Graduate Program
Biological Sciences
Degree Name
Master of Science (MS)
Semester of Degree Completion
Fall 2023
Thesis Director
Scott J. Meiners
Thesis Committee Member
Barbara S. Carlsward
Thesis Committee Member
Thomas Canam
Abstract
Grassland ecosystems comprise almost a fourth of all Earth’s land mass; however, due to ever-increasing rates of agricultural land conversion, these habitats are facing a large-scale biodiversity crisis. The degradation of grasslands extends beyond physical impacts, such as soil erosion, to include the loss of soil microbial communities as a serious risk to the health and productivity of these habitats. Cover cropping, commonly used in agriculture to revive agricultural soils, has rarely been applied to grassland restorations, and could combat or reverse the harmful effects of modern agriculture techniques. For the first chapter of my thesis, I used a greenhouse inoculation study to document the impacts of soil microbial communities of three cover crop treatments: a traditional spring oat (SO), a cover crop designed to improve soil health (SH), and no cover crop on six forb species common in restorations. This experiment was supplemented by a field harvest of three species that recruited the grassland restoration site that generated the soil inocula. The greenhouse study documented that cover crop and sterilization impacts on species performance varied greatly by species, with no one cover crop treatment overall performing best. For the second chapter, I assessed the potential of cover crops to aid restoration through vegetation surveys from the same restoration site. Metrics such as seeded/unseeded richness and cover as well as flowering cover were compared, and the community composition was tracked over the first growing season. Additionally, eight target species were compared to observe the impact of cover crops on individual success. I found that the plots containing spring oat cover crops contained higher cover of seeded, unseeded, and flowering species but the soil health plots contained higher richness of both seeded and unseeded species. Individual plant success varied wildly in both directionality and magnitude, but most indicated a cover crop × month interaction. The site trajectory suggested a shift from a site of many species in the early season, to a site dominated by a few abundant species in the late season. Overall, I concluded that cover crops do impact plant performance and allocation. I also saw evidence of weedy grass suppression and the increased flowering and seeded cover by Spring Oat cover crops, indicating potential utility in expediting grassland restoration. However, given the stochasticity of species responses, more time and research must be invested before advocating the use of cover crops in grassland restorations is justified.
Recommended Citation
Poland, Josh C., "The Influence of Cover Crops on Grassland Restoration" (2023). Masters Theses. 5001.
https://thekeep.eiu.edu/theses/5001
