Aquatic Ecosystems and Forest Thinning to Reduce Fires
Watershed Impacts of Forest Treatments to Control Wildfire
PRC releases landmark science report
Over the past decade, the debate over public forestlands management has centered on fire-and-fuels issues. While fuel reduction treatment or thinning has become the dominant forest management approach for public lands, the watershed impacts of this approach have been minimized, dismissed, and often ignored by many of those responsible for policy and on-the-ground decisions. Because of this conspicuous silence on the impacts to aquatics, Pacific Rivers Council commissioned consulting hydrologist Jonathan J. Rhodes to:
1) review the scientific literature;
2) examine a sampling of actual fuel treatment projects;
3) assess the potential impacts of fuel treatments relative to those of fire;
4) conduct a statistical analysis of the probability that treatments will effectively reduce fire severity in different forest types, based on historical fire occurrence data and duration of any fuel-reduction effectiveness;
5) develop recommendations for minimizing watershed impacts from fuel treatments.
The resulting peer-reviewed report, The Watershed Impacts of Forest Treatments to Reduce Fuels and Modify Fire Behavior, (February 2007) is the first of its kind to address in-depth how fuel treatments impact Western aquatic ecosystems.
Background
Forest fuel reduction treatments (thinning and other practices) aimed at modifying wildland fire behavior have been promoted for extensive implementation on Western public lands in an attempt to reduce fire severity and size. Unfortunately, mechanical fuel reduction treatments involve the same suite of activities as other types of logging, with the same set of impacts to soils, runoff, erosion, sedimentation, water quality, and stream structure and function. These treatments and the associated road system incur ecological costs because they involve a significant amount of damage to soils, vegetation, and hydrologic processes.
The impacts of fuel treatments on watersheds are especially of concern because aquatic systems are significantly and pervasively degraded, and many populations of aquatic species (including native trout and other salmonids) are highly imperiled and/or have experienced severe declines. Additional damage to aquatic systems further reduces the prospects for their persistence.
Report Findings
The report finds that the ecological costs of extensive thinning and other treatments are virtually inevitable: first, because many proposed projects necessarily involve repeated entries into the same area, which raises the scale of cumulative effects and effective level of disturbance; second, because (like other logging activities) the treatments damage soils, cause erosion, disrupt streamflows, and damage riparian areas; and third, the treatments fail to address the actual dominant causes of watershed degradation, such as road building and grazing.
Based on a detailed statistical analysis of a large body of fire data spanning many years, the report finds that mechanical fuel treatments are extremely unlikely to reduce the intensity of so-called catastrophic fires. In addition, the analysis found that only in a small number of cases would treated areas likely be in the path of intense fire over their intended lifetimes (i.e., the period of time after treatment when fuels are reduced). In other words, it is highly unlikely that a fire will burn through a treated area, and even if it does the treatment probably won't have any influence over the behavior of the fire.
The report concludes with a precise set of recommendations to reduce the ecosystem damage from mechanical fuel treatments, including limiting treatments in the most sensitive portions of watersheds and prohibiting the most destructive fuel treatment activities.
Download a two page summary of the report.
Download the full report.
PRC gratefully acknowledges the following foundations for their support of this paper:
Brainerd Foundation, Bullitt Foundation, Flintridge Foundation, General Service Foundation, Harder Foundation, Lazar Foundation, Mead Foundation, Weeden Foundation, Wilburforce Foundation
Other Materials:
Read about PRC efforts to provide advice on proposed legislation that promotes large-scale thinning projects.
Read a recent publication co-authored by PRC's Chris Frissell regarding current proposals to replace the Northwest Forest Plan with a plan focused on intensive thinning.
To read an abstract for the Bend Forest Stewardship conference prepared by Chris Frissell in September 2008, click here.
PRC Editorial Published in Oregonian, "Managing the Forests Defining clear policy for fighting forest fires"
Read our 2002 comments to Representative DeFazio regarding the current fire management debate.
Read our 2000 press release regarding a scientific report that shows logging and road building will not protect forests from fire.
Learn more about Post-Fire Management and Sound Science.
