In recent years, scientific investigations on the effectiveness of Protected Areas (PAs) in conse... more In recent years, scientific investigations on the effectiveness of Protected Areas (PAs) in conserving biodiversity and sustaining ecosystem functions under the impact of climate change have increasingly received more attention from researchers and park managers. In this study, we used a combination of species distribution modelling (SDM) and spatial hierarchical systematic conservation planning technique to delineate and prioritize areas for endemic plant species conservation under current and future (2050s, 2070s) climate conditions in Sikkim Himalaya. Data on endemic plant species occurrence were sourced from our already published studies and their potential suitable habitats under current and future climates were modelled using Maximum Entropy (MaxEnt) SDM. The MaxEnt habitat suitability projections of species were used in Zonation software to identify priority conservation areas in Sikkim Himalaya. We found that the existing PA network in the region was inadequate in conserving the endemic plant diversity either in the current or future climate scenarios. Based on our results, we propose addition of 896 square kilometres (sq km) to the existing PA network in the study area to ensure meaningful conservation goals. Additionally, we propose creation of 3 new PAs (Yumsedong, Lachen and Chungthang) and the need for expanding the boundaries of existing PAs (Maenam, Fambong Lho and Barsey) in the study area. Our analyses show that to mitigate the effects of ensuing climate change, a single large PA with wide geographic and elevational extents instead of several smaller PAs would be a more prudent strategy for conserving the plant diversity in the Himalaya.
Botanical Journal of the Linnean Society, Sep 1, 2003
The reproductive biology of two subspecies of Coptis teeta was studied. The species is an endange... more The reproductive biology of two subspecies of Coptis teeta was studied. The species is an endangered, herbaceous perennial, endemic to the Mishmi Hills in Eastern Himalaya. We investigated reproductive strategies of the subspecies, their breeding systems and reproductive output. They had contrasting reproductive strategies; ssp. teeta reproduces sexually and produces fewer ramets, while ssp. lohitensis propagates mostly vegetatively through a higher number of ramets. There is a resource adjustment between vegetative and sexual functions with a greater allocation to the former, particularly in ssp. lohitensis. Manual crosses showed that the species is self-and cross-compatible, but is essentially an autogamous selfer. Seed set in the species is generally low, with higher output in ssp. teeta and lower in ssp. lohitensis. The low fecundity is ascribed to a number of pre-and postfertilization events, including unsuitability of floral features for attracting pollinators, high pollen sterility and high rates of fruit and seed abortion. Sexual reproduction does not contribute significantly towards population increase in this species. This could be an important factor contributing to its rarity.
Reviews in Fish Biology and Fisheries, Nov 14, 2015
Golden mahseer, Tor putitora Hamilton, one of the largest freshwater fish of the Indian sub-conti... more Golden mahseer, Tor putitora Hamilton, one of the largest freshwater fish of the Indian sub-continent, inhabits mainly Himalayan rivers in the foothills. Among numerous freshwater fishes of the sub-continent, Golden mahseer is the most striking due to its large size, attractive golden colour, sustenance and sporting values. Tor putitora is known by various common names such as king mahseer, mighty mahseer and the tiger of water. Being a migratory fish, Golden mahseer undertakes periodic upstream migration during pre-monsoon and monsoon seasons from large rivers and higher order streams in the foothills to lower order streams for spawning. In recent years, conservationists, anglers and commercial fishermen have expressed concern over the declining populations of Golden mahseer due to indiscriminate fishing of brooders and juveniles besides the adverse effects of dams. Despite its ecological and economic importance, specific conservation measures by way of protective legal provisos are lacking for Golden mahseer in India. In view of its physical features, ecology and vulnerable conservation status, there is an exigent need to promote the Golden mahseer as a flagship conservation species of the Himalayan rivers. In view of the recent reports of unprecedented river regulation projects on the Himalayan rivers and need to draw global attention of conservationists, we review various aspects of ecology, life history, interesting features, traits and threats associated with the reduced chances of survival of Golden mahseer.
