Initial size hierarchy development within second-growth black spruce stands

• Published in: Canadian Journal of Forest Research
• Main Author: Newton, Peter F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1990
• Subjects: Ecology; Forestry; Global and Planetary Change; Newfoundland
• Online Access: http://dx.doi.org/10.1139/x90-229; http://www.nrcresearchpress.com/doi/pdf/10.1139/x90-229

Size hierarchy development is a commonly observed structural feature within naturally regenerating forest tree populations. The objective of this study was to describe initial size hierarchy development within second-growth black spruce (Piceamariana (Mill.) B.S.P.) stands. Three dense black spruce stands that developed naturally following conventional cut and skid harvesting, conducted in 1970, were selected for analysis within insular Newfoundland. Employing historical stand reconstruction techniques within 13 temporary sample plots of variable size, temporal and spatial establishment patterns, structural development patterns, and competitive relationships were described. Size inequality peaked during the period in which 87.5% of the population became established (degree of inequality within the height and volume frequency distributions as measured by the Gini coefficient). Subsequently, size inequality and asymmetry decreased (degree of asymmetry within the volume frequency distribution as measured by the skewness coefficient and Shapiro–Wilk's W statistic). The rate of decline in size inequality and asymmetry was inversely proportional to stand density. Temporal declines in individual-tree vigour across size classes were approximately proportional (vigour as measured by relative volume production rate). These patterns suggested competition was symmetric (individuals share the finite environmental resources equally or in direct proportion to their relative sizes). However, variation in individual-tree vigour, possibly due to temporal and spatial establishment pattern heterogeneity, negated the conclusive acceptance of the resource depletion hypothesis. Based on these observations, a size hierarchy developmental pattern is proposed for second-growth black spruce stands.