Changes in Net Primary Productivity (NPP) of vegetation in the northern foot of the Yinshan Mountains and its correlation with major climatic factors

The northern foothills of the Yinshan Mountains lie at the intersection of arid and semi-arid regions, where vegetation is predominantly composed of desert steppes. The ecological environment in this area is highly fragile, and vegetation dynamics serve as sensitive indicators of regional climate change. This study analyzes changes in vegetation net primary productivity (NPP) and its response to climatic factors from 2001 to 2020, employing Theil-Sen trend analysis and statistical methods to assess spatial and temporal patterns. Additionally, it investigates the relationship between NPP variability and climate variables. The results indicate the following:(1) The 20-year average NPP in the region is 152.3 gC/(m²·a), with interannual variation ranging from 103.9 to 194.7 gC/(m²·a). The spatial trend of NPP generally shows an upward trajectory, with slopes between 1 and 3. (2) There is a strong positive correlation between annual precipitation and annual NPP across 95.62% of the area, while no significant correlation is observed between annual NPP and annual mean temperature. Seasonally, spring temperature shows a significant positive correlation with annual NPP over 28.93% of the area. In contrast, summer temperature exhibits a significant negative correlation with NPP in 20.57% of the region, while autumn temperature shows no notable relationship. Regarding precipitation, spring precipitation has little influence, with only 0.5% of the area showing a significant positive correlation with annual NPP. Summer precipitation, however, displays a strong positive correlation across 95.66% of the region. Autumn precipitation has limited influence, with a significant positive correlation found in just 2.86% of the area.