基于植被指数开展汉江流域生态恢复力评估研究

基于2001—2020年各年度增强型植被指数（enhanced vegetation index, EVI）数据，分析汉江流域植被覆盖变化情况，并计算汉江流域15万个1 km×1 km基本单元的2001—2010年、2001—2011年、2001—2012年直至2001—2020年的EVI变化斜率，采用指数衰减方法拟合EVI变化斜率维持正、负趋势的时间，分析汉江全流域以及564个子流域的系统恢复力，评估生态系统稳定性以及可持续发展程度。结果表明：2001—2020年，汉江流域EVI增长了12.3%，流域植被覆盖情况在逐渐变好；汉江流域整体生态恢复力较好，拟合得出维持正趋势的基本单元与维持负趋势的基本单元衰减时间差为65.3年；汉江流域生态恢复力总体上呈现上游高、中下游低的分布特征。

Evaluation of ecological resilience of Hanjiang River Basin based on vegetation index

Based on the Enhanced Vegetation Index (EVI) data of each year from 2001 to 2020, the change of vegetation cover in the Hanjiang River Basin was analyzed, and the slope of EVI change of 150000 1 km×1 km basic units was calculated in 2001-2010, 2001-2011, 2001-2012 and 2001-2020 in the Han River Basin. The exponential decay method was used to fit the time when the change slope of EVI maintained a positive and negative trend, and the ecological resilience of the whole Hanjiang River Basin and 564 sub-basins was analyzed to evaluate the stability and sustainable development level of the ecosystem. The results showed that the EVI value of Hanjiang River Basin increased by 12.3% from 2001 to 2020, and the vegetation coverage of Hanjiang River Basin was getting better year by year. The overall ecological resilience of Hanjiang River Basin was good, and the decay time difference between the grid with a positive trend and the grid with a negative trend was 65.3 years. The ecological resilience of Hanjiang River Basin generally presented the distribution characteristics of high in the upper reaches and low in the middle and lower reaches.