The Virginia Piedmont's Forests
Forests Effect Water Quality
Forests Effect Water Quantity
Forests Effect on Air Quality
Forests and the Climate
The Importance of Forests for Wildlife Habitat


The Virginia Piedmont's Forests

Forests are the dominant land use in Virginia's northern Piedmont. Approximately 58% of the land from Loudoun County to Albemarle County is forested. However, the composition of these forests is changing. Between 2000 and 2005, Loudoun, Fauquier, and Culpeper gained forest cover, while Rappahannock, Madison, Greene and Albemarle lost up to 5% cover and Orange lost 5 - 10% cover (ASDA Forest Service/FIA 2005). Piedmont forests are also increasingly fragmented as land is permanently converted to other uses.

Forests Effect Water Quality

Forests are the most beneficial land cover for protecting and improving water quality. Forests effectively filter pollutants such as pesticides and fertilizers from agriculture and lawn care, oil runoff from roads, and deposition from polluted air. Forested land along streams or rivers is critical to successfully catching run-off before it reaches the water. Tree roots also help prevent erosion and sediment pollution by stabilizing stream banks. This natural process alleviates other forms of pollution as well, since parasites and microbes can cling to suspended soil particles in water.

Forests Effect Water Quantity

Because forests absorb precipitation, they moderate the flow of water through an area, preventing floods and droughts or reducing their severity. When rain falls onto hard, impervious surfaces it simply rushes toward the nearest waterway and this sudden deluge can cause the stream or river to overflow its banks. When rainwater is channeled rapidly downstream instead of absorbed by soil or plants, it is gone, so the area becomes vulnerable to drought. In a healthy watershed, most precipitation soaks into the ground or is stored in wetlands or absorbed by plants. The stored moisture can seep downward into aquifers from which it recharges streams, or it can be recycled through evaporation or transpiration into the air so that rain comes again.

Forests Effect Water Quantity

Trees remove pollutants such as nitrogen dioxide, carbon monoxide and sulfur dioxide from the air and generate oxygen in their place. According to The State of Chesapeake Forests (2006) report, "Forests and tree canopies absorb air pollutants that can induce asthma, cancer, and other health problems." Forests also account for most of the world's yearly photosynthesis and carbon storage, and therefore help stabilize global climate patterns.

Forests and the Climate

Forests play a major role in climatic feedback and in regulating temperature and precipitation patterns. They have a lower albedo than other land use types, meaning that they are less reflective, so they absorb incoming solar energy, making the surrounding climate cooler. Evapotranspiration occurring in forest canopies plays a critical role in circulating rainfall; when forests are cleared for other land use types, the surrounding climate becomes drier. Forests are also important carbon storage sinks. Forests account for most of the world's yearly photosynthesis and carbon storage. Photosynthesis by terrestrial vegetation removes approximately 110 billion metric tons of carbon from the atmosphere annually, roughly half of which is respired and half of which is stored in soils, sediments, and biomass. US forests sequester about 200 - 280 millions tons of carbon per year, which, depending on estimates, offset about 12- 25% of the US anthropogenic CO2 emissions. According to the Virginia Department of Forestry, Virginia forests offset nearly 20% of Virginia's CO2 emissions. Converting forests to other land uses greatly contributes to CO2 emissions as the trees are lost, debris is often burned and soil is disturbed. According to the Virginia Department of Forestry, the loss of forest and land to agricultural or urban uses contributes about 3% of Virginia's CO2 emissions each year.

The Importance of Forests for Wildlife Habitat

Hundreds of species ranging from plant to animal to insect are associated with US forested habitats. A generally accepted count is 689 tree species and 1,486 terrestrial animal species (227 mammals, 176 birds, 176 amphibians, 191 reptiles, and 475 butterflies.) Species richness varies geographically and overall biodiversity is highest in the South-in particular the Southeast. The number of mammals and forest amphibian species is highest in the Southeast compared with the rest of the nation. Fifteen percent of species at risk of extinction are associated with forest habitats. These at-risk species are concentrated geographically in Hawaii, on the West Coast, and in the Southeast.

Forest management activities that create a mosaic of habitats will generally increase biodiversity. Diversity in tree species and size classes translates into greater wildlife diversity through the variety of food sources and habitat provided. For instance, stands with fewer trees per acre allow more sunlight penetration which allows for several vertical layers to develop in the understory, thus encouraging biological diversity to develop. A critical aspect of an ecologically balanced forest is the presence of tree cavities and snags which provide food, nesting and denning sites for wildlife. A good rule of thumb is four standing snags per acre of forest. Older forests tend to support more dead trees or snags, which are important components for many nesting birds and nearly half of North America's 45 bat species.

If you have any questions regarding forests in the Piedmont region, please contact Megan Manner at (540) 347-2334 (x-25) or mmanner[at]pecva.org