Aims The co-occurrence of soil microorganisms and plants is of great significance in revealing the material cycle. The study of the community structure and co-occurrence network relationship of rhizosphere soil fungi of the relict plant Alsophila spinulosa can reveal the mechanism of constructing soil fungal communities. Methods The community structure and co-occurrence network characteristics of soil fungi in the rhizosphere of A. spinulosa were analysed using Illumina Miseq sequencing technology and co-occurrence networks. Results The rhizosphere soil fungal communities of A. spinulosa are significantly different from those in the nonrhizosphere soil. The rhizosphere soil fungal phylogeny of A. spinulosa was concentrated in Ascomycota, Mortierellomycota, and Rozellomycota. Aggregation of Cutaneotrichosporon, the main differential species, significantly affected the construction of the rhizosphere fungal community of A. spinulosa. The indicator fungal groups of the rhizosphere soil fungal community of A. spinulosa were significantly influenced by habitat. Saprotrophs are the main fungi responsible for material exchange in A. spinulosa. Increase in the relative abundance of animal pathogens was the main factor affecting the percentage of pathotroph. The rhizosphere soil fungal co-occurrence networks of A. spinulosa had high synergism and network connectivity, and more intense interspecies competition at the order level. Conclusions Overall, the rhizosphere soil fungal community of A. spinulosa altered significantly, with a stable co-occurrence network. Continuous in-depth study on the growth of the key soil fungi can help understand the growth mechanism of A. spinulosa.

In this study, the plant communities at five succession stages (herbage, herbage-shrub, shrub, tree-shrub, and tree) in the Zhenning Karst Plateau area of Guizhou were examined. The changes of plant functional characteristics in different succession stages were analyzed, as was the relationship between functional traits and environmental factors. The main results include the following. (1) During the succes-sion process, plant height, leaf dry matter mass, leaf area, leaf nitrogen content, and leaf phosphorus content gradually increased, whereas leaf thickness and specific leaf area decreased, and leaf C:P ratio and leaf N:P ratios did not change significantly. (2) Soil organic matter, soil total nitrogen, soil total phosphorus, soil C:N, soil C:P, and soil C:K increased at first and then decreased, reaching a peak at the tree-shrub stage. Soil total potassium fluctuated and soil bulk density gradually decreased and reached the lowest value at the tree-shrub stage. (3) Redundancy analysis (RDA) showed that the plant community shifted from a nutri-ent-poor soil environment to a nutrient-rich environment. Soil total phosphorus, soil C:K, soil organic mat-ter, soil C:N, and soil bulk density were the key environmental factors affecting the change of functional traits. (4) Structural equation modeling suggests that that specific leaf area and leaf nitrogen content had more sensitive responses to soil nutrient resources and environmental factors, respectively.

The relationships among species diversity, functional diversity, functional redundancy, and community stability are central to community and ecosystem ecology. This paper examines plant communities at different stages of vegetation restoration in the Guizhou karst plateau to study the relationship among functional diversity, functional redundancy, and stability of plant communities. The most important results include the following. (1) Species diversity (SD), functional redundancy (FR), and stability (STB) gradually increased with restoration, and there were significant differences among the different stages; functional diversity (FD) increased at first and then decreased, and reached the highest level at the tree irrigation stage. (2) Plant height (PLH) and specific leaf area (SLA) were functional traits that affected the diversity and stability of the plant community, and PLH was positively correlated with plant community diversity and stability, while SLA was negatively correlated with plant community diversity and stability. (3) During the community recovery, FD and FR interacted to maintain stability. In the early and late stages of recovery, the effect of functional redundancy on stability was greater than that of functional diversity, but it was the opposite in the middle stages. (4) The tree irrigation stage is the likely point at which the species diversity of plant communities in karst areas reached saturation, and the growth rate of functional redundancy after species diversity saturation was greater than that before saturation.