal of rain forest butterflies in tropical agricultural landscapes

Fragmentation of natural habitats can be detrimental for species if individuals fail to cross habitat boundaries to reach new locations, thereby reducing functional connectivity. Connectivity is crucial for species shifting their ranges under climate change, making it important to understand factors that might prevent movement through human-modified landscapes. In tropical regions, rain forests are being fragmented by agricultural expansion, potentially isolating populations of highly diverse forest-dependent species. The likelihood of crossing habitat boundaries is an important determinant of species dispersal through fragmented landscapes, and so we examined movement across rain forest-oil palm plantation boundaries on Borneo by using relatively mobile nymphalid butterflies as our model study taxon. We marked 1666 individuals from 65 species, and 19 percent (100/527) of recaptured individuals crossed the boundary. Boundary crossing was relatively frequent in some species, and net movement of individuals was from forest into plantation. However, boundary crossing from forest into plantation was detected in less than 50 percent (12/28) of recaptured species and was dominated by small-sized butterfly species whose larval host plants occurred within plantations. Thus, while oil palm plantations may be relatively permeable to some species, they may act as barriers to the movement of forest-dependent species (i.e., species that require rain forest habitat to breed), highlighting the importance of maintaining forest connectivity for conserving rain forest species.

opencc-zeroDec 2016View details →

Data from: Successional status, seed dispersal mode and overstorey species influence tree regeneration in tropical rain-forest fragments in Western Ghats, India

The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.

opencc-zeroDec 2016View details →

Data from: Habitat patterns in tropical rain forests: a comparison of 105 plots in northwest Borneo

Understanding the maintenance of high tropical tree species diversity requires disentangling the effects of habitat vs. geographic distance. Using floristic, topographic, and soil nutrient data from 105 0.6-ha plots in mixed dipterocarp forest throughout Sarawak, Malaysian Borneo, we explore the degree to which floristic patterns are habitat-driven from local to landscape scales. We assess how the floristic influence of geographic distance vs. abiotic factors varies from local to regional scales. We employ several multivariate analytical techniques and perform a hierarchical clustering of the research plots using the Steinhaus index of floristic dissimilarity, as well as Mantel analyses on matrices of floristic, habitat, and geographic distance. These analyses indicate that floristic variation is more strongly correlated with habitat than with geographic distance on the regional scale. On the local-landscape to community scale, we find evidence of a resource threshold above which habitat effects weaken; that is, below the resource threshold floristic similarity between sites is dominated by habitat effects, while above the threshold floristic similarity between sites is dominated by geographic-distance effects. We also find evidence that topography and soil nutrients correlate in part independently with floristics. These results, together with previous studies in the Neotropics, emphasize that tree species distribution and community composition are variously influenced by the interplay of both habitat and dispersal-driven effects.

opencc-zeroDec 2013View details →

Data from: Experimental defaunation of terrestrial mammalian herbivores alters tropical rain forest understory diversity

It has been suggested that tropical defaunation may unleash community-wide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause–effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understorey plant diversity. We established plot triplets (n = 25) representing three defaunation contexts: terrestrial-mammal exclosure (TE), medium/large mammal exclosure (PE) and open access controls (C). Seedlings/saplings 30–100 cm tall were marked and identified within each of these plots and re-censused three times to record survival and recruitment. In the periods 2010–2011 and 2011–2013, survival was greater in PE than in C plots and recruitment was higher in TE plots than in C plots. Overall, seedling density increased by 61% in TE plots and 23% in PE plots, whereas it decreased by 5% in C plots. Common species highly consumed by mammals (e.g. Brosimum alicastrum and Ampelocera hottlei) increased in their abundance in TE plots. Rarefaction curves showed that species diversity decreased in TE plots from 2008 to 2013, whereas it remained similar for C plots. Given the prevalence of tropical defaunation, we posit this is an anthropogenic effect threatening the maintenance of tropical forest diversity.

opencc-zeroDec 2017View details →

Data from: Litter removal in a tropical rain forest reduces fine root biomass and production but litter addition has few effects

