CORVALLIS, Ore. June
3, 2013. A new analysis led by the U.S. Forest Service’s
Pacific Northwest Research Station encourages resource managers
to consider a broadened view of forests as consumers of water.
A shift in thinking toward reducing the risk of water stress to
vegetation can help forests maintain their resilience and health
in a changing
climate, according to a paper published online in the journal Frontiers
in Ecology and the Environment.
“Our work emphasizes how forests primarily need and consume
water, and so managing forest health requires thinking about how
is available for forests, how forests use that water, and how management
strategies can mitigate increasing drought stress,” said
station research hydrologist Gordon Grant, who led the analysis.
More than half of the U.S. water supply comes from forest lands
where most precipitation falls, filters through soil, and, ultimately,
becomes streamflow. Current research demonstrates that many of
growing threats facing forests, like wildfire and insect outbreaks,
are linked to water stress from combinations of drought and a warming
climate. Climate change is projected to increase forest water stress
in many areas.
Along with co-authors Christina Tague, from the
University of California, Santa Barbara; and Craig Allen, from
the U.S. Geological Survey,
Grant reviewed a range of studies—mostly from the western
U.S. and in drought-stressed forests—to identify management
strategies that may retain water for forests, such as thinning
and soil water
Then, to demonstrate the potential effects of water-enhancing
strategies, the researchers used a model of vegetation, water,
and carbon cycling
on a forest site in New Mexico’s Bandelier National Monument,
which recently experienced a multi-year drought and associated
tree mortality. Modeling revealed that substantial ponderosa pine
during the 2002-2003 drought might have been prevented by small
increases in plant-available water via forest thinning, mulching
evaporation from the soil, or irrigation.
“Many of the strategies for addressing increased drought stress are
consistent with established forest management objectives and practices,
but increasing water availability to forests through the use of
specifically designed management activities has not been an explicit goal,” Grant
said. “Ultimately, these strategies would need to be tailored
to particular management objectives and landscapes.”
The Pacific Northwest Research Station—headquartered in Portland,
Oregon—generates and communicates scientific knowledge
that helps people make informed choices about natural resources
the environment. The station has 11 laboratories and centers
located in Alaska, Washington, and Oregon and about 390 employees.