Canadian Forest Service Publications
Variations in the growth and defect of aspen (Populus tremuloides Michx.) Clones in Northern Ontario. 1985. Weingartner, D.H.; Basham, J.T. Forest Research Report No. 111. 26p.
Issued by: Great Lakes Forestry Centre
Catalog ID: 33602
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Interclonal variation in trembling aspen (Populus tremuloides Michx.) was investigated for ten clones in each of six stands in northern Ontario. Significant (p<0.05) or highly significant (p<0.01) interclonal variation was observed in all stands for height, dbh, volume, % bark, % defect, % stain, natural pruning, stub height, and branch diameter; and nonsignificant variation was observed in one or more stands for breast height age, % advanced rot, % incipient rot and number of conks. Broad sense heritability estimates revealed that on the average less than one-third (1/3) of the phenotypic variation was the result of genetic constitution, except for height, % stain, and stub height where it was greater. The occurrence of the 17 wood decay fungi (Hymenomycetes) isolated was equal among clones within a stand in most instances. Fomes igniarius (L. ex. Fr.) Kickx. var. populinus (Nev.) Campb., Radulum casearium (Morg.) Lloyd, Peniophora polygonia (Pers. ex. Fr.) Bourd et Galz, and Armillaria mellea (Vahl ex. Fr.) Kummer occurred frequently and exhibited varying linear trends with age. The occurrence of P. polygoni in one stand appeared to be strongly influenced by its genotype and/or environment. Within the stands studied, 13 site parameters appeared to have little influence on the clonal variables. However, undefined site factors (possibly micro-climatic) appeared to have considerable impact on the % defect in four of the stands. Correlations between variables representing the external clone features and the internal features (stain and decay) were nonsignificant in most cases indicating that the features are probably independent. Interclonal variation for nine root characteristics was examined in three of the six stands, and was nonsignificant in some cases. Relationships between stem features (dimension and defect statistics) and root characteristics for individual trees were mostly nonsignificant. However, a significant positive relationship between dbh and the number of large roots was very prominent at all levels within the population. Multiple samples in one large clone (0.35 ha) covering three apparent sites showed that only height was significantly different among the samples, and that it was inversely related to % gravel in the B2 horizon but it was suggested that the relationship may not be causal, or the only one. Genetic influences, even though real and nontrivial, play a secondary role in the observed phenotypic variation in trembling aspen in northern Ontario.