Many studies have focused on the effects of climate change on plant growth, soil respiration, and even insect communities, yet very little attention has been paid to the effects of these gases on plant-soil feedbacks. Negative plant-soil feedbacks have been shown to maintain diversity in plant communities. In this study we examined the effects of elevated CO2 and O3 on the relationship between aspen (Populus tremuloides) and its soil community. We gathered soil from the Aspen FACE site that had been fumigated with elevated CO2, elevated O3, elevated CO2 and O3, or ambient air for eleven years, and had hosted only P. tremuloides or a mixed P. tremuloides and paper birch (Betula papyrifera) community. We grew five genotypes of P. tremuloides in soils from each tree community and fumigation treatment to address whether increased atmospheric levels of CO2 and O3 are likely to influence the relationship between plants and their soil community.
Results/Conclusions
Our results indicate that under ambient conditions P. tremuloides performed better in soil from the P. tremuloides-B. papyrifera community than in soil from the P. tremuloides community. Thus, P. tremuloides appear to experience negative feedbacks in their own soil. This relationship changed in soil that had experienced elevated CO2 and O3. Fumigation with CO2 eliminated any negative effects of aspen growth in its own soil, while fumigation with O3 alone or the combination of CO2 and O3 resulted in a switch from negative to positive feedbacks for P. tremuloides grown in P. tremuloides-cultured soil. These results have strong implications for the future of plant communities under climate change conditions. Our results suggest that elevated atmospheric CO2 and O3 may negate the enhancement of plant diversity typically afforded by negative plant-soil feedbacks.
