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Inlcudes
Excerpts from
Protecting
Maryland’s Green Infrastructure: The Case for Aggressive Public Policies DNR
Publication February 2002
Protection
of Maryland’s forests affects the economy, quality of life, and species
diversity throughout the state.
When forest lands, which are rich in natural resources, plant, and wildlife
habitat are developed, there are hidden costs incurred in the form of lost or
severely impaired ecosystem services. These services, such as cleansing the
air and filtering water, are fundamental requirements for human life and other
species. In the face of
tremendous increases in both population and land use, many people now realize
that these natural or ecosystem services must be afforded greater protection.
The breakdown in ecosystem functions is causing damages that are difficult and
costly to repair and are taking a toll on the health of plants, animals, and
humans.
Clean Air
Air
pollution is a major concern in Maryland and maintaining forested lands helps
provide a natural means of combating this pollution. Cleaning the air is a
basic function of trees. They
absorb carbon dioxide and release oxygen. They also absorb sulfur dioxide and
nitrogen oxide, the two major components of acid rain. In addition they trap
particles in the air and ozone that can be harmful to humans.
Air
quality affects the health of everyone and is a major factor in illnesses
ranging from cardiovascular disease to cancer and respiratory ailments.
The average American breathes 3,400 gallons of air each day.
Groundwater Supply and Stream Flows
Forested
watersheds capture, store, and allow infiltration of water - thus contributing
to the quantity of water available and the seasonal flow of water in streams.
We have enough evidence to understand that the effect of continued
deforestation is less rain, dried up land, and disappearing wildlife. Forested
watersheds reduce erosion, filter sediment, moderate flooding, and stabilize
stream banks. It’s the forests on the mountains that catch and hold water
for us, recharge ground water sources, and regulate stream flows. Forests and
other plant life help generate rainfall.
Trees absorb water from the soil and release it into the atmosphere, and this
water is eventually returned as precipitation.
A large tree can put 10 gallons of water a day back into the water
cycle. Scientific
studies of land becoming dry and parched have shown that vegetation is a
controlling factor in the exchange of water between the land and the
atmosphere, and that large-scale deforestation dries up an area’s climate.
Tree
loss in the Baltimore-Washington area from 1973 to 1997 reportedly resulted in
a 19% increase in runoff, an estimated 540 million cubic feet of water.
The findings were that costs to build storm water facilities to
intercept this runoff would cost $1.08 billion ($2/cubic foot of storage).
Erosion and Sedimentation
Forest vegetation helps
stabilize soils and prevent erosion. The
harmful impacts associated with erosion include damaged roads and structures,
increased sediment loads in streams and reservoirs, reduced water quality, and
damage to fish populations.
Carbon
Sequestering
During photosynthesis, trees
absorb CO2 and convert it into oxygen; carbon is also stored in the body of
the tree, in the soil surrounding its roots, and in debris that falls to the
ground. Logging these lands
produces the opposite effect and increases CO2 levels by releasing previously
stored carbon into the atmosphere. It is estimated that Maryland’s 2.9
million acres of forests sequester from 1.8 to 4.1 million metric tons of
carbon per year. Using the World
Bank’s figure, Maryland’s forests have the ability to store from $23
million to $84 million worth of carbon on an annual basis.
Wildlife Habitat and
Biodiversity
Habitat loss and fragmentation
have contributed greatly to a continuing loss of biodiversity in Maryland.
At least 110 plant and 60 animal species are no longer found in
Maryland, including elk, gray wolves, bison, and mountain lions.
Another 550 plant and 250 animal species are rare, threatened, or
endangered.
Habitat Fragmentation
Habitat fragmentation is
considered to be the greatest threat to forest wildlife, and the main cause of
species extinction. Logging and logging roads increase forest fragmentation.
The US Forest Service has documented many of the problems associated with
logging roads in forests including fragmentation of species populations,
introduction of harmful diseases and alien plants into the forest, the edge
effects of sunlight penetrating the forests, and road kill. Many species
suffer due to changes in their habitat, while other edge species (such as
white-tailed deer) thrive. This disrupts the natural balance of species and
causes a variety of problems.
Logging
reduces food for wildlife by creating forests of trees too young to be able to
produce quantities of seeds or nuts upon which wildlife depend. This decreases
the ability of a forest to support a number of species.
Water Quality and Rising Temperatures
Loss of forest generally leads to a decline in water
quality and often to increased water temperatures. When impervious land cover
(pavement, houses, etc.) is above 2%, pollution-sensitive brook trout are
never found. Maryland streams are
now home to only about 300,000 brook trout, which once numbered more than
three million. Currently, very
few Maryland streams are cool enough to support brook trout. Loss of forests is a key factor in the decrease in trout
habitat.