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• 531. [Article] Investigating Demographic and Evolutionary Factors Important for Fish Reintroduction

  Reintroduction programs are used to re-establish species back into their historical habitat. Most reintroduction programs have failed and few papers have evaluated factors that may be important to Pacific ...

  Citation × Citation Citation Abstract Copy Title: Investigating Demographic and Evolutionary Factors Important for Fish Reintroduction Author: Sard, Nicholas M. Reintroduction programs are used to re-establish species back into their historical habitat. Most reintroduction programs have failed and few papers have evaluated factors that may be important to Pacific salmon. The 158 meter tall Cougar Dam has blocked Chinook salmon (Oncorhynchus tshawytscha) from accessing 40 kilometers of historical spawning and rearing habitat for over 50 years. Here, I evaluated a Chinook salmon trap and transport reintroduction program above Cougar Dam on the South Fork McKenzie River, Oregon from 2007 to 2015. First, I evaluated if release location and date correlated with two measures of fitness based on adult assignments to age-0 juveniles collected above the dam and adult offspring returning to the South Fork McKenzie River, respectively. I found that release location and date had little to no effect on either measure of fitness. I also evaluated if there were fitness differences between hatchery and natural origin (HOR and NOR, respectively) adults. I found consistent fitness differences between males (RRS=0.48, p<0.001), but not females (RRS=0.72, p=0.81). In addition, I found that origin (p=0.352) no longer explained variation in fitness after accounting for variation in fork-length, which suggests that HOR fish may be less fit, in part, because they are 2-4 cm (95% CI) smaller, or perhaps younger. I also evaluated a measure of population productivity known as cohort replacement rate (CRR) - defined as the number of future spawners produced by a spawner. Based on genetic parentage assignments to NOR adults returning to the trap and transport facility, hereafter Cougar Trap, I found that adults reintroduced in 2007 and 2008 did not meet demographic replacement (CRR: 0.40 and 0.31, respectively). I also found a seasonal decline in the proportion of NOR adults produced above the dam that returned to the Cougar Trap. I also developed grandparentage assignment methods to determine how many precocial males and adfluvial Chinook salmon, two non-anadromous life history tactics, contributed to population productivity. I found 31 unsampled precocial males, as well as 48 age-4 and -5 probable adfluvial male and female adults contributed to the reintroduced population. My discovery of adfluvial Chinook salmon contributing to population productivity is significant because little is known about this life history tactic, and they provide resiliency to a reintroduced population. I show that adfluvial adults can be produced by anadromous mate pairs. Adfluvial adults increased CRR estimates; however, neither the 2007 or 2008 cohorts met replacement after incorporating this non-anadromous life history tactic (CRR: 0.46 and 0.35, respectively). Finally, I assessed if genetic variation in founding cohorts was maintained in their returning adult offspring returning to the South Fork McKenzie River, hereafter F₁ offspring. On average, 6 alleles were lost per locus between founding cohorts and their F₁ offspring. N[subscript e] estimates were high using either demographic or genetic methods (range: 344 to 893). My dissertation