## 4 Discussion
### The Changes in Dominant Factors Influencing the Evolution of Vegetation NPP  
Precipitation affects spatio-temporal changes of vegetation NPP in both dry and wet environments, temperature affects the rates of evaporation, and the synchronization of water and heat affects the growth state of the vegetation itself, thus affecting vegetation NPP. Compared with 2000-2010, human activities led to an obvious increase in areas with less vegetation NPP and a significant decrease in areas that promoted increases in vegetation NPP in 2011-2022 compared with 2000-2010. This might be due to the increase in human activities, including vegetation deforestation, corresponding with an improvement in living standards [39]. From the perspective of partial correlation, precipitation was mainly positively correlated in the north and negatively correlated in the south, which is related to the good hydrothermal conditions in the south and the cold and dry environment in the north. This is consistent with the research results of [PERSON] et al. [26], which found a positive relationship between NPP and precipitation in Northeast China. In terms of temperature, zones with positive correlations were mainly located in the Qinghai-Tibet Plateau and Northeast China. [PERSON] et al. [25] found that vegetation NPP of the Qinghai-Tibet Plateau was significantly positively affected by climate. Warm and humid climate change is an important driving force for the significant increase in vegetation NPP, which is consistent with the results of this study. Zones with negative correlations were mainly concentrated in the south, which is mainly related to the high latitude in Northeast China and the high altitude in the Qinghai-Tibet Plateau with low temperatures. An increase in temperature is conducive to plant photosynthesis and promotes the increase in vegetation NPP. In addition, precipitation and land use were the main factors affecting vegetation NPP in Northeast China, which is related to the high latitude and low precipitation in local areas. Due to the different research periods and driving factors, this is different from the research results obtained by [PERSON] et al. [43]. In North China and Northwest China, precipitation and soil type were the main factors affecting vegetation NPP (the maximum q-values were 0.832 and 0.866, respectively). The main reason is that the soil type in North China is dominated by the river alluvial yellow dry farming type, which is consistent with the research results of [PERSON] et al. [44]. The northwest region was mainly dominated by desertification, and precipitation was scarce, which was not suitable for vegetation growth. Precipitation became the dominant factor of changes in vegetation NPP in the northwest region. This is consistent with the research conclusion of [PERSON] et al. [45]. The imbalance and uncertainty of the spatial and temporal distribution of water resources will lead to the contradiction between the ecological environment and economic development in the arid area of Northwest China. The dominant factors in Southwest China were altitude and precipitation (the maximum q-value was 0.836). [PERSON] et al. [30] found that precipitation had a strong enhancing effect on NPP in Southwest China, which is consistent with the results of this study. The local plateau area accounted for a large proportion, with high altitude, cold and dry climate, and mainly alpine meadow vegetation. The photosynthesis of vegetation was weak, which is not conducive to increases in NPP [46; 47]. In Central South and East China, temperature and land use were dominant (the maximum q-values were 0.577 and 0.603, respectively). Although local precipitation and temperature levels were high, the temperature could not reach the dynamic balance of temperature and precipitation during vegetation photosynthesis, resulting in temperature being the dominant factor of vegetation NPP in Central South and East China.