Data from: Seed size predicts community composition and carbon storage potential of tree communities in rainforest fragments in India’s Western Ghats

Fragmentation is ubiquitous across tropical forests and drives marked shifts in tree community composition by differentially affecting species’ dispersal, establishment and survival. Such compositional shifts can potentially alter ecosystem-level properties such as above-ground carbon storage, but our understanding of the factors linking compositional shifts to carbon storage is limited. We compared tree communities of contiguous and fragmented tropical rainforests in the Western Ghats (India) and assessed the ability of various plant functional traits associated with seed dispersal, establishment and survival processes to predict species’ responses to fragmentation. Further, we assessed relationships between functional traits that predict tree community turnover and those that govern carbon storage to examine how fragmentation effects on species’ composition can alter the ability of tree communities to store carbon. Seed size, as indexed by seed length, was the best predictor of species’ responses, with larger-seeded species declining in fragments. Across species, seed length was positively correlated with maximum attainable height, which decreased by 10% on average at the community level in fragments. Such shifts towards smaller-seeded communities could decrease forest stature and reduce above-ground carbon stocks by 8%. Synthesis and applications. Our study highlights a previously undescribed mechanism by which fragmentation-driven declines of large-seeded tree species can reduce above-ground carbon stocks by promoting shorter-statured forests. These results imply that strict protection alone might be insufficient, and that a multi-pronged conservation strategy would be required to sustain carbon stocks in tropical forest fragments. Such interventions will need to combine restoration programmes for large-seeded tree species in fragments with broader-scale efforts to maintain hospitable and well-connected landscapes for their seed dispersers

Vegetation plot data from contiguous and fragmented rainforests in the Western Ghats, India

Plot size: 30m X 30m. Min DBH: 3cm

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

International audienceThe effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropicalrain 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 and18 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 ofearly-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstoreyon sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richnessoverall, but density and richness of old-growth species declined by62%and 48%, respectively, in fragments. Fragmentshad 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecificadults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Saplingspecies richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelatedto overstorey richness in continuous forests. Our results show that while forest fragments retain significant saplingdiversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regenerationof old-growth tropical rain forests

A way to model stochastic perturbations in population dynamics models with bounded realizations

In this paper, we analyze the use of the Ornstein-Uhlenbeck process to model dynamical systems subjected to bounded noisy perturbations. In order to discuss the main characteristics of this new approach we consider some basic models in population dynamics such as the logistic equations and competitive Lotka-Volterra systems. The key is the fact that these perturbations can be ensured to keep inside some interval that can be previously fixed, for instance, by practitioners, even though the resulting model does not generate a random dynamical system. However, one can still analyze the forwards asymptotic behavior of these random differential systems. Moreover, to illustrate the advantages of this type of modeling, we exhibit an example testing the theoretical results with real data, and consequently one can see this method as a realistic one, which can be very useful and helpful for scientists

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

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

Greater stability of carbon capture in species-rich natural forests compared to species-poor plantations

Tree plantations and forest restoration are leading strategies for enhancing terrestrial carbon (C) sequestration and mitigating climate change. While it is well established that species-rich natural forests offer superior C sequestering benefits relative to short-rotation commercial monoculture plantations, differences in rates of C capture and storage between longer-lived plantations (commercial or non-commercial) and natural forests remain unclear. Using a natural experiment in the Western Ghats of India, where late-20th century conservation laws prohibited timber extraction from monodominant plantations and natural forests within nature reserves, we assessed forests and plantations for aboveground C storage and the magnitude and temporal stability of rates of photosynthetic C capture (gross primary production). Specifically, we tested the hypothesis that species-rich forests show greater temporal stability of C capture, and are more resistant to drought, than monodominant plantations. Carbon stocks in monodominant teak (Tectona grandis) and Eucalyptus (Eucalyptus spp.) plantations were 30%–50% lower than in natural evergreen forests, but differed little from moist-deciduous forests. Plantations had 4%–9% higher average C capture rates (estimated using the Enhanced Vegetation Index–EVI) than natural forests during wet seasons, but up to 29% lower C capture during dry seasons across the 2000–18 period. In both seasons, the rate of C capture by plantations was less stable across years, and decreased more during drought years (i.e. lower resistance to drought), compared to forests. Thus, even as certain monodominant plantations could match natural forests for C capture and storage potential, plantations are unlikely to match the stability–and hence reliability–of C capture exhibited by forests, particularly in the face of increasing droughts and other climatic perturbations. Promoting natural forest regeneration and/or multi-species native tree plantations instead of plantation monocultures could therefore benefit climate change mitigation efforts, while offering valuable co-benefits for biodiversity conservation and other ecosystem services

Perceptions of priority issues in the conservation of biodiversity and ecosystems in India

We report on the results of a country-wide survey of people’s perceptions of issues relating to the conservation of biodiversity and ecosystems in India. Our survey, mainly conducted online, yielded 572 respondents, mostly among educated, urban and sub-urban citizens interested in ecological and environmental issues. 3160 ‘‘raw’’ questions generated by the survey were iteratively processed by a group of ecologists, environmental and conservation scientists to produce the primary result of this study: a summarized list of 152 priority questions for the conservation of India’s biodiversity and ecosystems, which range across 17 broad thematic classes. Of these, three thematic classes—‘‘Policy and Governance’’, ‘‘Biodiversity and Endangered Species’’ and ‘‘Protection and Conservation’’—accounted for the largest number of questions. A comparative analysis of the results of this study with those from similar studies in other regions brought out interesting regional differences in the thematic classes of questions that were emphasized and suggest that local context plays a large role in determining emergent themes. We believe that the ready list of priority issues generated by this study can be a useful guiding framework for conservation practitioners, researchers, citizens, policy makers and funders to focus their resources and efforts in India’s conservation research, action and funding landscape

The road to recovery: a synthesis of outcomes from ecosystem restoration in tropical and sub-tropical Asian forests

Current policy is driving renewed impetus to restore forests to return ecological function, protect species, sequester carbon and secure livelihoods. Here we assess the contribution of tree planting to ecosystem restoration in tropical and sub-tropical Asia; we synthesize evidence on mortality and growth of planted trees at 176 sites and assess structural and biodiversity recovery of co-located actively restored and naturally regenerating forest plots. Mean mortality of planted trees was 18% 1 year after planting, increasing to 44% after 5 years. Mortality varied strongly by site and was typically ca 20% higher in open areas than degraded forest, with height at planting positively affecting survival. Size-standardized growth rates were negatively related to species-level wood density in degraded forest and plantations enrichment settings. Based on community-level data from 11 landscapes, active restoration resulted in faster accumulation of tree basal area and structural properties were closer to old-growth reference sites, relative to natural regeneration, but tree species richness did not differ. High variability in outcomes across sites indicates that planting for restoration is potentially rewarding but risky and context-dependent. Restoration projects must prepare for and manage commonly occurring challenges and align with efforts to protect and reconnect remaining forest areas.The abstract of this article is available in Bahasa Indonesia in the electronic supplementary material.This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'