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• 1. [Article] Fire-mediated pathways of stand development in Douglas-fir/ western hemlock forests of the Pacific Northwest, USA

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Ecological ...

  Citation × Citation Citation Abstract Copy Title: Fire-mediated pathways of stand development in Douglas-fir/ western hemlock forests of the Pacific Northwest, USA Author: Tepley, Alan J., Swanson, Frederick J., Spies, Thomas A. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://esa.org/. Title: Fire-mediated pathways of stand development in Douglas-fir/ western hemlock forests of the Pacific Northwest, USA Author: Tepley, Alan J., Swanson, Frederick J., Spies, Thomas A. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://esa.org/. Close

• 2. [Article] Christmas tree nutrient management guide : western Oregon and Washington

  Revised September 2009. Reviewed January 2015. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog

  Citation × Citation Citation Abstract Copy Title: Christmas tree nutrient management guide : western Oregon and Washington Author: Chastagner, Gary A., Whithrow-Robinson, Bradford A., Landgren, Chal G., Hart, John M. (John Mervyn), 1947-, Fletcher, Richard A., Oregon State University. Extension Service, Bondi, Michael C. Revised September 2009. Reviewed January 2015. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog Title: Christmas tree nutrient management guide : western Oregon and Washington Author: Chastagner, Gary A., Whithrow-Robinson, Bradford A., Landgren, Chal G., Hart, John M. (John Mervyn), 1947-, Fletcher, Richard A., Oregon State University. Extension Service, Bondi, Michael C. Revised September 2009. Reviewed January 2015. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog Close

• 3. [Article] Sources of Variation in the Self-Thinning Boundary Line for Three Species with Varying Levels of Shade Tolerance

  The species self-thinning boundary line has been widely analyzed with a variety of statistical techniques. Most previous studies in the forestry literature have reported that the relationship does not ...

  Citation × Citation Citation Abstract Copy Title: Sources of Variation in the Self-Thinning Boundary Line for Three Species with Varying Levels of Shade Tolerance Author: Temesgen, Hailemariam, Weiskittel, Aaron, Gould, Peter The species self-thinning boundary line has been widely analyzed with a variety of statistical techniques. Most previous studies in the forestry literature have reported that the relationship does not differ across a range of stand and site factors, but these studies have primarily used statistical techniques that make model fitting subjective or interpretation of covariate significance difficult. There is growing evidence that the use of stochastic frontier analysis is an effective statistical means for objectively fitting the species self-thinning boundary line, offering the opportunity to test the influence of additional covariates. Using extensive even-aged coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco), western hemlock (Tsuga heterophylla), and red alder (Alnus rubra Bong.) data sets in the Pacific Northwest, we examined the assumption that the intercept and slope of the species self-thinning boundary line are insensitive to stand and site factors. Likelihood ratio tests indicated that site index, stand origin (natural versus planted), and purity (proportion of basal area in the primary species) significantly influenced the species self-thinning boundary line intercept for each of the species examined in this study. In Douglas-fir and western hemlock, the slope of the self-thinning boundary was also dependent on stand origin as well as site index in the case of Douglas-fir. Fertilization did not significantly influence the intercept or slope of the species self-thinning line for Douglas-fir and western hemlock. In addition, the inclusion of site aspect and dryness index marginally improved the red alder model of self-thinning, but neither site soil nor climatic variables improved the models for western hemlock and Douglas-fir. Thus, the species self-thinning boundary line can vary significantly among stands, and its variation is driven by several distinct factors; stochastic frontier analysis is an effective tool for identifying these factors. Title: Sources of Variation in the Self-Thinning Boundary Line for Three Species with Varying Levels of Shade Tolerance Author: Temesgen, Hailemariam, Weiskittel, Aaron, Gould, Peter The species self-thinning boundary line has been widely analyzed with a variety of statistical techniques. Most previous studies in the forestry literature have reported that the relationship does not differ across a range of stand and site factors, but these studies have primarily used statistical techniques that make model fitting subjective or interpretation of covariate significance difficult. There is growing evidence that the use of stochastic frontier analysis is an effective statistical means for objectively fitting the species self-thinning boundary line, offering the opportunity to test the influence of additional covariates. Using extensive even-aged coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco), western hemlock (Tsuga heterophylla), and red alder (Alnus rubra Bong.) data sets in the Pacific Northwest, we examined the assumption that the intercept and slope of the species self-thinning boundary line are insensitive to stand and site factors. Likelihood ratio tests indicated that site index, stand origin (natural versus planted), and purity (proportion of basal area in the primary species) significantly influenced the species self-thinning boundary line intercept for each of the species examined in this study. In Douglas-fir and western hemlock, the slope of the self-thinning boundary was also dependent on stand origin as well as site index in the case of Douglas-fir. Fertilization did not significantly influence the intercept or slope of the species self-thinning line for Douglas-fir and western hemlock. In addition, the inclusion of site aspect and dryness index marginally improved the red alder model of self-thinning, but neither site soil nor climatic variables improved the models for western hemlock and Douglas-fir. Thus, the species self-thinning boundary line can vary significantly among stands, and its variation is driven by several distinct factors; stochastic frontier analysis is an effective tool for identifying these factors. Close

