Abstract:

The spatio-temporal dynamics of net primary productivity （NPP） and its drivers play a critical role in understanding the global changes of terrestrial ecosystems and corresponding carbon balance. Based on the MOD17A3HGF dataset， we studied the spatio-temporal evolution of NPP in the Yellow River Basin from 2000 to 2019 using the trend analysis and Geo-Detector. Driving mechanisms including climate， topography and land cover were also explored for NPP variations using the Geo-Detector model. Results showed that： （1） The temporal variation of NPP （measuring by C） in the Yellow River Basin presented a significant growth trend from 2000 to 2019， with a rate of 5.75 g·m^-2·yr^-1. The annual average of NPP was 281.39 g·m^-2 with a range of 270-347 g·m^-2. In terms of the spatial distribution， The NPP showed a significant increasing trend in 99.53% of the Yellow River Basin. （2） The annual average of NPP of different land cover types was different. Forest was the most important types contributing to the ecosystems of the Yellow River Basin. （3） From 2000 to 2019， the average temperature， rain and altitude were among the most important natural factors that drove the spatial distribution of NPP. All natural factors showed an increasing contribution in explaining the NPP variation. The area with significant positive correlation between NPP and temperature and rain accounted for 23.20% and 44.17% of the total basin， respectively. There were significant differences in the contribution rate with the order of rain>temperature> altitude. The impact of interaction among the factors on NPP demonstrated two-factor enhancement.

Key words: NPP, Yellow River Basin, spatio-temporal distribution, nature factors, Geo-Detector