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1974 USDA FOREST SERVICE GENERAL TECHNICAL REPORT PNW-24 This file was created by scanning the printed publication. Text errors identified by the software have been corrected; however, some errors may remain. PACIFIC NORTHWEST , FOREST AND RANGE EXPERIMENT STATION U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICE PORTLAND, OREGON ABSTRACT Forest land generally produces considerable woody material other than that which is harvested as timber, needed for recycling of nutrients to the soil , or for sheltering wildlife and young forest seedlings. Excess forest residues, both living and dead, 'are often subject to treatment to reduce fire hazard, to eliminate obstruction to use and protection of the forest, and to remove unsightly accumulations of residue remaining after logging, road construction, or land clearing, or from thinning and pruning. The effects of these residues and of their treatment are frequently important , generally unmeasured, and are only poorly known. In this compendium, 27 research scientists have summarized the present state of knowledge of the effects of forest residues and residue treatments on the components of the forest environment: soil, water, air, fire, scenery, plant and forest growth, animal habitat, insects, and disease. In addition, they have questioned some current practices and have identified areas for research attention where current knowledge is lacking. Keywords: Environmental effects; forest residues--brush, slash; forest residue treatment--mechanical , prescribed burning; silviculture; coni ferae; Pacific Northwest; recommended research; fuel management. Mention of companies or products by name does not constitute an endorsement by the U.S. Department of Agriculture, nor does it imply approval of the product to the exclusion of others which may also be suitable. For Sale by Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock No. 0101-00389 MARGIN INDEX--Bend book and follow margin index to page with black edge marker. MANAGEMENT AND RESEARCH IMPLICATIONS SO1L MICROBES SOIL PROCESSES AND INTRODUCED CHEMICALS SOIL STABILITY AND WATER YIELD AND QUALITY FISH HABITAT AIR QUALITY INFLUENCES FIRE HAZARD AND CONFLAGRATION PREVENTION RECREATIONAL AND ESTHETIC CONSIDERATIONS BRUSHFIELD RECLAMATION AND TYPE CONVERSION REGENERATION ANT, GROWTH OF COASTAL DOUGLAS-FIR REGENERATION AND GROWTH OF WEST-SIDE MIXED CONIFERS NATURAL REGENERATION OF EAST-SIDE CONIFER FORESTS ARTIFICIAL REGENERATION MICROCLIMATE mrmL PoPuuTroNs AND DAMAGE HABITAT OF GRAZING ANIMALS DE CAY INSECTS AND OTHER ARTHROPODS DISEASES GLOSSARY METRIC CONVERSION FACTORS USDA Forest Service General Technical Report PNW-24 ENVIRONMENTAL EFFECTS OF FOREST RESIDUES MANAGEMENT IN THE PACIFIC NORTHWEST A State-of-Knowledge Compendium OWEN P. CRAMER . Organizer and Technical Editor 1974 PACIFIC NORTHWEST FOREST AND RANGE EXPERIMENT STATION Robert E. Buckman, Director Portland, Oregon FOREST SERVICE U.S. Deparbnent of Agriculture This Compendium is about the many important influences of natural and manmade forest residues on the*forests of the Northwest. The creation of residues is a normal part of harvest cutting, thinning, right-of-way clearing, and other cultural activities. Whether we call it brush or forest fuel or slash is of little consequence. By any name it presents both a challenge and an opportunity to land managers. Forest residues may simultaneously represent a major conflagration potential , an esthetics problem, an important source of soil nutrient, a factor in the habitat of forest regeneration as well as wildlife, and a source of raw materials for forest industries. Considered up to now primarily as the forester's solid waste disposal and potential air pollution problem, residues management affects many facets of forestry. It is time to take an integrated approach to both research and management of forest residues. In this Compendium we present a foundation of current knowledge on which the research and development work of our Forest Residues Reduction Program, already started, will continue to build. And forest managers will profit from decisionmaking aids currently being developed from this knowledge base; for example, guidelines for residue management in the forest environments of the Pacific Northwest are being compiled for publication in a separate document. The effects of forest residues and their treatments should influence how the forest manager provides for forest regeneration and growth while maintaining the other biological , physical , and esthetic components of the environment. The current knowledge of these effects is covered in some detail in the chapters of this volume. ROBERT E. BUCKMAN, Di rector Pacific Northwest Forest and Range Experi men t Stati on Port1 and, Oregon V