Maharaj Krishan Pandit
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uspmah@nus.edu.sg
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Publication Unreported yet massive deforestation driving loss of endemic biodiversity in Indian Himalaya(2007-01) Pandit, M.K.; Sodhi, N.S.; Koh, L.P.; Bhaskar, A.; Brook, B.W.; UNIVERSITY SCHOLARS PROGRAMME; BIOLOGICAL SCIENCESDeforestation is a primary driver of biotic extinctions in the tropics. The impacts of deforestation in tropical biodiversity hotspots are of particular concern because these regions contain high concentrations of globally endemic species. However, the effects of large-scale deforestation on native biotas within the biodiversity hotspot of Himalaya remain poorly documented. Here we report on an alarming trend of deforestation in the Indian Himalaya and project the likely consequential extinctions of endemic taxa (species and subspecies) by 2100 across a broad range of taxonomic groups, including gymnosperms, angiosperms, fishes, amphibians, reptiles, birds, and mammals. With the current level of deforestation, by 2100 only about 10% of the land area of the Indian Himalaya will be covered by dense forest (>40% canopy cover)-a scenario in which almost a quarter of the endemic species could be wiped out, including 366 endemic vascular plant taxa and 35 endemic vertebrate taxa. We also show that inaccurate reporting of forest cover data by governmental institutions can result in underestimations of the biological impacts of deforestation, as well as potential miscalculations in land-use decisions (e.g., the construction of hydroelectric dams). Large-scale conservation efforts, including forest protection and reforestation, are urgently needed to avoid the impending deforestation-driven biodiversity losses in the Himalaya. © 2006 Springer Science+Business Media B.V.Publication Potential Effects of Ongoing and Proposed Hydropower Development on Terrestrial Biological Diversity in the Indian Himalaya(2012-12) Pandit, M.K.; Grumbine, R.E.; UNIVERSITY SCHOLARS PROGRAMMEIndian Himalayan basins are earmarked for widespread dam building, but aggregate effects of these dams on terrestrial ecosystems are unknown. We mapped distribution of 292 dams (under construction and proposed) and projected effects of these dams on terrestrial ecosystems under different scenarios of land-cover loss. We analyzed land-cover data of the Himalayan valleys, where dams are located. We estimated dam density on fifth- through seventh-order rivers and compared these estimates with current global figures. We used a species-area relation model (SAR) to predict short- and long-term species extinctions driven by deforestation. We used scatter plots and correlation studies to analyze distribution patterns of species and dams and to reveal potential overlap between species-rich areas and dam sites. We investigated effects of disturbance on community structure of undisturbed forests. Nearly 90% of Indian Himalayan valleys would be affected by dam building and 27% of these dams would affect dense forests. Our model projected that 54,117 ha of forests would be submerged and 114,361 ha would be damaged by dam-related activities. A dam density of 0.3247/1000 km2 would be nearly 62 times greater than current average global figures; the average of 1 dam for every 32 km of river channel would be 1.5 times higher than figures reported for U.S. rivers. Our results show that most dams would be located in species-rich areas of the Himalaya. The SAR model projected that by 2025, deforestation due to dam building would likely result in extinction of 22 angiosperm and 7 vertebrate taxa. Disturbance due to dam building would likely reduce tree species richness by 35%, tree density by 42%, and tree basal cover by 30% in dense forests. These results, combined with relatively weak national environmental impact assessment and implementation, point toward significant loss of species if all proposed dams in the Indian Himalaya are constructed. ©2012 Society for Conservation Biology.Publication Climatic imprints in Quaternary valley fill deposits of the middle Teesta valley, Sikkim Himalaya(2007-01) Meetei, L.I.; Pattanayak, S.K.; Bhaskar, A.; Pandit, M.K.; Tandon, S.K.; UNIVERSITY SCHOLARS PROGRAMMEQuaternary alluvial sediments occur as distinct terrace and fan deposits in the middle Teesta valley in the belt between the Main Central Thrust and the Main Boundary Thrust in the Sikkim Himalaya. These sequences are characterized by lithofacies deposited by braided river channels, debris flows and hyperconcentrated flows. The channel flow deposits constitute relatively well sorted, well imbricated and clast-supported gravels with coarse to medium sand matrix. Mostly poorly sorted, weakly imbricated to disorganized matrix supported pebble to boulder gravels with silty sand represent debris flow deposits. Hyperconcentrated flow deposits consist of clast-supported, poorly developed sorted polymodal gravel facies with poorly developed imbricated fabric, and generally occupy the lower parts of the terrace and fan sequences. The alternation from hyperconcentrated flow to channel flow deposits is predominant in the sequence, and is possibly the response to different climate modes. The high discharge and supply of sediments as well as the dispersal and deposition of these materials in the trunk stream is attributed to millennial-multimillennial climatic perturbations during the Quaternary. Climate change has a dominant role in the valley aggradation and incision cycle. © 2006 Elsevier Ltd and INQUA.Publication Polyploidy in invasive plant species of