Impact of Vegetation Leaf Area Change on Global Terrestrial Water Storage in Recent 30 Years Based on GRACE and Reconstruction Data

Abstract

Vegetation change has an important impact on land water cycle by changing transpiration and other water exchange between land and atmosphere. Terrestrial water storage (TWS) is an important component of global water cycle and freshwater resources. However, the impact of vegetation change on terrestrial water storage under the background of global climate change is still unclear. Based on the GRACE satellite observed and GRACE-REC reconstructed global terrestrial water storage data, this study investigated the impact of global vegetation leaf area change on terrestrial water storage in recent 30 years. The results show that there is a significant positive correlation between leaf area index (LAI) and terrestrial water storage in the demand-limited region. The sensitivity of TWS on LAI change is high mainly in Australia, central and southern Africa, South Asia, Mediterranean region, western United States, southern South America and other regions with high temperature and low precipitation, and the analysis of GRACE-REC shows the sensitivity in demand-limited region has an increasing trend. Compared with climate factors such as temperature and precipitation, the TWS trend caused by LAI is nearly the same, and has the same sign (all positive or all negative) as that of originally TWS in about 63.6% global land area, and the LAI-related TWS trend is high in the region with annual average precipitation of 500-1000mm. In the six different global land cover classes, the sensitivity of TWS to the LAI change is much higher in semi-arid, grass cop, sparsely vegetated regions, and LAI plays an important role in the interannual variations of TWS in semi-arid, grass cop regions. This study emphasizes the important role of vegetation change in the land water cycle, which is of great significance to the management and utilization of water resources in the future, especially in the arid and semi-arid regions.