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How do plant–soil–microbial interactions mediate vegetation dynamics?

Studies have indicated that early- and mid-successional plants generally suffered from negative to neutral plant–soil feedback. However, the role of such plant–soil feedback during the postglacial primary succession of plants and microorganisms has not been fully understood.

In a study published in Science of The Total Environment, researchers from the Xishuangbanna Tropical Botanical Garden and the Chengdu Institute of Biology of the Chinese Academy of Sciences sought to uncover the drivers of ecosystem succession during glacial retreat based on plant competition, microbial community structure and plant–soil–microbial interactions. They tested whether plant–soil–microbial interactions explain plant primary succession in the Gongga Mountain glacial retreat chronosequence.

To determine how plant–soil–microbial interactions mediate the vegetation dynamics, the researchers treated soils from three stages of primary succession in the Mount Gongga glacial retreat with sterilized soil and living soil as controls, and then planted with combinations of intra- and inter-species competition.

The researchers then used plant biomass to assess inter-plant competitiveness and the effects of habitat legacies. They then measured soil microbial community composition (bacteria and fungi) and mycorrhizal colonization rates to estimate the patterns and drivers of plant–soil–microbial interactions on aboveground plant succession.

They found that plant–soil–microbial interactions were coincident with the occurrence of pioneer plants during primary succession in glacial retreat areas. The habitat legacy effect shifted from negative in the early stages to positive in the middle and late stages due to increasing nutrient availability and the presence of specific microbial groups.

In addition, ectomycorrhizal fungal specialists were most important for the plant–microbial interactions during the late successional stages. Turnover of pathogenic fungi determined habitat legacy effect, especially in the early stages.

"Our results provide a better ecological understanding and allow prediction of vegetation succession on young soils and the development of new ecosystems," said Li Weitao of XTBG.