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Pennsylvania
has 17 million acres of forestland, which covers 59% of the state.
Although it ranks 33rd among the states in land area, the commonwealth
ranks 12th in total timberland.
A Renewable, Natural Resource:
Forests are renewable resources (as opposed to perpetual resources
like solar energy or non-renewable resources, such as fossil fuels).
In Pennsylvania, it is estimated that timber is growing faster than
it is being harvested, i.e., the annual harvest is less than the
sustainable yield. 
In Pennsylvania, there are two major forest-type groups:
- Oak/hickory
(47% of the forests, mainly in the central and southern areas)
- Northern
Hardwoods (38% of the forests, mainly in the north and northwest),
including birch, sugar maple, and black cherry
Other forest-type
groups are oak/pine (2%), elm/ash/red maple (4%), and white/red
pine (5%). Commercially valuable species include black cherry, red
and white oak and sugar maple, with lower-value hardwoods being
red maple and hemlock.
Ecological processes that influence our forestland include:
- Succession
and competition among species: e.g., the northern red oak expands
its crown to out-compete shade-intolerant white ash trees, and
the black walnut emits a chemical from its roots that prevents
growth of nearby trees.
- Grazing:
Deer browse on the twigs and leaves of young trees, inhibiting
growth and forest regeneration. This also has a dramatic impact
on wildlife habitat and species biodiversity.
- Disease
and pests: Chestnut blight (a fungus) eliminates Chestnut trees,
except for small rootstock and saplings. White pine blister root,
Dutch elm disease, hemlock wooly adelgid, cherry scallop shell
moth, pear thrips, fall cankerworm, forest tent caterpillar, and
elm spanworm are all tree predators.
- Wind, lightening
(fire), drought, and rain.
Human influences
on the forest:
- Clearing,
as in clearing for development
- Harvesting
for products
- Fire:Humans
cause most wildfires, with debris burning and arson now the most
common causes.
- Taxes:The
need to pay property taxes influences landowner decisions regarding
management or the sale of their land. Private landowners in Pennsylvania
receive an estimated $380 million a year from timber sales.
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