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Data from: Distance-decay differs among vertical strata in a tropical rainforest

1. Assemblage similarity decays with geographic distance—a pattern known as the distance-decay relationship. While this pattern has been investigated for a wide range of organisms, ecosystems, and geographical gradients, whether these changes vary more cryptically across different forest strata (from ground to canopy) remains elusive. 2. Here, we investigated the influence of ground vs arboreal assemblages to the general distance-decay relationship observed in forests. We seek to explain differences in distance-decay relationships between strata in the context of the vertical stratification of assemblage composition, richness, and abundance. 3. We surveyed for a climate sensitive model organism, amphibians, across vertical rainforest strata in Madagascar. For each tree, we defined assemblages of ground-dwelling, understory, or canopy species. We calculated horizontal distance-decay in similarity across all trees, and across assemblages of species found in different forest strata (ground, understory, and canopy). 4. We demonstrate that within stratum comparisons exhibit a classic distance-decay relationship for canopy and understory communities but no distance-decay relationships for ground communities. We suggest that differences in horizontal turnover between strata may be due to local scale habitat and resource heterogeneity in the canopy, or the influence of arboreal traits on species dispersal and distribution. 5. Synthesis: Biodiversity patterns in horizontal space were not consistent across vertical space, suggesting that canopy fauna may not play by the same set of 'rules' as their conspecifics living below them on the ground. Our study provides compelling evidence that the above-ground amphibian assemblage of tropical rainforests is the primary driver of the classical distance-decay relationship.

opencc-zeroNov 2019View details →

Elevational contrast in predation and parasitism risk to caterpillars in a tropical rainforest

Invertebrate predators and parasitoids are among the most important natural enemies of insect herbivores. Yet, the strength of natural enemy pressure along an altitudinal gradient and interactions between groups of natural enemies (such as predation on parasitized prey) are not well known. Various methods are used to reveal mortality factors of herbivores. Predation pressure is usually assessed through exposure of artificial prey. However, this method cannot provide information about the attacks of parasitoids, or their eventual interactions with predators. Further, artificial or dead prey might not attract predators because they do not show expected host behavior, and this method mostly cannot distinguish between predation and scavenging. For the first time in a tropical rainforest, we quantified mortality factors along an altitudinal gradient using exposure of live caterpillars. We exposed a total of 800 live caterpillars of Talanga excelsalis moresbyensis Strand (Lepidoptera: Crambidae) on saplings of Ficus copiosa Steud. (Moraceae) at two elevations in primary tropical rain forest in Papua New Guinea (200 and 1 200 m a.s.l.). We exposed the caterpillars in two treatments: exposed to and protected from invertebrate predators and parasitoids. Disappearance of caterpillars was significantly higher in the exposed treatment. Further, caterpillar disappearance was significantly higher in lowlands than in highlands (43 vs. 12%). We consider the vast majority of the disappearance to be due to predation, as migration of the caterpillars from the focal trees was not observed (except one caterpillar). This estimate of invertebrate predation rate corresponds with studies which used artificial caterpillar models. No significant difference in parasitism rate between the two elevations was observed (12 vs. 13%). The combination of the disappearance and parasitism rate patterns means that larval parasitoids face stronger pressure from invertebrate predators through higher predation of their hosts in the lowlands than in the highlands.

opencc-zeroDec 2016View details →

Data from: Diversity in tropical ecosystems: the species richness and turnover of moths in Malaysian rainforests

As a contribution to accurate estimation of arthropod alpha and beta diversities in tropical forests, we present results of some of the largest moth samples ever collected in the Malaysian region. To estimate alpha diversity, light traps were run at three geographically distinct locations. We generated individual-based and coverage-based rarefaction curves to estimate sampling sufficiency and alpha diversity of the locations. Despite a large number of moths collected (67 282 individuals, from three locations), none of the rarefaction curves reached asymptote. The species accumulation curves based on the Chao1 richness estimator at each location suggested that, even when sampling yielded over 30 000 individuals, Chao1 could not reliably estimate the observed number of species. In one of the three locations, moths were collected systematically by light traps in 1979–1980 and 2000–2001. Despite over 160 trapping nights and 16 500 individuals collected in total, the estimated total number of species (2262) was well below the general collection conducted at the same location over a 35-year period [3921 species (1975–2013)]. Beta diversity was investigated using the samples collected at one location on two occasions over a 20-year period. The faunal composition has changed over the 20-year period, possibly as a result of extensive land-use change around the study location. We estimated the minimum sampling effort required to detect such changes by calculating type II errors. Unlike alpha diversity estimation, we found that only four replicate samples, each with only two trapping nights, would be sufficient to reliably detect changes in assemblage composition.

