New report: Greatest value of forests is sustainable wa...(ater supplies from forests due to climat...)

Among the findings of the report:

• Forests cover about one-third of the nation's land area, and although they have roles in timber production, habitat, recreation and wilderness, their most important output may be water.

• Forests provide natural filtration and storage systems that process nearly two-thirds of the water supply in the U.S.

• Demand for water continues to rise due to population growth, while forest acreage is declining and remaining forest lands are threatened by climate change, disease epidemics, fire and global climate change.

• Forest vegetation and soils, if healthy and intact, can benefit human water supplies by controlling water yield, peak flows, low flows, sediment levels, water chemistry and quality.

• Increases in water yield after forest harvesting are transitory; they decrease over time as forests re-grow, and in the meantime water quality may be reduced.

• Impervious surfaces such as roads and road drainage systems increase overland flow, deliver water directly to stream channels, and can increase surface erosion.

• Forest chemicals, including those used to fight fire, can adversely affect aquatic ecosystems, especially if they are applied directly to water bodies or wet soil.

• One of the biggest threats to forests, and the water that derives from them, is the permanent conversion of forested land to residential, industrial and commercial uses.

The report also outlined a number of research needs for the future, especially to improve specific predictions about the implications of forest harvests, disturbances by fire, insects and disease, climate change, land development, and sh
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