Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： In recent years, with global warming, the increase of drought events has a more important impact onthe photosynthesis of vegetation, and also seriously affects the balance of terrestrial ecosystems. Based on SPEIbase v.2.7 and GOSIF GPP data set, this paper studies the cumulative and time-delay effects of drought on GPP innorthern grassland. Sen’s slope test, MK trend test and Mann- Kendall mutation test were used to study thetemporal and spatial changes of GPP and SPEI during the study period. Pearson correlation analysis method wasused to explore the cumulative and time- delay effects of drought on GPP in the north grasslands. The resultsshowed that: (1) From 2001 to 2020, the annual average GPP of the northern grasslands showed a spatialdistribution pattern of high in the northeast and low in the southwest, and the annual average SPEI showed aspatial distribution pattern of low in the northeast and high in the southwest, and the annual average of SPEI andGPP showed an upward trend over time. (2) Drought has a cumulative effect on 84.99% of the northerngrassland, and the longest cumulative time scale is mainly concentrated in 3-4 months, covering 39.82% of thenorthern grassland; Drought had a lagging effect on 63.11% of the northern grassland, and mainly occurred in 7months, covering 19.73% of the northern grasslands. (3) By comparing the variation trends of drought anddrought under different water conditions, we found that the cumulative effect of drought on grassland GPP wasstronger than the time-lag effect.
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