The Distribution of Free Space and Its Relation to Canopy Composition at Six Forest Sites

Authors: Roman Dial1; Benjamin Bloodworth2; Andrew Lee2; Patrick Boyne2; Jeffrey Heys2

Source: Forest Science, Volume 50, Number 3, June 2004 , pp. 312-325(14)

Abstract:

Forest canopy free space, element density (clutter), and the distribution and relative abundance of coarse canopy elements were measured at six sites: two boreal (south-central Alaska), two temperate (Washington State and Victoria, Australia), and two tropical (Pacific Costa Rica and Malaysian Borneo). Great clutter, high relative abundance of dead elements, and shallow understory characterized boreal canopies. Presence of dead elements and deep understory characterized temperate sites, sharing clutter profiles that differed in magnitude but not shape from each other. Few dead elements, little obvious zonation, and constant, mid-canopy clutter characterized tropical sites. The neotropical site showed a clear overstory, while the paleotropical site did not. The results motivate three hypotheses: (1) forest canopies of similar latitude and climate have similar structure; (2) canopy zones form cohesive, repeatable structures as “understory” (near-ground nondominant vegetation bounding small free-spaces), “overstory” (high, dominant foliage bounding small free-spaces), “bole zone” (mid-canopy boles bounding the largest free spaces), and “dead zone” (unique to conifer sites and typified by dead elements and upwardly narrowing free-spaces above bole zone); and (3) Australian and paleotropical canopies, regions rich in vertebrate gliders, are an order of magnitude more open (less cluttered) than neotropical and North American canopies, regions poor in gliders. FOR. SCI. 50(3):312–325.

Keywords: Forest canopy structure; latitudinal gradient; forest comparison; gliding vertebrates; environmental management; forest; forest management; forest resources; forestry; forestry research; forestry science; natural resources; natural resource management

Document Type: Regular article

Affiliations: 1: Department of Environmental Science Alaska Pacific University 4101 University Drive Anchorage AK 99508 Phone: (907) 333-2321;, Fax: (907) 562-4276, Email: roman@alaskapacific.edu 2: Department of Environmental Science Alaska Pacific University 4101 University Drive Anchorage AK 99508

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