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Forest Basics | Boreal Forests | Rain Forests | Temperate Forests
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The structure and plant composition of forests change over time
in a process called succession. In forest succession a grassy field
or clearcut will eventually become a mature forest. Certain wildlife
will be favored in forests at different stages of succession because
of the types and amounts of habitat that are provided by that stage.
For example, early-successional forests have more fruit, seeds, and
woody browse but less nuts, acorns, and cavity trees than older
forests. Depending on the type of management that is applied to your
land, you will be creating or maintaining different successional
stages of forest and, as a result, providing habitat for different
groups of wildlife.
along streams keeps fish and wildlife habitat
There are two approaches to forest harvesting: even-aged and
uneven-aged management. Even-aged forest management removes most
overstory trees from a stand (like clearcuts) and produces stands
that are dominated by one age class as they regenerate. These
methods work best when you are trying to regenerate trees that are
not tolerant of shade, such as oak. Uneven-aged management creates
stands with at least three tree age classes by cutting scattered
individual trees (single-tree selection) or small groups of trees
(group-selection). Shade-tolerant tree species, like maple and
beech, regenerate best in these stands. Choosing not to harvest and
relying on succession also can be a good option in some situations.
However, recognize that this approach is similar to harvesting in
that some wildlife will be favored (e.g., late successional species)
whereas others will decline (e.g., early-successional species).
Based on your goals, the type of forest you have, and other site
characteristics, a professional forester or biologist can suggest
which method is appropriate for your land. Although these management
approaches differ greatly in which wildlife are favored, both early
and late successional species are important from a conservation
Woody debris is a
natural and important component of forest habitats.
Protect unique or important habitat
trees or locating high-use facilities near unique habitat features,
such as small ponds, temporary pools (vernal pools), rocky outcrops,
and seeps, can destroy the habitat they provide. If possible, do not
disturb the forest within at least 100 feet of these important
Enhance the vertical structure of the
understory and midstory vegetation intact. Forest animals usually
specialize on particular “layers” of the forest, depending on these
components for foraging or nesting substrates. Although removing
shrubs and saplings creates an open, park-like structure, it will
prohibit some understory-dependent species from using the area.
Maintain forested buffers along streams. Riparian habitats
perform critical ecological functions, as well as provide habitat
for a rich diversity of flora and fauna. Removing trees adjacent to
streams not only destroys riparian habitat for terrestrial wildlife
but also harms aquatic habitat by increasing water temperature and
sedimentation. To reduce the negative impacts, leave buffer strips
of unharvested trees (at least 50 to 100 feet wide) along both sides
of streams. Remember to keep roads and heavy-use trails at least 50
feet away from water and minimize the number of stream crossings for
roads. The wider the buffer, the more beneficial it will be for
wildlife and erosion control.
trees in harvested areas are used by a variety of birds for foraging
Retain decaying and dead trees (snags). Tree cavities
provide shelter, dens, nests, and foraging sites for many wildlife
species. For wildlife use, snags should be greater than 8-inch
diameter breast height (dbh). Leaving all standing dead trees is
best for wildlife, but at least one large (greater than 18-inch dbh)
cavity tree per few acres is needed for larger species that use
cavities, such as wood duck, pileated woodpecker, and mergansers.
Beech, basswood, and aspen are generally good cavity-producing
trees. Also, some damaged young trees also can be reserved to
provide future cavity trees. Trees with fungal conks, dead branches,
old scars, and soft or decaying wood (especially heartrot) are good
indicators of cavity potential. If you are concerned about safety
issues, a professional forester can evaluate safety threats posed by
a particular snag and then recommend actions that you can take to
minimize the risk.
Keep dead and down wood on the forest
floor. Many animals,
especially salamanders and small mammals, use logs, slash, and other
woody debris for cover, dens, nests, foraging sites, and even as
places for courtship displays. If possible, leave large logs that
will last longer than small logs. You may want to leave some woody
debris in piles to prevent quick decay, especially in wet sites.
These brush piles can be placed anywhere but are most useful near
edges, food sources, water, or areas with little cover.
If you are harvesting, retain some overstory
overstory trees, retained both individually and in small groups and
in a variety of species and sizes, provide perching, nesting, and
foraging opportunities to wildlife. In addition, by retaining at
least one individual tree of every species on your land, you
increase the probability of some seed production every year.
Sometimes retaining a single mature tree of a species uncommon to
your woodlot can preserve wildlife values not provided by a common
tree species. Making special efforts to retain trees that produce
mast (fruits, nuts, and seeds), such as beech, oak, cherry, and
dogwood, will be beneficial to many forest wildlife. Small groups of
conifers (evergreen trees like pine and hemlock) also can provide
important cover from snow and cold temperatures during the winter
An example of a
feathered, gradual forest edge. Shrubs can similarly help to soften
Create feathered and meandering edges rather than
straight or abrupt edges.
An edge is where two different types of habitats
meet. Edges can be abrupt, like the interface of a tall forest and a
farm field, or they can be gradual and feathered, like a forest
grading into a shrubfield and then a meadow. Some wildlife, such as
salamanders and certain forest birds, avoid using abrupt edges, and
those that use them may experience high rates of predation. Edges
can be associated with higher amounts of nest predation, fewer food
resources for some species, warmer air and soil temperatures, drier
conditions, and more wind than interior forest. Abrupt and highly
contrasting edges generally have more of these negative “edge
effects” than gradual or low-contrast edges. Low-contrast, gradual
edges can be made by allowing shrubs, saplings, and some overstory
trees to remain along the forest boundary. Edges can be feathered by
retaining more trees, shrubs, and saplings closer to the forest
interior and gradually fewer trees closer to the open area. Be sure
that the feathered edges add to rather than subtract from your
forest patch area (i.e., they make the forest stand larger rather
Try to maximize the “interior” of your forest
Forest interior is unbroken forest at least 300 feet from habitat
edges and usually is positively related to the size of a patch of
forest (i.e., the larger the patch size, the more forest interior
there is). To maximize the amount of interior forest, leave the
largest patch of uncut forest possible. You also can cut around the
borders of a forest stand rather than fragment the stand into
smaller ones. Try to keep disturbances, such as improved paths and
roads, from bisecting your forest patch. Circular and square-shaped
forest patches retain more forest-interior than oblong, rectangular,
or irregularly shaped patches. Do keep in mind that a small patch is
usually better than no patch at all. Even small patches can provide
habitat for some common species and, possibly, migrating birds.
often have distinct layers of vegetation in the understory (usually
lower than 10 to 15 feet), midstory, and canopy.
Encourage the growth of oaks, hickories, and other
mast-producing species in eastern forests.
Throughout much of
the eastern United States, forests are shifting from oak-hickory
composition to shade-tolerant stands of maple, cherry, or tulip.
Because these shade-tolerant species do not produce hard mast, nut
and acorn food resources for wildlife might decline in abundance.
Oaks and hickories generally require full sun conditions to
regenerate. Protecting seedlings and saplings from heavy deer
browsing and using prescribed burning in young stands may also
promote regeneration. A professional forester can best guide
management activities aimed at regenerating these species.