基于遥感数据的西藏高原自然生态系统脆弱性评估

Comprehensive Assessment of Natural Ecosystem Vulnerability in Tibetan Plateau Based on Satellite-derived Datasets

基于生态系统结构、功能、生境的脆弱性评价指标体系,以MODIS为基础数据源,评估了西藏高原自然生态系统的脆弱性,并揭示其空间异质性特征。结果表明:1分别基于气候、结构以及功能指标的西藏高原生态系统脆弱性程度空间分布呈现出相似规律,整体为从东南向西北脆弱性程度逐渐加剧的趋势;而基于地形指标的生态脆弱性则呈现相反的分布格局,说明了相对地形而言,气候因子对于西藏高原生态系统宏观分布状况更为重要;2综合生态系统结构、功能及气候和地形生境特征对脆弱性的影响,全区呈现从东南向西北综合脆弱性水平逐渐升高的趋势,在评估区范围内综合脆弱性等级为中等及以上的地区共占74%,整体脆弱性程度较大,其中综合脆弱性等级为很高水平的地区占了45.8%。明晰西藏高原自然生态系统的脆弱性程度及其空间分布特征,可为典型脆弱生态系统的监测和综合评估提供科学依据,进而有利于青藏地区生态环境治理工作的顺利进行。

The assessment index system was firstly of ecosystem structure-function-habitat. And then, constructed for ecosystem vulnerability from the viewpoint with MODIS satellite-derived datasets as the main data resource, this paper assessed the ecosystem vulnerability for Tibetan Plateau （TP） and detected its spatial heterogeneity. It is shown that the spatial patterns of TP ecosystem vulnerability, based on climatic factors, structural indices and functional indices, respectively, are consistent. The vulnerability degrees gradually increase from southeast to northwest of TP. However, the changing trend is opposite for topography-based vulnerability as- sessment. This indicates that compared with topography indices, including slope, relief amplitude, earth＇ s surface incision and roughness in elevation, climatic factors, such as monthly maximum temperature, monthly minimum temperature and drought severity index, are more important to determine the spatial pattern of ecosystem structure and function. Furthermore, taking the indices for ecosystem structure, function and habit （i.e. climate and topography） into account, both the comprehensive ecosystem vulnerability and its classification present the spatial characterization of increasing from southeast to northwest, similar to the above-mentioned trend. According to the spatial statistics in ArcGIS software, the classes higher than middle of ecosystem vulnerability accounts for 74% of evaluation area, while the very high class accounting for 45.8%, indicating the serious overall conditions for ecosystem vulnerability in TP. Identifying the ecosystem vulnerability degree and its spatial patterns can provide scientific basis for vulnerable ecosystem monitoring and comprehensive as- sessment, which is further helpful for ecological regulation and management in TP.