Natural and experimental tests of trophic cascades: gray wolves and white-tailed deer in a Great Lakes forest.

摘要: Herbivores can be major drivers of environmental change, altering plant community structure and changing biodiversity through the amount species plants consumed. If natural predators reduce herbivore numbers and/or alter foraging behavior, then may herbivory on sensitive plants, a trophic cascade will emerge. We have investigated whether gray wolves (Canis lupus) generate such cascades by reducing white-tailed deer (Odocoileus virginianus) saplings rare forbs in northern mesic forest (Land O' Lakes, WI). Our investigation used an experimental system exclosures areas high low wolf use that allowed us to examine role predation play direct reduction or indirectly behavior. found use, were 62 % less dense, visit duration was reduced 82 %, percentage time spent 43 %; addition, proportion browsed nearly sevenfold less. Average maple (Acer spp.) sapling height forb richness increased 137 117 versus respectively. The results exclosure experiments revealed negative impacts growth became negligible areas. conclude are likely generating which benefit maples trait-mediated effects herbivory, not kills.