UI '93 programme

Abstract

Due to global warming, climate extremes are increasing significantly, which is greatly impacting ecosystems dynamics. Identified as a key ecological area, southwest China (SWC) has experienced frequent extreme climatic events. Using daily meteorological data and Moderate-Resolution Imaging Spectroradiometer data, we analyzed the spatiotemporal variations of 21 extreme climate indices (ECIs) and 3 ecosystem metrics, namely, normalized difference vegetation index (NDVI), leaf area index (LAI), and gross primary production (GPP), as well as the responses of these metrics to ECIs during 2000–2018. Our results showed that the regionally averaged NDVI, LAI, and GPP increased significantly in this period with annual rates of 0.003, 0.04 m2 m−2, and 10.58 g C m−2, respectively (P < 0.001). Cold-related ECIs and consecutive wet days decreased, while warm-related ECIs, heavy precipitation days, and extreme precipitation intensity displayed the opposite trend. The sums (22.48%, 12.98%, and 32.70%, respectively) of the relative contribution proportions of the sensitive temperature-related ECIs (T-ECIs) to NDVI, LAI, and GPP were higher than that those (14.60%, 12.75%, and 16.37%, respectively) of the sensitive precipitation-related ECIs (P-ECIs). Ecosystem metrics were significantly correlated with most ECIs with time lags of 2–3-month. The correlation coefficients between large-scale atmospheric circulation indices and T-ECIs were significant (P < 0.05). The Atlantic Multidecadal Oscillation had a greater influence on T-ECIs than any other large-scale climatic oscillations. Our study indicated that T-ECIs had a greater impact on ecosystems than P-ECIs in SWC and that more attention should be paid to increasingly heavy precipitation and extreme high temperatures in the region.