Soil moisture seasonality alters vegetation response to drought in the Mongolian Plateau

The Mongolian Plateau (MP) experienced the most severe decadal drought of the past two millennia from 2000 to 2009 and several shorter-term droughts in the 2010s. Using satellite-based near-infrared reflectance of vegetation ( NI R V ), we examined changes in vegetation productivity of the MP from 2000 to 2018. During this time, soil moisture in March ( S M Mar ) mainly determined spring NI R V , and early-summer (June and July) precipitation mainly determined summer NI R V . Our study revealed three distinct periods: the severely dry period of 2000–2009, recovery in 2010–2012, and a relatively stable period with occasional short-term droughts after 2012. While vegetation productivity experienced a significant decrease during the severe decadal drought, summer and spring productivity quickly recovered after 2010, following an increase in growing season (GS) rainfall and winter snowfall. Greater S M Mar , which resulted from previous GS precipitation, contributed to smaller declines in vegetation productivity during the short-term droughts in 2014, 2015 and 2017. The decline in vegetation productivity during the severe decadal drought damaged livestock operations in Mongolia, but had a limited effect on operations in Inner Mongolia of China, where human intervention is stronger. Given evidence that drought impacts are increasing worldwide, it is important to understand the factors determining ecosystem drought responses. Many drought studies have focused on GS precipitation, but our results show that pre-GS SM can play an important role in determining drought impacts. Our results also demonstrate that strong interventions will be needed in order to sustain livestock operations during intensifying drought.