Ecological Indicators (Sep 2024)
Advanced precipitation enhances vegetation primary productivity in Central Asia
Abstract
Climate change is reshaping the seasonal distribution of precipitation patterns across Central Asia, affecting not only the total accumulation but also the timing of precipitation events. However, how seasonal precipitation timing (i.e., precipitation seasonality) shift and may influence dryland ecosystem responses have rarely been considered. Here we utilized gross primary productivity (GPP) data derived from satellite observations over 2001–2022 and a proxy of precipitation timing (precipitation center time index, PCT) to elucidate changes in precipitation timing and assess its impact on vegetation productivity along bioclimate gradients in Central Asia. Our findings revealed that, from southwest to northeast, the precipitation season gradually extended from spring (PCT ≤ 5.0) to summer (PCT ≥ 6.0). Notably, approximately 74.4 % of the study area exhibited a trend of advanced precipitation, particularly evident in regions characterized by earlier precipitation onset. Changes in precipitation timing were found to induce variations in vegetation productivity, albeit with spatial heterogeneity. About 82.0 % of the vegetated areas showed positive GPP anomalies with advanced precipitation, especially in the eastern drylands, while delayed precipitation depressed productivity, leading to negative GPP anomalies in nearly 65.9 % of the vegetation zones. Vegetation in arid regions demonstrated heightened susceptibility to altered precipitation timing, whereas this sensitivity diminished in humid regions characterized by greater moisture availability. More precipitation distributed in early growing season would be more favorable to increase GPP, especially in xeric sparse vegetation, grassland, rained cropland, and shrubland. Our study highlight that it is necessary to pay more attention to the effects of altered precipitation timing on changes in terrestrial ecosystem productivity related to carbon cycle, especially in dryland.
