挠力河流域湿地景观演变的累积效应

Analysis on cumulative effects of wetland landscape changes in Naoli River Watershed

基于累积效应方法和原理,利用遥感和GIS技术,分析了挠力河流域湿地景观时空演变过程及其产生的累积效应。结果显示,该流域湿地景观变化是人类土地开发活动不断叠加、影响强度和空间范围不断扩大的结果。产生的直接累积效应包括湿地景观面积丧失、景观结构破碎化、水文情势变化和生态系统退化;间接的累积效应主要包括生物多样性下降和区域气候趋暖变干。目前,挠力河流域湿地景观变化已经超过了阈值条件,累积效应达到了极为显著的程度。其中,湿地景观多样性趋于丧失,植物物种多样性发生显著变化,某些珍稀水禽种群数量显著下降,有些保护物种已经消失,流域湿地生态正面临极为严重的形势。

Research on the changing process of landscape in a longer spatial and temporal scale is one of the loci of landscape ecology in recent years. Furthermore, identifying cumulative effects caused by landscape changes is very important for environmental impact evaluation. The Naoli River Watershed was chosen as a study area, and our study focused on wetland landscape changing processes and their cumulative effects in historical periods. We use remote sensing, GIS techniques and geographical statistics regression for data analysis in this paper. The Naoli River watershed, characterized by rich wetland landscape and great changes in biodiversities in the Sanjiang Plain, China, has attracted global concern in recent years. Wetland landscape was in a very natural state before 1949, which was very rich in landscape types in the study area. And wetland landscape change experienced a process from the preliminary land reclamation phase （1945-1967） to an intermediate land reclamation phase （1967- 1983） and then a near-term reclamation phase （ 1983 - 2002）. As a result, wetland landscape changed in the study area. The direct and indirect cumulative effects were identified by analyzing the changing process of landscape types in the three large-scale land reclamation phases, as well as the impact of human activities on the scope and intensity of wetland landscapes in the watershed. The direct cumulative effects include loss of wetland landscape area, fragmentation of landscape structure and degradation of wetland ecosystem; the indirect cumulative effects caused by wetland landscape change include biodiversity change, hydrological regime change and local climate change in the watershed. At present, the diversity change of wetland landscape has gone over threshold condition. This phenomenon will bound to have great impacts on the regional ecological environment and economic sustainable development in the watershed.