Changes in Mortality and Size-Class Spatial Distribution Patterns in Pre-Closure and Post-Closure Conifer Plantations
Abstract:Spatial distribution patterns of first-year deaths, and of living tree vigor classes (formed by dividing height-measurement distributions at their approximate one-third points to demarcate shortest, intermediate, and tallest trees) were studied by joins-testing in 5- to 10-year-old pre-closure rectangular lattices (trees aligned in both rows and columns) of white spruce (Picea glauca (Moench) Voss) and red pine (Pinus resinosa Ait.). Frequencies of observed joins between members of the same vigor class exceeded statistical expectations for random adjacency in 86 of 100 pre-closure comparisons, 42 of these excesses being statistically significant. Only one of the 14 comparisons of opposite trend achieved borderline significance. Thus the preponderant tendency was for members of all pre-closure vigor classes to occur in clumps with other members of the same class. This pattern is interpreted as reflecting gradients of soil conditions, a conclusion supported by a comparable preponderance of joins-count deficits between members of vigor classes separated by at least two ranks. In contrast, rectangular lattice plantings of 17- and 18-year-old post-closure red pine showed consistently significant deficits of joins between members of the most vigorous (largest diametered) class of living trees, indicating a natural trend to regular distributions of the largest trees without the intervention of thinning. Significant excesses of joins were observed between these most vigorous trees and the spaces left by presumptive first-year deaths, also a complete reversal of the pre-closure pattern. Forest Sci. 32:559-575.
Document Type: Journal Article
Affiliations: Department of Ecology, Ethology, and Evolution, University of Illinois, Urbana, IL 61801
Publication date: 1986-09-01
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- Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
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