Energy values for whole trees and crowns of selected species.

Abstract

Energy values, BTU's (British thermal units) per ovendry pound, were determined for whole-tree and crown materials from western hemlock (Tsuga heterophylla (Raf.) Sarg.), coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii), and western redcedar (Thuja plicata Donn ex D. Don). Samples were collected from small-diameter stands in northwest Washington where whole-tree harvesting is underway. Samples of crown material representing each diameter class were composited into a single sample for each species. The whole-tree sample, collected from a van being loaded with hog fuel from the whole-tree chipping operation, was a mix of species and diameters. Crowns had a higher Btu value than did whole-tree material. With the exception of redcedar, energy values for crown material is higher than commonly used values for wood alone. Results of this study indicate that use of wood energy values may underestimate the product potential of hog fuel created from whole-tree chipping.

Citation

Howard, James O. 1988. Energy values for whole trees and crowns of selected species. Res. Note. PNW-RN-480. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 8 p