Background
White-tailed deer (Odocoileus virginianus)
browsing can affect ecosystem processes in forest communities.
Browsing influences the composition (species of plants
present), structure (arrangement of these plants) and
long-term dynamics (changes in composition, structure
and processes over time) of forests. While browsing
itself is a natural ecological process, persistent high
densities of deer can over-browse forests and alter
them in ways that may become detrimental to their long-term
integrity. Studies show that effects of deer overpopulation
on forest ecosystems include changes in tree recruitment,
and declines in diversity of native plant species, especially
herbaceous species. Alternatively, plant species not
eaten by deer or resilient to deer browsing (e.g. ferns,
grasses, and sedges) often show increases in abundance
and cover with increasing deer density. These changes
to the forest may have indirect effects on wildlife
habitat quality for small mammals, birds, and even deer.
High deer densities may also facilitate the spread of
exotic plant species such as garlic mustard (Alliarda
petiola) by removing competitors or altering habitat
conditions.
Overpopulation of white-tailed deer is a serious threat
to natural resources throughout the National Capital
Region Network. Natural resource managers are concerned
that unregulated deer populations might bring about
a long-term decline in both the abundance and diversity
of native plant species. Given the evidence that deer
can reduce tree regeneration, decrease plant species
diversity, and nesting cover for birds, deer density
data is needed to establish trigger points or thresholds
for the implementation of management practices to control
the deer populations when they exceed desired capacity.
Deer monitoring data will be used to document trends
in deer population density over time. This data can
then be compared to trends identified in our forest
health monitoring. This will give us a better understand
of the effects of overpopulation and allow natural resource
managers to make appropriate decisions regarding management
of deer and forests.
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