• 4. [Article] Increased harbor porpoise mortality in the Pacific Northwest, USA: understanding when higher levels may be normal

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Inter Research ...

  Citation × Citation Citation Abstract Copy Title: Increased harbor porpoise mortality in the Pacific Northwest, USA: understanding when higher levels may be normal Author: Rice, James M., Norman, Stephanie A., Raverty, Stephen A., Huggins, Jessica L., et al. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Inter Research and can be found at: http://www.int-res.com/journals/dao/dao-home/ Title: Increased harbor porpoise mortality in the Pacific Northwest, USA: understanding when higher levels may be normal Author: Rice, James M., Norman, Stephanie A., Raverty, Stephen A., Huggins, Jessica L., et al. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Inter Research and can be found at: http://www.int-res.com/journals/dao/dao-home/ Close

• 5. [Article] Impacts of Swiss needle cast on overstory Douglas-fir forests of the western Oregon Coast Range

  Article appears in Forest Ecology and Management (http://www.elsevier.com/wps/find/journaldescription.cws_home/503310/description#description) and is copyrighted by Elsevier.

  Citation × Citation Citation Abstract Copy Title: Impacts of Swiss needle cast on overstory Douglas-fir forests of the western Oregon Coast Range Author: Stone, Jeffrey K., Black, Bryan A., Shaw, David C. Article appears in Forest Ecology and Management (http://www.elsevier.com/wps/find/journaldescription.cws_home/503310/description#description) and is copyrighted by Elsevier. Title: Impacts of Swiss needle cast on overstory Douglas-fir forests of the western Oregon Coast Range Author: Stone, Jeffrey K., Black, Bryan A., Shaw, David C. Article appears in Forest Ecology and Management (http://www.elsevier.com/wps/find/journaldescription.cws_home/503310/description#description) and is copyrighted by Elsevier. Close

• 6. [Article] An examination of several methods of quantifying forest structure in headwater riparian forests of western Oregon

  Headwater streams are generally small, first-order streams that can comprise up to 80% (by stream length) of the drainage network in mountainous areas of the Pacific Northwest. These streams are intimately ...

