Yield and Wood Quality of Hybrid Cottonwood Grown in Two-Year Rotation. Forest Research Report No. 101

摘要

The results of a study of yield and wood quality of 2-year-old coppices grown on 4-year-old roots of 35 euramerican poplar clones in a replicated, intensively managed, dense plantation are described. The clonal variation was considerable in every aspect studied. The clonal averages for diameter at 1.37 m height ranged from 1.8 cm to 3.3 cm, and for total height ranged from 3.4 m to 5.2 m. The clonal production rates suggested by these limited samples vary from 26.7 m exp 3 /ha to 161.4 m exp 3 /ha in green volume, 23.1 t/ha to 94.5 t/ha for green biomass and were estimated to be 9.9 t/ha to 38.3 t/ha for oven-dry biomass. The clonal variation in branch green weight (13.2 to 34.6%), bark volume (14 to 24%) and pith volume (1 to 7%) was also considerable but not correlated to the total yield. The clonal values for average weighted specific gravity of bole xylem ranged from 0.234 to 0.341, and of bark from 0.157 to 0.510. The average weighted fiber length in bole xylem ranged from 0.60 mm to 0.87 mm, and in bark from 0.98 mm to 1.34 mm. The clonal variation in cell diameter, cell wall thickness, and in tension wood content was of the order of 30% or more. The wide variation in many of the yield and wood characteristics showed that high selection potential existed among the studied clones. The fiber-pulping parameters and the tissue composition suggested reasonable papermaking suitability of the analyzed wood. The pulp- and paper-making quality of the juvenile coppices was shown to be satisfactory by studies accomplished in several pulping research laboratories.