Many old-growth lowland tropical rain forests are potentially nutrient limited, and it has long been thought that many such forests maintain growth by recycling nutrients from decomposing litter. We investigated this by continuously removing (for ten years) freshly fallen litter from five (45 m x 45 m) plots, adding it to five other plots, there were five controls. From monthly measures over one year we show that litter removal caused lower: fine root (≤2 mm diameter) standing mass, fine root standing length, fine root length production and fine root length survivorship. Litter addition did not significantly change fine root mass or length or production. Nutrient concentrations in fine roots in litter removal plots were lower than those in controls for nitrogen (N), calcium (Ca) and magnesium (Mg), concentrations in fine roots in litter addition plots were higher for N and Ca. Chronic litter removal has resulted in reduced forest growth due to lack of nutrients, probably nitrogen. Conversely, long-term litter addition has had fewer effects.

opencc-zeroAug 2021View details →

Post‐agriculture rain forest succession on a tropical Pacific island

<p>We surveyed the tree and seedling community in 34 vegetation plots in mature and >50 y old secondary lowland rain forest on the Polynesian island of Tutuila, American Samoa. The main data set includes original data from the tree surveys as well as all repeat surveys of seedling plots. We also include all R code and data sets used in analyses, including soil and environmental data, species by plot matrices for NMDS, and processed data used for survival analysis.</p>

FIGURE 7 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 7. Lacandodrilus paludosus gen. et sp. nov. A. Paratype IEOL 2312. Internal, dorsal view of segments 11–14, showing the ovaria after removal of esophagus. dv= dorsal vessel, ff= female funnel, nc= nerve cord, nep= nephridia, ovr= ovarium, B. Holotype IEOL 3190, right spermathecae, lateral view. amp= ampulla, du= duct, mf= part of male funnel and seminal coagulum. Scale 100 µm.

FIGURE 8 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 8. Geographical location and type of vegetation (patch of palm trees) where Lacandodrilus paludosus gen. et sp. nov. was found.

FIGURE 2 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 2. Lacandodrilus paludosus gen. et sp. nov. A. Holotype IEOL 3190, setae a with a replacement seta from segment 12. B. Paratype IEOL 6567, seta a with a replacement seta from segment 9. Scale 50 µm.

FIGURE 6 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 6. Lacandodrilus paludosus gen. et sp. nov. Internal, dorsal view. A. Paratype IEOL 6565, segments 9–13. B. Holotype IEOL 3190, segments 11–14. dv= dorsal vessel, es= esophagus, ff= female funnel, gg= genital glands, mf= male funnels, ovr= ovarium, sg= septal glands, sv= seminal vesicles. Scale 0.5 mm.

FIGURE 5 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 5. Lacandodrilus paludosus gen. et sp. nov. Internal. A. Holotype IEOL 3190. Dorsal and left side view of segments 9 and 10 (scale 100 µm). B. Paratype IEOL 6568. Dorsal view of segments 15–19 (scale 200 µm). C. Paratype IEOL 6568. Nephiridium in situ of segment 24, right side (scale 100 µm). D. Paratype IEOL 6567. Extracted nephridium of segment 30 (scale 100 µm). dv= dorsal vessel, es= esophagus, gpl= granular peritoneal layer of nephridium, lc= lateral commisures, mf= male funnels, mt= muscular tube of nephridium, nc= nerve cord, nep= nephridia, sc= seminal coagulum, sg= septal glands.

FIGURE 4 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 4. Lacandodrilus paludosus gen. et sp. nov. Internal. Anterior region, dorsal view. Paratype IEOL 6568, segments 4–10. dv= dorsal vessel, es= esophagus, lc= lateral commisures, sg= septal glands. Scale 0.5 mm.

FIGURE 1 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 1. Lacandodrilus paludosus gen. et sp. nov. External. Anterior region. Holotype IEOL 3190 A. Ventral view, segments 1–18. B. Ventral view, segments 11–14. C. Paratype IEOL 6567, ventro-lateral view of segments 10–15. D. Paratype IEOL 6565, lateral view of segments 10–15. Arrows indicate the external band that corresponds to internal male gonoducts. Letters indicate the corresponding ventral (a, b) or lateral (c, d) setae. Scale 0.5 mm.

FIGURE 3 in A new semiaquatic worm (Annelida, Oligochaeta) from southeastern Mexican tropical rain forests

FIGURE 3. Lacandodrilus paludosus gen. et sp. nov. Internal. Anterior region, dorsal view. A. Holotype IEOL 3190, segments 1–24. B. Paratype IEOL 6565, segments 3–16. dv= dorsal vessel, es= esophagus, gg= genital glands, mf= male funnels, np= nephridia, ov= ovisac, sg= septal glands, sp= spermatheca, sv= seminal vesicles. Scale 1 mm.