At twenty deer per square mile the deer and habitat were pretty closely matched and the deer never had trouble surviving though the habitat in the mature forest part of the pen never got to recover.

At ten deer per square mile you couldn’t even find the deer because it was so think with under story you couldn’t see through it. If hadn’t been for one old doe named Millie, who would walk out to great you, and the occasional pile of pellets you would see we would have had a hard time convincing people there were even any deer in that pen.

Higher deer densities (20-30 deer per square mile) are associated with reduced
abundance of seedlings of preferred browse species and understory dominance by non-preferred
plants such as grasses, sedges, hay-scented and New York fern, and browse-resistant American
beech and striped maple seedlings. At even higher deer densities (40+ deer per square mile),
even the browse-resistant seedlings are heavily impacted. These white-tailed deer/plant
interactions were illustrated by deCalesta and Stout (1997) on a deer impact curve (facsimile
below). In typically-managed northern hardwood forests, with the amount of forage created by
timber management activities and natural disturbance regimes, densities below 10 - 15 deer per
square mile are associated with fully diverse plant communities: deer impact is sufficiently low
that no plant species are eliminated or greatly reduced by preferential browsing by deer. This
threshold is likened to “diversity carrying capacity”. When densities exceed 30 deer per square
mile, deer obtain enough nutrition from plant species resistant to high deer densities to maintain
body condition and a high reproductive rate: this point is likened to “nutrition carrying
capacity.” When deer densities are this high, significant reductions in plant diversity, vertical
habitat structure and species composition occur.