By Jennifer Moore Myers
In 1989, South Carolina’s Francis Marion National Forest lost close to a third of its pine and hardwood trees to Hurricane Hugo. USDA Forest Service land managers have spent the last thirty years recovering from that disturbance and working to meet the state’s growing needs for clean water, forest products, recreation areas, and wildlife habitat.
To that end, the Francis Marion adopted a new forest plan in 2017 focused upon restoring longleaf pine, the once-dominant southern species, across 33,000 acres of national forest lands.
This goal and the management work to implement it are based on a body of experimental research about forest ecology and hydrology — much of it conducted on the Santee Experimental Forest.
The Santee sits on the west side of the Francis Marion. Established in 1937, it’s a 6,100-acre living laboratory that has hosted many long-term studies on the effects of fire, hurricanes, and forest management practices on tree growth, streamflow, and wildlife communities.
SRS scientists and national forest managers have teamed up to study the impacts of replacing existing loblolly pine stands with longleaf pine.
Earlier, fine-scale studies suggest that water yield from longleaf pine landscapes may be greater than that from loblolly pine or mixed pine and hardwood stands due to differences in forest structure and composition between the two pine environments.
“Longleaf pine restoration is a priority for the Southern Region of the National Forest System,” says research soil scientist Carl Trettin. “This project is an opportunity to advance the current science on longleaf restoration to broader scales as well as support the Region and the Forest.”
An insect infestation that is killing hemlock trees in New England forests is having a significant impact on the water resources of forested ecosystems that provide essential water supplies to one of the nation’s most populous regions, according to research by Indiana University geographers and colleagues at three universities in Massachusetts.
The study is the first to show an increase in water yield—the amount of water reaching streams and rivers—resulting from forest damage caused by an insect pest called the hemlock woolly adelgid. Insect-damaged trees use less rainfall and allow more water to reach the ground and run off into waterways. With less foliage, the trees return less moisture to the atmosphere via transpiration and evaporation.
“We observed a 15 percent increase in annual water yield,” said Taehee Hwang, an assistant professor in the Department of Geography in the IU Bloomington College of Arts and Sciences. “But there are a lot of issues involved with this subject. Water quality may suffer as rainfall runs off more quickly from forested areas and carries higher concentrations of nutrients. The long-term picture may change as hemlocks are replaced with broad-leaved trees that have a different impact on water resources.”