  Citation × Citation Citation Abstract Copy Title: An examination of several methods of quantifying forest structure in headwater riparian forests of western Oregon Author: Haxton, Zane A. Headwater streams are generally small, first-order streams that can comprise up to 80% (by stream length) of the drainage network in mountainous areas of the Pacific Northwest. These streams are intimately connected with downstream reaches, serving as a source of sediment, woody debris, organic matter and nutrients. The surrounding forests can strongly influence the ecology of headwater streams by regulating microclimate, influencing nutrient and organic matter cycling process, and providing habitat for wildlife species. Central to the provision of ecosystem services by these headwater forests is their structure, the three-dimensional arrangement of trees, shrubs, snags and down wood in space. This thesis explored several methods of quantifying forest structure in headwater riparian forests of western Oregon. N-tree distance sampling, a sampling method where the nearest n trees to a sample point are measured, was compared with fixed plot and variable plot sampling for estimation of density and basal area in a simulation study using stem-mapped data taken from 8 headwater sites across western Oregon. In general, variable plot sampling gave the best statistical performance for estimation of basal area, while fixed plot sampling gave the best statistical performance for estimation of density. While n- tree distance sampling gave reasonable performance on some stem maps, the sampling method performed poorly for estimating density of populations with a clumped spatial pattern. Relative root mean square error of the best n-tree distance sampling estimator was up to 75% higher than for fixed plot sampling under these conditions. Neighborhood-based indices are a set of diversity measures that are based on the relationship between a reference tree and a certain number of nearest neighbors (i.e. trees to which it has the lowest horizontal distance). I compared the bias and relative root mean square error of several different methods of choosing reference trees for neighborhood-based index calculation, using stem-mapped data from the same 8 headwater sites. The selection of a random tree from a fixed plot gave the lowest absolute relative bias, but results with this method were quite variable, with relative root mean square error ranging from 33-67% for the species mingling index and 21-25% for the diameter differentiation index. The nearest-tree (selection of the nearest tree to the sample point) and azimuth (selection of the first tree from north in a fixed plot) methods were biased, but had lower variability, with relative root mean square error ranging from 31-64% for the species mingling index and 18-22% for the diameter differentiation index. The variable plot method gave highly variable results for all species combined, but performed well for some individual species. I close with an exploration of the use of measures of forest structure in characterizing the Trask Watershed, located in the headwaters of the northern Oregon Coast Range. The structure of the Trask Watershed is essentially even-aged, having regenerated in the aftermath of the Tillamook Burn. Douglas-fir and red alder are the most prevalent species, with western hemlock, western redcedar and noble fir locally abundant. While neighborhood-based indices were somewhat informative, they offered an impoverished picture of structural diversity in the Trask Watershed by ignoring the contribution made by tall shrubs such as vine maple and western hazelnut. Title: An examination of several methods of quantifying forest structure in headwater riparian forests of western Oregon Author: Haxton, Zane A. Headwater streams are generally small, first-order streams that can comprise up to 80% (by stream length) of the drainage network in mountainous areas of the Pacific Northwest. These streams are intimately connected with downstream reaches, serving as a source of sediment, woody debris, organic matter and nutrients. The surrounding forests can strongly influence the ecology of headwater streams by regulating microclimate, influencing nutrient and organic matter cycling process, and providing habitat for wildlife species. Central to the provision of ecosystem services by these headwater forests is their structure, the three-dimensional arrangement of trees, shrubs, snags and down wood in space. This thesis explored several methods of quantifying forest structure in headwater riparian forests of western Oregon. N-tree distance sampling, a sampling method where the nearest n trees to a sample point are measured, was compared with fixed plot and variable plot sampling for estimation of density and basal area in a simulation study using stem-mapped data taken from 8 headwater sites across western Oregon. In general, variable plot sampling gave the best statistical performance for estimation of basal area, while fixed plot sampling gave the best statistical performance for estimation of density. While n- tree distance sampling gave reasonable performance on some stem maps, the sampling method performed poorly for estimating density of populations with a clumped spatial pattern. Relative root mean square error of the best n-tree distance sampling estimator was up to 75% higher than for fixed plot sampling under these conditions. Neighborhood-based indices are a set of diversity measures that are based on the relationship between a reference tree and a certain number of nearest neighbors (i.e. trees to which it has the lowest horizontal distance). I compared the bias and relative root mean square error of several different methods of choosing reference trees for neighborhood-based index calculation, using stem-mapped data from the same 8 headwater sites. The selection of a random tree from a fixed plot gave the lowest absolute relative bias, but results with this method were quite variable, with relative root mean square error ranging from 33-67% for the species mingling index and 21-25% for the diameter differentiation index. The nearest-tree (selection of the nearest tree to the sample point) and azimuth (selection of the first tree from north in a fixed plot) methods were biased, but had lower variability, with relative root mean square error ranging from 31-64% for the species mingling index and 18-22% for the diameter differentiation index. The variable plot method gave highly variable results for all species combined, but performed well for some individual species. I close with an exploration of the use of measures of forest structure in characterizing the Trask Watershed, located in the headwaters of the northern Oregon Coast Range. The structure of the Trask Watershed is essentially even-aged, having regenerated in the aftermath of the Tillamook Burn. Douglas-fir and red alder are the most prevalent species, with western hemlock, western redcedar and noble fir locally abundant. While neighborhood-based indices were somewhat informative, they offered an impoverished picture of structural diversity in the Trask Watershed by ignoring the contribution made by tall shrubs such as vine maple and western hazelnut. Close

• 7. [Article] Thinning aged Douglas-fir : an analysis of mobilization costs and a log bucking strategy for revenue improvement

  Contract harvest operations have become the preferred approach to reducing the largest cost component of timber production through free market competition amongst logging contractors bidding or negotiating ...

