Forest succession improves the complexity of soil microbial interaction and ecological stochasticity of community assembly: Evidence from Phoebe bournei-dominated forests in subtropical regions

Abstract

Forest succession is a central ecological topic, due to the importance of the associated dynamic processes for terrestrial ecosystems. However, very little is currently known about the community assembly and interaction of soil microbial communities along forest successional trajectories, particularly regarding the microbial community dynamics in contrasting seasons. To bridge these knowledge gaps, we studied soil bacterial and fungal community compositions, assemblages, and co-occurrence networks in a well-established successional gradient of Phoebe bournei-dominated forest, spanning about 65 years of forest development in a subtropical region. Illumina MiSeq sequencing of 16S and ITS genes was employed for the assessment of soil bacterial and fungal community composition and diversity, respectively. The relative abundance and α–diversity of soil bacteria and fungi showed a differential trend over forest succession. The dominant fungal phyla (Basidiomycota and Ascomycota) changed more frequently than the dominant bacterial phyla (Proteobacteria, Acidobacteriota, and Actinobacteriota), indicating that soil fungi have a more sensitive relationship with forest succession compared with bacteria. The soil microbial community variation induced by forest succession was significantly affected by soil total phosphorus, dissolved organic carbon content and pH. Compared to deterministic processes, stochastic processes mainly dominated the community assembly of soil microbial communities. Meanwhile, the relative importance of stochasticity in soil fungal communities increased in the later stages. In Particular, dispersal limitation and drift accounted for a large proportion of bacterial and fungal community assembly, respectively. In addition, the co-occurrence networks of soil microbial communities became more complex as succession proceeds. Soil bacteria and fungi exhibited more competition and cooperation along the forest successional gradient. Collectively, our findings suggest that forest succession improves the complexity of soil microbial interactions and the ecological stochasticity of community assembly in Phoebe bournei-dominated forests, providing key insights into the relationship between microbial communities and forest succession.

Soil bacterial community structure and co‐occurrence networks in response to the succession of secondary forests in subtropical regions

“…The bacterial networks' topological properties were markedly affected by forest succession (Figure 4). The highest average degree of soil bacterial network was observed in CBMF, indicating that forest succession induced a more complex bacterial network (He et al, 2022). This result might be explained by the increase of nutrients in the soil (Table 1).…”

“…The OTUs with relative abundances >0.01% and that were present in >10% of samples were used to establish the bacterial co‐occurrence network, and correlation levels were set as | r | > 0.8 and P < 0.05. The figures depicting bacterial co‐occurrence networks were visualized using Gephi v 10.0 (He et al, 2022). The keystone taxa were identified based on within‐module connectivity (Zi) and among‐module connectivity (Pi): network hubs (nodes highly connected both within and between modules; Zi >2.5 and Pi >0.62), module hubs (highly connected nodes within modules; Zi >2.5), connectors (nodes connected between modules; Pi >0.62), and peripherals (nodes in modules with few outside connections; Zi <2.5 and Pi <0.62) (Olesen et al, 2007).…”

“…However, there are limitations to this study. Soil fungi were reported to have a more sensitive association with forest succession than bacteria, and they can better tolerate low pH environment than bacteria (He et al, 2022); however, we did not assess the fungal community in this study. Considering the crucial role of the soil fungal community in the cycling of nutrients and the decomposition of organic matter, further studies should be conducted to investigate the mechanisms that drive changes in the fungal community in response to forest succession.…”

“…Although the alterations to the microbial communities in soils from different types of forests have been described, soil bacterial communities might follow different succession patterns because of environmental heterogeneity (Liu et al, 2020). Besides, we know little about the intricacies of the co‐occurrence networks of the bacterial communities in soil during the succession of secondary forests (He et al, 2022; Zhang, Zhao, Kou, Liu, et al, 2023). A combined study of the microbial co‐occurrence network and community structure, together with ecological succession, would improve our knowledge concerning the functional characteristics of microbes in various ecosystems and identify the determination that govern alters in soil bacterial community in different stages of succession (Qiang et al, 2021).…”

Effect of Fe3+ on the nutrient removal performance and microbial community in a biofilm system

“…Conversely, an increase in the abundance of certain nitrification-related enzymes or microbes has been observed in the presence of Fe 3+ , whereas this contributes to a reduction in denitrification efficiency ( Huang et al, 2022 ). The assembly of microbial communities is associated with two important and complementary processes, namely deterministic processes based on the ecological niche theory, and stochastic processes based on the neutral theory ( He et al, 2022 ; Lu M. et al, 2022 ). In deterministic processes, microbial community patterns are assumed to be controlled by environmental filtering and various biological interactions ( Xiang et al, 2022 ; Zhang et al, 2022 ), whereas in stochastic processes, the roles of probabilistic diffusion and ecological drift are emphasized ( Chen et al, 2022 ; Liu J. et al, 2022 ).…”