Background: Studying diversity and distribution patterns of species along elevational gradients a... more Background: Studying diversity and distribution patterns of species along elevational gradients and understanding drivers behind these patterns is central to macroecology and conservation biology. A number of studies on biogeographic gradients are available for terrestrial ecosystems, but freshwater ecosystems remain largely neglected. In particular, we know very little about the species richness gradients and their drivers in the Himalaya, a global biodiversity hotspot. Methodology/Principal Findings: We collated taxonomic and distribution data of fish species from 16 freshwater Himalayan rivers and carried out empirical studies on environmental drivers and fish diversity and distribution in the Teesta river (Eastern Himalaya). We examined patterns of fish species richness along the Himalayan elevational gradients (50-3800 m) and sought to understand the drivers behind the emerging patterns. We used generalized linear models (GLM) and generalized additive models (GAM) to examine the richness patterns; GLM was used to investigate relationship between fish species richness and various environmental variables. Regression modelling involved stepwise procedures, including elimination of collinear variables, best model selection, based on the least Akaike's information criterion (AIC) and the highest percentage of deviance explained (D 2). This maiden study on the Himalayan fishes revealed that total and nonendemic fish species richness monotonously decrease with increasing elevation, while endemics peaked around mid elevations (700-1500 m). The best explanatory model (synthetic model) indicated that water discharge is the best predictor of fish species richness patterns in the Himalayan rivers. Conclusions/Significance: This study, carried out along one of the longest bioclimatic elevation gradients of the world, lends support to Rapoport's elevational rule as opposed to mid domain effect hypothesis. We propose a species-discharge model and contradict species-area model in predicting fish species richness. We suggest that drivers of richness gradients in terrestrial and aquatic ecosystems are likely to be different. These studies are crucial in context of the impacts of unprecedented ongoing river regulation on fish diversity and distribution in the Himalaya.
Impact Assessment and Project Appraisal, Jul 29, 2017
Teesta river basin in Eastern Himalaya is being subjected to cascade hydropower development. To a... more Teesta river basin in Eastern Himalaya is being subjected to cascade hydropower development. To assess the impacts of this developmental activity on fish fauna of the basin, fish habitats of the four largest tributaries in the basin were selected for the present study. A total of 18 large hydroelectric projects are planned on these rivers. Here, a total of 11 EIAs and 2 carrying capacity studies in Teesta basin were reviewed. Our investigations show that after commissioning all the projects, 52-88% of the free-flowing river stretches will be diverted and 7.6-24% of the riverine ecosystems will be converted into semi lacustrine ecosystems in different rivers. The cascade hydropower development is likely to affect more than 100 fish species. All the EIA reports reviewed have investigated fish species richness, impacts on fish fauna and fishery management plans. EIA studies and management plans, however, do not adequately address important ecological and conservation issues due to various limitations. An integrated fish conservation plan for the upper Teesta basin is suggested in this contribution.
Figure S1. Map of the study area showing sampling locations in Sikkim Himalaya, a part of the Eas... more Figure S1. Map of the study area showing sampling locations in Sikkim Himalaya, a part of the Eastern Himalayan biodiversity hotspot. Sampling was conducted in two different elevational zones: (i) 300-4000 m, and (ii) 4000-5300 m. In the lower zone (300-4000 m), nested quadrats of 10 m x 10 m were used for sampling, while in the upper zone (4000-5300 m) nested modified Whittaker plot (MWP) design of 20 m × 50 m was used. Above 5300 m, no sampling was performed due to inaccessibility of terrain and lack of any vegetation cover.
