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您的检索式：作者名="Bikram Pandey"
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| 1 | Monitoring the impact of climate change and human activities on grassland vegetation dynamics in the northeastern Qinghai-Tibet Plateau of China during 2000–2015显示文摘Climate change and human activities can influence vegetation net primary productivity(NPP), a key component of natural ecosystems. The Qinghai-Tibet Plateau of China, in spite of its significant natural and cultural values, is one of the most susceptible regions to climate change and human disturbances in the world. To assess the impact of climate change and human activities on vegetation dynamics in the grassland ecosystems of the northeastern Qinghai-Tibet Plateau, we applied a time-series trend analysis to normalized difference vegetation index(NDVI) datasets from 2000 to 2015 and compared these spatiotemporal variations with trends in climatic variables over the same time period. The constrained ordination approach(redundancy analysis) was used to determine which climatic variables or human-related factors mostly influenced the variation of NDVI. Furthermore, in order to determine whether current conservation measures and programs are effective in ecological protection and reconstruction, we divided the northeastern Qinghai-Tibet Plateau into two parts: the Three-River Headwater conservation area(TRH zone) in the south and the non-conservation area(NTRH zone) in the north. The results indicated an overall(73.32%) increasing trend of vegetation NPP in grasslands throughout the study area. During the period 2000–2015, NDVI in the TRH and NTRH zones increased at the rates of 0.0015/a and 0.0020/a, respectively. Specifically, precipitation accounted for 9.2% of the total variation in NDVI, while temperature accounted for 13.4%. In addition, variation in vegetation NPP of grasslands responded not only to long-and short-term changes in climate, as conceptualized in non-equilibrium theory, but also to the impact of human activities and their associated perturbations. The redundancy analysis successfully separated the relative contributions of climate change and human activities, of which village population and agricultural gross domestic product were the two most important contributors to the NDVI changes, explaining 17.8% and 17.1% of the total variation of NDVI(with the total contribution >30.0%), respectively. The total contribution percentages of climate change and human activities to the NDVI variation were 27.5% and 34.9%, respectively, in the northeastern Qinghai-Tibet Plateau. Finally, our study shows that the grassland restoration in the study area was enhanced by protection measures and programs in the TRH zone, which explained 7.6% of the total variation in NDVI. | XIONG Qinli XIAO Yang Marwa Waseem A HALMY Mohammed A DAKHIL LIANG Pinghan LIU Chenggang ZHANG Lin Bikram PANDEY PAN Kaiwen Sameh B EL KAFRAWAY CHEN Jun | 2019 | Journal of Arid Land2019，11，5： | 10 |
| 2 | Current climate overrides past climate change in explaining multi-site beta diversity of Lauraceae species in China显示文摘Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauraceae and to analyse their relationships to current climate and past climate change.Methods:We used ensembles of small models(ESMs)to map the current distributions of 353 Lauraceae species in China and calculated β_(sor) and its β_(sim) and β_(sne) components.We tested the relationship between β_(sor),β_(sne) and β_(sim) with current climate and past climate change related predictors using a series of simultaneous autoregressive(SAR_(err))models.Results:Spatial distribution of β_(sor)of Lauraceae is positively correlated with latitude,showing an inverse rela-tionship to the latitudinalα-diversity(species richness)gradient.High β_(sor) occurs at the boundaries of the warm temperate and subtropical zones and at the Qinghai-Tibet Plateau due to high β_(sne).The optimized SAR_(err) model explainsβ_(sor) andβ_(sne) well,but notβ_(sim).Current mean annual temperature determinesβ_(sor) and β_(sne) of Lauraceae more than anomalies and velocities of temperature or precipitation since the Last Glacial Maximum.Conclusions:Current low temperatures and high climatic heterogeneity are the main factors explaining the high multi-siteβ-diversity of Lauraceae.In contrast to analyses of the β-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers of β-diversity of evolutionarily more narrowly defined entities. | Ziyan Liao Youhua Chen Kaiwen Pan Mohammed A.Dakhil Kexin Lin Xianglin Tian Fengying Zhang Xiaogang Wu Bikram Pandey Bin Wang Niklaus E.Zimmermann Lin Zhang Michael P.Nobis | 2022 | Forest Ecosystems2022，9，2： | 1 |
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