@article {159714, title = {Biodiversity effects on seedling growth are modified by light environment across functional groups.}, journal = {Ecol Appl}, volume = {35}, year = {2025}, month = {2025 Jul}, pages = {e70087}, abstract = {

Numerous studies have shown that biodiversity influences the functioning of ecosystems over space and time. The sensitivity of such biodiversity-ecosystem effects to environmental heterogeneity, however, remains poorly understood. In forests, seedling recruitment is a critical phase of forest dynamics, and this phase is highly sensitive to environmental heterogeneity and biotic interactions with surrounding plants. In closed-canopy forests, local variation in light due to variation in canopy cover can result in heterogeneous microenvironments that can enhance or constrain seedling growth and ultimately forest regeneration. Here, we ask, how do light and seedling diversity influence the growth and biomass gain of seedlings in tropical forests? We tested the effects of and interactions between seedling diversity and light availability on the growth of seedlings consisting of tropical broad-leaved evergreen and deciduous forest species using a fully factorial manipulated experiment in the Andaman Islands, India. We compared results from this manipulated experiment with field observations from a long-term forest plot. We show that during the critical seedling establishment phase, species richness and light availability additively increased biomass accumulation of seedlings in communities consisting of evergreen and deciduous species. Moreover, the positive effect of light on biomass gain was consistent across species in these different functional groups. We conclude that the diversity effect on biomass gain is explained more by species complementarity across conditions rather than by compensatory effects by different species under different light conditions or simple probabilistic effects of including faster growing species in species-rich communities. Taken together, our results show that the potential for biodiversity to increase ecosystem functioning in seedling communities is modified by light availability. Although many factors are often important in designing replanting efforts in forest management or restoration, our results suggest that key factors are likely to be the interaction between neighborhood diversity and canopy-mediated light on forest understory, which can be managed to enhance seedling establishment at the early stages of forestry projects aimed at maintaining forest diversity, composition, and functioning.

}, keywords = {Biodiversity, Biomass, Forests, India, Light, Seedlings, Trees}, issn = {1051-0761}, doi = {10.1002/eap.70087}, author = {Anujan, Krishna and Shabnam, Alisha and Ali, Irfan and Gummadi, Ashok Kumar and Sankaran, Mahesh and Krishnadas, Meghna and Naeem, Shahid} } @article {158494, title = {Decadal scale fire dynamics in savannas and forests of the Nilgiri Biosphere Reserve, India}, year = {2025}, abstract = {
Background

The Nilgiri Biosphere Reserve (NBR) in the Western Ghats, India, contains a mosaic of savannas and forests. This landscape experiences wildfires regularly, but we lack an understanding of factors driving fire regimes in the region.

Aims

To examine the effects of climate, vegetation and human activity on wildfires in the NBR.

Methods

Using remotely sensed datasets, we examine how mean annual rainfall (MAR), topographic complexity and human activity influence fires in savannas and forests of the NBR across a wet (2001{\textendash}2010) and dry decade (2011{\textendash}2020).

Key results

Across both decades, savannas burned more frequently and over larger areas than forests. Burnt area and fire frequency in both habitats were higher in the wet decade. Human modification was the major driver of fire occurrence in the wet decade, but MAR took on greater importance in the dry decade.

Conclusions

Savannas and forests in the NBR have differing fire regimes. During dry periods, these systems are fuel limited and MAR best describes the occurrence of fires. During wet periods when fuel is not limiting, proxies for anthropogenic ignitions best explain fire occurrence.

Implications

Climate, vegetation and humans collectively determine fire regimes in the NBR. Fire management must integrate across all these factors at the landscape scale to be effective.

