The effect of soil microbial functional groups, abiotic and biotic factors on plant functional groups: insights from a tropical rainforest in Southwest China

Background and aims

Studying the relationship between plant functional groups and soil microbial functional groups, abiotic and biotic factors are important for understanding the mechanisms of species coexistence and ecological processes among biological communities, especially in species-rich tropical rainforests.

Methods

This study utilized the Competitor, Stress-tolerator, and Ruderal (CSR) theory for plant classification, and FAPROTAX and FUNGuild for soil bacterial and fungal functional guild analysis, and combined with abiotic and biotic factors. We use correlation analysis, multivariate regression analysis, random forest model, redundancy analysis and variance decomposition to analyze the data.

Results

(1) A total of 316 woody plant species were classified into four functional groups. The intermediate (Int, 53.48%) and competitor (C, 29.75%) functional groups comprised the majority of plant species, while the ruderal (R) functional group was least represented (1.27%). Dominant soil fungal functional groups included undefined saprotrophs, ectomycorrhizal, and soil saprotrophs, while key bacterial groups included chemoheterotrophs, nitrifiers, and nitrogen fixers. (2) Soil saprotrophs were positively correlated with the stress-tolerator (S) functional group but negatively with the Int functional group. The C functional group was positively associated with arbuscular mycorrhizal fungi. (3) Soil bacterial functional groups were the key driving factors affecting the relative abundance of plant functional groups, while abiotic and biotic factors were the important influencing factors.

Conclusion

This study sheds light on the relationship between plant functional groups and soil microbial functional diversity, biotic and abiotic factors, underlying processes for understanding tropical rainforest community dynamics.