Sustain Our Nation's Forests and Grasslands

Beyond Property Lines: A look at the importance of sustaining family forests

NORTH CAROLINA – Family forests have an enormous capacity to provide ecosystem services such as clean air and water, timber and non-timber forest products, wildlife habitat, scenic beauty and recreation.

According to USDA Forest Service research, sustaining these services depends on not only the condition of individual family forests but also the characteristics of bordering lands. “If the expansion of an urban area results in the loss of forest or if forest land is converted to farm land, an adjacent family forest’s ability to sustain ecosystem services is threatened,” says Kurt Riitters, research ecologist with the Eastern Forest Environmental Threat Assessment Center and the lead author of a study published in the journal Landscape and Urban Planning.

Riitters and co-author Jennifer Costanza, a North Carolina State University landscape ecologist and Center cooperator, assessed the threats to family forests by measuring changes in the landscape around them over a 10-year period.

They focused on changes in interior forest (unfragmented areas that maintain critical habitat and ecological functions) and human interface zones — areas bordering family forests that comprise urban development and agricultural operations.

The researchers consulted 2005 data from the Forest Inventory and Analysis program. For more than 132,000 FIA data collection plots, they categorized lands as family forests, non-family forests and public forests.

According to the 2005 FIA data, family forests covered 43 percent of total U.S. forest area, with more family forest area concentrated in the East. The researchers examined the patterns of areas around family forests.

By 2011, 46 percent of family forest land area was in a human interface zone, an increase of 1.5 percent since 2001. In comparison, 19 percent of non-family forest area and six percent of public forest area was in a human interface zone. Thirty-three percent of family forest area was in an agricultural interface, a zone that has been linked to ignition of wildland fires.

The study also identified broad areas where conservation of family forests, and interior forest in particular, could be targeted and leveraged to achieve far-reaching impacts. These areas include the eastern Great Plains steppe and parkland, Midwest broadleaf forest and the California coast, where interior forests are relatively rare, as well as most of the eastern U.S., where family forests dominate the landscape.

Knowledge of landscape patterns is essential when assessing forest sustainability, because patterns create, mediate, facilitate and impede ecosystem services that are essential for maintaining human well-being. This study can be a step toward assessing the sustainability of family forests and the ecosystem services they provide.

When forest is lost due to urban expansion, an adjacent family forest’s ability to sustain ecosystem services is threatened. Photo courtesy of Larry Korhnak, Interface South.