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Author: Nathan Jeremy Poage
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 230
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Book Description
Author: Nathan Jeremy Poage
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 230
Get Book Here
Book Description
Author: Nathan Poage
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 28
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Book Description
Author: Peter J. Weisberg
Publisher:
ISBN:
Category : Fire ecology
Languages : en
Pages : 512
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Book Description
Fire history and fire regimes were reconstructed for a 450 km2 area in the central western Oregon Cascades, using tree-ring analysis of fire scars and tree origin years at 137 sampled clearcuts. I described temporal patterns of fire frequency, severity, and size, and interpreted topographic influences on fire frequency and severity. I then evaluated the influences of fire history and topography on the development of forest structure. Ninety-four fire episodes were reconstructed for the 521-year period from 1475 to 1996. The average mean fire interval, Weibull median probability interval, and maximum fire interval of 4-ha sites were 97 years, 73 years, and 179 years, respectively. Fire regime has changed over time as a result of climate change, changing anthropogenic influences, and patterns of fuel accumulation related to stand development. Fire frequency and severity patterns were weakly but significantly associated with spatial variation in hillslope position, slope aspect, slope steepness, and elevation. Fire frequency was lower for higher elevations, lower slope positions, and more mesic slope aspects. Fire severity was lower for higher elevations, lower slope positions, more north-facing slopes, and more gradual slopes. Three fire regime classes were defined and mapped. Forest stand structures were strongly associated with stand age, fire history and topography. The number of years since the last high-severity fire was an important predictor for nearly all measured aspects of stand structure. Low-severity fires were important for creating variability in tree diameter sizes, reducing tree density and allowing more rapid diameter growth, and creating stand structures with many large snags and few overstory shade-tolerant trees. However, stands of the same age, and of the same general fire history, often had different structures. Much of this variation was explained by differences in topography. The strongly positive influence of wet aspects and high elevations on the relative dominance of shade-tolerant tree species has been important for shaping the structure of forest stands. Development of old-growth stand attributes (i.e., high stand basal area, maximum tree diameter, variability of tree diameters, and density of large Douglas-fir trees) appears to have been slowest on steeper slopes, wetter aspects, and higher elevations.
Author: James A. Freund
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 125
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Book Description
Regeneration of tree populations following stand-replacing wildfires is an important process in the multi-century development of Douglas-fir- western hemlock forests. Temporal patterns of tree establishment in naturally regenerated, mid-aged (100 to 350 years) Douglas-fir-dominated forests have received little study in comparison with the abundance of research on regeneration in older Douglas-fir stands (>400 years of age). Increment cores were obtained from 1455 trees in 18 mature and early old-growth forests in western Washington and northwestern Oregon USA in order to determine temporal patterns of natural Douglas-fir regeneration following stand-replacing wildfire. Continuous regeneration of Douglas-fir for many decades following initiating fire was evident in all of the stands. The establishment period averaged 60 (range 32 to 99) years. The pattern observed contrasts both with the view of rapid (one- to two-decade) regeneration of Douglas-fir portrayed in early forestry literature and with reports of establishment periods exceeding 100 years in older (>400 year) Douglas-fir- western hemlock stands. Current intensive production forestry practices directed toward rapid and uniform stand closure following logging have no precedent in the historic natural patterns of Douglas-fir regeneration documented in this study. Conversely, results of this study provide evidence that early seral ecosystems persisted for several decades following wildfires. Patterns of structural development in mid-successional Douglas-fir dominated forests - a period in which forest structures evolve from the relatively simple conditions found in young forests to the complex old forests - is poorly understood. Stand structure and composition was analyzed in nine early old-growth (200 to 350 year old) Douglas-fir-dominated stands in western Washington and Oregon, all of which originated following a single stand-replacement wildfire. Structure and composition of live tree populations (density, diameters, and heights) as well as dead tree structures (snags and logs) were quantified and compared with conditions in previously reported studies of older (400-600-year old) forests. Stand-level attributes were analyzed using descriptive statistics, nonlinear regression, principal components analysis, and two old-growth indices. Variability among stands in specific structural features was large but consistent with the current conceptual model of Douglas-fir forest development. Diameter distributions generally exhibited a reverse-J shape, a characteristic of >450-year-old forests. Douglas-fir populated the tallest height classes and shade-tolerant species (e.g., western hemlock and Pacific silver fir) were present in lower (co-dominant and intermediate) canopy positions. Coarse woody debris was abundant in early old-growth stands in the form of both snags (42-140 m3ha[superscript -1]) and logs (172-584 m3 ha[superscript -1]). Scores for early old-growth stands calculated using existing old-growth structural indices were comparable to those in older (400 to 600year old) forests. The structural conditions and variability in these early old-growth forests are useful guides for managers seeking to accelerate development of complex structures in young Douglas-fir forests.
