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HomeMy WebLinkAboutPre-Proposal Assessment of Deer Impacts on Sentinel Oaks.PDFPre-Proposal Assessment of deer impacts on sentinel oaks in Cayuga Heights Dr. Bernd Blossey Department of Natural Resources 211 Bruckner Hall, Cornell University Ithaca, NY 14853 Purpose The village of Cayuga Heights is proposing to reduce local deer populations due to a variety of negative irnpacts, including impacts on natural vegetation and natural areas. The conclusion that current deer population levels are responsible for the degradation of natural areas and forests in the village is contested by some members of the community. Furthermore, it is not entirely clear at whatt levels of the deer population negative impacts will subside or disappear entirely. The purpose of the proposed assessment is to develop baseline data on current deer impacts using oak sentinel seedlings. This assessment protocol is based on deer impact not deer numbers. Continuediuse of oak sentinel seedlings in future years will allow an assessment about the achieved reductions in deer impact if deer populations reductions are implemented. A more comprehensive asses;sment on regeneration and restoration potential of Cayuga Heights woodlands requires an extension of the proposed work program to include additional species. Proposed work program To assess the impact of deer, we propose to use "ssntinel" plantings of red oak (Quercus rubra). We have exprerimented with this approach for the past 3 years in my program and have obtained good results. We have implemented this "sentinel" approach in the Hudson River Valley and in the Finger Lakes Region. We require a minimum of 5 sites (approx. 1 acre) ideally spread through the village to capture the feeding activity of different deer "'subherds" with different travel patterns. At each site we propose to plant 40 several month old oak seedlings that we have grown from locally collected seed. Half of the individuals will be protected by a wire mesh fence (60om high) to prevent deer browse, the other will be left unprotected. Each seedling will be individually tagged using a unique numbered metal plaque. We will then measure the survival and growth of these individuals over time every 2-4 weeks during the growing season until late September and then again in May the following year. We will also record incidence of browse or other herbivory on our planted seedlings. We are able to discern sources of attack or mortality not just by deer. For example rodents are expected to have a significant role in plant mortality but the angled cut of rodent attack is easily distinguished from d.eer browse. Similarly, we can discern attack by invertebrates (insects, slugs) and will record their effects. If deer have negative impacts on survival or growth of oak sentinels we would expect to lhnd differences in survival and growth between individuals inside and outside the cages at each location. Alternatively, if deer are not responsible for poor oak seedling performance, survival and growth of caged and unprotected oak seedlings is expected to be similar at each site. Oak sentinels will need to be replanted each spring in the following years and then be followed as detailed above. Data generated from this and the following seasons can then serve as a baseline to assess whether a deer reduction program (if approved and implemented) is achieving the desired ecological benefits (measured as improved oak sentinel survival and increased growth) asl deer populations are reduced. The oak sentinel approach can also provide a guideline about how far deer numbers would need to be reduced to allow oak regeneration in the village of Cayuga H,eights. This project can also be expanded to include additional species of trees or herbaceous plants if the village (or individual landowners) are interested to further assess the ability of natural areas in Cayuga Heights to provide habitat for a rich and diverse forest understory plant community. Proiect Costs I am requestiing partial summer financial support ($1,000 per year) to offset purchases for cage materials and for either the graduate student or my Research Support Specialist. We will provide all seedlingr; (collected locally), cage materials and will plant and monitor seedlings over iime. We will provide updates in a report every year after the growing season. These costs will cover all expenses including seed collection, propagation, plantings, materials and project reporting.