Abstract
Urbanization has progressively intensified over the past few decades, transforming the structure and function of urban ecosystems and influencing the concentrations and spatial distributions of phosphorus (P) in the soil. This study collected 177 surface soil samples (to a depth of 20 cm) to understand the dynamics of soil P along a gradient of urbanization from a densely urbanized central city to less human-affected suburbs to a new exurban satellite in Chengdu, China. The results showed that concentrations of soil total P (TP) and its fractions (except Water-Po, NaOH-Pi, and Residual-P) in the central city and exurban satellite were significantly higher than in suburban areas (p < 0.05). Meanwhile, the concentrations of soil TP and its fractions (except Residual-P) significantly decreased with the increase in distance from the urban center (p < 0.05). These concentrations were significantly positively correlated with the densities of built-up areas and roads, and showed significant differences among different green space types. The results of generalized linear models indicated that the most decisive factors contributing to TP accumulation were the distance from urban center and green space type. Generally, green space type and density of built-up area were likely to be more crucial determinants governing soil inorganic P fractions compared with other factors, whereas the key factors affecting soil organic P fractions were varied. To conclude, urbanization is likely to lead to the accumulation of P and, thus, controlling the expansion of built-up areas and road areas is necessary to alleviate soil P accumulation in urban systems.
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•Soil P in the city was significantly higher than in suburban areas.•The concentrations of soil P showed significant differences among different green space types.•The concentrations of soil P decreased with the increase in distance from the urban center.•Soil P showed positive correlations with densities of built-up areas and roads.•Combinations of different driving factors in the urban system result in soil P accumulation.