Sumanta Bagchi

Indian Institute of Science Bangalore | IISC · Centre for Ecological Sciences

Stability of the soil carbon (C) pool under decadal scale variability in temperature and precipitation is an important source of uncertainty in our understanding of land‐atmosphere climate feedbacks. This depends on how two opposing C‐fluxes – influx from net primary production (NPP) and efflux from heterotrophic soil respiration (Rh) – respond to...

Grazing is the dominant land use across the world, and large mammalian herbivores exert strong influence over biogeochemical cycles. Grazing ecosystems feature C-rich soils, even though herbivores consume a major fraction of plant production to reduce detrital input to soil. Yet, counter-intuitively, moderate grazing can promote net soil-C storage...

Grazing by mammalian herbivores can be a climate mitigation strategy as it influences the size and stability of a large soil carbon (soil-C) pool (more than 500 Pg C in the world's grasslands, steppes, and savannas). With continuing declines in the numbers of large mammalian herbivores, the resultant loss in grazer functions can be consequential fo...

Grazing by large mammalian herbivores impacts climate as it can favor the size and stability of a large carbon (C) pool in the soils of grazing ecosystems. As native herbivores in the world's grasslands, steppes, and savannas are progressively being displaced by livestock, it is important to ask whether livestock can emulate the functional roles of...

Induced anti‐herbivore defences in plants can shape ecosystem structure and functions. Since these are known to be highly variable, quantifying their sources of variation remains important to understand their eco‐evolutionary roles. We conducted meta‐analysis of 647 experiments (paired control and treatment) from 192 studies to address sources of v...

Tapinoma onaele sp. nov. from the Kodagu region of the Western Ghats, India, is described as the fourth species in the Tapinoma lugubre species group. This species is morphologically close to Tapinoma himalaicum Bharti et al., 2013, as both have long scapes and deep and concave anteromedial clypeal margins. However, it differs from T. himalaicum in...

A new species of the genus Aenictus Shuckard, 1840 is described from the Western Ghats region, India, under the name A. kodagura Shakur & Bagchi, sp. nov. based on the worker caste. The new species belongs to the Aenictus pachycerus species group and shares affinities with A. sirenicus Yamane & Wang, 2015, in having a smooth head, smooth pronotum a...

Nutrient enrichment impacts grassland plant diversity such as species richness, functional trait composition and diversity, but whether and how these changes affect ecosystem stability in the face of increasing climate extremes remains largely unknown. We quantified the direct and diversity‐mediated effects of nutrient addition (by nitrogen, phosph...

Global change is associated with variable shifts in the annual production of aboveground plant biomass, suggesting localized sensitivities with unclear causal origins. Combining remotely sensed normalized difference vegetation index data since the 1980s with contemporary field data from 84 grasslands on 6 continents, we show a widening divergence i...

Plant diversity decline under nutrient addition in local grassland communities is typically ascribed to the loss of rare species, species with particular traits ill-suited for high nutrient levels, and displacement of many localized species with a few widespread species. Whether these changes result in stronger diversity decline and vegetation homo...

The gut microbiome can be shaped by both intrinsic host factors and extrinsic environmental factors. However, the relative importance of intrinsic and extrinsic factors in gut microbial composition has rarely been investigated, particularly for a single host across its natural range. Here, we characterise the gut microbiome of an endemic, endangere...

Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sp...

Little is currently known about how climate modulates the relationship between plant diversity and soil organic carbon and the mechanisms involved. Yet, this knowledge is of crucial importance in times of climate change and biodiversity loss. Here, we show that plant diversity is positively correlated with soil carbon content and soil carbon-to-nit...

Diversity-function relationships in producers, and how these are influenced by consumers, are well known. However, these are not well known for microbial decomposers in soil. It is also unknown whether and how consumers such as large mammalian herbivores influence soil microbial decomposer diversity-function relationships. We used a 14-year-old her...

Diversity-function relationships are well established for producers and their productivity. They are also evident among consumers. However, these are not well known for microbial decomposers and decomposition processes in soil. Further, it also remains unknown whether and how consumers, such as large mammalian herbivores who are a major feature acr...

Plant productivity varies due to environmental heterogeneity, and theory suggests that plant diversity can reduce this variation. While there is strong evidence of diversity effects on temporal variability of productivity, whether this mechanism extends to variability across space remains elusive. Here we determine the relationship between plant di...

