species and species groups 36 4 Outside-bark form-class segmented-profile coefficients for use when total height is known, for southern tree species and species groups. .. .. .. .. .. .. 39 5 Inside-bark form-class segmented-profile coefficients for use when height to 4-inch d.0.b. top is known, for southern tree species and species groups. .. .. .. . 42 6 Outside-bark form-class segmented-profile coefficients for use when height to 4-inch d.0.b. top is known, for southern tree species and species groups. .. .. 7 Inside-bark form-class segmented-profile coefficients for use when height to 7-inch d.0.b. top (southern softwood species) or 9-inch d.0.b. top

Vegetation and soils were sampled in adjacent 40-year-old stands of red pine (Pinusresinosa Ait.), jack pine (Pinusbanksiana Lamb.), white spruce (Piceaglauca (Moench.) Voss), and aspen (Populustremuloides Michx., P. grandidentata Michx.) on a very fine sandy loam soil in north-central Minnesota. Total tree biomass was greatest for red pine followed by aspen, spruce, and jack pine. Nutrient weights (N, P, K, Ca, Mg) in the trees were greatest in aspen followed generally by spruce, red pine, and jack pine. Particularly large proportions of biomass and nutrients were found in aspen bark and spruce foliage and branches. Understory biomass contributed less than 1.2% of the total organic matter in the vegetation–soil complex but contributed up to 5.0% of the nutrients. Exchangeable Ca in the surface soil was much lower under aspen and spruce than under the pines. No significant soil differences between species were detected below 36 cm. Harvesting the entire aboveground portion of the tree would remove up to three times more nutrients from the site than would harvesting only the bole.

Tree biomass is most commonly estimated using regressions of green or dry weight to tree dimensions. Rarely is it feasible for managers to develop their own predictive equations, so they must rely on published regressions and weight tables developed from those regressions. A guide is presented that will help each manager select the most appropriate equation available for a given situation. We also provide common regression models currently in use, statistics for comparing published equations, and practical examples of their application. Sources of weight tables and biomass regressions for northern species are also noted. North. J. Appl. For. 5:15-22, March 1988.

A sample of 79 trees from the Mississippi Delta is used to construct volume and weight tables for willow oak (Quercus phellos L.). By using the allometric model, D2H (squared diameter at breast height multiplied by total tree height) can predict volumes and weights of bole wood, bole wood plus bark, and bole wood plus bark plus limbs. Equations are presented for estimating merchantable bole volumes and weights at 2-inch intervals to top diameters of 2 to 12 inches. Additional equations are given for estimates using upper bole diameters at relative heights of 0.25H, 0.33H, and OJOH, which are significant improvements over the D'H equations.

Volume and dry-weight yield comparisons of 40-year-old planted red pine (Pinusresinosa Ait.), jack pine (Pinusbanksiana Lamb.), white spruce (Piceaglauca (Moench.) Voss), black spruce (Piceamariana (Mill.) BSP), and a naturally regenerated aspen (Populustremuloides Michx.) sucker stand show that red pine has the highest yields and black spruce the lowest. Volume yields of aspen, jack pine, and white spruce are similar, but weight yields of white spruce are much less than weight yields of either aspen or jack pine. It is recommended that yield comparisons within and between species should be done on a weight as well as a volume basis because large differences in densities can occur.