}, keywords = {fire management, Forests, savannas, Southern India, traditional burning practices, Western Ghats.}, doi = {doi.org/10.1071/WF24174 }, url = {https://www.publish.csiro.au/WF/WF24174 }, author = {Pradyumna Rajashekar and Aparna Krishnan and Varun Varma and Jayashree Ratnam and Mahesh Sankaran and Caroline E. R. Lehmann} } @article {112957, title = {The thermal niche and phylogenetic assembly of evergreen tree metacommunities in a mid-to-upper tropical montane zone.}, journal = {Proc Biol Sci}, volume = {289}, year = {2022}, month = {2022 Jun 29}, pages = {20220038}, abstract = {

Frost and freezing temperatures have posed an obstacle to tropical woody evergreen plants over evolutionary time scales. Thus, along tropical elevation gradients, frost may influence woody plant community structure by filtering out lowland tropical clades and allowing extra-tropical lineages to establish at higher elevations. Here we assess the extent to which frost and freezing temperatures influence the taxonomic and phylogenetic structure of naturally patchy evergreen forests (locally known as ) along a mid-upper montane elevation gradient in the Western Ghats, India. Specifically, we examine the role of large-scale macroclimate and factors affecting local microclimates, including patch size and distance from edge, in driving metacommunity structure. We find that the metacommunity shows phylogenetic overdispersion with elevation, with greater representation of extra-tropical lineages above 2000 m, and marked turnover in taxonomic composition of woody communities near the frost-affected forest edge above 2000 m, from those below 2000 m. Both minimum winter temperature and patch size were equally important in determining metacommunity structure, with plots inside very large dominated by older tropical lineages, with many endemics. Phylogenetic overdispersion in the upper montane metacommunity thus resulted from tropical lineages persisting in the interiors of large closed frost-free where their regeneration niche has been preserved over time.

}, keywords = {Biological Evolution, Cold Temperature, Fever, Forests, Phylogeny, Wood}, issn = {1471-2954}, doi = {10.1098/rspb.2022.0038}, author = {Das, Arundhati Abin and Ratnam, Jayashree} } @article {84066, title = {Three new species of Protosticta Selys, 1885 (Odonata: Zygoptera: Platystictidae) from the Western Ghats, India, with taxonomic notes on P. mortoni Fraser, 1922 and rediscovery of P. rufostigma Kimmins, 1958.}, journal = {Zootaxa}, volume = {4858}, year = {2020}, month = {2020 Sep 30}, pages = {zootaxa.4858.2.1}, abstract = {

Three new species of Protosticta Selys, 1885 (Odonata: Zygoptera: Platystictidae) from the Western Ghats biodiversity hotspot in India: P. cyanofemora sp. nov. (wet evergreen forests in Shendurney Wildlife Sanctuary, Kollam, Kerala and Kalakkad Mundanthurai Tiger Reserve, Tirunelveli, Tamil Nadu), P. myristicaensis sp. nov. (Myristica swamp at Kathalekan, Shivamogga, Karnataka) and P. sholai sp. nov. (montane sholas of Upper Manalar, Meghamalai Wildlife Sanctuary, Theni, Tamil Nadu) are described and illustrated. We compare these three new species with other Protosticta spp. from the Western Ghats based on new material and provide comprehensive differential diagnoses with determination key for males of all species occurring in the Western Ghats. The taxonomic validity of P. mortoni Fraser, 1922 is established with fresh specimens from Hassan, Karnataka, and rediscovery of P. rufostigma Kimmins, 1958 is reported from Kanyakumari Wildlife Sanctuary, Tamil Nadu.

}, keywords = {Animals, Animals, Wild, Biodiversity, Forests, India, Male, Odonata}, issn = {1175-5334}, doi = {10.11646/zootaxa.4858.2.1}, author = {Joshi, Shantanu and Subramanian, K A and Babu, R and Sawant, Dattaprasad and Kunte, Krushnamegh} } @article {74435, title = {Edge effects reduce α-diversity but not β-diversity during community assembly in a human-modified tropical forest.}, journal = {Ecol Appl}, volume = {29}, year = {2019}, month = {2019 12}, pages = {e01996}, abstract = {

