THE EFFECTS OF GRASSLAND RESTORATION ON PHYSICO-CHEMICAL PROPERTIES AND MICROBIAL COMMUNITIES OF SOIL

Non-native plants, such as tall fescue, have replaced native plants in most grasslands in the eastern United States, causing major declines in plant and animal diversity. The native prairies that remain are mainly found on soils (e.g. heavy clay over basalt bedrock) that are unsuitable for agriculture, but these sites tend to have high native plant diversity. It is unclear which methods are most effective for restoring native grasslands in the eastern United States. Furthermore, the relationship between soil degradation and native plant recovery is poorly understood. I first compared soil microbes and soil chemistry of non-native pastures to those of remnant native prairies. I then compared the effectiveness of four establishment (control, single spray, three-times spray + seeds, and organic + seeds) and two management (mowing and burning) treatments at restoring soils. I found that prairie remnants were distinct from fescue pastures both in terms of soil microbes and soil chemistry. Surprisingly, some measures of soil health (e.g. fungi-to-bacteria ratio and total carbon) were higher in non-native pastures than in native prairies. Following restoration, the fungi-to-bacteria ratio increased in the control, single spray, and spray-three-times treatments, but none of the other establishment treatments had significant effects on the soil variables. The ratio of Gram-positive to Gram-negative bacteria decreased over time when data from all treatments were combined. Management treatment (mowing vs. burning) had no effect on soil variables. My results did not identify a particular establishment or management method that led to a clear improvement in soil health. The results suggest that grasslands in our region can host diverse plant communities even if the soils are poor.