  Citation × Citation Citation Abstract Copy Title: Thinning aged Douglas-fir : an analysis of mobilization costs and a log bucking strategy for revenue improvement Author: Pilkerton, Stephen J. Contract harvest operations have become the preferred approach to reducing the largest cost component of timber production through free market competition amongst logging contractors bidding or negotiating for work. The goal of this research was to investigate economic components of harvesting operations not previously studied for steep slope thinning harvests in Douglas-fir (Pseudotsuga menziesii) stands. This research explored three important issues affecting Pacific Northwest costs and revenues. On the expense side, mobilization costs associated with wildlife protections restricting harvest operating seasons were modeled for nine Siuslaw National Forest timber sales. Mobilization costs resulting from seasonal restrictions imposed for nesting of northern spotted owl (Strix occidentalis) and marbled murrelet (Brachyramphus marmoratus) were $1.48 to $2.60 per 100 cubic feet (1 Ccf) for an array of sale volumes, cut tree sizes, and one-way mobilization distances. Total sale costs ranged from $7000 to $43000, depending on the number of mobilizations required. With respect to income, two studies were performed to evaluate revenue improvement through bucking-to-value strategies. The first evaluated a reduced set of log lengths that approach computer-generated optimal values and the potential for development of a bucking decision tool. The second sought value optimization with a log allocation constraint through the application of a combinatorial heuristic approach for the reduced set of log lengths to create the bucking pattern cutting card. A reduced set of five log lengths, two mill-length logs and three woods-lengths resulting from combinations of the mill-lengths, was evaluated for value recovery. Resulting values obtained 96 to 98 percent of full set optimal values for 45 and 65 year old stands, respectively. Value recovery exceeded current unaided bucking practices. A modified Simulated Annealing heuristic achieved 99.93 to 100 percent of known maximum for the unconstrained optimization. The SA generated bucking solutions improved value recovery by $2.61 to $2.73 per Ccf while meeting the preferred log allocation. The resulting bucking patterns were easily incorporated into a cutting card based on length to merchantable top. This approach reduced the number of logs handled, increased mill preferred long logs, decreased pattern count, and increased recovered value. Improved revenues exceeded estimated mobilization costs. Title: Thinning aged Douglas-fir : an analysis of mobilization costs and a log bucking strategy for revenue improvement Author: Pilkerton, Stephen J. Contract harvest operations have become the preferred approach to reducing the largest cost component of timber production through free market competition amongst logging contractors bidding or negotiating for work. The goal of this research was to investigate economic components of harvesting operations not previously studied for steep slope thinning harvests in Douglas-fir (Pseudotsuga menziesii) stands. This research explored three important issues affecting Pacific Northwest costs and revenues. On the expense side, mobilization costs associated with wildlife protections restricting harvest operating seasons were modeled for nine Siuslaw National Forest timber sales. Mobilization costs resulting from seasonal restrictions imposed for nesting of northern spotted owl (Strix occidentalis) and marbled murrelet (Brachyramphus marmoratus) were $1.48 to $2.60 per 100 cubic feet (1 Ccf) for an array of sale volumes, cut tree sizes, and one-way mobilization distances. Total sale costs ranged from $7000 to $43000, depending on the number of mobilizations required. With respect to income, two studies were performed to evaluate revenue improvement through bucking-to-value strategies. The first evaluated a reduced set of log lengths that approach computer-generated optimal values and the potential for development of a bucking decision tool. The second sought value optimization with a log allocation constraint through the application of a combinatorial heuristic approach for the reduced set of log lengths to create the bucking pattern cutting card. A reduced set of five log lengths, two mill-length logs and three woods-lengths resulting from combinations of the mill-lengths, was evaluated for value recovery. Resulting values obtained 96 to 98 percent of full set optimal values for 45 and 65 year old stands, respectively. Value recovery exceeded current unaided bucking practices. A modified Simulated Annealing heuristic achieved 99.93 to 100 percent of known maximum for the unconstrained optimization. The SA generated bucking solutions improved value recovery by $2.61 to $2.73 per Ccf while meeting the preferred log allocation. The resulting bucking patterns were easily incorporated into a cutting card based on length to merchantable top. This approach reduced the number of logs handled, increased mill preferred long logs, decreased pattern count, and increased recovered value. Improved revenues exceeded estimated mobilization costs. Close

• 8. [Article] Contemporary regional forest dynamics in the Pacific Northwest

  Recent climatic warming trends and increases in the frequency and extent of wildfires have prompted much concern regarding the potential for rapid change in the structure and function of forested ecosystems ...

