Associate Scientist in Conservation Biology
Center for Conservation and Sustainable Developmentr
Ph.D. student, Washington University in St. Louis
• Conservation Biology
• Endangered Species Recovery
• Restoration and Reintroduction Ecology
The effects of soil microbes on the growth and survival of the federally endangered Astragalus bibullatus. Dr. Albrecht’s and, his student, Rachel’s research interests include restoration ecology and conservation of rare species. Interactions between plants and soil microbes are known to influence the relative abundance of species and could be an important mechanism for explaining species rarity. For example, rare plants may accumulate species-specific soil pathogens faster than common plants, and maintain lower abundance as a result. Alternatively, if rare species maintain species-specific mutualists (e.g. mycorrhizal fungi) that promote their growth and survival, the absence of those soil mutualists could result in limited restoration success. This study will test whether plant-soil feedbacks contribute to the rarity of Astragalus bibullatus, a federally endangered forb known from only to eight populations in limestone cedar glade ecosystems. This species is threatened by habitat degradation due to fragmentation, woody encroachment, and altered disturbance regimes. As part of a long-term conservation program, previous efforts to restore A. bibullatus found that vertebrate herbivores and woody encroachment were important factors limiting the abundance of this species. However, even when these limiting factors are controlled, successful restoration of this species remains challenging, suggesting that other factors (e.g., plant-soil feedbacks) could be important in limiting this species’ performance. The goal of this study is to perform a plant-soil feedback experiment in the greenhouse using four co-occurring species: Pyne’s ground-plum (A. bibullatus); Tennessee milkvetch (A. tennesseensis), a rare but more widespread congener; gum plant (Grindelia lanceolata), a weedy forb of glades and outcrops; and little bluestem (Schizachyrium scoparium), a common perennial grass of glades. The experiment will consist of growing Pyne’s ground-plum and the other three species in a randomized 23 factorial design with the following three factors: (1) soil location origin (occupied vs. unoccupied restoration sites), (2) soil species origin (soil is currently being cultivated by the four plant species), and (3) soil microbes (sterilized vs. non-sterilized soil). The student will maintain the greenhouse experiment (e.g., water plants) and monitor the survival and growth of the four species in the different soil treatments. At the end of the experiment, the student will harvest all plants and measure their above- and below-ground biomass and perform analyses to determine the effects of plant-soil feedbacks on Pyne’s ground-plum and its congeners. The information gained from these studies will assist researchers from The Missouri Botanical Garden and The Tennessee Department of Conservation in future restoration efforts.