Author: P. H. Cochran

Publisher:

Published: 2000

Total Pages: 59

ISBN-13:

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Plots in two natural lodgepole pine (Pinus contorta Dougl. ex Loud.) stands with differing productivities were repeatedly thinned to one of five growing-stock levels (GSLs). Bole area was used to define GSLs. A linear relation between stand density index (SDI) and bole area was found after each thinning on the highly productive site, but the slope of this relation decreased with successive thinnings as trees grew larger. On the site with intermediate productivity, the upper limit for bole area was higher and a curvilinear SDI-bole area relation occurred. A constant bole area level probably does not represent the same competition level across a range of tree sizes. Low incidence of mortality caused by mountain pine beetle (Dendroctonus ponderosae Hopkins) occurred at SDIs below 170 for both sites. Concave curvilinear decreases in diameter growth occurred with increasing GSLs. Significant decreases in height growth with increasing GSLs were not detected. A convex curvilinear increase in gross basal-area growth and cubic-volume growth took place with increasing GSLs. Gross total cubicvolume PAIs increased with increasing SDIs for both sites until stand densities reached 95 percent of the normal stand SDI. These cubic-volume PAI-SDI curves then flattened with increasing SDIs. Maximum cumulative net cubic-volume (total and merchantable) and board-foot yields were produced at the intermediate growing-stock level at the high site. Little apparent differences in these yields occurred among the four highest GSLs at the intermediate site. Net total cubic-volume yield was higher for the three highest GSLs than net yields for unmanaged stands from yield tables at comparable sites and ages. These studies have not continued long enough to determine the approximate age of culmination of net mean annual cubic- or board-foot volume increments. Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) outgrew lodgepole pine for the range of stand ages on the highly productive site where the growth of both species was examined (33 to 58 years). Ponderosa pine should not be planted on lodgepole pine sites on flats and basins, however, because ponderosa pine is subject to radiation frost damage. Early spacing control coupled with later commercial thinnings to keep stand densities between SDI 114 and SDI 170 should reduce mortality considerably, allow most of the wood produced to be captured by merchantable trees, and greatly increase quadratic mean diameters and live crown ratios over unmanaged stands at the same age. These stands would be more pleasing visually, and their rotation ages may be longer.

Download or read book Growth of Lodgepole Pine Thinned to Various Densities on Two Sites with Differing Productivities in Central Oregon written by P. H. Cochran and published by . This book was released on 2000 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plots in two natural lodgepole pine (Pinus contorta Dougl. ex Loud.) stands with differing productivities were repeatedly thinned to one of five growing-stock levels (GSLs). Bole area was used to define GSLs. A linear relation between stand density index (SDI) and bole area was found after each thinning on the highly productive site, but the slope of this relation decreased with successive thinnings as trees grew larger. On the site with intermediate productivity, the upper limit for bole area was higher and a curvilinear SDI-bole area relation occurred. A constant bole area level probably does not represent the same competition level across a range of tree sizes. Low incidence of mortality caused by mountain pine beetle (Dendroctonus ponderosae Hopkins) occurred at SDIs below 170 for both sites. Concave curvilinear decreases in diameter growth occurred with increasing GSLs. Significant decreases in height growth with increasing GSLs were not detected. A convex curvilinear increase in gross basal-area growth and cubic-volume growth took place with increasing GSLs. Gross total cubicvolume PAIs increased with increasing SDIs for both sites until stand densities reached 95 percent of the normal stand SDI. These cubic-volume PAI-SDI curves then flattened with increasing SDIs. Maximum cumulative net cubic-volume (total and merchantable) and board-foot yields were produced at the intermediate growing-stock level at the high site. Little apparent differences in these yields occurred among the four highest GSLs at the intermediate site. Net total cubic-volume yield was higher for the three highest GSLs than net yields for unmanaged stands from yield tables at comparable sites and ages. These studies have not continued long enough to determine the approximate age of culmination of net mean annual cubic- or board-foot volume increments. Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) outgrew lodgepole pine for the range of stand ages on the highly productive site where the growth of both species was examined (33 to 58 years). Ponderosa pine should not be planted on lodgepole pine sites on flats and basins, however, because ponderosa pine is subject to radiation frost damage. Early spacing control coupled with later commercial thinnings to keep stand densities between SDI 114 and SDI 170 should reduce mortality considerably, allow most of the wood produced to be captured by merchantable trees, and greatly increase quadratic mean diameters and live crown ratios over unmanaged stands at the same age. These stands would be more pleasing visually, and their rotation ages may be longer.