research provides valuable information on factors that may be important to population productivity, as well as the maintenance of genetic variation in nascent populations established through reintroduction. Title: Investigating Demographic and Evolutionary Factors Important for Fish Reintroduction Author: Sard, Nicholas M. Reintroduction programs are used to re-establish species back into their historical habitat. Most reintroduction programs have failed and few papers have evaluated factors that may be important to Pacific salmon. The 158 meter tall Cougar Dam has blocked Chinook salmon (Oncorhynchus tshawytscha) from accessing 40 kilometers of historical spawning and rearing habitat for over 50 years. Here, I evaluated a Chinook salmon trap and transport reintroduction program above Cougar Dam on the South Fork McKenzie River, Oregon from 2007 to 2015. First, I evaluated if release location and date correlated with two measures of fitness based on adult assignments to age-0 juveniles collected above the dam and adult offspring returning to the South Fork McKenzie River, respectively. I found that release location and date had little to no effect on either measure of fitness. I also evaluated if there were fitness differences between hatchery and natural origin (HOR and NOR, respectively) adults. I found consistent fitness differences between males (RRS=0.48, p<0.001), but not females (RRS=0.72, p=0.81). In addition, I found that origin (p=0.352) no longer explained variation in fitness after accounting for variation in fork-length, which suggests that HOR fish may be less fit, in part, because they are 2-4 cm (95% CI) smaller, or perhaps younger. I also evaluated a measure of population productivity known as cohort replacement rate (CRR) - defined as the number of future spawners produced by a spawner. Based on genetic parentage assignments to NOR adults returning to the trap and transport facility, hereafter Cougar Trap, I found that adults reintroduced in 2007 and 2008 did not meet demographic replacement (CRR: 0.40 and 0.31, respectively). I also found a seasonal decline in the proportion of NOR adults produced above the dam that returned to the Cougar Trap. I also developed grandparentage assignment methods to determine how many precocial males and adfluvial Chinook salmon, two non-anadromous life history tactics, contributed to population productivity. I found 31 unsampled precocial males, as well as 48 age-4 and -5 probable adfluvial male and female adults contributed to the reintroduced population. My discovery of adfluvial Chinook salmon contributing to population productivity is significant because little is known about this life history tactic, and they provide resiliency to a reintroduced population. I show that adfluvial adults can be produced by anadromous mate pairs. Adfluvial adults increased CRR estimates; however, neither the 2007 or 2008 cohorts met replacement after incorporating this non-anadromous life history tactic (CRR: 0.46 and 0.35, respectively). Finally, I assessed if genetic variation in founding cohorts was maintained in their returning adult offspring returning to the South Fork McKenzie River, hereafter F₁ offspring. On average, 6 alleles were lost per locus between founding cohorts and their F₁ offspring. N[subscript e] estimates were high using either demographic or genetic methods (range: 344 to 893). My dissertation research provides valuable information on factors that may be important to population productivity, as well as the maintenance of genetic variation in nascent populations established through reintroduction. Close