Author: Nathan Jeremy Poage
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 328
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Book Description
The tree species and size structure of 9l old-growth forests dominated by Douglas-fir in central western Oregon was characterized using complete inventories of all trees larger than 20cm dbh over a mean area of 17.1ha at each site. Douglas-fir accounted for over 75% of the total average basal area (39.1 of 49.2 m2/ha) at each site. Conventional and multivariate analysis indicated that the non-Douglas-fir component accounted for most of the structural variation between sites. Multivariate analysis characterized six groups based on the similarities and differences among sites in basal area of small (20-50cm dbh), medium (50-100cm dbh), and large (> 100cm dbh) western hemlock, western red cedar, incense-cedar, grand fir, red alder, and bigleaf maple. The hypothesis that large-diameter, old-growth Douglas-fir in central western Oregon developed at low stand densities was supported by patterns of long-term diameter and basal area growth of trees, wide mean within-site age ranges (95% CI for mean = 134-214yr), and stem and crown characteristics. The diameters of the old-growth trees at ages 100 to 300yr were strongly, positively, and linearly related to their diameters at age 5Oyr and, more importantly, to their basal area growth rates as young, 50 year-old trees. Rapid and sustained growth by age 50yr was strongly correlated with large diameters at older ages, particularly at ages 100-200yr. Average periodic basal area increments (PAI[subscript]BA) of all trees increased for the first 30-4Oyr and then plateaued, remaining relatively high and constant from age 50 to 300yr. Over a third of the trees> 300 years old had not reached culmination of mean annual basal area increment (MAI[subscript]BA) by age 300yr. Low heights to live and dead meristematic branches suggest that many of the old-growth trees grew at low stand densities. Live branches occurred on over 50% of the bole, on average. Average height to diameter ratios of the old-growth trees were below 50 (unitless), indicating high mechanical stability. Compared to young-growth trees in high-density stands, young-growth trees in low-density stands have crowns and height-to-diameter ratios more similar to old-growth trees.
Author: John Duff Bailey
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 252
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Book Description
This research examined thinning effects on stand structure and species composition in 50- to 120-year-old Douglas-fir forests. Thirty-two paired stands (thinned and unthinned) were measured throughout western Oregon, as were 20 old-growth stands for comparison. Thinnings occurred 10 to 24 years previously and ranged in intensity from 8 to 60% volume removal. Overstory and intermediate tree characteristics, conifer and hardwood regeneration, and shrub/herbaceous species composition and cover were recorded. From this, I assessed whether thinning young stands promoted vegetation structure and composition associated with old-growth stands. Overstory trees in thinned stands had diameters, live crown ratios, crown radii, and radial growth rates greater than those in unthinned stands, and equal to or approaching those found in old-growth stands. Stand volume production was neither affected by earlier clearcut harvesting nor by thinning. Intermediate trees in thinned stands, like old-growth stands, were typically young saplings with radial growth rates and live crown ratios greater than those in unthinned stands (typically suppressed members of the original cohort). Living intermediate structure (multi-storied canopies) was common to thinned and old-growth stands. Given such overstory and intermediate tree responses, canopy leaf area in stands thinned>20 years previously was greater than in unthinned stands. Conifer regeneration density, frequency and growth rates were greater in thinned stands than in old-growth and unthinned stands. Densities and frequencies of tall shrubs were similar in thinned and old-growth stands, and greater than unthinned stands. Low shrub and herbaceous cover were 33% and 25% greater, respectively, in thinned than other stand types. Herbaceous species frequency and richness were similarly stimulated. Low shrub composition was altered by thinning (unthinned and old-growth stands did not ordinate differently). However, herbaceous species composition was similar across all stand types and showed more variability among sites than among stand types. Thinning appeared to create old-growth-type structure by stimulating overstory and intermediate tree crowns and growth rates, tall shrub densities and conifer regeneration. Though low shrub and herbaceous species cover and frequency were greatest in thinned stands, composition was not affected by thinning, nor by clearcut harvesting 50 to 120 years ago or other differences in stand origin.
