SGER: Response of Forest Community and Ecosystem Dynamics to Broad-Scale Deer Reduction

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

In early 2002, chronic wasting disease (CWD), a transmissible spongiform encephalopathy (TSE) of ungulates (deer and elk) was discovered in several wild white-tailed deer in SW Wisconsin. The disease is one of a group of unusual prion caused diseases, related to other TSEs such as bovine spongiform encephalopathy (BSE or 'mad cow disease'), and Creutzfeldt-Jakob disease (CJD), the human variant. The occurrence of the disease has provoked major concern for several reasons. 1) The devastating effect the disease can have on the deer herd; it is capable spreading and devastating the population. 2) Sport-hunting is both economically and socially important. In recent years the deer population in Wisconsin alone has been over 1.5 million animals, and 300-430,000 are harvested each year. The deer season is a multi-million dollar input to the economy. 3) The cattle industry would be seriously threatened if CWD turns out to be transmissible to cattle. The Wisconsin DNR has carried out more intensive sampling and testing of deer by killing a large sample (400) within a 15 km radius of the original infection area. As a result, the department has designated an area of over 300 mi2 (750 km2) as a deer eradication zone (Figs 1, 2). This will eliminate the 15,000-20,000 deer within the area. A larger, surrounding area of five counties is targeted for a 50% reduction in the deer population. The task is estimated to take three years, with most reduction in the first 1.5 years. This deer removal program creates a unique experimental system to study the effect of deer on ecosystem properties. The two overarching questions posed with this research are: (1) How will reductions in deer density affect tree species regeneration, understory herbaceous composition and diversity, and ecosystem processes; and (2) How will feedbacks occur within these dynamics, and how will they vary through time and across the spatial habitat heterogeneity that exists on the landscape? In each case, the research will assess treatment effects, magnitude and variability over time, and across a range of spatial scales from 100s - 10s of km, to 10s of m. This research will utilize treatment and control landscapes and nested sampling across the habitat heterogeneity within these landscapes to test the effect of deer on community composition and nutrient cycling.