Environmental Extremes Drive Plant and Soil Community Dynamics of Native and Disturbed Grasslands

Environmental drivers such as precipitation and temperature are important predictors of changes in plant community composition. Anthropogenic disturbances also alter plant composition, often leading to the invasion by non-native plant species. Global climate change will lead to more extreme changes in environmental factors, therefore, it is important to understand how both native and disturbed plant communities will respond to rapid changes in important drivers like precipitation and temperature. We looked at the response of plant and soil community dynamics by conducting a greenhouse experiment and by modeling current plant community responses to the environment using field observations. Our greenhouse experiment examined the plant and soil feedback (PSF) response of both cool- and warm-season native and non-native grasses to elevated temperatures (ambient and +5� C) and drought (100% and 75% field capacity). We also used linear modeling and AICc weighted model averaging to determine the relationships between plant species richness and several environmental variables (annual precipitation, annual evapotranspiration, and annual mean, maximum, and minimum temperature) in both native and disturbed sites across an east-west gradient across the tallgrass prairie region. In the greenhouse study, we found that experimental increases in temperature and drought had a significant influence on the direction and strength of native and non-native PSF response compared the PSF response under ambient conditions. Our modeling data show significant linear correlations between plant species richness and temperature-related drivers in disturbed sites. However, linear models best explained plant species richness of native sites as precipitation, while results from AICc weighted model averaging indicated that the interaction between temperature and precipitation was the strongest driver of plant community composition. Understanding how climate drives plant community composition will become more urgent under climate change predictions, and our results suggest that future environmental models used to predict plant community changes should incorporate interacting terms. Our results also emphasize the importance of native plant influence on PSFs under warmer and dryer conditions in community resilience to non-native invasion.Natural Resources and Ecology Managemen

Climate Affects Plant-Soil Feedback of Native and Invasive Grasses: Negative Feedbacks in Stable but Not in Variable Environments

This work is licensed under a Creative Commons Attribution 4.0 International License.The plant-soil feedback framework allows researchers to target the interaction of plants and root-associated microbes and to determine its interplay on plant-plant interactions. Plant-soil feedbacks in terrestrial ecology are well-documented, but the strength and direction of feedbacks as influenced by abiotic environmental factors, such as temperature and soil moisture, has not been fully explored. In our study, we examined plant-soil feedback responses of both cool- and warm-season native and non-native grasses to elevated temperatures (ambient and +5°C) and soil moisture (100 and 75% field capacity). In a previous experiment, grasses were grown under temperature and soil moisture conditions similar to our current study. The resultant trained soil communities served as the inoculum sources for our current experiment. We found that consistent training and experimental temperatures resulted in negative PSF, where plants produced greater biomass in soils conditioned by heterospecifics. However, the direction of PSF was reversed when training and experimental conditions were mismatched. That is, when training and experimental temperatures mirrored one another, negative PSF occurred, suggesting coexistence between the two species is likely under these conditions. However, when only training or testing temperatures were elevated, positive PSF were detected, favoring the non-native species. These alterations in plant-soil feedbacks were relatively consistent across pairings of warm- and cool-season grasses. Overall, our results indicate inconsistent year-to-year environmental conditions, such as extreme temperatures, may undermine the stabilizing forces of negative PSF and favor of non-native grasses