you ever walked from bright sunlight into the full shade of the
woods? On all but the most humid days, it feels as though someone
turned on the A/C. It can be 10-25 degrees cooler in the shade of a
tree than in full sun. Moisture added to the air as the tree
transpires increases this cooling effect. Some researchers have
found even more dramatic temperature reductions. Properly sited
shade trees can reduce electric bills and carbon dioxide emissions.
In the northern hemisphere, deciduous shade trees sited to the south
and west of buildings provide shade from the heat of the day in
summer. When leaves drop in fall, they allow the sun to shine
through, providing savings on heating costs. Evergreen trees planted
as windbreaks on the west side of a building can reduce heating
costs by 25 percent.
ecological benefits provided by large shade trees do not stop there.
They improve air quality by absorbing pollutants such as ozone and
nitrogen dioxide. They also intercept particulate matter from
industrial emissions, smoke, dust and pollen. Trees sequester carbon
dioxide by fixing carbon during photosynthesis and storing it as
biomass. While younger, very actively growing trees have higher
sequestration rates, roughly half the dried weight of a tree is
carbon, and so a big shade tree is keeping a lot of carbon tied up.
big concern for many urban areas is stormwater mitigation. Like many
older cities, the greater Pittsburgh area is under a consent decree
to stop combined sewer overflows into our three rivers. The danger
of these overflows to drinking water and recreational users is
substantial. In addition, storm events often cause localized
flooding that results in property damage and even fatalities.
Engineered or “gray” solutions are going to be very expensive for
everyone, and green infrastructure is one way to make those costs
Allegheny River in Pittsburgh
Some communities have already enacted stormwater fees to help pay
for upgrades to outdated sewage systems, and this trend is expected
to grow. Residential and commercial property owners can get a break
on these fees in many cases if they install green infrastructure or
take other steps to reduce impervious surfaces on their property.
Trees are big part of the solution because they intercept rainfall
with their foliage and branches, slowing its fall so that it has a
chance to be absorbed by the soil. When rain falls on impervious
surfaces, it runs off rapidly, causing erosion and carrying
pollutants and sediment into our waterways. Trees protect and
improve water quality by filtering stormwater and absorbing it with
their root systems. The bigger the tree, the bigger the benefits in
terms of managing stormwater.
Pin Oak in the front yard of a home
Properly sited and well-maintained trees – especially large shade
trees – can increase the sale price of otherwise identical houses by
an average of 5 percent. Many studies correlate shorter hospital
stays, reduced stress and lower crime rates with tree-lined streets
Trees also provide habitat for wildlife, from songbirds to
squirrels. In addition, they support a diverse community of insects,
many of which are beneficial and help keep insect pests in check.
Insects are also an important food source for baby songbirds; even
those that eat fruits and seeds as adults depend on the protein from
insects when they are young.
Trees offer beauty with flowers, attractive foliage that often
explodes in a riot of color in fall, and many have attractive fruit
or bark that offers winter interest. Plant a tree and reap the
Deicer & snow melter descriptions
Mulching leaves into your lawn