IMPACT AND MANAGEMENT OF MULTIPLE STRESSORS ON DEMOGRAPHY OF RARE AND ENDANGERED PLANT SPECIES
Forests in the eastern United States have undergone dramatic changes, and many plant species now exist in isolated or small populations and are considered threatened, endangered or of special concern (TES). Threats to long-term survival range from general habitat loss and fragmentation, to overabundant whitetailed deer populations, to invasive plants, animals, and diseases, acid rain, nutrient deposition, and climate change. Ideally, any management of plant populations or of various threats would be informed by (1) an analysis of the severity of a particular threat or of the cumulative threat posed by various stressors and (2) how a particular plant species/population responds to management of different stressors. Unfortunately, such guidelines are rarely available to land managers.
In a new project started in 2008, we are evaluating the contributions of native whitetailed deer and introduced species (plants, earthworms, slugs, and root feeding weevils) and increased nutrient deposition on demography of rare and endangered plant species. We are using Life Table Response Experiments (LTRE) manipulating the abundance of various stressors in field and common garden experiments to assess their contribution to demography of select plant species. In addition we will experiment with various restoration techniques to assess the possibility to restore depauperate or invaded areas under various stress scenarios.
While we have abundant evidence for the “ecosystem engineering” ability of deer or slug herbivory, plant or earthworm invasions, or nutrient deposition, our work will for the first time combine an assessment of these different stressors into a single study or model. At present, land managers have little quantitative evidence to support different management activities aimed to maintain T&E species. Should the focus be control of introduced plant species, prevention of earthworm invasion, control of the deer herd, or reductions in nutrient inputs? Our work aims to illuminate the severity of different stressors alone and in combination to allow prioritization of management efforts.
Bernd Blossey, DNR Cornell University
Amy Blair, DNR Cornell University
Evan Cooch, DNR, Cornel University
Victoria Nuzzo, Natural Area Consultants
Strategic Environmental Research and Development Program