Distribution of soil available nutrients and their response to environmental factors based on path analysis model in arid and semi-arid area of northwest China

The study on the distribution of soil available nutrients and their response to the natural environment can provide valuable data and theoretical guidance for supporting human agricultural activities, especially in arid and semi-arid area where the ecological environment is extremely fragile. Based on the soil sampling and survey data set, this study established the path analysis model of SANs (soil available nutrients, including ammonium nitrogen (AN), available phosphorus (AP) and available potassium (AK)) with topography, climate and vegetation in order to explore how environmental factors interact to affect the content of SANs. Then, we combined Pearson correlation analysis and statistical analysis to explore the distribution of SANs under different environmental conditions and the response of vegetation growth to climate changes, in order to further reveal the availability of soil nutrients. The results showed that vegetation was the most important direct factor affecting AN and AP, and AK was the most sensitive to climate changes. The indirect effects of topography and climate on SANs were much greater than their direct effects. Elevation largely predicted the change of climate environment, and the regional climate directly controlled the growth of vegetation. These indirect effects strengthened the connection between topography as well as climate factors and SANs. It is worth noting that the response of vegetation to temperature and precipitation had time lag, which would have a certain impact on the content of SANs response to the environmental changes. This study is of great significance for improved understanding of soil nutrients supply and how ecosystems respond to soil nutrients availability in arid and semi-arid area.