A s the Intergovernmental Panel on Climate Change (IPCC) gets ready to publish the first instalme... more A s the Intergovernmental Panel on Climate Change (IPCC) gets ready to publish the first instalment of its latest report, many critics of the reports have been harking back to the previous effort-and the glaring mistake it made in stating that the Himalayan glaciers would disappear by 2035. The situation in the Himalayas is not as dire as that, but it is certainly perilous. And although the IPCC overstated the timescale, the threat to the mountains from global warming and other pressures is genuine and must be addressed. Just this summer, the Indian Himalayan state of Uttarakhand witnessed what many described as the most horrific devastation in human memory. Cloudbursts, flash floods, landslides, human deaths and destruction were unleashed within a day. Human casualties were put in the thousands, and estimates of economic loss range from US$500 million to around $2 billion. Similarly, a monsoon flood hit Pakistan in 2010, killing more than 2,000 people, displacing millions and costing $40 billion. Policy-makers in India and elsewhere are reluctant to accept a glaring and dangerous truth: combined human activities have stressed the Himalayas close to their limit. We need positive action, not least a restriction on the number of tourists who visit during the monsoon season from June to September. Too many of them are unaware of the risks they run. Thousands of visitors perished in the Uttarakhand disaster. Policy-makers must actively engage with scientists and experts on the problems facing the Himalayas and their people to make sustainable development work. Global warming can grab the headlines, but many of the other pressures on the fragile mountain region are more mundane. The human population is increasing fast in the Himalayas, and so is the speed of the landscape changes needed to support it. Cattle grazing and rampant deforestation-on current trends, one-third of the total Indian Himalayan forest cover could be gone by 2100-will drive nearly one-quarter of endemic species to extinction and disrupt the natural flow of water. A changed Himalayan landscape caused by human activities and warming means transformed natural ecosystems through biological invasions and reduced native biodiversity. People need energy, and in the Himalayas that means hydropower and dams. Nearly 400 new dams are proposed for the Indian and Tibetan Himalayas in the next decade or so. With them will come more change to ecosystems and more people displaced from submerged settlements. Such rampant dam-building in a region with high seismic activity and fragile geology shows that the policy-makers who approve these schemes either do not understand the scientific evidence or choose to ignore it. The Himalayas are just 45 million years (Myr) old-mere striplings compared with the Climate change and human activities are pushing the fragile ecosystem ever closer to instability,warns Maharaj K. Pandit.
Botanical Journal of the Linnean Society, Aug 1, 2000
Cytogenetic investigations of 13 natural populations of Cop& &eta, an endemic and endangered medi... more Cytogenetic investigations of 13 natural populations of Cop& &eta, an endemic and endangered medicinal plant from the Eastern Himalaya, were carried out. About 70-80% individuals in some of the populations were synaptic mutants. The predominantly sexually breeding plant populations were confined to higher cooler latitudes, whereas the mutant apomict inhabited lower warmer latitudes. The breeding systems were observed to be associated with morphological differentiation and ecological preference of some populations. Individuals of subsp. tee& reproduced sexually as well as vegetatively, but those of subsp. lohi& have adapted almost entirely to a vegetative mode of reproduction. Though no variation was observed in somatic chromosome number and karyotypes, the two subspecies differed significantly with respect to their male meiotic behaviour and rhizome morphology. The mutants either produced little fertile pollen or were completely sterile, leading to low seed production or none at all. This has resulted in low reproductive fitness, localized distribution and small population sizes of the taxon.
Modeling Earth Systems and Environment, Aug 7, 2021
Formation of the Himalaya resulted from collision of the Indian and the Eurasian plates around th... more Formation of the Himalaya resulted from collision of the Indian and the Eurasian plates around the early Cenozoic (55–45 million years ago). Various geo-physical changes, namely disappearance of Tethys Sea, formation of land bridges and evolution of monsoon system followed the collision. These changes are cumulatively responsible for high plant endemism in the Himalaya. Here, we show that the high plant endemism in the Himalaya is likely linked to changes in geology, geomorphology and climate during the past millions of years. We used phylogenetic supertrees and ancestral area reconstructions to investigate the rates and biogeographic source areas of the Himalayan endemic plant species assembly through different geological time periods. Our results show that Eastern Himalaya (EH) harbors twice the number of plant endemics than the Western Himalaya (WH). The time-calibrated phylogenies revealed that maximum endemic diversifications of plant families in both the EH and WH occurred during 35–20 million years ago (Oligocene–Miocene), the period that coincided with evolution of the South West Asian monsoon. Further, the majority of plant endemics in the EH have ancestral lineages from South East Asian and Sino-Japanese regions. The WH endemic taxa have ancestor lineages from Southeast Chinese, Sino-Japanese, Irano–Turanian, and Central Asiatic regions. The high endemic plant diversity in the Himalaya is a result of immigration of ancestral lineages from the neighboring regions followed by their local radiations and diversifications after the formation and intensification of monsoon system.
