Spatiotemporal dynamics and climate impact of vegetation NPP in the northern Shanxi Province region based on the improved CASA model

  Objective  The purpose of this study is to explore the influence of factors such as climate and vegetation types on the net primary productivity (NPP) of vegetation in the northern Shanxi Province of northern China, and to clarify the response of vegetation to climate change in arid and semi-arid regions, and to ensure vegetation restoration and sustainable development in ecologically fragile areas. It has important reference value.

  Method  Based on the improved CASA (Carnegie-Ames-Stanford approach) model, this paper simulates vegetation NPP in northern Shanxi Province from 2000 to 2020, quantifies its temporal and spatial distribution pattern, changing trend and spatial variability, and analyzes the correlation between climatic factors and vegetation NPP.

  Result  The annual values of vegetation NPP (calculated by C) in the study area ranged from 225.28 to 484.09 g/m² from 2000 to 2020, with a mean value of 349.76 g/m² and the average annual growth rate was 8.75 g/m². The annual values of vegetation NPP showed a pattern of high in the east and low in the west, and high in the south and low in the north. The annual values of NPP were mainly concentrated in the range of 200−400 g/m², accounting for 65.15% of the total area of the study area, and the magnitude of NPP annual values of each vegetation type was woodland (691.79 g/m²) > scrub (492.97 g/m²) > cropland (378.39 g/m²) > grassland (343.85 g/m²) > unused land (277.45 g/m²) > construction land (223.96 g/m²). The area proportion of each degree of variation of vegetation NPP in the study area from large to small was general stability (46.4%) > stable (30.9%) > less stable (17.9%) > very stable (4.8%), and the stability showed a decreasing trend from southeast to northwest in spatial scale. Vegetation NPP showed a significant positive correlation with precipitation, an insignificant correlation with temperature, and a negative correlation with solar radiation.

  Conclusion  The vegetation NPP in northern Shanxi Province shows a fluctuating upward trend during the study period, with obvious heterogeneity in spatial distribution and overall volatility. Among the three meteorological factors, precipitation, temperature and solar radiation, both precipitation and solar radiation can affect the NPP of vegetation, and precipitation has the most significant impact on the NPP of vegetation in northern Shanxi Province.