CBF-PA: Trees Are A Cool Solution To Water Pollution

By Harry Campbell, PA Executive Director, Chesapeake Bay Foundation

These arid days of summer aren’t so dogged, spent under the cool canopy of an old oak tree, a cold drink in hand, and a refreshing breeze on your face.

While looking for relief and grabbing some shade, we might pause to appreciate the health, economic, and esthetic values that trees add to our lives.

Planting trees as streamside buffers is one of the most affordable ways to reduce the harmful runoff of nitrogen, phosphorus, and sediment that pollutes Pennsylvania waters.

The Commonwealth is lagging well behind in its goals to reduce pollution of its streams and rivers and ultimately, the Chesapeake Bay.

To get back on track, the Pennsylvania must reduce nitrogen pollution by an additional 14.6 million pounds, or 22 percent, by the end of this year.

Trees and their roots can filter as much as 60 percent of nitrogen, 40 percent of phosphorus, and nearly half of sediment in runoff. A single mature oak tree can absorb over 40,000 gallons of water per year.

Trees are the answer to multiple pollution reduction challenges in the Commonwealth. To meet its commitments by 2017, Pennsylvania must also add 22,000 acres of forest and grass buffers to Penn’s Woods. Another very tall task.

Streamside buffers also help reduce erosion, and provide shade, critical food, and shelter for wildlife. Trees stabilize stream banks and lower water temperatures which are vital to a thriving aquatic ecosystem.

Enhanced by the presence of trees, microbes and insects like caddisflies, stoneflies and mayflies in cool, wooded streams consume runoff nutrients and organic matter. Some native mayflies, for example, thrive at 68 degrees but perish at 70.

Native brook trout flourish in cool, clean water and are returning to streams where buffers have been installed.

Trees are also valuable around the home. When included in urban and suburban landscaping, trees absorb pollution and provide shade. A single large tree in the front yard can intercept 760 gallons of water in its crown, reducing stormwater runoff. The beauty of trees is evident in every neighborhood.

Trees provide benefits wherever they stand. The U.S. Department of Agriculture reports that one acre of forest can absorb six tons of carbon dioxide and put out four tons of oxygen, enough to meet the annual needs of 18 people.

Trees have economic benefits. The U.S. Forest Service reports that healthy, mature trees add an average of 10 percent to a property’s value, and when placed around buildings can reduce air conditioning needs by 30 percent.

Native plants are preferred and more than 130 native tree species grow across Pennsylvania. Popular types include the oaks, hickories, maples, dogwood, red bud, sycamore, and honey-locust.

Late summer and early fall are optimum months to plant trees in order to take advantage of cooler soil temperatures and the ability of trees to establish strong root systems.

In the meantime, enjoy the shade. Summer is the ideal time to consider new plantings and how and where more trees will make our lives better.