PREFACE Forest residues are increasingly important to the forest manager. They play a complex role as a source of soil nutrient, a fire hazard, an eyesore, an obstruction, a source of shade and shelter, a potential source of forest insect pests and possibly disease as well as air pollution or additional fiber. Natural forest residues have accumulated during the period of organized fire suppression resulting in increased conflagration potential in many areas. Public sensitivity to the esthetics of timber harvesting residue has become acute as has the general pressure to evaluate the impact on the whole environment of any manipulation of a portion of the environment. This summary of present knowledge of environmental impacts of residues and the various treatments of residues will provide a basis for: 7. Guiding forest resource managers in their selection of residue treatment alternatives. 2. Planning an intensive, broad research and development program on effects of residue and residue treatments. 3. Designing equipment for treating forest residue. Forest management policy, hence, residue management policy, is established ' on the basis of scientific, legal , social , and economic considerations. This Compendium will help provide a source of scientific information for considera- tion by lawmakers and policymakers. It might be considered a base for forest environmental qual i ty "criteria. I' Emphasis is on the effects of various kinds and treatments of forest residues on the environment; i .e. , their physi'cal and biological influences. Specifically not emphasized are value judgments related to official policy, law, custom, or social value. Al'so avoided are: 1. Effects of cutting area layout or logging method. 2. Utilization practice and potential. 3. Economics of either th-e residues or their treatments. Both the concept and knowledge of the effects of forest residues are in a state of development. The very definition of forest residues has changed during the formulation of the research and development program sponsoring this Compendium. At first, the definition included only slash; now it encompasses both living and dead, mostly unwanted, woody materials that accumulate naturally on the forest floor or are left after timber harvesting. Little research has been conducted to determine the optimum amount of residue needed to maintain or improve soil conditions for best regeneration survival and growth or to presenka "natural" appearance. The amounts and kinds of residue that comprise a maximum tolerable fire hazard have not been determined. The effects of a1 ternative residue treatments on the component forest resources such as soil and trees are only partly known. Residues represent both negative and positive environmental values and, to management, may be both an impediment and an environmental variable that can be manipulated to advantage. A heterogeneous association of residues may comprise: (1) a fuel complex which could sustain conflagrations; (2) an intricate arrange- ment of materials which stabilizes soil and sustains continuing growing capacity; (3) a composite of dead and living material which furnishes the habitat not only for game animals and fish but even for the microflora and microfauna so essential to the forest ecosystem. Environmental management of forest residues involves much more than disposal or uti1 ization. To adequately specify and meet environmental management require- ments, we must organize present knowledge in a workable decision frameyork. Specific elements of knowledge needed for such a framework are assembled herein. Although no attempt is made to quantify cost and benefit values, or more important, to evaluate the trade-off compromises that must often be made, the authors have tried to identify the residue conditions and effects that clearly are environmental ly unacceptable. The reader will encounter apparent contradictions between authors. This is to be expected since individual contributors address themselves to different environmental components and to different management goals and constraints. In some cases, there may appear to be no really acceptable alternative. This is to be expected when goals are unrealistic or knowledge is lacking. To prepare this Compendium, the authors, specialists in many disciplines, have put aside their immediate duties to explore the pertinent literature, to summarize their personal knowledge, to appraise present practices, and to suggest research aimed at resolving unanswered questions. They have been thorough in identifying voids and disparity while recording documented knowledge and expert opinion in many fields. To these author scientists we are greatly indebted. We gratefully recognize the assistance of the San Dimas Equipment

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