蒙古高原干旱时空特征及对植被物候的累积影响 postprint

Abstract: The Mongolian Plateau is a crucial ecological zone in northern China. The SPEIbase 2.9 dataset and the logistic curvature extremum method based on cumulative NDVI data were used to elucidate the spatiotemporal dynamics of drought and its impact on vegetation phenology in the Mongolian Plateau. The vegetation phenology dataset was inverted to explore the cumulative impact of drought on the start and end of the growing season (SOS and EOS, respectively) in the Mongolian Plateau from 1982 through 2022. Different time scales of Standardized Precipitation Evapotranspiration Index (SPEI) showed significant decreasing trends. With larger timescales, the drought degree intensified, and the area of drought increased significantly. The droughts were particularly severe in the central and western regions. Earlier and later SOS were observed in 50.03% and 49.97% of regions, respectively, and later and earlier EOS were observed in 67.85% and 32.15% of regions, respectively. Overall, SOS and EOS were delayed in the desert steppe. In contrast, the SOS occurred earlier in the coniferous forest and later in the northern part of the forest steppe. Correlation values for SPEI and SOS were maximal during a 1-12 months timescales for 79.62% of the region in the Mongolian Plateau (excluding deserts); over an intermediate-term timescale, a drought duration of 7-9 months had a significant impact on the SOS. Negative correlations between SPEI and EOS over a 1~12 months timescales were highest for 54.15% of the study area, primarily over a 1-3 months timescales. Our findings can help elucidate the factors critical for drought prevention and predict its impact on vegetation phenology and productivity in the Mongolian Plateau.