Modeling Earth Systems and Environment, Jun 1, 2016
That the Himalaya are warming at much higher rates than the global average is known. Here, we ass... more That the Himalaya are warming at much higher rates than the global average is known. Here, we assess the future potential distribution of major plant communities in Sikkim Himalaya due to climate change using field observations and maximum entropy modelling approach. We collected data on presence and elevational distribution ranges of 584 endemic angiosperm species during field surveys at 121 sampling locations using 625 study plots and along an elevational gradient of 300-5,300 m. This field data was supplemented by already published records. Endemic species were classified into different growth forms, viz. trees, climbers, shrubs, and herbs. A total of 37,376 different species distribution models (SDMs) were built using climate projections available from 8 different general circulation models and 4 representative concentration pathways. SDMs were built for current climate (average climate for 1950-2000), 2050 (average climate for 2041-2060), and 2070 (average climate for 2061-2080). We found that about 16 and 18 % of endemic angiosperm species are likely to lose their potential habitat by 2050 and 2070, respectively. Meadows may likely lose about 1 and 3 % of their current geographical spread to shrublands by 2050 and 2070, respectively. Weak and insignificant values of phylogenetic signal among the growth forms indicated that climate-induced impacts were spread across the phylogenies. We report significant increase in the habitable areas of shrubs and their northward expansion, gradually replacing the herbaceous communities. This change can alter the structure and function of the Himalayan highland ecosystems besides depleting bioresource base and endangering the local livelihoods.
Some sort of standdown will happen-and conservation should come into the discussions." Conservati... more Some sort of standdown will happen-and conservation should come into the discussions." Conservation could be part of the toolkit for diplomacy between China and India.
In recent years, scientific investigations on the effectiveness of Protected Areas (PAs) in conse... more In recent years, scientific investigations on the effectiveness of Protected Areas (PAs) in conserving biodiversity and sustaining ecosystem functions under the impact of climate change have increasingly received more attention from researchers and park managers. In this study, we used a combination of species distribution modelling (SDM) and spatial hierarchical systematic conservation planning technique to delineate and prioritize areas for endemic plant species conservation under current and future (2050s, 2070s) climate conditions in Sikkim Himalaya. Data on endemic plant species occurrence were sourced from our already published studies and their potential suitable habitats under current and future climates were modelled using Maximum Entropy (MaxEnt) SDM. The MaxEnt habitat suitability projections of species were used in Zonation software to identify priority conservation areas in Sikkim Himalaya. We found that the existing PA network in the region was inadequate in conserving the endemic plant diversity either in the current or future climate scenarios. Based on our results, we propose addition of 896 square kilometres (sq km) to the existing PA network in the study area to ensure meaningful conservation goals. Additionally, we propose creation of 3 new PAs (Yumsedong, Lachen and Chungthang) and the need for expanding the boundaries of existing PAs (Maenam, Fambong Lho and Barsey) in the study area. Our analyses show that to mitigate the effects of ensuing climate change, a single large PA with wide geographic and elevational extents instead of several smaller PAs would be a more prudent strategy for conserving the plant diversity in the Himalaya.
Botanical Journal of the Linnean Society, Sep 1, 2003
The reproductive biology of two subspecies of Coptis teeta was studied. The species is an endange... more The reproductive biology of two subspecies of Coptis teeta was studied. The species is an endangered, herbaceous perennial, endemic to the Mishmi Hills in Eastern Himalaya. We investigated reproductive strategies of the subspecies, their breeding systems and reproductive output. They had contrasting reproductive strategies; ssp. teeta reproduces sexually and produces fewer ramets, while ssp. lohitensis propagates mostly vegetatively through a higher number of ramets. There is a resource adjustment between vegetative and sexual functions with a greater allocation to the former, particularly in ssp. lohitensis. Manual crosses showed that the species is self-and cross-compatible, but is essentially an autogamous selfer. Seed set in the species is generally low, with higher output in ssp. teeta and lower in ssp. lohitensis. The low fecundity is ascribed to a number of pre-and postfertilization events, including unsuitability of floral features for attracting pollinators, high pollen sterility and high rates of fruit and seed abortion. Sexual reproduction does not contribute significantly towards population increase in this species. This could be an important factor contributing to its rarity.