  Citation × Citation Citation Abstract Copy Title: Contemporary regional forest dynamics in the Pacific Northwest Author: Reilly, Matthew J. (Matthew Justin), 1975- Recent climatic warming trends and increases in the frequency and extent of wildfires have prompted much concern regarding the potential for rapid change in the structure and function of forested ecosystems around the world. Episodes of mortality in wildfires and insect outbreaks associated with drought have affected large areas and altered landscapes, but little is known about the cumulative effects of these disturbances at the regional scales. I used data from two different forest inventories in the Pacific Northwest to develop a framework for tracking regional forest dynamics and examine variation in tree mortality rates among vegetation zones that differ in biophysical setting as well as recent and historical disturbance regimes. In the second chapter I developed an empirically based framework for tracking regional forest dynamics using regional inventory data collected from 2001 to 2010. I characterized the major dimensions of forest structure and developed a classification incorporating multiple attributes of forest structure including biomass, size, and density of live trees, the distribution and abundance of dead wood, and the cover of understory vegetation. A single dimension related to live tree biomass accounted for almost half of the variation in a principal components analysis of structural attributes, but dimensions related to density and size of live trees, dead wood, and understory vegetation accounted for as much additional variation. Snags and biomass of dead and downed wood were related to multiple dimensions while understory vegetation acted independent of other dimensions. Results indicated that structural development is more complex than a monotonic accumulation of live biomass and that some components act independently or emerge at multiple stages of structural development. The hierarchical classification reduced the data into three “groups” based on live tree biomass, followed by eleven "classes" that varied in density and size of live trees, and finally twenty-five structural types that differed further in the abundance of dead wood and cover of understory vegetation. Most structural types were geographically widespread but varied in age of dominant trees by vegetation zone indicating that similar structural conditions developed in environments with different biophysical setting, climate, and disturbance/successional histories. Low live biomass structural types (<25 Mg/ha) differed in live tree density and the abundance of live and dead legacies, demonstrating that the variation in early developmental stages depends on the rate of tree establishment and the nature and severity of recent disturbance. Forests in early developmental stages made up less than 20% of most vegetation zones and diverse types with live or dead legacies associated with wildfires were rare. Moderate live biomass structural types (25-99 Mg/ha) represented multiple mid, mature, and late developmental stages, some of which lack analogs in existing conceptual models of structural development such as lower density woodlands with big trees. These structural types included two that have high densities of snags indicative of recent episodes of mortality; together these made up as much as 10% of some dry vegetation zones. Several high live biomass structural types (100->300 Mg/ha) were identified and substantiated the diversity and relative dominance of mature and later developmental stages, particularly in wet vegetation zones. The relative abundance and make up of structural types varied widely by vegetation zone. Most forests in wet vegetation zones had moderate to high live biomass and were in mid and mature developmental stages, while diverse early developmental stage stages were extremely rare. Dry forests had a far greater range of variation in the relative abundance of structural types which is partially attributable to the greater range of climatic conditions they included, but also to the occurrence of recent episodes of mortality associated with wildfires and insects. In the third chapter I examined variation in tree mortality rates using a different regional inventory that occurred from the mid-1990s to the mid-2000s. I compared the distribution of rates among stands in different vegetation zones and stages of structural developmental. I developed a simple framework based on changes in live tree density and mean tree size and examined trends in structural change associated with disturbances at different levels of mortality across all stages of structural development. Most plots were within the range of "background" mortality rates reported in other studies (<1.0 %/yr) and extremely high "stand-replacing" levels of mortality (>25%/yr) were rare. Approximately 30% of plot mortality rates occurred at intermediate levels (>1%/yr and <25%/yr) as result of insects and fire, highlighting the importance of conceptualizing mortality as a continuum as opposed to just “background” or “stand-replacement” to fully represent dynamics at a regional scale. The distributions of mortality differed among many vegetation zones. Levels of mortality were primarily <2.5%/yr in western hemlock, silver fir, and mountain hemlock vegetation zones where fires were rare and insects and pathogens occurred predominantly at endemic levels. Rates were highest in subalpine forests and higher elevation grand fir and Douglas-fir forests as a result of fire and insects. Mortality rates in ponderosa pine, the hottest driest forest vegetation zone, were surprisingly low, and there was little to no mortality in plots with no evidence of disturbance. Mortality rates varied among developmental stages in all vegetation zones but few consistent patterns emerged. Levels of mortality were often lowest in early