Human Impacts on Minnesota Prairie Genetics: Salted Environments, Echinacea Hybrids, and Local Seed Sourcing

Abstract

Humans are modifying various aspects of the environment, from building roadways, to moving species beyond their range, to purposefully reconstructing plant communities. These actions affect both the current distribution of populations and the potential for populations to persist. In this dissertation, I examine two human-caused impacts to plant populations and one aspect of efforts to support native plant communities. In chapter one, I focus on the impact of sodium chloride, a road de-icing agent. Such agents can damage plants and change dominant species along roadsides. I carried out two experiments, planting a pedigreed population of the native prairie legume Chamaecrista fasciculata into a roadside environment and into four greenhouse salinity treatments. I tracked their survival and reproduction. Using Aster models, I detected potential to adapt both to roadside salinity and to low salinity in the greenhouse. I also detected gene-by-environment interactions in both experiments. These results indicate a potential to adapt, but a potential which may be slowed by gene-by-environment interactions. In chapter two, I focus on the interaction of Echinacea pallida, introduced outside of its range, on local populations of E. angustifolia. I used controlled crosses and monitored their seed set and the survival of the progeny over five years. Crossing of the two species produces offspring capable of surviving multiple years. Comparing conspecific and heterospecific crosses, I found that conspecific crosses of E. angustifolia resulted in lower pollen compatibility and survival to year four than did conspecific crosses with E. pallida or heterospecific crosses. These results demonstrate a risk to E. angustifolia populations by E. pallida populations planted nearby. In chapter three, I focus on efforts to remediate human impacts through restoration of Minnesota prairie plant communities, which depends on the production and use of source-identified seeds. Restoration practice often emphasizes use of seeds sourced from populations near the restoration site, but demand frequently outstrips supply. I conducted focus group interviews with groups of producers and users of locally-sourced seeds to identify strengths and weaknesses with current practices. Participants discussed continued increases in production and use of these plant materials but also identified aspects where improvement is needed.