Variability in pulping and fiber characteristics of hybrid poplar trees due to their genetic makeup, environmental factors, and tree age

The variability in fiber and pulping characteristics caused by the genetic makeup of five hybrid poplar clones was investigated. Specific gravity for the five varied from 0.30 to 0.36. Pulp yield varied significantly (49-57%) . Variation in pulp yield correlated well with the alpha-cellulose content of the wood. However, higher yield did not always translate into higher pul p production due to differences in specific gravity (digester packing). Strength properties (tear and tensile) also varied significantly among clon es. The drier and warmer growing environment found in northeast Oregon, whe re irrigation was required, yielded trees with slightly longer fibers and h igher specific gravities and pulp yields (3-4%) compared to trees of the sa me clone grown in the cooler, wetter environment typical of western Oregon. The effect of tree age was investigated by separating and characterizing w ood from each annual ring. Fiber length and pulp yield increased with age, as did tear index at a given tensile index.