Eutrophication impacts plant diversity such as species richness, functional trait diversity and composition of grassland communities globally, but whether and how these changes affect the functional stability of grasslands under increasing climate extremes is unknown. We quantify the direct and diversity-mediated effects of nutrient addition on fun...

Ecological models predict that the effects of mammalian herbivore exclusion on plant diversity depend on resource availability and plant exposure to ungulate grazing over evolutionary time. Using an experiment replicated in 57 grasslands on six continents, with contrasting evolutionary history of grazing, we tested how resources (mean annual precip...

The influence of native mammalian herbivores on ecosystem functions is declining as domestic livestock have displaced them to become the dominant grazers across the world. Alongside rewilding, restoration, and conservation, it is now important to address whether livestock can assume the functional roles of displaced native herbivores in grasslands,...

Nutrients and herbivores are well-known drivers of grassland diversity and stability in local communities. However, whether they interact to impact the stability of aboveground biomass and whether these effects depend on spatial scales remain unknown. It is also unclear whether nutrients and herbivores impact stability via different facets of plant...

1. Understanding how biodiversity is distributed is increasingly becoming important under ongoing and projected human land use. Measures of beta diversity, and its partitions, can offer insights for conservation and restoration of biodiversity. 2. We ask how different species, functional groups, and land use contribute to beta diversity, and whethe...

Land-use and climate change are known to be the greatest threat to biodiversity. The effects of both are even more pronounced in the fragile high-elevation trans-Himalayas and there is an urgent need to understand how biodiversity is being affected in this ecosystem as a consequence of human induced land-use and climate change. To study this, we us...

The effects of altered nutrient supplies and herbivore density on species diversity vary with spatial scale, because coexistence mechanisms are scale dependent. This scale dependence may alter the shape of the species–area relationship (SAR), which can be described by changes in species richness (S) as a power function of the sample area (A): S = c...

Aim Animal migrations influence ecosystem structure, dynamics and persistence of predator and prey populations. The theory of migratory coupling postulates that aggregations of migrant prey can induce large‐scale synchronized movements in predators, and this coupling is consequential for the dynamics of ecological communities. The degree to which h...

Nutrients and herbivores have independent effects on the temporal stability of aboveground biomass in grasslands; however, their joint effects may not be additive and may also depend on spatial scales. In an experiment adding nutrients and excluding herbivores in 34 globally distributed grasslands, we found that nutrients and herbivores mainly had...

Arbuscular mycorrhizal fungal (AMF) symbioses with plants can be influenced by top-down forces such as grazing, and also by bottom-up forces such as soil resource availability, both of which are being altered by anthropogenic and global change drivers. While the influence of each of these factors on AMF symbioses has been widely studied, explicit t...

Background/Question/Methods Understanding the patterns of how biodiversity is distributed has been a central question in ecology. Need to understand this has gained priority in recent times due to an accelerated human induced land-use change leading to global declines in biodiversity. To understand these patterns of biodiversity distribution, beta-...

Protanilla flamma sp. n. from Goa, India is described, which is the thirteenth species in the genus Protanilla and the second record of this genus from the country. The new species morphologically appears close to P. lini Terayama, 2009 in terms of mandibular teeth count and the structure of petiolar and post-petiolar nodes. However, it can be very...

Grasslands are subject to considerable alteration due to human activities globally, including widespread changes in populations and composition of large mammalian herbivores and elevated supply of nutrients. Grassland soils remain important reservoirs of carbon (C) and nitrogen (N). Herbivores may affect both C and N pools and these changes likely...

Human–wildlife conflict arising from livestock‐losses to large carnivores is an important challenge faced by conservation. Theory of prey–predator interactions suggests that revival of wild prey populations can reduce predator's dependence on livestock in multiple‐use landscapes. We explore whether 10‐years of conservation efforts to revive wild pr...

A more anthropocentric approach in recent times has modified our natural world drastically with human land use patterns dictating many of the observable patterns in our surroundings. One-third of terrestrial ecosystem are grazing ecosystems, a potential carbon (C) sink. Grazing ecosystems could be natural (native herbivores) or managed (livestock)....

Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet,...

