Wolves facilitate the recovery of browse-sensitive understory herbs in Wisconsin forests

We asked whether wolf re-colonization would facilitate increased growth and reproduction of three browse-sensitive plant species. We hypothesized plant size and the proportion of reproductive individuals would be lowest in areas with no wolves, intermediate where wolves had been present for 4–6 years, and highest where wolves had been present for 12–13 years. Two plant species exhibited significantly greater reproduction where wolves were present for 12–13 years. Mean leaf size of indicator plants was significantly greater in areas where wolves were present for 12–13 years, as compared with that in areas where wolves were not present or were present for 4–6 years, but the effect size appears small. While the return of wolves to this region is likely to benefit browse-sensitive plant species, our findings suggest that wolf recovery will not generate a trophic cascade of sufficient magnitude to halt or reverse the loss of plant diversity in the Great Lakes region in the near term.