Impacts of extreme climate and vegetation phenology on net primary productivity across the Qinghai-Xizang Plateau, China from 1982 to 2020  

作　　者：SUN Huaizhang ZHAO Xueqiang CHEN Yangbo LIU Jun 

机构地区：[1]School of Geography and Planning,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Journal of Arid Land》2025年第3期350-367,共18页干旱区科学(英文版)

基　　金：supported by the National Natural Science Foundation of China (U2243227)。

摘　　要：The net primary productivity(NPP) is an important indicator for assessing the carbon sequestration capacities of different ecosystems and plays a crucial role in the global biosphere carbon cycle. However, in the context of the increasing frequency, intensity, and duration of global extreme climate events, the impacts of extreme climate and vegetation phenology on NPP are still unclear, especially on the Qinghai-Xizang Plateau(QXP), China. In this study, we used a new data fusion method based on the MOD13A2 normalized difference vegetation index(NDVI) and the Global Inventory Modeling and Mapping Studies(GIMMS) NDVI_(3g) datasets to obtain a NDVI dataset(1982–2020) on the QXP. Then, we developed a NPP dataset across the QXP using the Carnegie-Ames-Stanford Approach(CASA) model and validated its applicability based on gauged NPP data. Subsequently, we calculated 18 extreme climate indices based on the CN05.1 dataset, and extracted the length of vegetation growing season using the threshold method and double logistic model based on the annual NDVI time series. Finally, we explored the spatiotemporal patterns of NPP on the QXP and the impact mechanisms of extreme climate and the length of vegetation growing season on NPP. The results indicated that the estimated NPP exhibited good applicability. Specifically, the correlation coefficient, relative bias, mean error, and root mean square error between the estimated NPP and gauged NPP were 0.76, 0.17, 52.89 g C/(m^(2)·a), and 217.52 g C/(m^(2)·a), respectively. The NPP of alpine meadow, alpine steppe, forest, and main ecosystem on the QXP mainly exhibited an increasing trend during 1982–2020, with rates of 0.35, 0.38, 1.40, and 0.48 g C/(m^(2)·a), respectively. Spatially, the NPP gradually decreased from southeast to northwest across the QXP. Extreme climate had greater impact on NPP than the length of vegetation growing season on the QXP. Specifically, the increase in extremely-wet-day precipitation(R99p), simple daily intensity index(SDII), and hottest day(TXx)

关 键 词：net primary productivity(NPP) extreme climate indices vegetation phenology Carnegie-Ames-Stanford Approach(CASA)model random forest(RF) SHapley Additive ex Planations(SHAP) Qinghai-Xizang Plateau 

分 类 号：Q948[生物学—植物学] X171.1[环境科学与工程—环境科学]