Drought Assessment on Vegetation in the Loess Plateau Using a Phenology-Based Vegetation Condition Index

Frequent droughts induced by climate warming have caused increasing impacts on the vegetation of Loess Plateau (LP). However, effects drought are highly dependent when occurs and how long it lasts during growing season. Unfortunately, most existing indices ignore differences in different growth stages. In this study, we first established a phenology-based condition index, namely weighted index (WVCI), which accounts for sensitivity to assigning specific weights phenological stages vegetation. Then, used WVCI reveal temporal spatial variations vegetative from 2001 2019 over LP aspects frequency, trend relative deviation. The results showed that (1) experienced frequent study period, but mainly mild moderate droughts. frequencies decreased southeast northwest, extreme rarely occurred mountainous areas plains. (2) tended ease, only few Hetao Plain, Ningxia Plain Fenwei an drought. (3) After 2012, departure percentage was positive, indicating above-average conditions. (4) Compared with well-established proved ability monitor assess annual scale LP. As result, our research could help develop implement drought-resistance disaster-prevention measures