Manish Kumar, Pandit Maharaj K, Telwala Yasmeen, Nautiyal Dinesh C, Koh Lian Pin, Tiwari Sudha
Department of Environmental Studies, University of Delhi, Delhi, 110007, India.
Centre for Interdisciplinary Studies of Mountain and Hill Environment, University of Delhi, Delhi, 110007, India.
J Plant Res. 2017 Sep;130(5):829-844. doi: 10.1007/s10265-017-0946-0. Epub 2017 Apr 25.
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.
尽管经过了数十年的研究，但生态学家们仍在争论物种丰富度的空间格局是如何在地球上的海拔梯度上形成的。这些研究结果模棱两可，可能源于研究设计、采样力度和数据分析的差异。在本研究中，我们证明了喜马拉雅东部海拔300 - 5300米梯度上2781种（2197种非特有种和584种特有种）被子植物的丰富度格局呈驼峰状，依赖于研究范围的空间尺度（所研究海拔梯度的比例）且具有特定的生长形式。在所有生长形式（乔木、灌木、藤本植物和草本植物）中，特有种的峰值海拔高于非特有种。丰富度格局受最大外貌类群（草本植物）的比例代表影响。我们表明，随着研究范围空间尺度的增加，丰富度格局从单调型转变为驼峰型，且所有生长形式的丰富度最大值都向更高海拔转移。我们的研究表明，环境能量（气温、太阳辐射和潜在蒸散）和水分可利用性（土壤含水量和降水量）的组合是喜马拉雅地区海拔梯度上植物物种丰富度格局的主要驱动因素。这项研究强调了在研究植物物种分布的海拔梯度时考虑特有性、生长形式和空间尺度的重要性，并推进了我们对宏观生态格局如何形成的理解。