Edge effects can alter the spatial organization of diversity in fragmented habitats. For tropical forests, however, there has been large variation in the strength and direction of such effects reported by different studies. For long-lived organisms like trees, one reason for inconsistent patterns might be due to most studies having examined patterns of diversity and compositional variation in older life stages that bear the legacy of a forest past. Younger life stages can reveal ongoing processes of assembly, but multi-stage examinations are rare. For seedling, sapling, and adult life stages of trees in a human-modified wet tropical forest in the Western Ghats Biodiversity Hotspot (India), we examined how proximity to forest edges (edge influence) modified the spatial organization of diversity. Specifically, for each life stage we tested whether edge influence led to loss of α- and γ-diversity and decreased β-diversity in this landscape. We found lower α- and γ-diversity closer to forest edges, but only for seedlings. Seedling composition at 90-100\ m from forest edges diverged from composition of sites within 60\ m, suggesting that edge influence restricted the recruitment of some species to interior sites. In contrast, β-diversity was greater near edges than interior forest for all life stages and most prominently for seedlings. Furthermore, β-diversity at edges was primarily driven by species turnover, suggesting either marked species-environment associations or dispersal limitation. Low turnover at 90-100\ m implies that β-diversity arose from stochastic fluctuations in occurrences and abundances of the same species set. Overall, we find that high β-diversity structured spatial patterns of diversity near edges, but recruitment bottlenecks are likely to reduce alpha diversity of forest fragments. Our results also corroborate the need to maintain sufficiently large areas of tropical forest free from edge effects to avoid the loss of interior forest species. To improve landscape-scale diversity of fragmented landscapes, restoration efforts should focus on recovery of species that are unable to regenerate near forest edges.

}, keywords = {Aged, Biodiversity, Ecosystem, Forests, Humans, India, Trees, Tropical Climate}, issn = {1051-0761}, doi = {10.1002/eap.1996}, author = {Krishnadas, Meghna and Kumar, Arun N and Comita, Liza S} } @article {45430, title = {Physiological stress responses in wild Asian elephants Elephas maximus in a human-dominated landscape in the Western Ghats, southern India.}, journal = {Gen Comp Endocrinol}, volume = {266}, year = {2018}, month = {2018 09 15}, pages = {150-156}, abstract = {

Increasing anthropogenic pressures on forests, especially in the tropical regions of the world, have restricted several large mammalian species such as the Asian elephant to fragmented habitats within human-dominated landscapes. In this study, we assessed the effects of an anthropogenic landscape and its associated conflict with humans on the physiological stress responses displayed by Asian elephants in the Anamalai Hills of the Western Ghats mountains in south India. We have quantified faecal glucocorticoid metabolite (FGM) concentrations in focal individual elephants within and across herds, inhabiting both anthropogenic and natural habitats, and evaluated their physiological responses to different socio-ecological situations between November 2013 and April 2014. Physiological stress responses varied significantly among the tested elephant age- and sex categories but not across different types of social organisation. Adults generally showed higher FGM concentrations, even in the absence of stressors, than did any other age category. Males also appeared to have higher stress responses than did females. Although there was no significant variation in mean stress levels between elephants on the plateau in the absence of human interactions and those in adjacent, relatively undisturbed forest habitats, FGM concentrations increased significantly for adult and subadult individuals as well as for calves following drives, during which elephants were driven off aggressively by people. Our study emphasises the general importance of understanding individual variation in physiology and behaviour within a population of a seriously threatened mammalian species, the Asian elephant, and specifically highlights the need for long-term monitoring of the stress physiology and behavioural responses of individual elephants across both human-dominated and natural landscapes. Such studies would not only provide comprehensive insights into the adaptive biology of elephants in changing ecological regimes but also aid in the development of effective management and conservation strategies for endangered populations of the species.

}, keywords = {Animals, Animals, Wild, Elephants, Feces, Female, Forests, Geography, Glucocorticoids, Humans, India, Linear Models, Male, Metabolome, Models, Biological, Stress, Physiological}, issn = {1095-6840}, doi = {10.1016/j.ygcen.2018.05.009}, author = {Vijayakrishnan, Sreedhar and Kumar, Mavatur Ananda and Umapathy, G and Kumar, Vinod and Sinha, Anindya} }