Soil microbes regulate forest succession in a subtropical ecosystem in China: evidence from a mesocosm experiment
Abstract
© 2018, Springer International Publishing AG, part of Springer Nature. Aims: Ecological forest succession can be influenced by plant-plant interactions that exert contrasting effects on early- and late-successional species. In this study, we explored the role of indirect plant-plant interactions and the underlying microbial mechanisms in forest succession. Methods: In a mesocosm experiment, we used Schima superba, a widespread mid-successional species in subtropical China, as a model species to explore how inoculating the rhizosphere soil of Schima affected the performances of two early-successional species (Pinus massoniana and Rhodomyrtus tomentosa) and two late-successional species (Cryptocarya chinensis and Machilus chinensis). All direct and indirect correlations between plant performance and soil microbial composition were examined using partial least square path models. Results: Schima inoculum inhibited the growth of the early-successional species but had little effect on the growth of the late-successional species. Inoculation reduced non-arbuscular mycorrhizal fungi (non-AMF) colonization in both species groups but increased arbuscular mycorrhizal fungi (AMF) colonization in the late-successional species. The percentage of root lesions in the early-successional species increased with inoculation, while that in the late-successional species decreased. Plant nutrient acquisition was not responsive to inoculation. According to the path models, soil microbes explained 51% of the growth variances in the early-successional species but barely explained any growth variances in the late species. Conclusions: Schima may increase the competitive advantage of the late-successional species over early-successional species by inhibiting the mutualistic association between non-AMF and the latter, which in turn may facilitate forest succession.