opencc-zeroDec 2016View details →

Data from: Foraging impacts of Asian megafauna on tropical rainforest structure and biodiversity

Megaherbivores are known to influence the structure, composition, and diversity of vegetation. In Central Africa, forest elephants act as ecological filters by breaking tree saplings and stripping them of foliage. Much less is known about impacts of megafauna on Southeast Asian rain forests. Here, we ask whether herbivory by Asian megafauna has impacts analogous to those of African forest elephants. To answer this, we studied forest (1) structure, (2) composition, (3) diversity, and (4) tree scars in Belum and Krau, two protected areas of Peninsular Malaysia, and compared the results with those obtained in African forests. Elephants are abundant in Belum but have been absent in Krau since 1993. We found that stem density and diversity, especially of tree saplings, were higher in Krau than in Belum. Palms and other monocots were also more abundant in Krau. In Belum, however, small monocots (<1 m tall) were very abundant but larger ones (>1 m tall) were virtually absent, suggesting size-selective removal. The frequency of stem-break scars was equal at Belum and Krau but less than in Central Africa and greater than in the Peruvian Amazon where tapirs are the only megafauna. Pigs and tapirs could also contribute to the high frequency of tree scars recorded in Malaysian forests. Forest-dwelling elephants in Asia seem to have a reduced impact on tree saplings compared to African forest elephants, but a very strong impact on monocots.

Data from: Tropical rainforest conversion and land-use intensification reduce understory plant phylogenetic diversity

1. Conversion of rainforest into agricultural land affects multiple facets of tropical plant diversity. While the effects of tropical land use change and intensification on species diversity are comparatively well studied, the effects on phylogenetic diversity and structure of plant communities are largely unknown. Furthermore, it is not clear how the loss of native species and addition of alien species collectively affect phylogenetic diversity and structure. 2. We investigated the phylogenetic diversity and structure of understorey plants; a diverse and ecologically important, yet poorly studied group. We studied four prominent land use systems (tropical lowland rainforest, jungle rubber agroforest, rubber plantations and oil palm plantations) in the lowlands of Sumatra (Indonesia), a region experiencing dramatic land use changes. 3. Across the four systems, we investigated differences in four metrics of phylogenetic community structure (phylogenetic diversity, mean pairwise distance, mean nearest taxon distance and their abundance-weighted variants). Our analyses were based on a comprehensive vegetation survey consisting of 32 plots, 1,197 species of vascular plants, and 146,599 plant individuals. 4. Our results showed that forest conversion into agricultural systems leads to a pronounced loss of phylogenetic diversity. Furthermore, the standard effect size of mean pairwise distance indicated a gradual change from clustered to overdispersed phylogenetic community structure with increasing land use intensity from forest over jungle rubber to the monoculture plantations. In most land use systems, the presence or absence of alien plant species did not affect phylogenetic structure. Only in oil palm plantations, removing alien species from the data led to a more overdispersed structure. In conclusion, conserving the phylogenetic diversity and structure requires efficient protection of the last remaining rainforests. 5. Synthesis and applications. Forest conversion into agricultural areas negatively affects phylogenetic understorey plant diversity and leads to a shift from clustered to overdispersed phylogenetic community structure. These trends are partly driven by alien species particularly in oil palm plantations. Protecting the remaining rainforests, and considering multi-species agroforestry systems in favour of intensive monoculture plantations are thus imperative to conserve phylogenetic plant diversity and community structure.

opencc-zeroAug 2019View details →

Data from: Nutrient scarcity strengthens soil fauna control over leaf litter decomposition in tropical rainforests

Soil fauna is a key control of the decomposition rate of leaf litter, yet its interactions with litter quality and the soil environment remain elusive. We conducted a litter decomposition experiment across different topographic levels within the landscape replicated in two rainforest sites providing natural gradients in soil fertility to test the hypothesis that low nutrient availability in litter and soil increases the strength of fauna control over litter decomposition. We crossed these data with a large dataset of 44 variables characterizing the biotic and abiotic microenvironment of each sampling point and found that microbe-driven Carbon (C) and Nitrogen (N) losses from leaf litter were 10.1 and 17.9 % lower, respectively, in the nutrient-poorest site but this among-site difference was equalized when meso- and macrofauna had access to the litterbags. Further, on average soil fauna enhanced the rate of litter decomposition by 22.6%, and this contribution consistently increased as nutrient availability in the microenvironment declined. Our results indicate that nutrient scarcity increases the importance of soil fauna on C and N cycling in tropical rainforests. Further, soil fauna is able to equalize differences in microbial decomposition potential thus buffering to a remarkable extent nutrient shortages at an ecosystem level.

