Global patterns of water storage in the rooting zones of vegetation

The rooting-zone water-storage capacity—the amount of water accessible to plants—controls the sensitivity of land–atmosphere exchange of water and carbon during dry periods. How the rooting-zone water-storage capacity varies spatially is largely unknown and not directly observable. Here we estimate rooting-zone water-storage capacity globally from the relationship between remotely sensed vegetation activity, measured by combining evapotranspiration, sun-induced fuorescence and radiation estimates, and the cumulative water defcit calculated from daily time series of precipitation and evapotranspiration. Our fndings indicate plant-available water stores that exceed the storage capacity of 2-m-deep soils across 37% of Earth’s vegetated surface. We fnd that biome-level variations of rooting-zone water-storage capacities correlate with observed rooting-zone depth distributions and refect the infuence of hydroclimate, as measured by the magnitude of annual cumulative water-defcit extremes. Smaller-scale variations are linked to topography and land use. Our fndings document large spatial variations in the efective root-zone water-storage capacity and illustrate a tight link among the climatology of water defcits, rooting depth of vegetation and its sensitivity to water stress.
Nature Geoscience, 16 (3)
ISSN:1752-0908
ISSN:1752-0894