Impacts of tree species on soil chemical properties in the reforested urban forests

Abstract

Aims: Reforestation has been considered as an effective way to mitigate the adverse environment impacts from urbanization, while the role of different reforested forests on urban soil is not well known. This study aims to detect the forest soil properties across urban-nonurban gradients and explore whether and how the reforested trees affect urban soil. Methods: We collected soil and litter samples in reforested forests in Wuhan (a megacity in central China), measured their chemical properties, and compared them with the surrounding nonurban forests. We then investigated the effects of three common reforested trees Pinus massoniana, Camphora officinarum and Quercus variabilis on the urban forest soils. Results: We found that forest soils were more acidic but lower of N content in the urban areas than in the nonurban areas. There were significant differences in litter chemical properties (pH, organic C, N, P) among the forests planted with different trees, while only the differences in pH and P were consistent with those of forest soils. Furthermore, the more C. officinarum in an urban forest, the higher the pH in the soils, indicating a potential function of mitigating the soil acidification. Conclusions: Although urbanization changed forest soil chemical properties, the tree species used in reforestation can affect urban forest soils through producing litter with various properties. Therefore, the biological method, i.e. planting appropriate trees will be a natural solution to address the soil problems in urban areas.