Predator-prey interactions where livestock are killed by carnivores, are a serious global challenge. Conservation interventions to address this conflict are inadequately guided by ecological theory, and instead rely on pragmatic experiential decisions. I review four families of theoretical models that can accommodate essential features of this huma...

Understanding spatial-temporal patterns of terrestrial vegetation response to climate change (long-term greening/browning) is important for developing strategies to mitigate degradation. Semi-arid rangelands are especially susceptible to degradation, which challenges wildlife conservation and human-livelihoods that depend on livestock production. I...

Woody encroachment is of global concern in arid and semiarid regions around the world. Due to reduction in grass (forage), woody encroachment is viewed as ecosystem disservice and degradation, even though this may not reduce ecosystem functions. Often, management perceptions of degradation remain inadequately informed by knowledge of ecosystem proc...

Plant communities are structured by both competition and facilitation. The interplay between the two interactions can vary depending on environmental factors, nature of stress, and plant traits. However, whether positive or negative interactions dominate in regions of high biotic and abiotic stress remains unclear. We studied herbaceous plant commu...

Large populations of migratory birds cross the Himalayas during their annual migrations through the Central Asian Flyway, and Himalayan wetlands are critical habitats for many bird species (Namgail et al., 2009; Namgail & Yom-Tov, 2009). In the Ladakh region of the Himalayas, wetlands are important summer breeding grounds for waterbirds and other s...

http://onlinelibrary.wiley.com/doi/10.1002/eap.1544/full Quantification of rates and patterns of community dynamics is central for understanding the organization and function of ecosystems. These insights may support a greater empirical understanding of ecological resilience, and the application of resilience concepts toward ecosystem management....

Full text: https://authors.elsevier.com/a/1USgvcA-ISBJN Understanding factors that regulate carbon (C) pools is of high importance for offsetting greenhouse-gas emissions. Soils represent a vast C pool, whose size and stability are strongly influenced by land-use. Grazing, by native herbivores and livestock, is the predominant land-use across over...

Theoretical models suggest that competitive coexistence of consumers over shared resources can occur only under very restrictive conditions. Yet, in apparent defiance of the competitive exclusion principle, large numbers of species form natural communities while sharing a small number of limiting resources. Consumers not only coexist, but also show...

Plants allocate biomass to aboveground (shoot) and belowground (root) structures to capture light and nutrients, respectively. Plant allocation strategies are a key feature of ecosystem structure, and function, as they have broad influence over material and energy flow. Herbivores can exercise strong control over plant allocation, and thereby influ...

Resilience‐based approaches are increasingly being called upon to inform ecosystem management, particularly in arid and semi‐arid regions. This requires management frameworks that can assess ecosystem dynamics, both within and between alternative states, at relevant time scales. We analysed long‐term vegetation records from two representative sites...

India, a mega-diverse country in terms of both biodiversity and people, is battling environmental problems on many fronts: chronic dependence on natural resources, dwindling ecosystem services, declining environmental quality, effects of climate change and a biodiversity crisis. We review the current focal areas and infrastructure for ecological re...

Grazing can have implications for ecosystem management, biodiversity conservation, human livelihoods and global biogeochemical cycles. Grazers can either depress or promote plant production, with weak or strong effects on vegetation composition. Such variability is a major challenge for sustaining production while avoiding undesirable vegetation sh...

Resilience-based frameworks, including state-and-transition models (STM), are being increasingly called upon to inform policy and guide ecosystem management, particularly in rangelands. Yet, multiple challenges impede their effective implementation: (1) paucity of empirical tests of resilience concepts, such as alternative states and thresholds, an...

Species coexistence involving trophic interactions has been investigated under two theoretical frameworks—partitioning shared resources and accessing exclusive resources. The influence of body size on coexistence is well studied under the exclusive resources framework, but has received less attention under the shared-resources framework. We investi...

Background/Question/Methods Resilience-based ecological frameworks, including state-and-transition models (STM), are being increasingly called upon to guide ecosystem management and inform natural resource policy. Yet multiple challenges continue to impede their application, including limited empirical assessments of non-equilibrium theory, infre...

Large mammalian herbivores may have positive, neutral, or negative effects on annual net aboveground plant production (NAP) in different ecosystems, depending on their indirect effects on availability of key nutrients such as soil N. In comparison, less is known about the corresponding influence of grazers, and nutrient dynamics, over annual net be...

