Publication Date:
2004-11-01
Description:
In northern Rocky Mountains moist forests, timber harvesting, fire exclusion, and an introduced stem disease have contributed to the decline in western white pine (Pinus monticola Dougl. ex D. Don) abundance (from 90% to 10% of the area). Relations between canopy openings (0.1–15 ha) and western white pine growth within different physical settings are identified. Objectives include relating western white pine seedling and sapling growth to canopy opening attributes (defined by fisheye photography), identifying western white pine competitive thresholds (occupancy, competitive advantage, free-to-grow status) in relation to opening size, and relating canopy opening attributes to overstory density descriptors. We sampled 620 western white pine plus competing trees, canopy opening characteristics, landscape position, and overstory density descriptors. Analysis included log-linear and polynomial regression. Visible sky (canopy opening) and tree age were significantly related to growth of selected pines. Radiation explained less variation in growth than canopy opening. Thresholds for western white pine to occupy a site (〉23% canopy opening), gain a competitive advantage (〉50% canopy opening), and achieve free-to-grow status (〉92% canopy opening) over western hemlock were developed. There was a significant although weak (R2 〈 0.12) relation between canopy opening and overstory density descriptors.
Print ISSN:
0045-5067
Electronic ISSN:
1208-6037
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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