I am looking for a Ph D student interested in vegetation dynamics in prairie remnants and prairie restorations. The Nature Conservancy has restored 1,500 acres of grassland and manages 2,000 acres of remnant prairies and uses prescribed fire and grazing to increase habitat quality around Grand Island, Nebraska. However, it is increasingly clear that environmental factors such as soil composition and fertility, drought susceptibility, site history and species pools significant influence the vegetation composition. For instance, observationally, we see that remnant prairies are often dominated by invasive grasses and are low in forb diversity. Even when subjected to years of management to suppress invasive grasses and repeated over-seeding attempts, forb diversity fails to increase. Conversely, cropland restorations planted with 150-230 species successfully establish diverse plant communities. However, these restorations are threatened by the same invasive grass species and we see large variation among sites. There seems to be environmental variability, presently unaccounted for, that is hindering successful efforts to rehabilitate remnant prairies and restored prairies.
We are currently examining how management (including fire and grazing), site history and site environmental factors correlate with vegetation composition, diversity, and the abundance of at-risk and invasive species. For this we have set up 800 permanently marked plots that are annually monitored for plant composition and abundance. In addition we have data of site history, management, soil fertility, soil texture and will collect productivity, nitrogen and water availability data in the next year. Based on this we will analyze the factors that control diversity, and propose hypotheses for management strategies that increase diversity, decrease the prevalence of invasive species, and increase the abundance of at-risk species. As a next step, we will experimentally examine these hypotheses on factors that controls plant diversity and how we may change the competitive balance among plant species to favor natives, increase the abundance of rare and threatened species, and decrease the prevalence of exotic weeds. If you are interested in such a research project for your Ph D, please contact me. This requires an interest in both basic and applied community and ecosystem ecology. Johannes (Jean) M H Knops School of Biological Sciences University of Nebraska 348 Manter Hall Lincoln, NE 68588 Phone (402) 310 3904 Email: jkno...@unl.edu
