Soil properties regulating water constraint by dominating ecosystem water demand in water-limited ecosystems

Abstract

Abstract The influence of soil properties on soil water uptake and usage by vegetation remains inadequately understood. Prior studies predominantly correlated soil properties with wilting points and field water capacity; however, our novel framework investigates how soil properties drive ecosystem-level constraints on vegetation growth through soil water. In this study, a new paradigm was introduced for understanding the relationship between vegetation growth and soil moisture, characterized by a critical soil moisture threshold that delineates the transition of vegetation into a moisture-limited state. This threshold declines sufficiently with soil desiccation. Our results highlight the pivotal role of soil properties in modulating this critical soil moisture threshold to meet the water demands of vegetation growth at the ecosystem-level. Globally, the regulation by soil properties ranges on the critical soil moisture threshold ranges from −0.18 cm3/cm3 to +0.16 cm3/cm3. The positive effect of soil properties in lowering this threshold for vegetation water demand significantly mitigated water constraints, thereby enhancing the vegetation growth. Notably, sandy soil textures were found to positively affect the lowering of critical soil moisture threshold in water-limited ecosystems. Our study provides valuable insights into the intricate role of soil properties in shaping global vegetation growth and proposes a new conceptual framework for their incorporation into the earth system models.