Land‐Atmosphere Drivers of Landscape‐Scale Plant Water Content Loss

Abstract

©2020. The Authors. Plant water content observations using microwave remote sensing measurements allow monitoring of landscape-scale plant water stress. During soil drying following rainfall events, we use a Granger causality framework to quantify the degree to which environmental factors drive satellite-based plant water content loss across Africa's diverse biomes. After soil drying into the water-limited regime, satellite observations show that plants dry while solar radiation, vapor pressure deficit, and diurnal temperature amplitude increase. We find that soil drying primarily drives plant water content loss across African drylands, though with regional effects of diurnal temperature amplitude increases (found to indicate vapor pressure deficit increases here). We also detect interactions between these factors that reinforce plant drying during periods of soil moisture loss. Our results provide observational evidence across Africa that individual and interactive components of surface drying and heating can all drive plant water stress, especially during intermittent poststorm drying periods.