developmental stages but varied in later stages where they were lowest in wet vegetation zones and highest in subalpine and dry vegetation zones. Application of a simple framework indicated that multiple trajectories of structural change were common at levels of mortality <2.5%/yr, but structural change at higher levels was predominantly associated with a “thinning” trajectory defined by decreases in density and increases in mean tree size. Results indicated that the rate and magnitude of mortality related change during the study period varies widely across the region. Rapid change has occurred in subalpine, grand fir/white fir, Douglas-fir, and ponderosa pine vegetation zones where disturbances such as insects and fire were widespread. However, these disturbances have potentially restored some aspects of historical structure by reducing overall density and increasing the dominance of bigger trees. In western hemlock, silver fir, and mountain hemlock vegetation zones where higher levels of mortality related to disturbances were rare, wildfires have increased landscape diversity by creating diverse early successional habitats and most change was more subtle but may be manifest oevr longer periods if current trends continue. This examination of short-period mortality rates and associated structural change across a broad geographic provides context for understanding trends from localized studies and potential ecological consequences of mortality, but there is still a great deal of uncertainty as to how the effects of a changing climate and disturbance regimes will manifest themselves over longer time scales. This dissertation is one of the first field based assessments of recent forest dynamics at a regional scale. The results of both chapters, each based on a different dataset, told a similar story. The abundance of structural types in various vegetation zones estimated during the mid-2000s was consistent with the cumulative effects of tree mortality during the preceding decade. It was evident that wildfire effects and recent mortality were small relative to the regional extent of the study and have contributed to structural diversity and restoration of historic structure in stands where fire exclusion and past logging has increased total stand density and decreased the dominance of big trees. However, the rate of change and cumulative effects of recent forest dynamics varied widely by geographic location and vegetation zone and there was greater variability and uncertainty regarding the effects of mortality at smaller landscape scales where individual events like large wildfires have the potential to rapidly alter the landscape structure and composition. Assessing this variability and the scales at which trade-offs (e.g. losses of old-growth and creation of diverse early developmental stages) occur will be an important next step in understanding the cumulative ecological effects of recent wildfires and tree mortality on Pacific Northwest forests. Title: Contemporary regional forest dynamics in the Pacific Northwest Author: Reilly, Matthew J. (Matthew Justin), 1975- Recent climatic warming trends and increases in the frequency and extent of wildfires have prompted much concern regarding the potential for rapid change in the structure and function of forested ecosystems around the world. Episodes of mortality in wildfires and insect outbreaks associated with drought have affected large areas and altered landscapes, but little is known about the cumulative effects of these disturbances at the regional scales. I used data from two different forest inventories in the Pacific Northwest to develop a framework for tracking regional forest dynamics and examine variation in tree mortality rates among vegetation zones that differ in biophysical setting as well as recent and historical disturbance regimes. In the second chapter I developed an empirically based framework for tracking regional forest dynamics using regional inventory data collected from 2001 to 2010. I characterized the major dimensions of forest structure and developed a classification incorporating multiple attributes of forest structure including biomass, size, and density of live trees, the distribution and abundance of dead wood, and the cover of understory vegetation. A single dimension related to live tree biomass accounted for almost half of the variation in a principal components analysis of structural attributes, but dimensions related to density and size of live trees, dead wood, and understory vegetation accounted for as much additional variation. Snags and biomass of dead and downed wood were related to multiple dimensions while understory vegetation acted independent of other dimensions. Results indicated that structural development is more complex than a monotonic accumulation of live biomass and that some components act independently or emerge at multiple stages of structural development. The hierarchical classification reduced the data into three “groups” based on live tree biomass, followed by eleven "classes" that varied in density and size of live trees, and finally twenty-five structural types that differed further in the abundance of dead wood and cover of understory vegetation. Most structural types were geographically widespread but varied in age of dominant trees by vegetation zone indicating that similar structural conditions developed in environments with different biophysical setting, climate, and disturbance/successional histories. Low live biomass structural types (<25 Mg/ha) differed in live tree density and the abundance of live and dead legacies, demonstrating that the variation in early developmental stages depends on the rate of tree establishment and the nature and severity of recent disturbance. Forests in early developmental stages made up less than 20% of most vegetation zones and diverse types with live or dead legacies associated with wildfires were