• 532. [Article] Evaluation of species composition by four methods on two perennial grass pastures (Festuca arundinacae Schreb. and Lolium perenne L.) grazed lightly and heavily in western Oregon

  The present study was undertaken to evaluate the seasonal botanical composition of two grass pastures, tall fescue (Festuca arundinacea Schreb.) and perennial ryegrass (Lolium perenne L.). Botanical composition ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of species composition by four methods on two perennial grass pastures (Festuca arundinacae Schreb. and Lolium perenne L.) grazed lightly and heavily in western Oregon Author: Pessot Zorich, Rafael The present study was undertaken to evaluate the seasonal botanical composition of two grass pastures, tall fescue (Festuca arundinacea Schreb.) and perennial ryegrass (Lolium perenne L.). Botanical composition was determined by four methods: dry-weight-rank, weight-estimate, hand separation, and the constituent differential, with cattle and sheep grazing at two intensities. The pastures were sampled eight times during the growing season (March 23-July 8), taking 50, 25, 5, and 5 observations with the dry-weight-rank, weight-estimate, hand separation, and constituent differential methods, respectively, using a 2.4-square-foot circular plot. New sets of multipliers had to be determined for the dry-weight-rank method. Three different ways of grouping the data were tested. Best results were obtained in both pastures when all the data were grouped from all grazing treatments, because no significant differences were detected among the experimental errors in the analyses of variance used to test data arrangements. Consequently, the use of only one set of multipliers was found to be more practical. The same ways of grouping the data were used to calculate the regression equations to give the most accurate correction for the weight-estimate method. Uncorrected data were also tested. It was determined that best results were obtained in the fescue pastures when all the data were grouped within each of the grazing treatments. In the ryegrass pastures, on the other hand, all data collected in each sampling period was found to be the best arrangement, provided that the number of observations is increased to compensate for greater pasture variability. An analysis of variance was run on the information obtained with each method in both pastures. It was concluded that, in the fescue sections, the methods gave similar results regardless of the kind of livestock, grazing intensity, and sampling period. Units grazed by cattle showed a lower fescue percentage, especially those heavily grazed, than those grazed by sheep; grazing intensity did not affect the trend of the fescue percentages in the mixture which declined as the season progressed. In ryegrass pastures, the ryegrass percentages obtained in each case were influenced by all four treatments: methods, kind of livestock, grazing intensity, and sampling periods. It is apparent from this study that the constituent differential method is the most promising one, and more attention should be directed to it in the future. A study is proposed to explore some of the factors influencing the use of the constituent differential method for determining production and botanical composition on mixed grass-legume pastures. Title: Evaluation of species composition by four methods on two perennial grass pastures (Festuca arundinacae Schreb. and Lolium perenne L.) grazed lightly and heavily in western Oregon Author: Pessot Zorich, Rafael The present study was undertaken to evaluate the seasonal botanical composition of two grass pastures, tall fescue (Festuca arundinacea Schreb.) and perennial ryegrass (Lolium perenne L.). Botanical composition was determined by four methods: dry-weight-rank, weight-estimate, hand separation, and the constituent differential, with cattle and sheep grazing at two intensities. The pastures were sampled eight times during the growing season (March 23-July 8), taking 50, 25, 5, and 5 observations with the dry-weight-rank, weight-estimate, hand separation, and constituent differential methods, respectively, using a 2.4-square-foot circular plot. New sets of multipliers had to be determined for the dry-weight-rank method. Three different ways of grouping the data were tested. Best results were obtained in both pastures when all the data were grouped from all grazing treatments, because no significant differences were detected among the experimental errors in the analyses of variance used to test data arrangements. Consequently, the use of only one set of multipliers was found to be more practical. The same ways of grouping the data were used to calculate the regression equations to give the most accurate correction for the weight-estimate method. Uncorrected data were also tested. It was determined that best results were obtained in the fescue pastures when all the data were grouped within each of the grazing treatments. In the ryegrass pastures, on the other hand, all data collected in each sampling period was found to be the best arrangement, provided that the number of observations is increased to compensate for greater pasture variability. An analysis of variance was run on the information obtained with each method in both pastures. It was concluded that, in the fescue sections, the methods gave similar results regardless of the kind of livestock, grazing intensity, and sampling period. Units grazed by cattle showed a lower fescue percentage, especially those heavily grazed, than those grazed by sheep; grazing intensity did not affect the trend of the fescue percentages in the mixture which declined as the season progressed. In ryegrass pastures, the ryegrass percentages obtained in each case were influenced by all four treatments: methods, kind of livestock, grazing intensity, and sampling periods. It is apparent from this study that the constituent differential method is the most promising one, and more attention should be directed to it in the future. A study is proposed to explore some of the factors influencing the use of the constituent differential method for determining production and botanical composition on mixed grass-legume pastures. Close

• 533. [Article] Evidence of a trophic cascade among wolves, elk, and aspen in Yellowstone National Park, USA

  According to general top-down trophic theory, in the presence of carnivores, herbivore behavior and/or densities could change and result in an overall decrease in herbivory on plant communities. In this ...

