. Twenty-year growth of thinned and unthinned ponderosa pine in the Methow Valley of northern Washington. The Timber Stand and Understory Vegetation The stand in which plots were established had stagnated, with over 2,300 stems per acre, averaging only 3 inches in diameter and 23 feet high. Ten years later,the unthinned plots appeared unchanged (fig. 2). Although the stand was 47 years old, the trees were remarkably healthy and had none of the diseases common to some dense ponderosa pine stands east of the Cascade Range. Even though growth in height and diameter was slow, crowns of the dominan
. Twenty-year growth of thinned and unthinned ponderosa pine in the Methow Valley of northern Washington. The Timber Stand and Understory Vegetation The stand in which plots were established had stagnated, with over 2,300 stems per acre, averaging only 3 inches in diameter and 23 feet high. Ten years later,the unthinned plots appeared unchanged (fig. 2). Although the stand was 47 years old, the trees were remarkably healthy and had none of the diseases common to some dense ponderosa pine stands east of the Cascade Range. Even though growth in height and diameter was slow, crowns of the dominants occupied about 50 percent of total tree height, but branches and needles were short. At the time of thinning, trees were growing only inch per decade in diameter and feet in height. Estimating site index was difficult because the stand was stagnated, and density had probably inhibited height growth of dominant and codominant trees. In a nearby stand where stand dimensions appeared to be normal, as defined by Meyer (1961), site index was estimated to be site quality class V, or about 62 feet at 100 years of age. Mortality, as evidenced by some dead stems throughout the stand, was light; only a few trees per acre died each decade. No beetle activity was evident, and mortality was attributed to gradual suppression. Before thinning, the understory was a sparse stand of spindly shrubs and scattered forbs and grasses having a usable forage yield of only animal unit month1 per acre per year—"... a level of forage production that requires 17 acres per month or 68 acres per summer grazing season to provide the necessary forage for one cow" (Sassaman et al. 1973). Pinegrass (Calamagrostis rubescens Buckl.) is the predominant grass in the area and balsamroot (Balsamorhiza sagittate (Pursh) Nutt.) the dominant forb (fig. 3). Scattered clumps and individual plants of antelope bitterbrush {Purshia tridentata (Pursh) DC.) were found throughout the stand. 1 One anim
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Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
