## 4 Discussion  
In order to further investigate the drivers of desertification land change from 2010 to 2020, the NPP values in 2010 and 2020 in Urat front flag were estimated using MODIS image data and CASA model and their spatial distribution was analyzed using ArcGIS.  
NPP has the most intuitive way to convey the degradation of vegetation productivity and can be distinguished from the other forms of desertification land types. As illustrated in Figure 7a, the annual NPP per unit area in 2010 in the Urat front flag can reach a maximum of 306.3 gC/m\({}^{2}\), with an annual average value of 122.2 gC/m\({}^{2}\), in which the NPP of the Dashetai Ranch in Bayannur City, Zhongtan Farm in Bayannur City, the southwestern part of Dashetai Town, and some parts of Mingan Town is significantly higher than the NPP of vegetation in the western and central and northeastern regions. This phenomenon indicates that in the central and northern regions of the study area, the climate is arid, precipitation is scarce, vegetation is sparse, desertification is severe, and NPP is low. As illustrated in Figure 7b, the variation in NPP in 2020 is relatively obvious. The annual NPP can reach a maximum of 354.5 gC/m\({}^{2}\), while the annual average value is 159.5 gC/m\({}^{2}\), which exhibits an increase of 48.2 gC/m\({}^{2}\) compared with 2010, and the areas with strong vegetation growth were mainly concentrated in the southern, north-central, and east-central regions. In the eastern and southern parts of the study area, more farms, pastures, grasslands, forests, and water resources are reorganized, and the vegetation NPP is higher. There are obvious differences in spatial distribution over the past 10 years, and the results of desertification control are remarkable.  
According to earlier studies, changes in vegetation NPP result from a synergistic impact of human activities and climate change [62; 63; 64; 65; 66; 67]. The annual average NPP of vegetation in the Urat front flag from 2010 to 2020 has a distinct spatial differentiation pattern (Figure 7),  
Figure 7: Spatial distribution of vegetation NPP in Urat front flag.  
with an overall growing distribution in a band from west to east, and the differences are related to hydrothermal conditions. The northwestern Bayannur City Xin'an Farm and the north-central Dashetai Town have a higher vegetation NPP due to grassland and woodland planting. The northeastern Xiaoshetai Town and parts of northern Sudulun Town have poor natural conditions and a relatively low vegetation NPP, and the south-central Erdenbrag Sumu is dominated by a stable continental climate with insufficient precipitation, sparse vegetation cover, and low vegetation NPP. The NPP of vegetation is also higher because the southern part is bordered by the Yellow River, with good climatic conditions and sufficient water resources. In summary, climate change is the primary factor influencing vegetation recovery in Urat former banner, while precipitation is the primary climatic factor controlling vegetation growth. Wet climatic conditions and sufficient precipitation are conducive to vegetation growth, and this effect is especially significant in arid and semi-arid areas. The effect of precipitation on vegetation is primarily through affecting vegetation photosynthetic efficiency and plant activity, thereby influencing vegetation organic matter production.