Abstract
Vegetation net primary productivity (NPP) is an important aspect of the global carbon cycle, and its change is closely related to climate change. This study analyzed the spatial-temporal variation of the standardized precipitation evapotranspiration index (SPEI) and NPP in the Mongolian Plateau, and investigated the effect of drought on NPP. To this end, NPP was simulated using the Carnegie-Ames-Stanford Approach (CASA) model. The results showed that from 1982 to 2014, NPP exhibited an upward trend in different seasons, and a significant increasing trend in most areas in the growing season and spring. The degree of drought also showed an increasing trend in each season. Moreover, the decrease in NPP and SPEI in Mongolia was larger than that in Inner Mongolia. Vegetation showed a positive correlation with SPEI in the growing season and summer, but a negative correlation in the other seasons. Moreover, the impact of drought on vegetation in the growing season showed a lag effect, whereas the lag response was inconspicuous during the early stages of the growing season. Different vegetation NPP responded strongly to the SPEI of the current month and the previous month.
Highlights
With the aggravation of global warming and drying, the frequency of droughts has increased sharply, posing a significant threat to human survival [1,2,3]
The coefficient of determination (R2) was 0.814 (p < 0.001), showing a significant correlation. These results indicated that the Carnegie-Ames-Stanford Approach (CASA) model is suitable for estimating the Net primary productivity (NPP) of the Mongolian Plateau
Moderate Resolution Imaging Spectroradiometer (MODIS) data were used to verify the NPP simulated by the CASA model, and the results proved that the CASA model could effectively reflect the productivity status of vegetation in the Mongolian Plateau
Summary
With the aggravation of global warming and drying, the frequency of droughts has increased sharply, posing a significant threat to human survival [1,2,3]. With climate warming and the intensification of human activities, droughts have caused many ecological problems [10]. Studying the causes and changes in drought is significant for solving the problem of drought. NPP is an important basis for regulating terrestrial ecological processes and an important variable characterizing vegetation activity, it reflects the dynamic response of the carbon cycle to global climate change [12]. NPP has become an indispensable index and the focus in studies on the impact of climate change on terrestrial ecosystems [15]. Quantitative analysis of the spatial and temporal changes of NPP is of great significance for understanding changes in ecosystems
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