rare. Moderate live biomass structural types (25-99 Mg/ha) represented multiple mid, mature, and late developmental stages, some of which lack analogs in existing conceptual models of structural development such as lower density woodlands with big trees. These structural types included two that have high densities of snags indicative of recent episodes of mortality; together these made up as much as 10% of some dry vegetation zones. Several high live biomass structural types (100->300 Mg/ha) were identified and substantiated the diversity and relative dominance of mature and later developmental stages, particularly in wet vegetation zones. The relative abundance and make up of structural types varied widely by vegetation zone. Most forests in wet vegetation zones had moderate to high live biomass and were in mid and mature developmental stages, while diverse early developmental stage stages were extremely rare. Dry forests had a far greater range of variation in the relative abundance of structural types which is partially attributable to the greater range of climatic conditions they included, but also to the occurrence of recent episodes of mortality associated with wildfires and insects. In the third chapter I examined variation in tree mortality rates using a different regional inventory that occurred from the mid-1990s to the mid-2000s. I compared the distribution of rates among stands in different vegetation zones and stages of structural developmental. I developed a simple framework based on changes in live tree density and mean tree size and examined trends in structural change associated with disturbances at different levels of mortality across all stages of structural development. Most plots were within the range of "background" mortality rates reported in other studies (<1.0 %/yr) and extremely high "stand-replacing" levels of mortality (>25%/yr) were rare. Approximately 30% of plot mortality rates occurred at intermediate levels (>1%/yr and <25%/yr) as result of insects and fire, highlighting the importance of conceptualizing mortality as a continuum as opposed to just “background” or “stand-replacement” to fully represent dynamics at a regional scale. The distributions of mortality differed among many vegetation zones. Levels of mortality were primarily <2.5%/yr in western hemlock, silver fir, and mountain hemlock vegetation zones where fires were rare and insects and pathogens occurred predominantly at endemic levels. Rates were highest in subalpine forests and higher elevation grand fir and Douglas-fir forests as a result of fire and insects. Mortality rates in ponderosa pine, the hottest driest forest vegetation zone, were surprisingly low, and there was little to no mortality in plots with no evidence of disturbance. Mortality rates varied among developmental stages in all vegetation zones but few consistent patterns emerged. Levels of mortality were often lowest in early developmental stages but varied in later stages where they were lowest in wet vegetation zones and highest in subalpine and dry vegetation zones. Application of a simple framework indicated that multiple trajectories of structural change were common at levels of mortality <2.5%/yr, but structural change at higher levels was predominantly associated with a “thinning” trajectory defined by decreases in density and increases in mean tree size. Results indicated that the rate and magnitude of mortality related change during the study period varies widely across the region. Rapid change has occurred in subalpine, grand fir/white fir, Douglas-fir, and ponderosa pine vegetation zones where disturbances such as insects and fire were widespread. However, these disturbances have potentially restored some aspects of historical structure by reducing overall density and increasing the dominance of bigger trees. In western hemlock, silver fir, and mountain hemlock vegetation zones where higher levels of mortality related to disturbances were rare, wildfires have increased landscape diversity by creating diverse early successional habitats and most change was more subtle but may be manifest oevr longer periods if current trends continue. This examination of short-period mortality rates and associated structural change across a broad geographic provides context for understanding trends from localized studies and potential ecological consequences of mortality, but there is still a great deal of uncertainty as to how the effects of a changing climate and disturbance regimes will manifest themselves over longer time scales. This dissertation is one of the first field based assessments of recent forest dynamics at a regional scale. The results of both chapters, each based on a different dataset, told a similar story. The abundance of structural types in various vegetation zones estimated during the mid-2000s was consistent with the cumulative effects of tree mortality during the preceding decade. It was evident that wildfire effects and recent mortality were small relative to the regional extent of the study and have contributed to structural diversity and restoration of historic structure in stands where fire exclusion and past logging has increased total stand density and decreased the dominance of big trees. However, the rate of change and cumulative effects of recent forest dynamics varied widely by geographic location and vegetation zone and there was greater variability and uncertainty regarding the effects of mortality at smaller landscape scales where individual events like large wildfires have the potential to rapidly alter the landscape structure and composition. Assessing this variability and the scales at which trade-offs (e.g. losses of old-growth and creation of diverse early developmental stages) occur will be an important next step in understanding the cumulative ecological effects of recent wildfires and tree mortality on Pacific Northwest forests. Close