气候干旱化背景下云南地区生态系统脆弱性的变化特征

Variation of ecosystem vulnerability under the background of climate aridity change in Yunnan Variation

基于CASA模型模拟云南省1982—2019年植被NPP,根据IPCC脆弱性框架分析其生态脆弱性时空变化特征,并结合标准化蒸散指数(SPEI)探讨干旱对生态脆弱性的影响。结果表明:近38年研究区生态脆弱性总体呈波动上升趋势,增长比例最为明显的是极度脆弱区,面积比例增加了2.7%;生态脆弱性空间分布差异较大,以轻度与中度脆弱区为主(85%);重度与极度脆弱区占比较少,主要分布在横断山区以及高山峡谷区域;大部分地区(53%)生态脆弱性与干旱呈正相关,随干旱等级增大,生态脆弱性增大,其中呈显著正相关的区域(面积占比15%)主要集中在横断山区、高山峡谷地带,受干旱影响显著;随干旱频率上升,轻度与中度脆弱区比例增加显著;热带森林植被生态脆弱性整体上最高,但受干旱的持续性影响不显著;持续性干旱对亚热带森林、灌丛、草地与高山植被的生态脆弱性有较显著的影响。

Based on the CASA model, NPP of vegetation in Yunnan province from 1982 to 2019 was simulated. The spatio-temporal variation characteristics of ecological vulnerability were analyzed according to the IPCC vulnerability framework,and the impacts of drought on ecological vulnerability were discussed in combination with the standardized evapotranspiration index(SPEI). The results showed that in the past 38 years, the overall ecological vulnerability of the study area fluctuated and increased, and and the area proportion of extremely vulnerable area increased by 2.7% by 2.7%. The spatial distribution of ecological vulnerability was significantly different, mainly in mild and moderate vulnerable areas(85%). Severe and extremely vulnerable areas were less, mainly distributed in Hengduan mountain area and alpine canyon area. In most areas(53%), the ecological vulnerability was positively correlated with drought, and the ecological vulnerability increased with the increase of drought level. The areas with a significant positive correlation(15%) were mainly concentrated in the Hengduan mountain area and the alpine vegetation area, which were significantly affected by drought. With the increase of drought frequency, the proportion of mild and moderate vulnerable areas increased significantly. The ecological vulnerability of tropical forest vegetation was the highest on the whole, but it was not significantly affected by the persistence of drought. Persistent drought has a significant impact on the ecological vulnerability of subtropical forests, shrubs, grasslands and alpine vegetation.