Ecology Letters (2010) 13: 959–968 Grazing occurs over a third of the earth’s land surface and may potentially influence the storage of 109 Mg year−1 of greenhouse gases as soil C. Displacement of native herbivores by high densities of livestock has often led to overgrazing and soil C loss. However, it remains unknown whether matching livestock den...

A mechanistic understanding of the highly variable effects of herbivores on plant production in different ecosystems remains a major challenge. To explain these patterns, the compensatory continuum hypothesis (CCH) predicts plants to compensate for defoliation when resources are abundant, whereas the growth rate hypothesis (GRH) makes the opposite...

This study investigates ecosystem function in the Trans-Himalayan grazing ecosystem in northern India. First, herbivory-tolerance in plants was studied under a full-factorial arrangement of experimental clipping, irrigation and fertilization. In absence of fertilization, plants compensated for defoliation if not irrigated, but failed to compensate...

IntroductionRangeland vegetationWildlife of the Trans-Himalayan rangelandsPastoralism in the Trans-HimalayaGrazing impacts and conflicts between pastoralism and wildlife conservationTowards better conservation management in Trans-Himalayan rangelandsAcknowledgementsReferences

Background/Question/Methods Land-use practices determine whether global greenhouse-gas emissions can be offset by soil-C sequestration. Grazing is a predominant land-use occurring on nearly a third of the earth’s terrestrial surface, and influences the potential for 109 Mg·y-1 of soil-C storage. Historically, nearly all natural grazing ecosystems...

Grouping characteristics and population structure of chital (Axis axis Erxleben), sambar (Cervus unicolor Kerr), nilgai (Boselaphus tragocamelus Pallas) and chinkara (Gazella bennetti Sykes) were studied in dry tropical forests of Ranthambhore Tiger Reserve in semi-arid western India during November 2000 to April 2001. Mean and typical group sizes...

The Tibetan gazelle Procapra picticaudata is on the verge of extinction in India with only c. 100 individ-uals remaining in the Hanle Valley of eastern Ladakh and Sikkim. Conservation planning and initiation of a recovery programme are hindered by lack of ecological information on the species and we therefore assessed the biotic and abiotic correla...

The Tibetan gazelle Procapra picticaudata is on the verge of extinction in India with only c. 100 individuals remaining in the Hanle Valley of eastern Ladakh and Sikkim. Conservation planning and initiation of a recovery programme are hindered by lack of ecological information on the species and we therefore assessed the biotic and abiotic correlat...

(Jina, 1995), graze the rangelands of Changthang. TheChangpa are Buddhists and share cultural and linguisticaffinities with Tibet (Rizvi, 1996). They lost access toseveral traditional pastures on the Tibetan side when Indiaand China fought a war in the region in 1962 (Ahmed,1997). Around the same time, the Indian side saw a heavyinflux of Tibetan r...

Questions: Density dependence is thought to restrict exponential growth as well as give rise to size structure in populations. Size hierarchy in trees from tropical dry deciduous forests is studied to ask (1) whether nature of competition is symmetric or asymmetric and (2) what is the self thinning trajectory under a natural gradient of tree densit...

"Tibetan gazelle Procapra picticaudata is endemic to the Tibetan plateau. During the early twentieth century, it was distributed over a range of c. 20,000 km2 in Ladakh, India. Although its conservation status is believed to be secure, our surveys initiated in 2000 found that the gazelles population in Ladakh has undergone a precipitous decline. To...

Livestock predation by large carnivores and their retaliatory persecution by pastoralists are worldwide conservation concerns. Poor understanding of the ecological and social underpinnings of this human¿wildlife conflict hampers effective conflict management programs. The endangered snow leopard Uncia uncia is involved in conflict with people acros...

The high-altitude rangelands of the Trans-Himalaya represent a grazing ecosystem which has supported an indigenous pastoral community for millennia alongside a diverse assemblage of wild herbivores including burrowing mammals (pikas and voles). Pastoralists consider the small mammals to cause rangeland degradation and as competitors for their lives...

Prey depletion is a major (but often neglected) factor driving the current decline of tigers ( Panthera tigris L.) (Karanth & Stith 1999). Thus conservation planning for the tiger in a fragmented, human-dominated landscape requires reliable information on prey densities from various parts of its range. We report numerical and biomass density of six...