Forest Regeneration is Lacking
Forests are dynamic and complex ecosystems continuously
influenced by natural and human-caused disturbances, such as
weather events, insects and diseases, white-tailed deer browsing,
and timber harvesting. Pennsylvania’s forests generally depend
on natural regeneration from seed and stump sprouts. Failure
to establish young trees of desired and appropriate species in
advance of a disturbance allows other vegetation, such as ferns,
grasses, and shrubs, to take over the forest.
Scientific evidence suggests that there is a regeneration problem
in many forests across Pennsylvania due
to a lack of tree seedlings. Suggested
reasons for this lack include white-tailed
deer overbrowsing, competition from
other plants, and soil acidification. Most
experts agree that all of these factors
play a role in the problem, with white-
tailed deer overbrowsing often cited
as most significant. Since deer feed
selectively, species not preferred by deer,
The Pennsylvania Regeneration Study
To gain a better understanding of current and future regeneration
issues, the Forest Service and the Bureau of Forestry initiated
The Pennsylvania Regeneration Study, which expands traditional
FIA measurements to include detailed assessments of the forest
understory.
Based on the following considerations—current white-tailed deer
densities, understory conditions, and established guidelines for
regenerating hardwood forests for those sites where overstory
disturbance has created light conditions where regeneration
should occur—only 50 percent of the study
sites had sufficient seedlings and saplings to
replace the existing forest with a similar tree
composition. In other words, if disturbed,
such as through a windstorm, insect or
disease outbreak, or timber harvest, half of
Pennsylvania’s forests are at risk of failing to
regenerate! If this analysis includes stands
with closed canopies, the outlook is even more
negative.