Author: Laurie A. Gilligan
Publisher:
ISBN:
Category : Oregon oak
Languages : en
Pages : 170
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Book Description
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 (
Author: John Fredrick Thilenius
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages : 302
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Book Description
Quercus garryana dominated plant communities are found in the interior coastal valleys and on foothills from southeastern Vancouver Island, British Columbia, south to San Francisco, California. They occur as savannas, intermixed with a variety of conifers, and in almost pure stands. The diversity of habitats occupied by the species and the variety of vegetation associated with it provide an opportunity for a basic synecological investigation of plant communities having a common, important member. The study was designed to describe the floristic composition and structure of the Quercus garryana communities, to determine their ecological relation to the physical environment, and clarify successional status. It provides a framework for future autecological investigations of the component species and is directed at furnishing a fuller understanding of the synecology of an important segment of the vegetation of western Oregon. Two levels of sampling were used during the study. The first was a rapidly applied, qualitative method. This reconnaissance technique was designed to provide an assessment of dominance, size-class distribution, and composition of the species comprising the vegetation. Information on influential habitat factors was also obtained. Sampling at this level enabled the examination of many stands, provided a record of each stand, and served as the basis for the selection of stands for more quantitative sampling. One hundred forty stands were examined during the reconnaissance phase of the study. Subjective evaluation of these stands supported by an analysis using marginal punch cards determined that only a few species were dominating the tall shrub and low shrub-herbaceous layers of the understory and that certain combinations of these dominant species were being repeated geographically through the study area. The second sampling phase was based on the reconnaissance information and was designed to provide a quantitative record of the species complexes or plant communities delineated during reconnaissance. This method was applicable by a single investigator and measured the dominance, frequency, size distribution, and density of tree species; and the percent coverage and percent frequency of shrubs, herbs, and grasses. Soil profile descriptions were made in each stand where the vegetation was quantitatively sampled. Salient features of the physical environment were also recorded as were indications of past and present land uses. Forty seven stands were sampled. Quercus garryana was the cverstory tree dominant in all of these stands. The understory pecies were found to fall into four major communities. From mesic to xeric these were: the Corylus cornuta/Polystichum munitum community, the Prunus avium/Symphoricarpos albus community, the Amelanchier alnifolia/Symphoricarpos albus community, and the Rhus diversiloba community. These communities were named for the species usually dominating the tall shrub and low shrub layers. Seven soil series served as the substrate of these communities; Steiwer, Carlton, Peavine, Dixonville, Nekia, Olympic, and Amity. The understory plant communities of the Quercus forest show considerable variation and intergradation. Changes are a matter of shifts in species dominance rather than alterations in species composition. The absence of environmental extremes in the Willamette Valley and heavy present and historical land use have increased this intergradation. The presence of large, open-form Quercus garryana trees surrounded by smaller forest-form trees indicates that the present Quercus forests have developed from a savanna. The cause of this change in gross physiognomy is probably the control of the repeated ground fires which swept the pre-settlement savanna. Mature Quercus trees are not harmed by ground fires, but such fires would tend to keep dense reproduction from occurring. The present abundance of Rhus diversiloba in the under story may be directly related to heavy livestock grazing. The interconnected root system of ground cover and liana-form Rhus provides the species with a grazing resistance mechanism. The liana Rhus is out of reach of grazing animals. Photosynthate transferred from the liana to the ground cover plants would aid the latter in retaining vigor even under heavy grazing pressure. Thus it would have an advantage over other plants that were also being grazed, eventually becoming the ground layer dominant. Both Pseudotsuga menziesii and Acer macrophyllum appear to be successional to Quercus garryana. Acer is better adapted to mesic sites than Quercus. Pseudotsuga will succeed Quercus on less mesic sites. The successional trends are promoted by livestock grazing which opens up the ground layer and facilitates seedling establishment especially for Pseudotsuga. On some sites Prunus avium, an introduced species, is becoming part of the overstory canopy. It reproduces vigorously in its own shade and will become an important member of the Quercus forest in the future. Quercus garryana reproduction was more abundant on drier, exposed sites and the species seems to be able to perpetuate itself on these locations.
Author: Dean Apostol
Publisher: Island Press
ISBN: 1610911032
Category : Science
Languages : en
Pages : 505
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Book Description
The Pacific Northwest is a global ecological "hotspot" because of its relatively healthy native ecosystems, a high degree of biodiversity, and the number and scope of restoration initiatives that have been undertaken there. Restoring the Pacific Northwest gathers and presents the best examples of state-of-the-art restoration techniques and projects. It is an encyclopedic overview that will be an invaluable reference not just for restorationists and students working in the Pacific Northwest, but for practitioners across North America and around the world.
Author: Constance A. Harrington
Publisher:
ISBN:
Category : Competition (Biology)
Languages : en
Pages : 28
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Book Description
Oregon white oak savannas and woodlands represent a biological and cultural legacy in the Pacific Northwest. Many Oregon white oak stands are deteriorating owing to invasion and eventual overtopping by Douglas-fir or other conifers. Releasing the shade-intolerant oak trees from overtopping conifers can often restore these oak stands. When planning a release operation, there are many factors to consider such as timing and intensity of release, which trees to select for release, and management of the understory. A carefully executed oak release can minimize damage to oak trees, and followup treatments may reduce the spread of invasive plants. This guide answers the most commonly asked questions related to oak release.