Singapore(2006-07) Pandit, M.K.; Tan, H.T.W.; Bisht, M.S.; UNIVERSITY SCHOLARS PROGRAMME; BIOLOGICAL SCIENCESSingapore is a recognized global hotspot for invasive species and many introduced plant species have become major weeds there. Some of the common invasive taxa, such as Asystasia gangetica ssp. micrantha, Mimosa pigra, Neptunia plena, Panicum maximum, and Urochloa mutica, are spread over large areas and dominate the indigenous flora in some habitats. In a study aimed at understanding the relationship between polyploidy and invasiveness, we show that all the investigated invasive taxa are polyploids. A. gangetica ssp. micrantha, N. plena, and P. maximum vary in chromosome number and ploidy level across the world, but we recorded only one chromosome count for each of these species in Singapore. Similarly, the cytology of M. pigra and U. mutica also revealed that these species are polyploid, each with only one chromosome number across all populations. The results indicate that one polyploid line in each of these species has been selected favourably and has become invasive. We also show that all the species exhibit normal male meiosis and possess high percentages of pollen fertility. Based on the present study and an analysis of previously reported ploidy levels, we suggest that these taxa are probably of allopolyploid origin. We conclude that polyploidy and an effective reproductive system are a perfect mix for successful invasion by these species in Singapore. © 2006 The Linnean Society of London.Publication Climate-Induced Elevational Range Shifts and Increase in Plant Species Richness in a Himalayan Biodiversity Epicentre(2013-02-20) Telwala, Y.; Brook, B.W.; Manish, K.; Pandit, M.K.; UNIVERSITY SCHOLARS PROGRAMMEGlobal average temperature increase during the last century has induced species geographic range shifts and extinctions. Montane floras, in particular, are highly sensitive to climate change and mountains serve as suitable observation sites for tracing climate-induced biological response. The Himalaya constitute an important global biodiversity hotspot, yet studies on species' response to climate change from this region are lacking. Here we use historical (1849-50) and the recent (2007-2010) data on temperature and endemic species' elevational ranges to perform a correlative study in the two alpine valleys of Sikkim. We show that the ongoing warming in the alpine Sikkim Himalaya has transformed the plant assemblages. This study lends support to the hypothesis that changing climate is causing species distribution changes. We provide first evidence of warmer winters in the region compared to the last two centuries, with mean temperatures of the warmest and the coldest months may have increased by 0.76±0.25°C and 3.65±2°C, respectively. Warming-driven geographical range shifts were recorded in 87% of 124 endemic plant species studied in the region; upper range extensions of species have resulted in increased species richness in the upper alpine zone, compared to the 19th century. We recorded a shift of 23-998 m in species' upper elevation limit and a mean upward displacement rate of 27.53±22.04 m/decade in the present study. We infer that the present-day plant assemblages and community structure in the Himalaya is substantially different from the last century and is, therefore, in a state of flux under the impact of warming. The continued trend of warming is likely to result in ongoing elevational range contractions and eventually, species extinctions, particularly at mountaintops. © 2013 Telwala et al.Publication Continuing the search for pattern among rare plants: Are diploid species more likely to be rare?(2006-03) Pandit, M.K.; UNIVERSITY SCHOLARS PROGRAMMEQuestions: Are diploid plant species more endangered than polyploids? Does ploidy play any role in rarity and invasiveness of plant species? Data studied: I surveyed and analysed ploidy levels of more than 1000 plant species, including 75 endangered taxa and 43 invasive species, on the Indian subcontinent to test the relationship between ploidy and both rarity and invasiveness. Search method: Null hypothesis: I examined the null hypothesis that diploids and polyploids were equally represented in the sets of endangered and non-endangered/non- invasive species. Logistic regressions; I performed simple logistic regressions (logit model) of the probability of species endangerment and invasiveness on number of chromosomes. Where necessary, plant family was included as a co-factor in the regressions, to partially control for the effects of phylogenetic autocorrelation among species. Conclusions: I show that diploid plant species in the Indian subcontinent are more likely to be rare than are polyploids. The analysis revealed that the diploid-polyploid ratio for non-endangered plants of the subcontinent follows known trends (with 50.5% diploid), but that a significantly larger fraction of the endangered species (64%) are diploid. Clear polyploids comprise only 36% of the endangered species. In contrast, a significantly larger fraction of invasive species studied (72%) are polyploids, with many displaying high levels of polyploidy. The relationship between diploidy and both plant rarity and invasiveness was highly significant. I also find that, in general, plant species with more chromosomes have less likelihood of being endangered than the species with fewer chromosomes. Using a simple logistic regression (logit model), I show that phylogeny has a significant effect on species endangerment and that chromosome number is negatively and significantly correlated to the probability that a species is endangered. © 2006 M.K. Pandit.