Reviews in Fish Biology and Fisheries, Nov 14, 2015
Golden mahseer, Tor putitora Hamilton, one of the largest freshwater fish of the Indian sub-conti... more Golden mahseer, Tor putitora Hamilton, one of the largest freshwater fish of the Indian sub-continent, inhabits mainly Himalayan rivers in the foothills. Among numerous freshwater fishes of the sub-continent, Golden mahseer is the most striking due to its large size, attractive golden colour, sustenance and sporting values. Tor putitora is known by various common names such as king mahseer, mighty mahseer and the tiger of water. Being a migratory fish, Golden mahseer undertakes periodic upstream migration during pre-monsoon and monsoon seasons from large rivers and higher order streams in the foothills to lower order streams for spawning. In recent years, conservationists, anglers and commercial fishermen have expressed concern over the declining populations of Golden mahseer due to indiscriminate fishing of brooders and juveniles besides the adverse effects of dams. Despite its ecological and economic importance, specific conservation measures by way of protective legal provisos are lacking for Golden mahseer in India. In view of its physical features, ecology and vulnerable conservation status, there is an exigent need to promote the Golden mahseer as a flagship conservation species of the Himalayan rivers. In view of the recent reports of unprecedented river regulation projects on the Himalayan rivers and need to draw global attention of conservationists, we review various aspects of ecology, life history, interesting features, traits and threats associated with the reduced chances of survival of Golden mahseer.
Background: Studying diversity and distribution patterns of species along elevational gradients a... more Background: Studying diversity and distribution patterns of species along elevational gradients and understanding drivers behind these patterns is central to macroecology and conservation biology. A number of studies on biogeographic gradients are available for terrestrial ecosystems, but freshwater ecosystems remain largely neglected. In particular, we know very little about the species richness gradients and their drivers in the Himalaya, a global biodiversity hotspot. Methodology/Principal Findings: We collated taxonomic and distribution data of fish species from 16 freshwater Himalayan rivers and carried out empirical studies on environmental drivers and fish diversity and distribution in the Teesta river (Eastern Himalaya). We examined patterns of fish species richness along the Himalayan elevational gradients (50-3800 m) and sought to understand the drivers behind the emerging patterns. We used generalized linear models (GLM) and generalized additive models (GAM) to examine the richness patterns; GLM was used to investigate relationship between fish species richness and various environmental variables. Regression modelling involved stepwise procedures, including elimination of collinear variables, best model selection, based on the least Akaike's information criterion (AIC) and the highest percentage of deviance explained (D 2). This maiden study on the Himalayan fishes revealed that total and nonendemic fish species richness monotonously decrease with increasing elevation, while endemics peaked around mid elevations (700-1500 m). The best explanatory model (synthetic model) indicated that water discharge is the best predictor of fish species richness patterns in the Himalayan rivers. Conclusions/Significance: This study, carried out along one of the longest bioclimatic elevation gradients of the world, lends support to Rapoport's elevational rule as opposed to mid domain effect hypothesis. We propose a species-discharge model and contradict species-area model in predicting fish species richness. We suggest that drivers of richness gradients in terrestrial and aquatic ecosystems are likely to be different. These studies are crucial in context of the impacts of unprecedented ongoing river regulation on fish diversity and distribution in the Himalaya.
