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• 1. [Article] Relationship between allometric variables and biomass in western juniper (Juniperus occidentalis)

  A tenfold expansion of western juniper (Juniperus occidentalis spp. occidentalis) into the sagebrush steppe has led to the degradation of the economic and ecological potential of these landscapes. Land ...

  Citation × Citation Citation Abstract Copy Title: Relationship between allometric variables and biomass in western juniper (Juniperus occidentalis) Author: Sabin, Breanna S. A tenfold expansion of western juniper (Juniperus occidentalis spp. occidentalis) into the sagebrush steppe has led to the degradation of the economic and ecological potential of these landscapes. Land managers have enacted numerous methods to reduce distributions and densities of these trees. Assessment of above ground juniper biomass, expressed overall as well as in each of four fuel - size classes is useful information to land managers for several reasons. These include: enhance smoke management for prescribed burns, appraise feasibility of locating biomass cogeneration power plants, and extrapolating known nutrient and carbon concentrations contained within juniper to the landscape scale. Two sites were selected within Lake County, OR for this research. Allometric measurements including canopy area, canopy volume, age, height, basal diameter were taken from 129 trees and 56 of these were destructively sampled to obtain biomass of each tree; by size classes as well as over all. Regression statistics were utilized to find the correlation between allometric and biomass measurements. Of the allometric variables measured for this research, canopy volume, canopy area, and basal diameter were the strongest predictors of biomass found, with respective R2 values of 0.88, 0.87, 0.81. The proportion of biomass within each of the four size classes was: 34% for size class 1, 15% for size class 2, 23% for size class 3, and 28% for size class 4. Average biomass for these sites was 2,482 kg/ha for the Fort Rock site and 5,410 kg/ha for the Lakeview site. These models can be used to estimate biomass for co-generation plants, estimate nutrient pools and fuel loads, and predict changes in community biomass based on species or growth form groups. Title: Relationship between allometric variables and biomass in western juniper (Juniperus occidentalis) Author: Sabin, Breanna S. A tenfold expansion of western juniper (Juniperus occidentalis spp. occidentalis) into the sagebrush steppe has led to the degradation of the economic and ecological potential of these landscapes. Land managers have enacted numerous methods to reduce distributions and densities of these trees. Assessment of above ground juniper biomass, expressed overall as well as in each of four fuel - size classes is useful information to land managers for several reasons. These include: enhance smoke management for prescribed burns, appraise feasibility of locating biomass cogeneration power plants, and extrapolating known nutrient and carbon concentrations contained within juniper to the landscape scale. Two sites were selected within Lake County, OR for this research. Allometric measurements including canopy area, canopy volume, age, height, basal diameter were taken from 129 trees and 56 of these were destructively sampled to obtain biomass of each tree; by size classes as well as over all. Regression statistics were utilized to find the correlation between allometric and biomass measurements. Of the allometric variables measured for this research, canopy volume, canopy area, and basal diameter were the strongest predictors of biomass found, with respective R2 values of 0.88, 0.87, 0.81. The proportion of biomass within each of the four size classes was: 34% for size class 1, 15% for size class 2, 23% for size class 3, and 28% for size class 4. Average biomass for these sites was 2,482 kg/ha for the Fort Rock site and 5,410 kg/ha for the Lakeview site. These models can be used to estimate biomass for co-generation plants, estimate nutrient pools and fuel loads, and predict changes in community biomass based on species or growth form groups. Close

• 2. [Article] Establishing Design Values for Potential Utilization of Western Juniper as a Building Material

  Western juniper (Juniperus occidentalis) is a conifer that is native to Oregon, California, Washington, Nevada, and Idaho. Juniper is known to have highly decay resistant heartwood and is a popular choice ...

