Kraft-pulping evaluation of decayed trembling aspen (Populustremuloides) from Ontario

Kraft-pulping data of sound and decayed trembling aspen (Populustremuloides Michx.) samples from five clones in Ontario are reported. From each clone, samples consisted of one sound bolt and three bolts from each of three major types of stem decay of aspen in central Canada, caused by Fomesigniarius (L. ex Fr.) Kichx., Radulumcasearium (Morg.) Lloyd, and Peniophorapolygonia (Pers. ex Fr.) Bourd.Average yields for sound and decayed woods were 57.5 and 51.9% ovendry wood, respectively; equivalent to an average decrease of 9.7% ovendry pulp due to decay. A decrease of 11.5% was obtained when only advanced decays were considered.Screen rejects were greater for both sound and decayed wood than in previous studies, even at low permanganate numbers. They appeared to be dependent on the type of decay.Pulp strengths from incipient-decayed wood differed little from those of sound wood, but those from the advance-decayed wood showed substantial decreases. Tear factor was the most affected (20-29% lower), and breaking length least affected, by decay (13-9% lower).