Impact Assessment and Project Appraisal, Jul 29, 2017
Teesta river basin in Eastern Himalaya is being subjected to cascade hydropower development. To a... more Teesta river basin in Eastern Himalaya is being subjected to cascade hydropower development. To assess the impacts of this developmental activity on fish fauna of the basin, fish habitats of the four largest tributaries in the basin were selected for the present study. A total of 18 large hydroelectric projects are planned on these rivers. Here, a total of 11 EIAs and 2 carrying capacity studies in Teesta basin were reviewed. Our investigations show that after commissioning all the projects, 52-88% of the free-flowing river stretches will be diverted and 7.6-24% of the riverine ecosystems will be converted into semi lacustrine ecosystems in different rivers. The cascade hydropower development is likely to affect more than 100 fish species. All the EIA reports reviewed have investigated fish species richness, impacts on fish fauna and fishery management plans. EIA studies and management plans, however, do not adequately address important ecological and conservation issues due to various limitations. An integrated fish conservation plan for the upper Teesta basin is suggested in this contribution.
Figure S1. Map of the study area showing sampling locations in Sikkim Himalaya, a part of the Eas... more Figure S1. Map of the study area showing sampling locations in Sikkim Himalaya, a part of the Eastern Himalayan biodiversity hotspot. Sampling was conducted in two different elevational zones: (i) 300-4000 m, and (ii) 4000-5300 m. In the lower zone (300-4000 m), nested quadrats of 10 m x 10 m were used for sampling, while in the upper zone (4000-5300 m) nested modified Whittaker plot (MWP) design of 20 m × 50 m was used. Above 5300 m, no sampling was performed due to inaccessibility of terrain and lack of any vegetation cover.
A s the Intergovernmental Panel on Climate Change (IPCC) gets ready to publish the first instalme... more A s the Intergovernmental Panel on Climate Change (IPCC) gets ready to publish the first instalment of its latest report, many critics of the reports have been harking back to the previous effort-and the glaring mistake it made in stating that the Himalayan glaciers would disappear by 2035. The situation in the Himalayas is not as dire as that, but it is certainly perilous. And although the IPCC overstated the timescale, the threat to the mountains from global warming and other pressures is genuine and must be addressed. Just this summer, the Indian Himalayan state of Uttarakhand witnessed what many described as the most horrific devastation in human memory. Cloudbursts, flash floods, landslides, human deaths and destruction were unleashed within a day. Human casualties were put in the thousands, and estimates of economic loss range from US$500 million to around $2 billion. Similarly, a monsoon flood hit Pakistan in 2010, killing more than 2,000 people, displacing millions and costing $40 billion. Policy-makers in India and elsewhere are reluctant to accept a glaring and dangerous truth: combined human activities have stressed the Himalayas close to their limit. We need positive action, not least a restriction on the number of tourists who visit during the monsoon season from June to September. Too many of them are unaware of the risks they run. Thousands of visitors perished in the Uttarakhand disaster. Policy-makers must actively engage with scientists and experts on the problems facing the Himalayas and their people to make sustainable development work. Global warming can grab the headlines, but many of the other pressures on the fragile mountain region are more mundane. The human population is increasing fast in the Himalayas, and so is the speed of the landscape changes needed to support it. Cattle grazing and rampant deforestation-on current trends, one-third of the total Indian Himalayan forest cover could be gone by 2100-will drive nearly one-quarter of endemic species to extinction and disrupt the natural flow of water. A changed Himalayan landscape caused by human activities and warming means transformed natural ecosystems through biological invasions and reduced native biodiversity. People need energy, and in the Himalayas that means hydropower and dams. Nearly 400 new dams are proposed for the Indian and Tibetan Himalayas in the next decade or so. With them will come more change to ecosystems and more people displaced from submerged settlements. Such rampant dam-building in a region with high seismic activity and fragile geology shows that the policy-makers who approve these schemes either do not understand the scientific evidence or choose to ignore it. The Himalayas are just 45 million years (Myr) old-mere striplings compared with the Climate change and human activities are pushing the fragile ecosystem ever closer to instability,warns Maharaj K. Pandit.
