Natural restoration enhances soil multitrophic network complexity and ecosystem functions in the Loess Plateau

Abstract

Natural restoration of abandoned land is a widely used strategy to restore ecosystem functions. Previous studies mainly focused on restoring the diversity of a limited number of organism groups, ignoring that biodiversity loss occurs across multiple trophic levels and that ecological processes depend on complex interactions. In this study, the effects of natural restoration on diversity and network of multiple soil trophic groups and 10 variables related to a broad range of ecosystem functions were investigated along a 50-year natural restoration chronosequence. The diversity of different trophic groups had distinct responses to natural restoration. Furthermore, the complexity of soil networks, indicated by co-occurrence patterns across trophic levels, significantly increased with progressing succession. Ecosystem multifunctionality was significantly positively associated with soil network complexity than diversity in all individual and multiple trophic groups (multitrophic diversity). After controlling for confounding factors of ecosystem multifunctionality, these relationships remained robust, including geographic location and soil attributes. Moreover, the positive association between multifunctionality and soil biodiversity across restoration sites could be indirectly due to the soil network complexity. Diversity levels of soil archaea and invertebrates, and soil nutrient cations were significantly associated with the interconnectivity of complex multitrophic networks. Therefore, this study provides insights into the important role of soil network structure in maintaining ecosystem functioning, highlighting the necessity of considering potential interactions among soil organisms in the restoration of degraded ecosystems rather than simply focusing on the number of species.