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.”
By Desmond O’Boyle
The Forests to Faucets partnership originally began in 2010 as a response to a series of wildfires, namely the 1996 Buffalo Creek and 2002 Hayman wildfires. Since its inception, the partnership’s goals have grown to not only reduce catastrophic wildfires, but to also restore forests impacted by reservoirs, erosion and beetle devastation. On Monday, Feb 27, Forests to Faucets was granted a $33 million extension to continue its ongoing projects.
Lawrence Lujan is the regional press officer for the Rocky Mountain Region of the U.S. Forest Service, one of the organizations involved in the partnership. He says the specific strategies will be identified in a 5-year plan.
“Some of the tools in the toolbox include, thinning, prescribed fire, replanting trees, especially in areas that have been impacted by previous fires,” said Lujan. “We’ll be decommissioning roads, taking actions to minimize erosion and sedimentation of reservoirs.”
Locations for forest restoration and wildfire fuels reduction projects include Dillon, Strontia Springs, Gross, Antero, Eleven Mile Canyon, Cheesman and Williams Fork reservoirs. The partnership anticipates treating more than 40,000 acres of land.
A 10-year logging impacts study by University of Kentucky forestry researchers rates management practices used in the state’s prolific hardwood forests effective and advises only minor changes to better protect more than 90,000 streams and rivers.
The study advises doubling the minimum distance between waterways and logging roads or skid trails. Current practice is a minimum of 25 feet, or 55 feet in steeper grounds.
The combination of thriving forest industries and access to an abundance of large and small waterways makes protecting the commonwealth’s water a priority. The UK Department of Forestry has been a partner in the development of best management practices (BMPs) in woodlands since the Kentucky legislature created the Agriculture Water Quality Authority in 1994. The authority’s mission is to alleviate pollution to surface and groundwater resources from agriculture and forestry activities.
UK forestry professors, Jeff Stringer, silviculture, and Chris Barton, forest hydrology and watershed management, oversaw more than a dozen graduate students and a number of undergraduate interns from 2004 to 2014 who examined logging impacts on forest resources in eight watersheds located in Robinson Forest, the UK College of Agriculture, Food and Environment’s research and education forest in southeastern Kentucky. Loggers harvested two watersheds using the current standard for best management practices. They logged four other watersheds using two different BMP treatments that the researchers theorized would provide more protection. Two additional watersheds were left unharvested as controls.
“At the end of the day, what we saw was that our current recommended BMPs do a pretty good job of protecting our water resources,” Barton said. “With that said, we also found that the best management practice changes we made in the other watersheds actually provided some additional protection. Our BMP treatment that provided the most protection was not statistically different than the unharvested control for nearly all of the parameters examined.”
One change resulting from the study was to increase the distance between streams and skid trails and logger roads. The process of mechanically moving trees can create erosion, which ends up in streams.