Effect of overstory and understory vegetation treatments on removal of planted northern red oak acorns by rodents

We documented patterns in the removal of planted northern red oak (Quercus rubra) acorns by rodents in red pine (Pinus resinosa) stands during a field study of oak regeneration in northern Lower Michigan. Each stand contained four overstory treatments assigned at random: clearcut, 25% cover, 50% cover, and uncut (control). Each level of canopy cover contained four randomly assigned understory treatments: shrub-layer removal, herb-layer removal, litter removal, and a control. Rodents removed acorns from 59% of the seed spots in the uncut control and 12% of the seed spots in the clearcut treatment. This five-fold difference was significant. Acorns were removed from 48% and 40% of the seed spots in the 75% and 50% canopy cover treatments, respectively. Differences in acorn removal between understory treatments were not significant. These results suggest that overstory vegetation treatments can influence the removal of planted acorns by rodents, which has implications for the use of direct seeding for artificially regenerating northern red oak.