不同管理主体对泸沽湖流域生态系统影响的比较分析

行政边界将自然生态系统从主观上切割为可供管理的空间单元,而人类介入一个相对完整的生态系统,会从根本上影响生态系统的格局和生态学过程,这种影响对流域生态系统更为显著。以我国西南川滇两省交界处的泸沽湖流域生态系统为例,运用对比分析法,先从不同行政尺度定性比较了流域两侧生态系统管理主体在自然、社会、经济子系统方面的差异性。再采用遥感与地理信息系统变化监测技术,定量分析流域省界两侧土地利用类型、林分结构、归一化植被指数、生态系统服务功能等关键要素上的差异,形成对流域省界两侧生态系统功能的差异性的全面认识,从而对产生生态系统功能差异的驱动力进行了分析。最后,以此为基础,有针对性的提出了泸沽湖流域综合管理的对策,以实现泸沽湖流域生态系统的可持续发展。

Comparative analysis of Lugu Lake watershed ecosystem function under different management authorities

Wide Participation and cooperation among scientists, social economists, public and government are critical to efficient natural resource management. Environmental management authorities in China are now facing challenges of constructing a comprehensive and integrated framework for protecting environment, conserving natural resources and improving ecosystem function, with administrative boundaries as a barrier. In this paper, we use comparative analysis approach and satellite change detection analysis to study Lugu Lake watershed ecosystem, which is a trans-boundary lake lying at the border of Sichuan and Yunnan province, south-west China. Four factors that may greatly influence Lugu Lake watershed ecosystem are selected and compared between Sichuan and Yunnan portion of our study area at five different scales: province, city, county, town and village. These four factors are environmental management approaches, natural environment, local society and economy. To quantitatively analyze and compare the structure and function difference of Lugu Lake watershed ecosystem between Sichuan and Yunnan portion, we build an index system based on key environmental elements, including land-cover, forest stand structure, the value of ecosystem service, normalized difference vegetation index (NDVI), and calculate their values in these tow portions of our study area. Driving force for Lugu Lake ecosystem function division is analyzed and countermeasures for trans-boundary watershed management are provided. Results showed that Lugu Lake watershed ecosystem was facing different degree of tourism pressure, agriculture pressure, public participation and environmental management approaches between Sichuan and Yunnan portion. Particularly, Lugu watershed ecosystem in Yunnan portion faces much more tourism pressure and public attention. The environmental management authorities developed more environmental-friendly regulations. The area of Lugu watershed ecosystem in Sichuan province faced more agriculture pressure. Satellite image interpretation showed that the most obvious difference in land-cover between Sichuan and Yunnan province of the study area was the forest ecosystem. In Sichuan province 71.16% of land was covered by forests, while forest covered 52.71% of land in Yunnan province. The data collected from 40 forest field plots showed that Yunnan province had more primeval forest than Sichuan province in the study area, while NDVI results showed an opposite trend in the number of areas with increasing vegetation index (28.59% in Sichuan and 25.58% in Yunnan). Although Sichuan province contributed more to the total value of Lugu Lake watershed ecosystem service in our study area (3847.05 105 yuan renminbi (RMB) for the Sichuan portion and 2637.52 105 yuan for the Yunnan portion), Yunnan exceeded Sichuan in the value per km2. No single factor was found driving ecosystem change on either side of the border. We concluded that different pressure of human activities, especially tourism pressure, environmental management consciousness, and management approaches of local environmental management authorities, such as the implement of the Regulations on Restoring Farmland to Forest, were the major causes of the change in watershed ecosystem along Sichuan and Yunnan border of our study area.