Science Basis For Changing Forest Structure To Modify Wildfire Behavior And Severity

This report describes the kinds, quality, amount, and gaps of scientific knowledge for making informed decisions on fuel treatments used to modify wildfire behavior and effects in dry forests of the interior Western United States (especially forests dominated by ponderosa pine and Douglas-fir). A review of scientific principles and applications relevant to fuel treatment primarily for the dry forests (ponderosa pine and Douglas-fir dominated) of the Western United States is provided for the following topics: fuels, fire hazard, fire behavior, fire effects, forest structure, treatment effects and longevity, landscape fuel patterns, and scientific tools useful for management and planning.

This synthesis provides an ecological foundation for management of the diverse ecosystems and fire regimes of North America, based on scientific principles of fire interactions with vegetation, fuels, and biophysical processes. Although a large amount of scientific data on fire exists, most of those data have been collected at small spatial and temporal scales. Thus, it is challenging to develop consistent science-based plans for large spatial and temporal scales where most fire management and planning occur. Understanding the regional geographic context of fire regimes is critical for developing appropriate and sustainable management strategies and policy. The degree to which human intervention has modified fire frequency, intensity, and severity varies greatly among different ecosystems, and must be considered when planning to alter fuel loads or implement restorative treatments. Detailed discussion of six ecosystems--ponderosa pine forest (western North America), chaparral (California), boreal forest (Alaska and Canada), Great Basin sagebrush (intermountain West), pine and pine-hardwood forests (Southern Appalachian Mountains), and longleaf pine (Southeastern United States)-- illustrates the complexity of fire regimes and that fire management requires a clear regional focus that recognizes where conflicts might exist between fire hazard reduction and resource needs. In some systems, such as ponderosa pine, treatments are usually compatible with both fuel reduction and resource needs, whereas in others, such as chaparral, the potential exists for conflicts that need to be closely evaluated. Managing fire regimes in a changing climate and social environment requires a strong scientific basis for developing fire management and policy.

The second edition of Mixed Severity Fires: Nature’s Phoenix focuses on wildfire as a keystone ecological process that has shaped plant and animal communities for over 400 million years. The book will describe the renewal process that follows wildfires in forests and chaparral ecosystems as "nature’s phoenix" by drawing from examples of wildfire effects in several regions of the world.In addition, the book will describe management and policies that have contributed to wildfire problems, including climate change and land-use practices incompatible with nature’s phoenix and what must happen to get to coexistence with wildfires that are not going away no matter how much we try to suppress or alter fire behavior. This second edition of Mixed Severity Fires: Nature’s Phoenix provides a comprehensive reference for documenting and synthesizing fire's ecological role. Comprehensive and complete reference on wildfire ecology that includes the latest science and citations Debunks debates on wildfire management that can be used by conservation groups and decision-makers to shift egregious wildfire policies Contains a broad synthesis of the ecology of mixed- and high-severity fires, covering such topics as vegetation, birds, mammals, insects, aquatics, and management actions

Fire, in conjunction with landforms and climate, shapes the structure and function of forests throughout the Western United States, where millions of acres of forest lands contain accumulations of flammable fuel that are much higher than historical conditions owing to various forms of fire exclusion. The Healthy Forests Restoration Act mandates that public land managers assertively address this situation through active management of fuel and vegetation. This document synthesizes the relevant scientific knowledge that can assist fuel-treatment projects on national forests and other public lands and contribute to National Environmental Policy Act (NEPA) analyses and other assessments. It is intended to support science-based decisionmaking for fuel management in dry forests of the Western United States at the scale of forest stands (about 1 to 200 acres). It highlights ecological principles that need to be considered when managing forest fuel and vegetation for specific conditions related to forest structure and fire hazard. It also provides quantitative and qualitative guidelines for planning and implementing fuel treatments through various silvicultural prescriptions and surfacefuel treatments. Effective fuel treatments in forest stands with high fuel accumulations will typically require thinning to increase canopy base height, reduce canopy bulk density, reduce canopy continuity, and require a substantial reduction in surface fuel through prescribed fire or mechanical treatment or both. Long-term maintenance of desired fuel loadings and consideration of broader landscape patterns may improve the effectiveness of fuel treatments.