Data from: Effect of distance to edge and edge interaction on seedling regeneration and biotic damage in tropical rainforest fragments: a long‐term experiment

In forest fragments, edge effects can influence forest regeneration, but little is known about how edge effects influence seedling performance and the interaction between seedlings and their natural enemies over time. In central Amazonia, we recorded survival and growth (in height and leaf number) and damage by insect herbivores and leaf‐fungal pathogens of Chrysophyllum pomiferum (Sapotaceae) seedlings that were exposed to different numbers of edges and to different distances from the forest edge. Grown seedlings were transplanted into one‐square‐metre plots within 1‐ha blocks located in the centre (no edge), the edge (one edge), and the corner (two edges), and at different distances from the edge towards the interior (i.e., 20, 40, 60, 80, and 100 m) of two rectangular fragments (10‐ and 100‐ha in size). Plots were visited once every 2 months for 1 year (1992–1993) and thereafter every 2 years for almost 8 years (1993–2001). Overall, results showed that seedling survival, height, leaf number, and biotic damage varied over time with the presence of nearby edges and with the distance from the edge. Survival was lower in fragment edges and corners than in centres. Increase in height was similar for all positions within the 100‐ha fragment, whereas in the 10‐ha fragment seedling height had a greater increase at the edge and corner than in the centre. Furthermore, survival increased with distance from the edge as did leaf number, whereas height showed a lower increase closer to the edge than farther away. Regarding biotic damage, for both fragments herbivory was greater at the centres and decreased with edge proximity over time, whereas leaf‐fungal damage was greater at the corners than in the edges and increased significantly over time. Biotic damage was correlated with seedling size. Small seedlings were more susceptible to fungal attack, whereas larger seedlings were so to herbivores. Synthesis. This study demonstrated that despite stochastic environmental factors seedling survival, growth, and biotic damage by herbivores and fungal pathogens varied with the level of edge exposure and proximity, which may threaten forest regeneration in the long term.

opencc-zeroDec 2015View details →

Data from: Tropical rainforests that persisted: inferences from the Quaternary demographic history of eight tree species in the Guiana shield

How Quaternary climatic and geological disturbances influenced the composition of Neotropical forests is hotly debated. Rainfall and temperature changes during and/or immediately after the last glacial maximum (LGM) are thought to have strongly affected the geographical distribution and local abundance of tree species. The paucity of the fossil records in Neotropical forests prevents a direct reconstruction of such processes. To describe community-level historical trends in forest composition, we turned therefore to inferential methods based on the reconstruction of past demographic changes. In particular, we modelled the history of rainforests in the eastern Guiana Shield over a timescale of several thousand generations, through the application of approximate Bayesian computation and maximum-likelihood methods to diversity data at nuclear and chloroplast loci in eight species or subspecies of rainforest trees. Depending on the species and on the method applied, we detected population contraction, expansion or stability, with a general trend in favour of stability or expansion, with changes presumably having occurred during or after the LGM. These findings suggest that Guiana Shield rainforests have globally persisted, while expanding, through the Quaternary, but that different species have experienced different demographic events, with a trend towards the increase in frequency of light-demanding, disturbance-associated species.

opencc-zeroDec 2011View details →

Data from: Diversity partitioning confirms the importance of beta components in tropical rainforest Lepidoptera

Tropical beta diversity, and particularly that of herbivorous insects in rainforests, is often considered enormous, but this notion has recently been challenged. As tropical beta diversity is highly relevant to our view on biodiversity, it is important to gain more insights and resolve methodological problems that may lead to the contradictions in different studies. We used data on two ecologically distinct moth families from Southeast-Asia and analyzed separately the contribution of beta components to overall species richness at three spatial scales. Observed diversity partitions were compared under different types of null models. We found that alpha diversity was lower than expected from null models, whereas hierarchical beta components were larger than expected. Beta components played a significant role in shaping gamma diversity, and their contribution can be high (multiplicative beta >5). We found a reduction of beta components when comparing primary forests and agricultural sites (cf. "biotic homogenization"), but even in these habitats beta components were still substantial. Our analyses show that beta components do play an important role in our data on tropical herbivorous insects, and that these results are not due to lumping different habitats when sampling environmental gradients.

