Quadratic mean diameter is the measure of average tree diameter conventionally used in forestry, rather than arithmetic mean diameter. The historical and practical reasons for this convention are reviewed. West. J. Appl. For. 15(3):137-139.

AuthorsHarrington, Constance A.; Curtis, Robert O. Height growth and site index curves for red alder. Res. Pap. PNW-358. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 1985. 14 p. New height growth and site index curves for red alder (Alnus rubra Bong.) were developed from stem analysis data. The analyses use a reference (site index) age of 20 years and are applicable to natural stands between 5 and 50 years of age in western Washington and northwestern Oregon. The new curves are polymorphic and provide a better fit to observed patterns of height growth than the previously available curves. Although differences from previously available curves are not large, the new curves should be an improvement, particularly for use in short-rotation management. Recommendations associated with the new curves for converting breast height age to total age vary with site quality. Relationships between red alder height growth or site index and selected site characteristics are briefly discussed. Abstract Summary 1 lntroduction 1 The Data

A close relationship between organic-matter content and bulk density was found in the acid till forest soils of the Green Mountains of Vermont. Reasonably good estimates of bulk density can be made from determinations of organic matter content. Thus, the difficulties of direct determination of bulk density in these stony soils can be avoided. A method of determining bulk density, including a correction for stone content, is described for use in these stony soils.

Curtis, Robert O. 1995. Extended rotations and culmination age of coast Douglas-fir: old studies speak to current issues. Res. Pap.

Silvicultural knowledge and practice have been evolving in the Pacific Northwest for nearly a century. Most research and management activities to date have focused on two major topics: (1) methods to regenerate older, naturally established forests after fire or timber harvest; and (2) growth and management of young stands. Today forest managers can reliably regenerate the major conifer and hardwood species under most conditions by using combinations of natural and artificial regeneration. They also can control stand density and species composition and growth of individual trees, thereby influencing stand structure. Available growth models can reasonably predict the outcome of growing conifer stands under a range of densities, species composition, and management scenarios, providing tree numbers by size class as well as crown characteristics and wood yields.Most silvicultural efforts have been financed through and directed toward production of wood. Although some other values have been produced or improved in conjunction with such activities, public interest and emphasis on nontimber values have increased. It has become apparent that some values are not benefitted by silvicultural practices aimed solely at wood production. In most situations, however, desired nontimber values can be enhanced by silvicultural measures implemented for their direct benefit or by some modifications of practices applied primarily to produce wood. We discuss the historical development of silviculture in the Pacific Northwest and review the silvicultural practices currently available to forest managers. We then point out how these practices can be modified and used to maintain and produce wildlife habitat, diverse stand structures (including those usually associated with old forests) and pleasing scenery, while also producing wood products. Most of the silvicultural knowledge needed to design and implement regimes for integrated production of these multiple values already exists.Keywords: Ecosystem management, multiple use, silvicultural systems, wildlife habitat, thinning, landscape management, forest ecology, Douglas-fir. Contents Regeneration Methods Natural RegenerationDirect Seeding and Planting Shaping Development of Young Natural Stands and Plantations Social Expectations and Silvicultural OpportunitiesEarly Density Control The above quotation, from the preface to the first edition of Foundations of Silviculture Upon an Ecological Basis (Tourney 1928), emphasizes the fact that silvicultural practice and the research in silviculture and the ecological relations that underpin it antedate the settlement of much of North America. The early foresters in the Pacific Northwest (and elsewhere in the United States) began with forest management concepts imported from Europe. These concepts were in part unsuited to the economic and social conditions existing in the United States at that time (ca. 1900), and to species and climatic conditions that differed somewhat from those of Europe. But this introduction of forestry concepts began a con...