Plant-soil feedbacks in remnant and restored tallgrass prairie

Background/Question/Methods

Interactions and feedbacks between plants and the soil microbial community are now recognized as drivers of plant community diversity and structure. However, human disturbances, such as agriculture and fertilization, can dramatically alter the soil microbial community. This presents additional challenges to those who try to restore native plant communities. However, our understanding of interactions between plant communities and soil microbial communities is still limited, which also limits our ability to improve restoration techniques. We tested the strength and direction of feedbacks between plants and soil microbial communities in soils from three remnant and three restored prairies for eight tallgrass prairie species. For each site, soils were first trained by all species included in this experiment. Then, seedlings of all species were grown in soil trained by each of the eight species. After two months, the relative growth of each species in their own soil as compared to seedlings grown in other species’ soil was used to calculate interaction coefficients indicating the strength and direction of plant-microbe feedbacks. Interaction coefficients were calculated for each study site separately and compared to the abundance of that species at each study site.

Results/Conclusions

The strength and direction of plant-microbe feedbacks varied between sites, but were generally negative, supporting their potential role in promoting plant species coexistence. Contrary to other’s findings, variation in the strength of plant-microbe feedback was not a strong predictor of plant species abundance within or between study sites. Further, feedbacks were not consistently different between remnant and restored prairies, suggesting that differences in plant species abundance between these two communities cannot be explained by differences in plant-microbe feedbacks. Despite significant variation in the strength of plant-microbe feedbacks across sites, there were consistent effects of some species’ soil on other species, with soil trained by some species consistently promoting the productivity of other species and other soils consistently reducing the productivity of other species.