opencc-zeroDec 2015View details →

Data from: Fine partitioning of epiphyte habitat within Johansson zones in tropical Australian rainforest trees

For over three decades, the Johansson zones have been widely used in epiphyte studies as a way of stratifying the host tree into habitat zones, however, the usefulness of this system has been questioned. We test the effectiveness of the Johansson zones by grouping epiphyte species by the substrate and microclimatic attributes of their individual occurrences and assessing the fidelity of these groups to the Johansson zones. Habitat characteristics were recorded for every individual epiphyte on 30 trees in the lower montane rainforests of north-eastern Australia. Twenty-four epiphyte species were agglomerated into four groups using Ward's method. Group 4 was highly distinct and included shade loving species and nomadic vines from the lower zones of the host trees. Group 3 contained species from the most exposed habitats. Group 1 had higher light levels and lower substrate thickness than Group 2, yet both groups had close to identical distributions over the Johansson zones. This suggests that groups of epiphyte species may utilise different micro-sites within the same zone. While the Johansson zones are a useful tool in epiphyte studies, finer partitioning of habitat within the host tree may be missed.

opencc-zeroDec 2018View details →

Data from: Short distance pollen dispersal and low genetic diversity in a subcanopy tropical rainforest tree, Fontainea picrosperma (Euphorbiaceae)

Gene flow via pollen movement affects genetic variation in plant populations and is an important consideration in plant domestication. Fontainea picrosperma is a subcanopy rainforest tree that is of commercial interest because it is the source of tigilanol tiglate, a natural product used for the treatment of solid tumors. We identify patterns of pollen-mediated gene flow within natural populations of F. picrosperma and estimate genetic parameters and genetic structure between adult and juvenile groups using microsatellite markers. Our results show pollination events occur over much shorter distances than reported for tropical canopy species. At least 63 % of seeds are sired by male trees located within 30 m of the mother. On average, 27 % of the local male population contributed to successful reproduction of F. picrosperma with most fathers siring a single seed, however, the contributions to reproduction were uneven. Larger male trees with more flowers had gre ater reproductive success than those with less flowers (P < 0.05). There were comparatively low levels of genetic variation across the species (HE = 0.405 for adult trees and 0.379 for juveniles) and we found no loss of genetic diversity between adult and juvenile trees. Short distance pollen flow and low genetic diversity is theoretically a prelude to genetic impoverishment, however F. picrosperma has persisted through multiple significant climatic oscillations. Nevertheless, the remaining low genetic diversity is of concern for domestication programs which require maximal genetic diversity to facilitate efficient selective breeding and genetic improvement of this commercially significant species.

opencc-zeroDec 2016View details →

Data from: Ants as ecological indicators of rainforest restoration: community convergence and the development of an Ant Forest Indicator Index in the Australian wet tropics

Ecosystem restoration can help reverse biodiversity loss, but whether faunal communities of forests undergoing restoration converge with those of primary forest over time remains contentious. There is a need to develop faunal indicators of restoration success that more comprehensively reflect changes in biodiversity and ecosystem function. Ants are an ecologically dominant faunal group and are widely advocated as ecological indicators. We examine ant species and functional group responses on a chronosequence of rainforest restoration in northern Australia, and develop a novel method for selecting and using indicator species. Four sampling techniques were used to survey ants at 48 sites, from grassland, through various ages (1–24 years) of restoration plantings, to mature forest. From principal components analysis of seven vegetation metrics, we derived a Forest Development Index (FDI) of vegetation change along the chronosequence. A novel Ant Forest Indicator Index (AFII), based on the occurrences of ten key indicator species associated with either grassland or mature forest, was used to assess ant community change with forest restoration. Grasslands and mature forests supported compositionally distinct ant communities at both species and functional levels. The AFII was strongly correlated with forest development (FDI). At forest restoration sites older than 5–10 years that had a relatively closed canopy, ant communities converged on those of mature rainforest, indicating a promising restoration trajectory for fauna as well as plants. Our findings reinforce the utility of ants as ecological indicators and emphasize the importance of restoration methods that achieve rapid closed-canopy conditions. The novel AFII assessed restoration status from diverse and patchily distributed species, closely tracking ant community succession using comprehensive species-level data. It has wide applicability for assessing forest restoration in a way that is relatively independent of sampling methodology and intensity, and without a need for new comparative data from reference sites.

