黄河流域植被总初级生产力对持续性干旱水分亏缺的响应

Response of gross primary productivity of vegetation to persistent drought-induced water deficit in the Yellow River Basin

利用植被总初级生产力和高精度分层土壤含水量数据分析了2001—2020年黄河流域生长季总初级生产力时空分布和变化特征,量化了流域不同深度土壤湿度之间的相关关系,探究了不同植被类型在生长季的总初级生产力对土壤连续水分亏缺事件的响应关系。结果表明:黄河流域总初级生产力空间上呈东高西低、南高北低的分布特征,生长季耕地累积总初级生产力最大、林地次之、草地最小,研究期内流域总初级生产力整体呈上升趋势,耕地相对增速最大、草地次之、林地最小;流域土壤湿度在空间和时间上均有显著差异,表层土壤含水量波动对深层土壤含水量的影响随深度增加而减小,林地和耕地表层与深层土壤含水量的相关性远高于草地;流域草地和耕地总初级生产力对土壤水分的深度敏感区间为0~40 cm,林地的深度敏感区间为0~100 cm,在深度敏感区间内,随着土壤连续水分亏缺天数的增加,草地和耕地总初级生产力依次经历短暂平稳、加速下降、降速趋缓的变化过程,而林地总初级生产力则表现出短暂下挫、长时间平稳、加速下降的变化特征。

Using data on the gross primary productivity(GPP)of vegetation and high-precision stratified soil moisture content,the spatiotemporal distribution and change characteristics of GPP during the growing season in the Yellow River Basin from 2001 to 2020 were analyzed.The correlation between soil moisture at different depths in the basin was quantified,and the response of GPP of different vegetation types to continuous soil moisture deficit events during the growing season was investigated.The results indicate that GPP in the Yellow River Basin exhibits a spatial distribution characterized by higher in the east and south,and lower in the west and north.During the growing season,the cumulative GPP is highest in cropland,followed by woodland and grassland.There is an overall increasing trend of GPP in the basin in the study period,with cropland showing the highest relative growth rate,followed by grassland and woodland.There are significant spatial and temporal differences in soil moisture across the basin.The influence of surface soil moisture fluctuation on deep soil water content diminishes with increasing depth,and the correlation between surface and deep soil moisture contents in woodland and cropland is much higher than that in grassland.The sensitive depth range of GPP to soil moisture is 0 to 40 cm in grassland and cropland in the Yellow River Basin,while it extends to 0 to 100 cm in woodland.Within the depth sensitive zones,as the duration of continuous soil moisture deficit increases,GPP of grassland and cropland undergoes a process of brief stability,followed by an accelerated decline,and then a decelerated decline.In contrast,GPP of woodland shows a brief decline,followed by a process of prolonged stability,and then an accelerated decline.