Skink trapping: Interactive Effects of Deer, Fire and Nitrogen

In 2000 we began to examine impacts of three anthropogenic effects on successional grasslands in an area with rapid woody encroachment toward white pine forest. We established a factorial experiment that manipulates N (0 or 3 g m-2 yr-1), fire (none or every 2nd year), and deer (fenced or open to deer), with a total of 32 plots, each 20 x 20 m. We hypothesized that the response of this ecosystem to the combined effects of fire, N, and herbivory would depend on the ability of pine and other species to invade and the magnitude of their response to the different disturbance factors: warm-season grasses increase with and encourage fire, resist herbivores, and inhibit woody plant invasion (Davis et al. 1998, Inouye et al. 1994); cool-season plants are favored by N deposition (Tilman 1987) but are fire-intolerant and palatable to herbivores; legumes tolerate fire but decrease with herbivory and N deposition; and finally, woody plants are fire-intolerant and may be more susceptible to herbivory. We are measuring treatment effects on composition and diversity of plants and consumers (insects, small mammals, lizards) as well as plant and soil C and N.