Plant-microbial feedback in secondary succession of semiarid grasslands

Plant-soil feedback (PSF) is an important driver of plant community dynamics. The role of plant species in PSF has been emphasized for secondary succession processes; however, microbial responses to PSF and the underlying mechanisms responsible for their effects on plant succession remain poorly understood, particularly in semiarid grassland ecosystems. Here, we conducted a greenhouse experiment using soil collected from early-, mid-, and late-successional plant communities to measure net pairwise PSF for species grown under monoculture. Soils conditioned by pre-successional species had a positive feedback effect on subsequent plant species, whereas soil conditioned by subsequent plant species had a negative feedback effect on pre-successional species. The feedback effect of plants from different successional stages on soil bacterial and fungal communities was mainly positive. However, the bacterial genera in the soil conditioned by early- and mid-successional species and fungal classes in the soil conditioned by early- successional species had a negative feedback effect on late-successional species. Thus, the effects of soil fungal and bacterial communities on species in other successional stages varied with taxonomic level. Our results provide insight into the manner in which soil microbial communities influence PSF responses during secondary succession processes.