Effects of shading and herb/liana eradication on the assembly and growth of woody species during soil translocation in Southwest China

Abstract

Due to the intensification of human activities and global climate change, large areas of forest have been degraded and converted to other land uses. Soil translocation, which transfers the topsoil of donor forest to the receiving site to allow for the germination and reestablishment of soil seed bank and seedling, is a promising method for restoring vegetation that is similar to the donor forest. However, the lower similarity between the germinated community and donor forest has diminished its application against the ecological restoration and biodiversity compensation. We hypothesized that the exposure of donor forest soil to strong sunlight and early herb/liana competition may block germination and establishment of woody species (trees and shrubs) following soil translocation. To test this, here we investigated the effect of shading and weeding treatment on woody species assembly and seedlings growth at a karst rocky desertification area in southwest China. The results showed that soil translocation in blank control significantly increased the richness and similarity of woody species compared with receiving site. Moreover, soil translocation with shade treatment not only increased the richness and density of species during the germination period, but it also improved the survival and growth of most species—especially Osteomeles anthyllidifolia, Fraxinus malacophylla, Quercus baronii, and Rhamnus parvifolia—when compared with soil translocation in blank control after 18 months. Additionally, although soil translocation with blank control and weeding, and soil translocation with shade and weeding increased neither the number of woody species nor the density of shrubs species, they improved the density and similarity of tree species as well as the similarity of shrub species. We concluded that soil translocation with shade and weeding is likely more effective and helpful to restore the vegetation that is more similar to the donor forest in semi-humid regions of southwest China and comparable regions worldwide. But in practice, only soil translocation with moderate shade is deemed the optimal restoration method because it maintain the “recovery effect” while decrease the labor cost. Nevertheless, we should further assess the longer-term development and stabilization of established vegetation.