Multiscale Spatiotemporal Variations of Ecosystem Water Limitation and Its Divergent Drivers on the Tibetan Plateau

ABSTRACT

Ecosystem functions are profoundly influenced by changes in moisture and heat conditions. Previous research predominantly focused on water‐energy limitations on the Tibetan Plateau (TP) using moisture indicators, which often ignored the critical role of energy factors, and study examining water or energy limitation regimes from an ecosystem perspective remains scarce. In this study, we employed the ecosystem limitation index ( ELI ), which comprehensively assesses how ecosystem functional processes respond to both water and energy constraints from multiple source data, to evaluate the spatiotemporal variations of ecosystem water limitation across the TP from 1986 to 2018, and the dominant drivers behind the changes were also investigated. A widespread decrease in ecosystem water limitation across the TP was found during 1986–2018, whereas decreased ELI was observed in 54.1% of the total area, and regions with water‐limited regimes exhibited a downward trend. Three dominant ecosystems, including alpine grasslands, alpine meadows and alpine deserts, showed decreases in ELI , whereas other ecosystems exhibited upward trends. At the grid scale, ELI variation in 28.4% of the total area was primarily driven by rising temperatures, followed by changes in precipitation in 23.6% of the total area. At the ecosystem scale, water and vegetation growth collectively explained over 50% of the ELI variation across all ecosystems. These findings provide insights into the ecosystem water‐energy shift regime on the TP, thus improving our understanding of the carbon cycle change on the TP.