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J Plant Res ; 130(5): 829-844, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28444520


Despite decades of research, ecologists continue to debate how spatial patterns of species richness arise across elevational gradients on the Earth. The equivocal results of these studies could emanate from variations in study design, sampling effort and data analysis. In this study, we demonstrate that the richness patterns of 2,781 (2,197 non-endemic and 584 endemic) angiosperm species along an elevational gradient of 300-5,300 m in the Eastern Himalaya are hump-shaped, spatial scale of extent (the proportion of elevational gradient studied) dependent and growth form specific. Endemics peaked at higher elevations than non-endemics across all growth forms (trees, shrubs, climbers, and herbs). Richness patterns were influenced by the proportional representation of the largest physiognomic group (herbs). We show that with increasing spatial scale of extent, the richness patterns change from a monotonic to a hump-shaped pattern and richness maxima shift toward higher elevations across all growth forms. Our investigations revealed that the combination of ambient energy (air temperature, solar radiation, and potential evapo-transpiration) and water availability (soil water content and precipitation) were the main drivers of elevational plant species richness patterns in the Himalaya. This study highlights the importance of factoring in endemism, growth forms, and spatial scale when investigating elevational gradients of plant species distributions and advances our understanding of how macroecological patterns arise.

Biodiversidade , Fenômenos Fisiológicos Vegetais , Plantas , Altitude , Ecossistema , Geografia , Índia , Desenvolvimento Vegetal , Dispersão Vegetal , Temperatura Ambiente
PLoS One ; 8(2): e57103, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23437322


Global 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 19(th) 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.

Altitude , Biodiversidade , Clima , Ecossistema , Plantas , Geografia , Siquim