  Citation × Citation Citation Abstract Copy Title: Evidence of a trophic cascade among wolves, elk, and aspen in Yellowstone National Park, USA Author: Halofsky, Joshua S. According to general top-down trophic theory, in the presence of carnivores, herbivore behavior and/or densities could change and result in an overall decrease in herbivory on plant communities. In this dissertation, I examined the potential relationship between gray wolf (Canis lupus) presence and absence on elk (Cervus elaphus) herbivory of aspen (Populus tremuloides). Based on aspen tree cores and an age-diameter relationship, I approximated aspen origination dates both within and outside two elk exclosures to study long-term patterns of aspen recruitment in the Gallatin elk winter range of northwestern Yellowstone National Park, USA. From aspen data, I concluded that while a host of interacting biophysical factors may influence aspen recruitment and growth, the observed pattern of aspen decline is most correlated with elk herbivory, coincident with the presence and absence of wolves. Outside of the elk winter range, but still within the northwestern portion of the park, I studied growth patterns of clonal upland aspen thickets since wolf reintroduction. Growth patterns were compared in an area burned in the 1988 fires to an adjacent area that was unburned. From the results, I proposed that in addition to any wolf-mediated changes in elk densities, a recoupling of fire with increased elk predation risk in the presence of wolves may improve upland clonal aspen recruitment. To examine the potential for a trophic cascade from the perspective of elk, I measured vigilance behavior in female elk throughout the park during both winter and summer seasons. After vigilance behavior was recorded, I noted the distance to, and type of, objects that could have impeded observed female elk escape from predators. From my model selection procedure, I concluded elk foraging behavior appeared to vary with physical features in the landscape. This variation in foraging behavior with risk of predation provides a potential mechanism to explain the patchy release of preferred woody browse species within the Park. Therefore, in addition to density-mediated effects, the results are consistent with a behaviorally-mediated top-down trophic cascade between wolves, elk, and aspen. Title: Evidence of a trophic cascade among wolves, elk, and aspen in Yellowstone National Park, USA Author: Halofsky, Joshua S. According to general top-down trophic theory, in the presence of carnivores, herbivore behavior and/or densities could change and result in an overall decrease in herbivory on plant communities. In this dissertation, I examined the potential relationship between gray wolf (Canis lupus) presence and absence on elk (Cervus elaphus) herbivory of aspen (Populus tremuloides). Based on aspen tree cores and an age-diameter relationship, I approximated aspen origination dates both within and outside two elk exclosures to study long-term patterns of aspen recruitment in the Gallatin elk winter range of northwestern Yellowstone National Park, USA. From aspen data, I concluded that while a host of interacting biophysical factors may influence aspen recruitment and growth, the observed pattern of aspen decline is most correlated with elk herbivory, coincident with the presence and absence of wolves. Outside of the elk winter range, but still within the northwestern portion of the park, I studied growth patterns of clonal upland aspen thickets since wolf reintroduction. Growth patterns were compared in an area burned in the 1988 fires to an adjacent area that was unburned. From the results, I proposed that in addition to any wolf-mediated changes in elk densities, a recoupling of fire with increased elk predation risk in the presence of wolves may improve upland clonal aspen recruitment. To examine the potential for a trophic cascade from the perspective of elk, I measured vigilance behavior in female elk throughout the park during both winter and summer seasons. After vigilance behavior was recorded, I noted the distance to, and type of, objects that could have impeded observed female elk escape from predators. From my model selection procedure, I concluded elk foraging behavior appeared to vary with physical features in the landscape. This variation in foraging behavior with risk of predation provides a potential mechanism to explain the patchy release of preferred woody browse species within the Park. Therefore, in addition to density-mediated effects, the results are consistent with a behaviorally-mediated top-down trophic cascade between wolves, elk, and aspen. Close

• 534. [Article] Buffer strip dynamics in the Western Oregon Cascades

  Although buffer strips have long been used as a protection tool when logging near streams, long-term studies investigating buffer strip dynamics are rare. Steinblums et al. (1984) inventoried 40 buffer ...

