2001—2013年若尔盖地区植被退化的时空格局分析

Spatio-temporal Analyses of Vegetation Degradation Patterns in Zoige from 2001 to 2013

为了解若尔盖地区生态变化的过程,利用2001—2013年的MODIS-NDVI数据,以植被覆盖度为指标监测若尔盖地区植被退化过程,采用主成分分析方法筛选景观指数分析了植被退化格局的时空特征。结果表明:近年来研究区植被退化以2008年为节点分为2个阶段,第1阶段退化范围逐年扩大,第2阶段局部地区退化得到控制但整体退化加重;PD,AI和FRAC_AM指数揭示了研究区植被退化格局破碎度增大的过程,第1阶段较低退化程度的斑块密度不断增大,第2阶段较重退化程度的斑块持续侵入并相连成片。虽然该区生态环境治理已取得一定的效果,但生态恶化的趋势并未得到根本遏制,且植被退化主要发生在北部地区。

To understand the process of ecological change in Zoige, the vegetation degradation information was obtained based on vegetation coverage using MODIS-NDVI data from 2001 to 2013. The dynamics of vegetation degradation patterns were disclosed by landscape metrics screened by principle component analy- sis （PCA）. The results showed that vegetation degradation in Zoige could be typically divided into two phases when taking 2008 as a point. The first was characterized by expanding year after year, while the second by the degradation partially controlled in some area but entirely aggravated. The indices of PD, AI and FRAC_AM revealed the different fragmentation processes of vegetation degradation pattern. The ten- der vegetation degradation patches increased gradually in the first stage, while heavy degradation patches invaded and was joined in the second stage. Although some results had been obtained by regional ecological environment management, the trend of the ecological deterioration had not fundamentally been restrained. Vegetation degradation occurred mainly in the north.