Environmental News
Environmental News from Boulder, Colorado
CU researchers: Beetle killed trees are better than logging for watersheds
Jan 14th
buffers watersheds from nitrate pollution
A research team involving several scientists from the University of Colorado Boulder has found an unexpected silver lining in the devastating pine beetle outbreaks ravaging the West: Such events do not harm water quality in adjacent streams as scientists had previously believed.
According to CU-Boulder team member Professor William Lewis, the new study shows that smaller trees and other vegetation that survive pine beetle invasions along waterways increase their uptake of nitrate, a common disturbance-related pollutant. While logging or damaging storms can drive stream nitrate concentrations up by 400 percent for multiple years, the team found no significant increase in the nitrate concentrations following extensive pine beetle tree mortality in a number of Colorado study areas.
“We found that the beetles do not disturb watersheds in the same way as logging and severe storms,” said Lewis, interim director of CU’s Cooperative Institute for Research in Environmental Sciences. “They leave behind smaller trees and other understory vegetation, which compensate for the loss of larger pine trees by taking up additional nitrate from the system. Beetle-kill conditions are a good benchmark for the protection of sub-canopy vegetation to preserve water quality during forest management activities.”
A paper on the subject was published in the Jan. 14 issue of the Proceedings of the National Academy of Sciences.
“The U.S. Forest Service and other agencies have established harvesting practices that greatly mitigate damage to forests caused by logging, and they deserve credit for that,” said Lewis. “But this study shows just how important the survival of smaller trees and understory vegetation can be to stream water quality.”
In waterways adjacent to healthy pine forests, concentrations of nitrate is generally far lower than in rivers on the plains in the West like the South Platte, said Lewis. Nitrate pollution is caused by agricultural runoff from populated areas and by permitted discharges of treated effluent from water treatment facilities.
“In Colorado, many watersheds have lost 80 to 90 percent of their tree canopy as a result of the beetle epidemic,” said Lewis, also a faculty member in CU-Boulder’s ecology and evolutionary biology department. “We began to wonder whether the loss of the trees was reducing water quality in the streams. We knew that forestry and water managers were expecting big changes in water quality as a result of the pine beetle outbreak, so we decided to pool our university and federal agency resources in order to come up with an answer.”
Study co-author and CU-Boulder Research Associate James McCutchan of CIRES said the new results should help forest managers develop more effective ways to harvest timber while having the smallest effect possible on downstream ecosystems. “This study shows that at least in some areas, it is possible to remove a large part of the tree biomass from a watershed with a very minimal effect on the stream ecosystem,” he said.
Understory vegetation left intact after beetle outbreaks gains an ecological advantage in terms of survival and growth, since small trees no longer have to compete with large trees and have more access to light, water and nutrients, said McCutchan. Research by study co-author and former CU undergraduate Rachel Ertz showed concentrations of nitrate in the needles of small pines that survived beetle infestations were higher than those in healthy trees outside beetle-killed areas, another indication of how understory vegetation compensates for environmental conditions in beetle kill areas.
The researchers used computer modeling to show that in western forests, such a “compensatory response” provides potent water quality protection against the adverse effects of nitrates only if roughly half of the vegetation survives “overstory” mortality from beetle kill events, which is what occurs normally in such areas, said Lewis.
Other study co-authors included Leigh Cooper, Thomas Detmer and Thomas Veblen from CU-Boulder, John Stednick from Colorado State University, Charles Rhoades from the U.S. Forest Service, Jennifer Briggs and David Clow from the U.S. Geological Survey and Gene Likens of the Cary Institute of Ecosystem Studies in Millbrook, N.Y.
The severe pine beetle epidemic in Colorado and Wyoming forests is part of an unprecedented beetle outbreak that ranges from Mexico to Canada. A November 2012 study by CU-Boulder doctoral student Teresa Chapman showed the 2001-02 drought greatly accelerated the development of the mountain pine beetle epidemic.
The researchers measured stream nitrate concentrations at more than 100 sites in western Colorado containing lodgepole pines with a range of beetle-induced tree damage. The study area included measurements from the Fraser Experimental Forest near Granby, Colo., a 23,000-acre study area established by the USFS in 1937.
The new study was funded by the USFS, the USGS, the National Science Foundation, the National Oceanic and Atmospheric Administration and the National Park Service. CIRES is a joint research institute between CU-Boulder and NOAA.
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Boulder County Commissioners reject agreement with Denver Water Board on the proposed Gross Reservoir expansion
Jan 8th
After hearing to more than six hours of public testimony over a span of two public hearings – Dec. 20 and Jan. 7 – and receiving more than 200 written communications from Boulder County residents, the Board of County Commissioners unanimously decided not to support the IGA.
The intergovernmental agreement was signed by the Denver Water Board on December 19, 2012, and would have served in lieu of review of the reservoir expansion project under the Boulder County Land Use Code. The IGA had been negotiated by the staffs of Boulder County and Denver Water as a way to address the impacts of the project and to define appropriate mitigation measures, but ultimately didn’t go far enough in protecting the quality of life for residents in the area in the opinion of the County Commissioners.
While they acknowledged some benefits that would result from the proposed agreement, the County Commissioners indicated that the terms of the proposed agreement did not do enough to protect the health, safety and welfare of their constituents or the environment and that they thought it was premature to enter into any agreement before the release of the Final Environmental Impact Statement, which is due later in 2013.
Following the release of the final EIS, the commissioners will work with county staff on a thorough response to the findings, and continue to work with members of the public to address ongoing concerns about the impacts of the proposed project.
Visit www.bouldercounty.org/property/build/pages/moffatgrossiga.aspx for more information. To view the archived video from last night’s hearing, visit the hearings page and select the business meeting for Jan. 7 at www.bouldercounty.org/gov/meetings/pages/hearings.aspx.
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Boulder county commissioners take oil and gas panel to task over water-testing
Jan 7th
Boulder County – Earlier today, the Colorado Oil and Gas Conservation Commission (COGCC ) adopted a new rule for groundwater testing that has been deemed one of the weakest in the nation by citizens and environmental advocates:
“The Boulder County Commissioners are extremely disappointed that the Colorado Oil and Gas Conservation Commission has decided against putting in place a science-based groundwater protection plan to ensure oil and gas development will not have a detrimental impact to the state’s groundwater resources.
This is especially true in the Greater Wattenberg Area, a large geographic area that includes parts of eastern Boulder County and is exempted wholesale from the statewide rule, making this significant expanse of land subject only to a cursory testing requirement despite having some of the most intensive drilling activity in the state.
This type of rulemaking at the state level is a prime example of why local governments should be able to respond directly to their citizens’ concerns and provide for their community’s request for more protection.”
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