Spatiotemporal Correlations and Drivers of Ecosystem Services and Functional Dynamics in Arid Regions

Climate stress is intensifying in many dryland regions, altering the balance between ecosystem services (ESs) and ecohydrological functioning. Here, we present an integrated framework to assess these changes, combining 4 ESs—water yield, carbon storage, food production, and habitat quality—with 3 functional indicators: precipitation-use efficiency (PUE), water-use efficiency (WUE), and the transpiration-to-evapotranspiration ratio (TET). These variables are synthesized into 2 composite indices—the combined ecosystem services assessment index (CESAI) and the ecohydrological functioning index (EFI)—to track changes, relationships, and key climatic drivers in Uzbekistan from 2000 to 2020. We find a consistently positive coupling between ES provision and ecohydrological functioning, with a clear decadal shift: Both CESAI and EFI declined in 2000–2010 and then recovered in 2011–2020. Croplands, wetlands, and shrublands contributed most to this rebound, benefiting from irrigation, groundwater recharge, or drought-tolerant traits. In contrast, forests and grasslands continued to lose both service supply and functional capacity. Rising vapor pressure deficit (VPD) and falling soil moisture emerged as the dominant climatic pressures. These findings underscore the need for differentiated ecosystem management strategies that enhance functional integrity and mitigate exposure to hydroclimatic extremes—particularly increasing aridity and soil moisture loss—thereby supporting the long-term sustainability of ESs and functioning in dryland regions.