The Landscape–Atmosphere Continuum Determines Ecological Change in Alpine Lakes of SE Tibet
Remote alpine regions were considered to be largely unimpacted by anthropogenic disturbance, but it is now clear these areas are changing rapidly. It is often difficult to identify the causal processes underpinning ecological change because the main drivers (direct and indirect climate forcing, land use change and atmospheric deposition) are acting simultaneously. In addition, alpine landscapes are morphometrically complex with strong local environmental gradients creating natural heterogeneity which acts as a variable filter to climate and anthropogenic forcing, emphasizing the need for analyzing responses at multiple sites. The eastern margin of Tibet is a hotspot of global biodiversity and is affected by both atmospheric N and dust deposition, whereas regional climate warming is comparatively recent. Here we use 210Pb and 137Cs dated sediment records from nine alpine lakes, and statistical measures of diatom ecological change (turnover and PCA axis 1 scores) to determine regional scale patterns in community response to global environmental change forcing over approximately the last 150 years. The study lakes showed contrasting ecological responses with increased nutrient input as the primary driver of change, mediated by lake morphology and catchment characteristics. Turnover rates of diatom composition, although low, are significantly associated with lake volume, lake area, altitude and DOC.
Keywordslake morphology diatom turnover rate nutrient nitrogen climate
We are grateful to all staff members who helped collect samples, and Xiayun Xiao for providing the chronology data of Tiancai Lake. This study was supported by the National Key Research and Development Program of China (2017YFA0605203) to Yang Xiangdong. National Basic Research Program of China (2015CB953804) to Hu Zhujun. Science Fund for Creative Research Groups of the National Natural Science Foundation of China (41621002) to Yang Xiangdong. N.J. Anderson acknowledges the support of a Royal Society Wolfson Merit award and the Chinese Academy of Sciences (for a visiting professorship to NIGLAS). Xiao Xiayun acknowledges support from National Science Foundation of China Grants (41572149).
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