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Water Yields from Southern Appalachian Watersheds in Decline since the 1970s
http://www.srs.fs.usda.gov/news/613[font face=Serif][font size=5]Water Yields from Southern Appalachian Watersheds in Decline since the 1970s[/font]
[font size=4]Climate change and gradual shifts in forest structure implicated[/font]
June 1, 2016
[font size=3]Otto, NC — In the densely populated southeastern U.S., forested watersheds are particularly important to drinking water supplies. Recent estimates show that forests in the Southeast deliver surface drinking water to an estimated 48.7 million people, with streams from the mountainous Southern Appalachian region alone providing water supplies to 10 million people, many of them living in major cities such as Atlanta, Georgia.
Newly published research from the U.S. Forest Service shows water yields from unmanaged forested watersheds in the southern Appalachian Mountains declining by up to 22 percent a year since the 1970s. Changes in water yield were largely related to changes in climate, but disturbance-related shifts in forest species composition and structure over time also played a role. The study findings have implications for managing the forest composition of watersheds to ensure water supply under future climate change.
"Climate and land use change have long been linked to changes in water yield," said Peter Caldwell, research hydrologist for the Forest Service Southern Research Station (SRS) and primary author of the article recently published in the journal Global Change Biology. "This study is one of the first to show that gradual and subtle changes in forest structure and species composition, driven by climate change -- as well as invasive insects and pathogens that act on a fraction of tree species within a forest -- can also affect water yield."
The scientists analyzed 76 years of data (1938 through 2013) collected from six unmanaged, reference watersheds at the SRS Coweeta Hydrologic Laboratory located in the southern Appalachian Mountains in North Carolina, to determine whether annual water yield from those watersheds has changed over time, and if so, to determine causes for significant changes. They tied measurements of climate and streamflow to data collected in long-term vegetation plots and measurements of water use by individual tree species.
…[/font][/font]
[font size=4]Climate change and gradual shifts in forest structure implicated[/font]
June 1, 2016
[font size=3]Otto, NC — In the densely populated southeastern U.S., forested watersheds are particularly important to drinking water supplies. Recent estimates show that forests in the Southeast deliver surface drinking water to an estimated 48.7 million people, with streams from the mountainous Southern Appalachian region alone providing water supplies to 10 million people, many of them living in major cities such as Atlanta, Georgia.
Newly published research from the U.S. Forest Service shows water yields from unmanaged forested watersheds in the southern Appalachian Mountains declining by up to 22 percent a year since the 1970s. Changes in water yield were largely related to changes in climate, but disturbance-related shifts in forest species composition and structure over time also played a role. The study findings have implications for managing the forest composition of watersheds to ensure water supply under future climate change.
"Climate and land use change have long been linked to changes in water yield," said Peter Caldwell, research hydrologist for the Forest Service Southern Research Station (SRS) and primary author of the article recently published in the journal Global Change Biology. "This study is one of the first to show that gradual and subtle changes in forest structure and species composition, driven by climate change -- as well as invasive insects and pathogens that act on a fraction of tree species within a forest -- can also affect water yield."
The scientists analyzed 76 years of data (1938 through 2013) collected from six unmanaged, reference watersheds at the SRS Coweeta Hydrologic Laboratory located in the southern Appalachian Mountains in North Carolina, to determine whether annual water yield from those watersheds has changed over time, and if so, to determine causes for significant changes. They tied measurements of climate and streamflow to data collected in long-term vegetation plots and measurements of water use by individual tree species.
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