  Citation × Citation Citation Abstract Copy Title: Establishing Design Values for Potential Utilization of Western Juniper as a Building Material Author: Miyamoto, Byrne Western juniper (Juniperus occidentalis) is a conifer that is native to Oregon, California, Washington, Nevada, and Idaho. Juniper is known to have highly decay resistant heartwood and is a popular choice for finished furniture. With recent forest management practices over the past 100 years have resulted in an immense population increase in western juniper stands, transforming the grasslands/sagebrush into juniper forests. Landowners have been encouraged to cutback western juniper to restore grassland habitat, but there is no major market associated with juniper. This study assessed the strength and durability properties of western juniper in order to develop design values in collaboration with the West Coast Lumber Inspection Bureau (WCLIB). The data will be presented to American Lumber Standard Committee (ALSC) for inclusion in the National Design Specification. Design values assigned to western juniper will allow contractors to use this species in structural and non-structural applications, especially for State funded projects. Samples were harvested from three locations in eastern Oregon, one location in northeast California, and one location in southwest Idaho. Tests were performed according to procedures described in ASTM Standard D143 small-clear specimens for compression, bending, and shear. Average strength values were calculated and compared to similar wood species. Most properties were similar to those of other species, but modulus of elasticity was significantly lower. The differences between species might be attributed to cell wall structure and distribution of lignin in the cells. Design values for western juniper were calculated using the strength values following the ASTM Standard D245 procedure for establishing structural grades and related allowable properties for visually graded lumber. Durability of western juniper was assessed using laboratory decay tests, marine tests, and ground contact exposure. The long term marine durability and ground contact tests are still on going. The laboratory decay test indicated that western juniper heartwood was highly resistant to attack by brown and white rot fungi. Title: Establishing Design Values for Potential Utilization of Western Juniper as a Building Material Author: Miyamoto, Byrne Western juniper (Juniperus occidentalis) is a conifer that is native to Oregon, California, Washington, Nevada, and Idaho. Juniper is known to have highly decay resistant heartwood and is a popular choice for finished furniture. With recent forest management practices over the past 100 years have resulted in an immense population increase in western juniper stands, transforming the grasslands/sagebrush into juniper forests. Landowners have been encouraged to cutback western juniper to restore grassland habitat, but there is no major market associated with juniper. This study assessed the strength and durability properties of western juniper in order to develop design values in collaboration with the West Coast Lumber Inspection Bureau (WCLIB). The data will be presented to American Lumber Standard Committee (ALSC) for inclusion in the National Design Specification. Design values assigned to western juniper will allow contractors to use this species in structural and non-structural applications, especially for State funded projects. Samples were harvested from three locations in eastern Oregon, one location in northeast California, and one location in southwest Idaho. Tests were performed according to procedures described in ASTM Standard D143 small-clear specimens for compression, bending, and shear. Average strength values were calculated and compared to similar wood species. Most properties were similar to those of other species, but modulus of elasticity was significantly lower. The differences between species might be attributed to cell wall structure and distribution of lignin in the cells. Design values for western juniper were calculated using the strength values following the ASTM Standard D245 procedure for establishing structural grades and related allowable properties for visually graded lumber. Durability of western juniper was assessed using laboratory decay tests, marine tests, and ground contact exposure. The long term marine durability and ground contact tests are still on going. The laboratory decay test indicated that western juniper heartwood was highly resistant to attack by brown and white rot fungi. Close

• 3. [Article] Persistence of western juniper resource islands following canopy removal

  Western juniper (Juniperus occidentalis) cover has more than doubled within the last century and currently occupies over 9 million acres in the Intermountain West. Encroachment has altered the spatial ...

  Citation × Citation Citation Abstract Copy Title: Persistence of western juniper resource islands following canopy removal Author: Miwa, Christopher Western juniper (Juniperus occidentalis) cover has more than doubled within the last century and currently occupies over 9 million acres in the Intermountain West. Encroachment has altered the spatial distribution of soil nutrients and plants in these systems, forming nutrient enriched 'resource islands,' under tree canopies. The purpose of this study was to determine the persistence of resource island characteristics after restoration treatment (tree removal). The study site was a BLM grazing allotment in Eastern Oregon where trees had been cut 1, 8 and 15 years ago. In each age class and in uncut western juniper woodlands juniper stumps or trees were randomly selected for sampling. At each bole three radial transects, set at 120º from each other, were marked and soil cores were collected to 5-cm depth at distances of 50, 100, 150 and 300-cm from the bole then combined to a single composite sample per distance class. Samples were analyzed for total C and N, soluble P, K, Ca, Fe, Si, Al and Na, inorganic NH₄ and NO₃, pH and gravimetric water content. Fifteen years after canopy removal there was still strong evidence of western juniper resource islands. Canopy soils were generally significantly higher in Ctot, Ntot, NO₃‾, P, K and Ca compared to intercanopy soils in all treatments; however, accumulations for several elements appeared to degrade with time since canopy removal, and at different rates. We attribute resource island persistence to deep litter mats beneath relic canopies. Due to the strong zonal distribution of understory vegetation in juniper duff and bare zones these nutrient enriched areas will continue to influence long-term successional pathways and should be taken into account for restoration purposes, such as seeding of forbs and grasses. Title: Persistence of western juniper resource islands following canopy removal Author: Miwa, Christopher Western juniper (Juniperus occidentalis) cover has more than doubled within the last century and currently occupies over 9 million acres in the Intermountain West. Encroachment has altered the spatial distribution of soil nutrients and plants in these systems, forming nutrient enriched 'resource islands,' under tree canopies. The purpose of this study was to determine the persistence of resource island characteristics after restoration treatment (tree removal). The study site was a BLM grazing allotment in Eastern Oregon where trees had been cut 1, 8 and 15 years ago. In each age class and in uncut western juniper woodlands juniper stumps or trees were randomly selected for sampling. At each bole three radial transects, set at 120º from each other, were marked and soil cores were collected to 5-cm depth at distances of 50, 100, 150 and 300-cm from the bole then combined to a single composite sample per distance class. Samples were analyzed for total C and N, soluble P, K, Ca, Fe, Si, Al and Na, inorganic NH₄ and NO₃, pH and gravimetric water content. Fifteen years after canopy removal there was still strong evidence of western juniper resource islands. Canopy soils were generally significantly higher in Ctot, Ntot, NO₃‾, P, K and Ca compared to intercanopy soils in all treatments; however, accumulations for several elements appeared to degrade with time since canopy removal, and at different rates. We attribute resource island persistence to deep litter mats beneath relic canopies. Due to the strong zonal distribution of understory vegetation in juniper duff and bare zones these nutrient enriched areas will continue to influence long-term successional pathways and should be taken into account for restoration purposes, such as seeding of forbs and grasses. Close