Summit County Citizens Voice

Forest Service researchers document trend toward more extreme weather

Forest Service research suggests that conversion from hardwood forests to pine could reduce runoff and water yield.

By Summit Voice

SUMMIT COUNTY — U.S. Forest Service researchers in western North Carolina said they’re seen a shift toward more extreme precipitation patterns since the 1980s.

“We found significant increases in temperature and in the frequency of extreme wet and dry years since the 1980s,” said  Chelcy Ford. “These findings tied with those on management and streamflow have implications for managers in any area where changes in precipitation patterns could occur.”

The scientists at the Forest Service Southern Research Station used long-term data from the 5,600-acre Coweeta Hydrological Laboratory to examine the feasibility of managing forests for water supply under the changing weather conditions forecast for the future.

Management approaches used in Coweeta watershed studies include conventional thinning strategies as well as more intensive approaches such as converting hardwood stands to pines. Partly because pines keep their needles year-round, conversion from hardwoods to pines decreases streamflow.

For this study, Coweeta researchers asked whether vegetation on managed watersheds responded differently to extreme dry and wet years than vegetation on unmanaged watersheds.

“The answer in almost all cases was yes,” Ford said. “But from a streamflow perspective, the extreme case of converting hardwood forest to pine produced the largest effect on available surface water. Though it might be a good option for mitigating climate change under future scenarios of increased precipitation, species conversion from hardwood forest to pine would be a poor choice under drier scenarios where it could worsen water shortages by reducing the amount of available water in streams.”

The study was published in the September issue of the journal Ecological Applications.

“Long-term data from experimental forests are truly the foundation of Forest Service research,” Ford said. “For this study we took one of the longest continuous records of climate and hydrology and coupled it with data from the long-term forest management experiments on the paired watersheds to look at both precipitation patterns and the feasibility of using forest management to sustain water supply.”

Land managers and policy makers are looking to forests for options to offset the effects of climate change. The Coweeta research may inform choices that could help make ecoystems more resilient to the weather effects of a changing climate,

Ford and her fellow authors concluded that land managers must look closely at the risks and vulnerabilities involved in managing for climate change, especially in relation to water supply.

“Managers need to carefully weigh the risks of adopting one strategy over another,” Ford said. “They also need to realize that any strategies they consider will have to address these risks at the regional or even more fine-scaled level, taking into account possible changes to local precipitation patterns.”

Filed under: climate and weather, Environment, forests, global warming, US Forest Service Tagged: | climate, Forest health, Forest management, forests, global warming, U.S. Forest Service, United States Forest Service