Author: Roy R. Silen
Publisher:
ISBN:
Category : Oregon oak
Languages : en
Pages : 18
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Book Description
Author: Julia Michalak
Publisher:
ISBN:
Category : Biodiversity
Languages : en
Pages : 216
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Book Description
Land-cover and climate change pose significant challenges to ecological planning and management. Ecological responses to these changes are mediated by the interactions between landscape structure, biodiversity, and ecosystem function. I use a case study of Oregon white oak in the rapidly urbanizing coastal Pacific Northwest to explore these interactions and their implications for planning. Biodiversity changes dramatically as urban development intensifies. Yet the subsequent impacts on ecological functions remain relatively unexplored. I hypothesize that urbanization alters the community composition of acorn-dispersing animal species, and that this, in conjunction with fine-scaled habitat and foraging interactions, will generate unique dispersal and regeneration patterns in urban oak woodlands. I tracked the dispersal of individual acorns directly to test whether dispersal differs in urban and non-urban landscapes and used experimental acorn plantings and observations of seedling and sapling abundance to test whether urbanization influences later stages of oak regeneration. I found that more acorns were consumed and dispersal distances were shorter in urban oak woodlands making acorn dispersal services inferior to those in non-urban landscapes. Seedling production and abundance did not differ between urban and non-urban sites, although young saplings were less abundant in urban oak woodlands. Understanding the effects of landscape patterns on regeneration processes is essential for learning how to manage urban oak ecosystems. Due to their complexity, understanding how ecological systems will respond to climate change is highly uncertain. I evaluate potential climate impacts on Oregon white oak in the Willamette Valley using a range of information sources to identify consensus, uncertainty, and knowledge gaps in our understanding of oak vulnerability. Based on this assessment, I develop resource response scenarios to incorporate irreducible uncertainty directly into the planning process and identify flexible and robust adaptation strategies for oak management. As land-cover and climate changes intensify, ecological planning practice must expand to include human-dominated landscapes, such as urbanizing regions, productively. In addition, management plans must be flexible and robust to future uncertainties. Understanding the ecological implications of these changes, and developing appropriate management and adaptation strategies, are essential tasks for ecological planners in the next century.
Author: Peter Jay Gould
Publisher:
ISBN:
Category : Forest landscape management
Languages : en
Pages : 56
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Book Description
In recent years, interest has increased in restoring Oregon white oak (Quercus garryana Dougl. ex Hook.) and prairie landscapes in the Pacific Northwest, especially where elements of historical plant communities are intact. We evaluated the effect of alternative management scenarios on the extent and condition of Oregon white oak, the extent of prairie, and the harvest and standing volumes of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) within a 2934-ha portion of Fort Lewis, Washington (named the Tenalquot Planning Area for the purpose of the project). A landscape-level analysis of the scenarios was completed using a geographic information system, a forest growth model (ORGANON), and landscape visualization software (EnVision). The scenarios ranged from no active management to restoration of the historical extent of oak and prairies within the planning area. The results indicate that the window of opportunity for restoring oak and prairie landscapes in the Puget Sound lowlands and other regions is small, and aggressive management is needed to maintain or enhance these landscapes. The project demonstrates the value of landscape-level analyses and the use of new technologies for conveying the results of alternative management scenarios.
Author: Madelinn R. Schriver
Publisher:
ISBN:
Category : California black oak
Languages : en
Pages : 222
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Book Description
Oregon white oak (Quercus garryana) and California black oak (Q. kelloggii) woodlands are unique ecosystems in the Pacific West that support high levels of biodiversity, yet little is known about their current and historic stand establishment patterns, nor the variability of stand structure and its effect on oak-tree growth. With concerns of local extirpation due to native Douglas-fir (Pseudotsuga menziesii) encroachment, my research objectives were to characterize the variability of age and stand structure, current tree regeneration, and oak growth in 10 mixed oak-conifer woodlands from xeric to mesic site conditions in the North Coast region of California. Each site varied from open canopy oak-dominant woodland to closed canopy conifer-dominant forest. Most white and black oak trees established from 1850 to 1910 with minimal (
Author: United States. Forest Service
Publisher:
ISBN:
Category : Oregon oak
Languages : en
Pages : 4
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Book Description
Author: Jerry F. Franklin
Publisher:
ISBN:
Category : Botany
Languages : en
Pages : 426
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Book Description
Major vegetational units of Oregon and Washington and their environmental relationships are described and illustrated. After an initial consideration of the vegetation components in the two States, major geographic areas and vegetation zones are detailed. Descriptions of each vegetation zone include composition and succession, as well as discussion of variations associated with environmental gradients. Three chapters treat the forested zones found in the two States. Major emphasis is on the distinctive mesic temperate forests found in western Washington and northwestern Oregon. The interior valley forests, shrub lands, and prairies found between the Coast and Cascade Ranges in western Oregon are treated in a single chapter as are subalpine and alpine mosaics of tree-dominated and meadow communities. Unusual habitats, such as areas of recent vulcanism, serpentines, and ocean strand, are individually described. Soils, geology, and climate are considered in broad outline in an early chapter and in greater detail within discussions of individual geographic areas and vegetation zones. Appendices are included for definition of the various soil types, scientific and common plant names, and a subject index. An extensive bibliography is included to direct the reader to other references.