Author: Michael C. Wimberly
Publisher:
ISBN:
Category : Forest ecology
Languages : en
Pages : 356
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Book Description
Knowledge about vegetation patterns and ecological processes in unmanaged, late-successional watersheds is needed to provide a foundation for forest management strategies aimed at conserving native biodiversity. I examined influences of environmental variability and disturbance history on forest structure and composition in the Cummins Creek Wilderness, located on the central Oregon coast. Climatic and topographic variables explained the majority of hillslope community composition, while fire history explained most of the variability in hillslope forest structure. Forest structure and composition in riparian areas was related to a climatic gradient as well as position in the stream network. The abundance of two fire-sensitive species, Tsuga heterophylla (western hemlock) and Picea sitchensis (Sitka spruce), decreased with distance from old-growth patches, possibly reflecting a seed dispersal gradient that occurred following fires 80 to 140 years ago. I developed predictive maps of understory conifer patterns using remote sensing, aerial photographs, digital elevation models and stream maps. I predicted P. sitchensis regeneration based on distance from the coast and topography, and T. heterophylla regeneration based on crown size, percent hardwood composition, topography, and distance from old-growth patches. Although I found statistically significant relationships between understory patterns and GIS predictor variables, the models explained only low to moderate amounts of the overall variability. Landscape-scale simulations of T. heterophylla showed that population expansion through gap-phase recruitment was limited by short seed dispersal distances in closed-canopy forests, the requirement for canopy gap disturbances to facilitate overstory recruitment, and the lag between recruitment and reproduction. Although fine-scale habitat features can influence the amount of regeneration in a gap when seed sources are present, the fire regime may ultimately control the abundance of T. heterophylla at the landscape scale through dispersal limitations. Brief increases in fire frequency can cause a sustained decrease in the amount of T. heterophylla on the landscape once fire frequency is reduced below a threshold value. Our results emphasize the complexity and diversity of forest vegetation at the watershed scale. Environmental variability, disturbance history, and dispersal limitations have all played a role in creating the current landscape patterns in the Cummins Creek Wilderness.
Author: Pete Bettinger
Publisher: Academic Press
ISBN: 012809706X
Category : Science
Languages : en
Pages : 363
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Book Description
Forest Management and Planning, Second Edition, addresses contemporary forest management planning issues, providing a concise, focused resource for those in forest management. The book is intermixed with chapters that concentrate on quantitative subjects, such as economics and linear programming, and qualitative chapters that provide discussions of important aspects of natural resource management, such as sustainability. Expanded coverage includes a case study of a closed canopy, uneven-aged forest, new forest plans from South America and Oceania, and a new chapter on scenario planning and climate change adaptation. Helps students and early career forest managers understand the problems facing professionals in the field today Designed to support land managers as they make complex decisions on the ecological, economic, and social impacts of forest and natural resources Presents updated, real-life examples that are illustrated both mathematically and graphically Includes a new chapter on scenario planning and climate change adaptation Incorporates the newest research and forest certification standards Offers access to a companion website with updated solutions, geographic databases, and illustrations
Author: Andrew N. Gray
Publisher: DIANE Publishing
ISBN: 1437926126
Category : Nature
Languages : en
Pages : 52
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Book Description
Old-growth forests provide unique habitat features and landscape functions compared to younger stands. The goals of many forest mgmt. plans in the Pacific NW include increasing the area of late-successional and old-growth forests. This study describes existing old-growth forests in the northern Oregon Coast Range that might serve as examples of desired future conditions and developmental pathways. Results suggest that although old-growth forests can develop along multiple pathways, stand composition and productivity constrain development such that expecting all late-successional stands to have the full complement of old-growth attributes may not be realistic. Illustrations. This is a print on demand report.
Author: Sally J. Campbell
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 38
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Book Description
