Wang Xiao-Hong, Liu Xian-Feng, Sun Gao-Peng, Liang Juan
School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China.
Ying Yong Sheng Tai Xue Bao. 2022 Aug;33(8):2105-2112. doi: 10.13287/j.1001-9332.202208.021.
To quantitatively evaluate the effects of drought on vegetation productivity in the Qinling-Daba Mountains, we analyzed the temporal and spatial characteristics of gross primary productivity (GPP) and drought, identified the fluctuation of negative GPP extremes under different vegetation types, and quantified the drought vulnerability and drought risk of GPP from 2001 to 2020 with MODIS GPP products and standardized precipitation evapotranspiration index (SPEI). The results showed that the annual GPP from 2001 to 2020 had an increasing trend in 98.0% of areas in the Qinling-Daba Mountains. The GPP of all vegetation types except wetlands increased significantly. SPEI decreased in 23.8% of area in the Qinling-Daba Mountains from 2001 to 2020. The number of negative GPP extremes had no significant trend, but abnormal GPP fluctuations had intensified, especially in the cultivated land. After 2011, the proportion of concurrent negative GPP extreme and drought had decreased for all vegetation types, but the spatial and temporal range of drought in these negative GPP extremes showed an expanding trend. Compared with the pattern during 2001-2010, the proportion of area with positive drought vulnerability and drought risk increased by 104.1% and 6.7% after 2011, indicating that the area with drought-induced GPP decline had expanded. Among all the vegetation types, drought caused the largest decrease of GPP in wetlands. The results revealed that drought led to an aggravation of GPP fluctuations and increased frequency of GPP extremes in the Qinling-Daba Mountains from 2001 to 2020, which resulted in GPP decline with different magnitudes in most vegetation types.
为定量评估干旱对秦岭—大巴山植被生产力的影响，我们分析了总初级生产力（GPP）和干旱的时空特征，确定了不同植被类型下负GPP极端值的波动情况，并利用MODIS GPP产品和标准化降水蒸散指数（SPEI）对2001年至2020年GPP的干旱脆弱性和干旱风险进行了量化。结果表明，2001年至2020年，秦岭—大巴山98.0%的区域年GPP呈上升趋势。除湿地外，所有植被类型的GPP均显著增加。2001年至2020年，秦岭—大巴山23.8%的区域SPEI下降。负GPP极端值的数量没有显著趋势，但GPP的异常波动加剧，尤其是在耕地中。2011年后，所有植被类型中负GPP极端值与干旱同时出现的比例均有所下降，但这些负GPP极端值中干旱的时空范围呈扩大趋势。与2001—2010年相比，2011年后干旱脆弱性和干旱风险为正的区域比例分别增加了104.1%和6.7%，表明干旱导致GPP下降的区域有所扩大。在所有植被类型中，干旱导致湿地的GPP下降幅度最大。结果表明，2001年至2020年，干旱导致秦岭—大巴山GPP波动加剧，GPP极端值频率增加，导致大多数植被类型的GPP出现不同程度下降。
