Treesearch

This chapter presents a synthesis of current computer modeling tools that are, or could be, adopted for use in evaluating the cumulative watershed effects of fuel management. The chapter focuses on runoff, soil erosion, and slope stability predictive tools. Readers should refer to chapters on soil erosion and stability for more detailed information on the physical processes involved.

Considerable effort is devoted to evaluating cumulative watershed impacts during planning for forestry activities on federally managed lands. With the recently increased emphasis on reducing forest fuels, cumulative impact analyses must now evaluate a new suite of activities over a broader scale than had generally been considered in the past. It is useful to review the concept of cumulative impacts and the variety of methods used for impact analysis to identify approaches capable of addressing the new challenges.

Fuels management is an active term. It is an intentional, planned activity defined by consideration of fire behavior, silvicultural principles, ecological constraints, and the economic and technical limitations of the tools selected to implement the treatment. A forest operation is a tool used to manipulate vegetation or site condition in order to achieve some desired management objectives. Given the wide range of forest operations that can be employed to treat forest fuel, it is imperative to employ a tool that is well-matched to both operational needs and treatment constraints. Selecting...

As the severity and extent of wildfires increase, efforts to reduce forest densities on public lands by thinning and prescribed burning also are increasing. The intentional suppression of fires in the western United States, beginning in the early 1900s, has altered the extent, frequency, and severity of wildfires (Agee 1993; Baker 1993). Reductions in timber harvest and in grazing, when combined with the suppression of wildfires, have resulted in higher fuel loadings, which increase the risk of high severity wildfires (Norris 1990). Changes in the fire regime may also cause vegetation...

There have been numerous studies worldwide demonstrating that changes in forest density can cause a change in water yield. Bosch and Hewlett (1982), Hibbert (1967), Stednick (1996) and Troendle and Leaf (1980) have summarized the findings from most of these studies. In general, as Hibbert (1967) observed, reducing forest cover increases water yield; establishing forest cover on sparsely vegetated land decreases water yield; and response to treatment is highly variable and, for the most part, unpredictable.

Fuel management practices in the Rocky Mountain region may include prescribed fire, timber harvesting (patch cuts, thinning, high-grading, or selective logging), mechanical treatments (mulching, chipping or chunking), chemical treatments, or grazing to reduce undesirable species (Chapter 4). The application of any of these treatments has the potential to affect water quality. Understanding the effects of land use practices on hydrologic processes is of primary importance when assessing water quality effects. Unlike agriculture where there are often many activities each year, fuel management...

Soil quality, function, and productivity potential are interrelated concepts that cover the range of soil properties and their associated ecological processes. Since the passage of the National Forest Management Act in 1976 (NFMA) and related legislation, management of National Forest lands must be done is such a way as to maintain their productive potential as demonstrated through implementation, effectiveness, and validation (research) monitoring. However, the concept of site productivity is not well defined, and the impacts of timber removal or fire on soil productive potential are not...

A significant increase in fuel management treatments is underway as the Forest Service and other natural resource agencies implement the National Fire Plan (USDA USDI 2001), the Healthy Forests Restoration Act (GAO 2003; HFRA 2003), and the President’s Healthy Forest Initiative (Dombeck and others 2004; Graham and others 2004; Stephens and Ruth 2005). One of the four goals of the National Fire Plan Comprehensive Strategy is to reduce hazardous fuel, thus potentially decreasing the risk of severe wildfire and modifying fire behavior so that some wildland fires may be more readily and safely...

Aquatic communities in North America evolved with disturbance regimes (for example, glaciation, erosion, tectonics, volcanism, fire) that varied in frequency, intensity, and severity (Poff 1992; Power and others 1988; Resh and others 1988). Disturbance has been recognized for its importance in the organization and maintenance of aquatic ecosystems (Reeves and others 1995), in shaping species resilience and persistence (Reice and others 1990; Yount and Niemi 1990), and structuring the evolution of aquatic organisms (Lake 2000; Malanson 1984; Schlosser 1990; Sedell and others 1990). Disturban...

Fire suppression in the last century has resulted in forests with excessive amounts of biomass, leading to more severe wildfires, covering greater areas, requiring more resources for suppression and mitigation, and causing increased onsite and offsite damage to forests and watersheds. Forest managers are now attempting to reduce this accumulated biomass by thinning, prescribed fire, and other management activities. These activities will impact watershed health, particularly as larger areas are treated and treatment activities become more widespread in space and in time. Management needs,...