Data from: Dry-season decline in tree sapflux is correlated with leaf turgor loss point in a tropical rainforest

1. Water availability is a key determinant of forest ecosystem function and tree species distributions. While droughts are increasing in frequency in many ecosystems, including in the tropics, plant responses to water supply vary with species and drought intensity, and are therefore difficult to model. Based on physiological first principles, we hypothesized that trees with a lower turgor loss point (πtlp), i.e., a more negative leaf water potential at wilting, would maintain water transport for longer into a dry season. 2. We measured sapflux density of 22 mature trees of 10 species during a dry season in an Amazonian rainforest, quantified sapflux decline as soil water content decreased, and tested its relationship to tree πtlp, size, and leaf predawn and midday water potentials measured after the onset of the dry season. 3. The measured trees varied strongly in the response of water use to the seasonal drought, with sapflux at the end of the dry season ranging from 37 to 117% (on average 83 ± 5 %) of that at the beginning of the dry season. The decline of water transport as soil dried was correlated with tree πtlp (Spearman ρ≥0.63), but not with tree size or predawn and midday water potentials. Thus, trees with more drought-tolerant leaves better maintained water transport during the seasonal drought. 4. Our study provides an explicit correlation between a trait, measurable at the leaf level, and whole-plant performance under drying conditions. Physiological traits such as πtlp can be used to assess and model higher-scale processes in response to drying conditions.

FIGURES 27–33 in A new tropical montane firefly genus and species, active during winter and endemic to the southeastern Atlantic Rainforest (Coleoptera: Lampyridae)

FIGURES 27–33 Araucariocladus hiems sp. nov., male abdomen: 27, terga I–VI dorsal; 28, syntergite, dorsal; 29, sternum IX, ventral; 30, sternum VIII and pygidium, ventral; 31–33 aedeagus, 31, dorsal, 32, lateral, 33, ventral. Scale bar: 1.0 mm (27), 0.5 mm (28–30), 0.2 mm (31–33).

FIGURES 3–13 in A new tropical montane firefly genus and species, active during winter and endemic to the southeastern Atlantic Rainforest (Coleoptera: Lampyridae)

FIGURES 3–13 Araucariocladus hiems sp. nov.: 4–7, male head overview, 3, dorsal; 4, ventral; 5, lateral; 6, frontal; 7, posterior; 8–9, mandible; 10, antenna; 11–13, frontal tentoria, detail, 11, frontal; 12, lateral; 13, dorsal. Scale bar: 0.5 mm (3–9), 2.0 mm (10), 0.5 mm (11–13).

FIGURES 21–26 in A new tropical montane firefly genus and species, active during winter and endemic to the southeastern Atlantic Rainforest (Coleoptera: Lampyridae)

FIGURES 21–26 Araucariocladus hiems sp. nov., pterothorax and associated structures: 21, dorsal; 22, ventral; 23, lateral; 24, elytron ventral; 25, left wing; 26 pro, meso and metalegs (top-down). Scale bar: 1.0 mm (21–23), 2.0 mm (24–26).

FIGURES 1–2 in A new tropical montane firefly genus and species, active during winter and endemic to the southeastern Atlantic Rainforest (Coleoptera: Lampyridae)

FIGURES 1–2. Araucariocladus hiems sp. nov.: 1, male dorsal habitus; 2, ventral. Scale bar: 2.0 mm (1–2).

FIGURES 14–20 in A new tropical montane firefly genus and species, active during winter and endemic to the southeastern Atlantic Rainforest (Coleoptera: Lampyridae)

FIGURES 14–20 Araucariocladus hiems sp. nov., prothorax: 14, pronotum dorsal; 15, ventral; 16, frontal; 17, posterior; 18, lateral; 19, prosternum dorsal, 20, ventral. Scale bar: 0.5 mm (14–20).

FIGURES 52 in Three new species of Pergalumna (Acari: Oribatida: Galumnidae) from the tropical rainforest of Veracruz, Mexico

FIGURES 52‾53. Pergalumna dactilaris sp. nov. 52. Left leg III of holotype, paraxial view; 53. Left leg IV of holotype, paraxial view. Scale bars 20 µm.

FIGURES 41 in Three new species of Pergalumna (Acari: Oribatida: Galumnidae) from the tropical rainforest of Veracruz, Mexico

FIGURES 41‾44. Pergalumna dactylaris sp. nov. 41. Notogaster, dorsal view; 42. Ventral plate; 43. Prodorsum; 44. Lateral region, pteromorph and legs ommited. Scale bars 50 µm.