2004—2013年珠江流域植被变化及其胁迫分析

Analysis of vegetation variation and stress factors in the Pearl River Basin from 2004 to 2013

植被对区域气候调节、水文循环等有着重要作用,在近年来中国南部地区极端气候频发的背景下,研究植被变化及胁迫意义重大。以珠江流域为研究区,利用MODIS EVI分析了植被的变化规律,并通过美国军事气象卫星DMSP灯光数据和气象数据探讨分析了人类活动和自然环境对植被变化的胁迫。结果显示:2004年到2013年期间珠江流域内年平均EVI介于0.33—0.38之间,EVI从高到底依次是常绿阔叶林>混交林>多树的草地>常绿针叶林>草地,不同植被类型的EVI变化趋势基本一致,同一植被类型EVI年际变化较小,其中混交林和草地年际最大变化量分别为0.07和0.04,而常绿阔叶林、常绿针叶林和多树的草地年际最大变化量均为0.06;在2004年至2013年年间,城市化水平增长了约71%,其年发展变化与EVI的年变化趋势相反;通过对比分析发现珠江流域人类活动对植被变化影响高于自然环境,即DMSP灯光变化与EVI变化的相关系数明显高于气温和降水。

In recent years, extreme weather events have happened frequently in the south of China, especially with the frequent occurrence of droughts. Vegetation is an important environmental factor, which is a comprehensive reflection of human activities and the natural environment. In this study, we selected the Pearl River Basin as a study area, using MODIS Enhanced Vegetation Index data, and analyzed the vegetation changes resulting from human activity and natural environment. Where human activities are present, our analysis mainly used DMSP data from the United States military meteorological satellite to analyze light data changes from 2004 to 2013. Natural environments were analyzed mainly by meteorological stations; the main parameters analyzed included mean daily temperature and precipitation. The results show that in the Pearl River Basin, the yearly average Enhanced Vegetation Index was between 0.33 to 0.38 during 2004 to 2013, the order of Enhanced Vegetation Index was as follows： evergreen broad-leaved forest 〉 mixed forest 〉 woody savannas 〉 evergreen coniferous forest 〉 grassland. In addition, during this period, the level of urbanization increased by approximately 71%, and the changes in urban development trends were opposite to those of Enhanced Vegetation Index. Thus, the results of this study showed that human activity is the major stress factor causing vegetation changes in the Pearl River Basin and that the natural environment is not dominant.