The Landscape–Atmosphere Continuum Determines Ecological Change in Alpine Lakes of SE Tibet

• Published in: Ecosystems (New York) 2018-08, Vol.21 (5), p.839-851
• Main Authors: Hu, Zhujun, Yang, Xiangdong, Anderson, Nicholas John, Li, Yanling
• Format: Article
• Language: English
• Subjects: Alpine ecosystems; Alpine regions; Anthropogenic factors; Atmospheric pollution deposition; Biodiversity; Biomedical and Life Sciences; Cesium 137; Cesium isotopes; Cesium radioisotopes; Climate; Climate change; Deposition; Ecological effects; Ecological monitoring; Ecology; Environmental changes; Environmental gradient; Environmental Management; Geoecology/Natural Processes; Global warming; Heterogeneity; Hydrology/Water Resources; Lake morphology; Lakes; Land use; Landscape; Lead isotopes; Life Sciences; Morphology; Mountain lakes; Original Articles; Physical characteristics; Plant Sciences; Sediments (Geology); Zoology
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-017-0187-z

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.