基于MODIS遥感数据的福建植被生产力时空分布与干旱响应分析OA北大核心CSTPCD

Global warming has intensified drought occurrences,but their impacts on ecosystem carbon cycle remain unclear.This study analyzes the spatio-temporal variations of Gross Primary Productivity(GPP)and Net Primary Productivity(NPP)in Fujian Province from 2001 to 2021 using MODIS data.We employed Sen's trend analysis,the Mann-Kendall test,Pearson's correlation analysis and other methods to assess drought's influence on vegetation productivity anomalies.Additionally,we explored cumulative and lagged effects of drought events.The results showed that:1)Annual average GPP and NPP exhibited a"high southeast,low northwest"pattern,with regional differences of 37.4%and 65.1%,respectively.Nearly 80.8%of the region showed an increasing GPP trend,concentrated in southern and southeastern agricultural lands and fruit plantations.Conversely,NPP showed a downward trend in over 59.7%of areas,mainly in central and inland mountainous evergreen broad-leaved forests and savannas.2)Vegetation GPP exhibited significant year-to-year fluctuations with a weak overall upward trend(4.86 g∙m-2∙a-2[in terms of carbon,the same below],p=0.130).However,pronounced annual increases exceeding 15 g∙m-2∙a-2 occurred in 6.7%of the regions.NPP showed a weak declining trend(-1.05 g∙m-2∙a-2,p=0.396),with annual decreases exceeding 6 g∙m-2∙a-2 in 4.9%of the regions.3)Moderate drought(52.5%)was the dominant type during the study period,followed by light drought(34.0%).A significant negative correlation existed between the standardized anomaly indices of GPP and NPP and the drought index(SPEI),with the correlation coefficients(r)-0.624(p=0.002)and-0.531(p=0.013),respectively.This implies higher GPP and NPP during severe droughts and lower values during light drought years or no drought years.The most pronounced GPP response to drought occurred in the drought month with a short cumulative/lagging effect.The initial drought stage exhibited an increasing GPP trend,but this growth weakened and even reversed with prolonged drought.