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• 1. [Article] Stand structures of Oregon white oak (Quercus garryana) woodlands and their relationships to the environment in southwestern Oregon

  Large areas of non-coniferous communities in southwestern Oregon are thinned to reduce fire hazard and accomplish ecosystem restoration, under the assumption that current fuel loads are unnaturally high. ...

  Citation × Citation Citation Abstract Copy Title: Stand structures of Oregon white oak (Quercus garryana) woodlands and their relationships to the environment in southwestern Oregon Author: Gilligan, Laurie A. Large areas of non-coniferous communities in southwestern Oregon are thinned to reduce fire hazard and accomplish ecosystem restoration, under the assumption that current fuel loads are unnaturally high. Although Oregon white oak (Quercus garryana) woodlands are a characteristic landscape component in this region, little is known about their current or historical stand structures. Managers lack information on which to base restoration-focused fuel reduction prescriptions. I inventoried 40 Oregon white oak dominated woodlands across 2 study areas in southwestern Oregon, and describe here their stand characteristics and age structures. I assessed whether these varied systematically with site conditions or recorded fire history. Stands included various proportions of single- and multiple-stemmed trees and a range of tree densities and diameter- and age-class distributions. Variables that may indicate site moisture status were weakly associated with multivariate gradients in stand structure, and fire history also appeared related to several stand structures. Peak establishment of living Oregon white oaks generally occurred during 1850-1890, sometimes occurred in the early 1900’s, and recruitment rates were low post-fire suppression. Recruitment of sapling-sized oak trees (< 10 cm dbh, 1.3 m tall) was generally low and their ages ranged from 5 to 164 yr; they were not necessarily recent recruits. The range of stand and age structures, and the variation in their apparent relations to site factors and history, suggests that site-by-site management prescriptions may more effectively accomplish restoration goals than do current treatments. Prescriptions should include follow-up monitoring with attention to effects on oak recruitment. Title: Stand structures of Oregon white oak (Quercus garryana) woodlands and their relationships to the environment in southwestern Oregon Author: Gilligan, Laurie A. Large areas of non-coniferous communities in southwestern Oregon are thinned to reduce fire hazard and accomplish ecosystem restoration, under the assumption that current fuel loads are unnaturally high. Although Oregon white oak (Quercus garryana) woodlands are a characteristic landscape component in this region, little is known about their current or historical stand structures. Managers lack information on which to base restoration-focused fuel reduction prescriptions. I inventoried 40 Oregon white oak dominated woodlands across 2 study areas in southwestern Oregon, and describe here their stand characteristics and age structures. I assessed whether these varied systematically with site conditions or recorded fire history. Stands included various proportions of single- and multiple-stemmed trees and a range of tree densities and diameter- and age-class distributions. Variables that may indicate site moisture status were weakly associated with multivariate gradients in stand structure, and fire history also appeared related to several stand structures. Peak establishment of living Oregon white oaks generally occurred during 1850-1890, sometimes occurred in the early 1900’s, and recruitment rates were low post-fire suppression. Recruitment of sapling-sized oak trees (< 10 cm dbh, 1.3 m tall) was generally low and their ages ranged from 5 to 164 yr; they were not necessarily recent recruits. The range of stand and age structures, and the variation in their apparent relations to site factors and history, suggests that site-by-site management prescriptions may more effectively accomplish restoration goals than do current treatments. Prescriptions should include follow-up monitoring with attention to effects on oak recruitment. Close