C I N T R A F O R
Special Paper Abstract
Forest Pruning and Wood Quality
D. Hanley, C. Oliver, D. Maguire, D. Briggs, R. Fight. 1995. (403 pp) SP20 $35.00
Within the next three decades, much of the timber produced in the western United States will come from forests that have been planted or forests that have been managed fairly intensively even though naturally regenerated. These stands will have both advantages and disadvantages compared with ones. They will generally grow at faster rates, and so provide more lumber for society, but they will face certain challenges as well. Because these forests will probably be harvested at a much younger age, they may not yield the high quality wood and diversity of wildlife habitats that previous forests - unless they are carefully managed.
Concern for sustaining the quality of wood produced, and other values associated with western coniferous forests, has been an important aspect of forest management of many decades. Early efforts were made to ensure the growth of forests through fire protection and regeneration supplemented by weed control, thinning, fertilization, and maintenance of biodiversity, among other measures.
In light of the prospect of increased reliance on younger forests, the question is whether the quality of wood can ho maintained. at a level capable of providing a socially valuable product. This question arose in the 1950s, and one response was to undertake research on pruning. At that time, however, the abundance of high quality older timber, confidence in technological innovations in processing, and the general lack of efficient pruning and thinning regimes made pruning seem superfluous.
During the 1980s, as foresters and forest products managers came to realize that timber harvested in future decades would be increasingly knotty unless active measures were taken to reduce the knots, several symposia and conferences were held that addressed the wood quality issue. Publications resulting from these meetings include Douglas-fir: Stand Management for the Future (College of Forest Resources, University of Washington) and Juvenile Wood: What Does It Mean to Forest Management and Forest Products? (Forest Products Research Society). In addition, short courses on wood quality and forest management were offered at several universities in the United States and Canada The concept of pruning was again suggested and analyzed in these symposia conferences, and short courses. Forest pruning caught the imagination of foresters, timberland owners, policymakers, and the public as it became clear that pruning could promote the formation of high quality wood as well as providing associated economic, social, and environmental benefits in the long term, and also provide employment and biodiversity in the short term. Thinning continued to gain interest as several priming trials and demonstrations were done by state, federal, provincial, and private landowners; report float abroad showed that other regions of the world would be producing pruned wood; field trips were held to demonstrate pruning equipment and techniques; and short courses were offered on wood quality and stand management. Various research and develop-ment efforts were undertaken on pruning techniques, equipment, growth responses, arid product recovery. Several forest management organizations began extensive pruning trials that have expanded into operational practices.
Concerns about maintaining the biodiversity of forests led to interest in managing forests for a variety of stand structures across the landscape. Foresters saw that diversity would also be needed in silvicultural operations; and as they realized that pruning could help provide a variety of commodity and non-commodity products-including high quality wood, employment, and wildlife habitat-it became even more attractive as a silvicultural method.
Incorporating pruning into forest management in the western United States involves considerations of wood quality, supply, and utilization; policy and management infrastructure; biological responses; management and decision systems; and input from those experienced in pruning both in the western United States and abroad. By 1992, there was sufficient interest in pruning that a symposium was held to assimilate knowledge on these various consid-erations.
"Pruning Conifers in Northwestern North America: Opportunities, Tech-niques, and Impacts" was held in Olympia, Washington, USA, March 24-26, 1992. The first two days of this symposium featured presentations by scien-tists, forest managers, policymakers forest products specialists, and others experienced in matters concerning pruning. The third day was devoted to a field trip to visit various pruning trials and observe pruning equipment and tech-niques.
The sponsor of the symposium was the University of Washington College of Forest Resources. Cosponsors were the British Columbia Ministry of Forests; the Center for International Trade in Forest Products, College of Forest Resources; the Stand Management Interest Group, College of Forest Re-sources; the USDA Forest Service Pacific Northwest Region; and the USDA Forest Service Pacific Northwest Research Station.
This book is based on the symposium. Because of the time lag between the symposium and publication of the book, many things relative to pruning had changed and consequently the authors were invited to update their papers based on these changes. Other chapters containing additional information were also included. The various sections of the book address different aspects considered important to pruning, and all of these aspects must be taken into account for pruning to become a successful operational practice in the western United States.
The first section gives an overview of pruning from different perspectives, including biodiversity, wood quality opportunities, wood supply, economics, and management. The second section examines in depth the supply and projected need for clear wood, and the third deals with environmental and policy concerns related to pruning The biological aspects are then discussed, followed by descriptions of approaches taken in New Zealand, where pruning has been practiced intensively for several years. The next section discusses in-fluences affecting the decision to prune, and which stands to prune, and the last section describes how pruning can be implemented, featuring case studies, contracts, and information on pruning equipment. Because of the many disciplines and specialized terminologies represented in the book, a glossary has been appended as a reference source.