Abstract：
Vegetation makes an outstanding contribution to the stability of ecosystems and to a certain extent reflects the state of the terrestrial ecosystem. Drought conditions greatly affect the growth and development process of vegetation due to its remarkable stochasticity and complexity. Due to the complex coupling mechanism between vegetation and drought, the research on vegetation drought risk is still limited. In this work, we focus on Northwest China and use the improved vegetation health index (VHI) and other multi-source data. We selected indicator factors based on both hazard and vulnerability, and adopt three weight determination methods, namely entropy method, critic method, and coefficient of variation method, to construct the corresponding index model, and also to establish a vegetation drought risk assessment model to quantitatively evaluate the drought risk of vegetation in northwest China. Results show that the percentage of each drought category remarkably changed during the period encompassing 1981-2020, and the vegetation drought shows deterioration in more areas of northwest China. The vegetation drought risks derived from the three weight determination methods were generally consistent, but differed for a particular vegetation type. The overall spatial distribution pattern of vegetation drought risk in Northwest China is higher in the west and lower in the east, and the vegetation in southern Qinghai and northwestern Xinjiang presents higher drought risk. This study may be used as a tool to provide quantitative basis for vegetation protection and vegetation drought management.
摘要：
植被对生态系统的稳定做出了突出贡献，在一定程度上反映了陆地生态系统的状况。干旱条件因其显著的随机性和复杂性而极大地影响着植被的生长发育过程。由于植被与干旱之间复杂的耦合机制,关于植被干旱风险的研究还很有限。在这项工作中,我们将重点放在西北地区，并使用改进的植被健康指数（VHI）和其他多源数据。我们选择了基于危险和脆弱性的指标因素，并采用三种重量测定方法，即熵值法，批评方法,和变异系数法，构建相应的指数模型，建立植被干旱风险评价模型,对西北地区植被干旱风险进行定量评价。结果表明，在1981-2020年期间，每种干旱类别的百分比都发生了显着变化，并且西北地区更多地区的植被干旱显示出恶化。三种权重确定方法得出的植被干旱风险基本一致，但对于特定的植被类型不同。西北地区植被干旱风险总体空间分布格局,西部较高,东部较低,青海南部和新疆西北部的植被具有较高的干旱风险。该研究可为植被保护和植被干旱管理提供定量依据。