Botanical Journal of the Linnean Society, Aug 1, 2000
Cytogenetic investigations of 13 natural populations of Cop& &eta, an endemic and endangered medi... more Cytogenetic investigations of 13 natural populations of Cop& &eta, an endemic and endangered medicinal plant from the Eastern Himalaya, were carried out. About 70-80% individuals in some of the populations were synaptic mutants. The predominantly sexually breeding plant populations were confined to higher cooler latitudes, whereas the mutant apomict inhabited lower warmer latitudes. The breeding systems were observed to be associated with morphological differentiation and ecological preference of some populations. Individuals of subsp. tee& reproduced sexually as well as vegetatively, but those of subsp. lohi& have adapted almost entirely to a vegetative mode of reproduction. Though no variation was observed in somatic chromosome number and karyotypes, the two subspecies differed significantly with respect to their male meiotic behaviour and rhizome morphology. The mutants either produced little fertile pollen or were completely sterile, leading to low seed production or none at all. This has resulted in low reproductive fitness, localized distribution and small population sizes of the taxon.
Modeling Earth Systems and Environment, Aug 7, 2021
Formation of the Himalaya resulted from collision of the Indian and the Eurasian plates around th... more Formation of the Himalaya resulted from collision of the Indian and the Eurasian plates around the early Cenozoic (55–45 million years ago). Various geo-physical changes, namely disappearance of Tethys Sea, formation of land bridges and evolution of monsoon system followed the collision. These changes are cumulatively responsible for high plant endemism in the Himalaya. Here, we show that the high plant endemism in the Himalaya is likely linked to changes in geology, geomorphology and climate during the past millions of years. We used phylogenetic supertrees and ancestral area reconstructions to investigate the rates and biogeographic source areas of the Himalayan endemic plant species assembly through different geological time periods. Our results show that Eastern Himalaya (EH) harbors twice the number of plant endemics than the Western Himalaya (WH). The time-calibrated phylogenies revealed that maximum endemic diversifications of plant families in both the EH and WH occurred during 35–20 million years ago (Oligocene–Miocene), the period that coincided with evolution of the South West Asian monsoon. Further, the majority of plant endemics in the EH have ancestral lineages from South East Asian and Sino-Japanese regions. The WH endemic taxa have ancestor lineages from Southeast Chinese, Sino-Japanese, Irano–Turanian, and Central Asiatic regions. The high endemic plant diversity in the Himalaya is a result of immigration of ancestral lineages from the neighboring regions followed by their local radiations and diversifications after the formation and intensification of monsoon system.
Modeling Earth Systems and Environment, Jun 1, 2016
That the Himalaya are warming at much higher rates than the global average is known. Here, we ass... more That the Himalaya are warming at much higher rates than the global average is known. Here, we assess the future potential distribution of major plant communities in Sikkim Himalaya due to climate change using field observations and maximum entropy modelling approach. We collected data on presence and elevational distribution ranges of 584 endemic angiosperm species during field surveys at 121 sampling locations using 625 study plots and along an elevational gradient of 300-5,300 m. This field data was supplemented by already published records. Endemic species were classified into different growth forms, viz. trees, climbers, shrubs, and herbs. A total of 37,376 different species distribution models (SDMs) were built using climate projections available from 8 different general circulation models and 4 representative concentration pathways. SDMs were built for current climate (average climate for 1950-2000), 2050 (average climate for 2041-2060), and 2070 (average climate for 2061-2080). We found that about 16 and 18 % of endemic angiosperm species are likely to lose their potential habitat by 2050 and 2070, respectively. Meadows may likely lose about 1 and 3 % of their current geographical spread to shrublands by 2050 and 2070, respectively. Weak and insignificant values of phylogenetic signal among the growth forms indicated that climate-induced impacts were spread across the phylogenies. We report significant increase in the habitable areas of shrubs and their northward expansion, gradually replacing the herbaceous communities. This change can alter the structure and function of the Himalayan highland ecosystems besides depleting bioresource base and endangering the local livelihoods.
Some sort of standdown will happen-and conservation should come into the discussions." Conservati... more Some sort of standdown will happen-and conservation should come into the discussions." Conservation could be part of the toolkit for diplomacy between China and India.
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Papers by Maharaj Pandit