Impacts of extreme climate change from 2000 to 2022 on net primary productivity in the Gaoligong Mountains

Global climate change has increased the frequency and intensity of extreme weather events, significantly impacting the net primary productivity (NPP) of vegetation. Understanding the relationship between NPP and extreme climate events in ecologically sensitive areas is essential for effective ecological strategies. This study analyzed the spatiotemporal distribution characteristics of net primary productivity (NPP) from 2000 to 2022 and its response to extreme climate conditions. Utilizing the flexible space-temporal DAta fusion (FSDAF), the study integrated MODIS and Landsat data from 2000 to 2022 to generate a high-resolution NDVI dataset (30 m, 16-day). The NPP was estimated using the Carnegie-Ames-Stanford approach (CASA) model. We also evaluated the effects of 13 extreme climate indices (ECIs) on NPP in the Gaoligong Mountains. The results showed that (1) annual NPP exhibited an upward trend (slope = 1.5), with the most significant increase occuring in January (slope = 0.35, p < 0.001); (2) the climate in the study area has displayed a clear warming trend, with significant increases in extreme temperature indices (TXx, TNx, TN90p, TX90p, TMAXmean, and TMINmean, p < 0.001), while extreme precipitation indices (RX1day, RX5day), showd a relatively small trend of change and not significant; (3) At the seasonal scale, the responses of NPP to ECIs varied significantly among different vegetation types. The correlations between NPP and ECIs were markedly stronger in spring and autumn than in summer and winter, with temperature-related indices showing the strongest explanatory power for variations in NPP. (4)The response of NPP to extreme temperatures and precipitation is primarily characterized by a lag effect, typically delayed by 1-2 months, and is observed across different vegetation types. (5) extreme temperatures, particularly TX90p, TXx, TMAXmean, and DTR, are the key climatic factors affecting NPP. These results offer insights into the impact of climate extremes on NPP, which can inform future ecological management strategies.