Soil phosphorus variation regulated by changes in land use spatial patterns during urbanization in western Chengdu, China

Abstract Alterations in the composition and configuration of land uses during urbanization exert significant impacts on variations in soil phosphorus (P). Here, we analyzed the concentrations of soil total P and P fractions in 75 soil samples from vegetated lands with different urbanization intensity (UI) in western Chengdu, China. Characteristics of land use spatial pattern were investigated in 300 m buffer zones around each soil sample location according to five landscape metrics. The relationships between soil P variations and land use spatial patterns were analyzed by stepwise multiple regression. The results show that land uses exhibited highly fragmented, complex and heterogeneous features with increasing UI; concentrations of soil total P and P fractions, except for residual P, displayed accumulated trends. The built-up land and traffic green land predominated in medium- and high-UI landscapes and showed positive relationships with the soil P. By contrast, the cultivated land, forest land and industrial green land were more commonly distributed in low-UI landscapes and showed negative correlations with soil P. Furthermore, park green land, residential green land and public green land occupied small proportions of the study area and exhibited varied associations with soil P in landscapes with varied UI. The main factors affecting the soil P variations were the proportion of forest land, patch shape and landscape dispersion in a low-UI landscape. Soil P variations in medium-UI landscapes were controlled by the proportions of built-up land and residential green land, landscape dispersion and diversity. Additionally, soil P variations in high-UI landscapes only were regulated by the proportions of built-up land and public green land. The results reveal that the development of a variety of landscape planning schemes for different UI landscapes can be pivotal to maintaining or improving soil P balance, obtaining functional soil ecosystems, and securing a low environmental risk in urbanized areas.