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Managing White-tailed Deer in Forest Habitat
From an Ecosystem Perspective
Pennsylvania Case Study
Report of the Deer Management Forum


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Deer populations tend to increase in response to timber harvest or other overstory
disturbance, such as large-scale wind events. They grow the fastest following disturbances that
increase the abundance of woody and herbaceous vegetation less than 5 feet tall and increase
mast production. Forest stands that contain an abundance of browse (buds, twigs, and leaves of
woody plants) within 5 feet of the ground are highly preferred by deer. The current year’s growth
of most hardwood species has a high nutrient content and is among the most highly palatable
items in their diet. In Pennsylvania’s hardwood forests, germination, survival, and seedling
growth are increased by disturbances that open the canopy and increase the amount of light
reaching the forest floor, that is, where deer impacts are low enough to allow these responses to
occur and where a residual of low, shade-casting plants such as ferns or shade-tolerant small
trees are not left behind. Similarly, silvicultural regeneration methods or natural disturbances that
remove all or most of the overstory (e.g., clearcutting, shelterwood seed cutting,87 selection
cutting of large groups,88 windthrow that creates large openings), where advance regeneration
(shade-suppressed seedlings) or a seed bank is present, will promote the development of high-
density browse. As seedlings grow and a new forest enters the sapling and poletimber (small
adult) stages of development, trees grow out of the reach of deer and cast sufficient shade to
substantially decrease the abundance of other browse produced. Where deer population density is
below some threshold near a given location’s ecological carrying capacity (see box on page 16
and Chapter 11), young hardwood stands in Pennsylvania can grow out of reach of deer in 3 to
10 years, depending on the local climate, site conditions, and species composition.89
The abundance and diversity of herbaceous plants used as food by deer first increase and
then decline after canopy removal. The growth of tree seedlings and shrubs invading a site after
disturbance and advance regeneration accelerates in the increased light to form a closed canopy.
This canopy substantially reduces the density and growth of herbaceous plants originally
stimulated by the disturbance and associated higher light. As trees reach the sapling stage they
shade and suppress shrub growth and further seedling recruitment. After closed tree canopies
develop, browse production remains low for several decades until trees achieve heights greater
than 50 feet. At around that stage, canopy cover generally falls somewhat below 100% due to the

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