  Citation × Citation Citation Abstract Copy Title: Buffer strip dynamics in the Western Oregon Cascades Author: Sherwood, Kim Although buffer strips have long been used as a protection tool when logging near streams, long-term studies investigating buffer strip dynamics are rare. Steinblums et al. (1984) inventoried 40 buffer strips 1 to 15 years old in the western Oregon Cascades beginning in the summer of 1975. Numerous site and stand characteristics were evaluated and regional regression equations were developed to predict survival of the buffer strips (Steinblums et al. 1984). During the summer of 1990, 20 of the original buffer strips (Steinblums et al. 1984) were selected for reinventory to assess overstory conifer changes and density of conifer regeneration. Three sites had experienced severe windthrow followed by salvage logging, and a fourth could not be matched with original field notes. The 1990 comparison utilized the 16 remaining sites. Four diameter classes (10-14 inches DBH, 15-29 inches DBH, 30-44 inches DBH, and 45 inches DBH) were used to evaluate changes in overstory conifers since the original study. Density and basal area of each class were evaluated for each of the three common coniferous species (western hemlock, western redcedar, and Douglas-fir), and combined conifers. Average combined conifer densities of these late successional buffer strips increased from 54 to 59 trees per acre since the earlier study (Steinblums et al. 1984); average combined conifer basal area decreased from 299 to 263 ft^2 per acre since the original study. Ingrowth was most common in the two smallest diameter classes, with the majority of buffer strips showing increases in density and basal area. Average combined conifer density increased from 32 to 41 trees per acre; average combined conifer basal area increased from 64 to 76 ft^2 per acre. Western hemlock was the major contributor to the increases. Western redcedar and Douglas-fir represented relatively minor components of the two smallest diameter classes in both samplings. While combined conifer basal area increases were small, density increased as much as 900%. Decreases in density and basal area were common for conifers 30-44 inches DBH, with the majority of losses evident among western hemlock. However, Douglas-fir also exhibited some declines in this class. Western redcedar was relatively unchanged since the original study. Density losses ranged from 0 to 50% of the original buffer; basal area losses ranged from 0 to 72%. Density and basal area losses typically occurred among conifers 45 inches DBH. Though trees of this size were not prevalent, basal area losses from this class ranged from 0 to 84% of the original sample value. Conifer regeneration data indicate these buffer strips are sufficiently stocked to maintain conifers over time. Average densities of saplings (<8 inches DBH and >3 feet tall) ranged from nearly 200 to 3600 trees per acre. Title: Buffer strip dynamics in the Western Oregon Cascades Author: Sherwood, Kim Although buffer strips have long been used as a protection tool when logging near streams, long-term studies investigating buffer strip dynamics are rare. Steinblums et al. (1984) inventoried 40 buffer strips 1 to 15 years old in the western Oregon Cascades beginning in the summer of 1975. Numerous site and stand characteristics were evaluated and regional regression equations were developed to predict survival of the buffer strips (Steinblums et al. 1984). During the summer of 1990, 20 of the original buffer strips (Steinblums et al. 1984) were selected for reinventory to assess overstory conifer changes and density of conifer regeneration. Three sites had experienced severe windthrow followed by salvage logging, and a fourth could not be matched with original field notes. The 1990 comparison utilized the 16 remaining sites. Four diameter classes (10-14 inches DBH, 15-29 inches DBH, 30-44 inches DBH, and 45 inches DBH) were used to evaluate changes in overstory conifers since the original study. Density and basal area of each class were evaluated for each of the three common coniferous species (western hemlock, western redcedar, and Douglas-fir), and combined conifers. Average combined conifer densities of these late successional buffer strips increased from 54 to 59 trees per acre since the earlier study (Steinblums et al. 1984); average combined conifer basal area decreased from 299 to 263 ft^2 per acre since the original study. Ingrowth was most common in the two smallest diameter classes, with the majority of buffer strips showing increases in density and basal area. Average combined conifer density increased from 32 to 41 trees per acre; average combined conifer basal area increased from 64 to 76 ft^2 per acre. Western hemlock was the major contributor to the increases. Western redcedar and Douglas-fir represented relatively minor components of the two smallest diameter classes in both samplings. While combined conifer basal area increases were small, density increased as much as 900%. Decreases in density and basal area were common for conifers 30-44 inches DBH, with the majority of losses evident among western hemlock. However, Douglas-fir also exhibited some declines in this class. Western redcedar was relatively unchanged since the original study. Density losses ranged from 0 to 50% of the original buffer; basal area losses ranged from 0 to 72%. Density and basal area losses typically occurred among conifers 45 inches DBH. Though trees of this size were not prevalent, basal area losses from this class ranged from 0 to 84% of the original sample value. Conifer regeneration data indicate these buffer strips are sufficiently stocked to maintain conifers over time. Average densities of saplings (<8 inches DBH and >3 feet tall) ranged from nearly 200 to 3600 trees per acre. Close

• 535. [Article] Fisheries Co-management: An Experiential Account from Phang Nga Bay, Thailand

  Research Paper

  Citation × Citation Citation Abstract Copy Title: Fisheries Co-management: An Experiential Account from Phang Nga Bay, Thailand Author: Tandavanitj, Sanchai, Nabhitabhata, Jaruwat, Silpachai, Damrong, Henocque, Yves, Pimoljinda, Jate Research Paper Title: Fisheries Co-management: An Experiential Account from Phang Nga Bay, Thailand Author: Tandavanitj, Sanchai, Nabhitabhata, Jaruwat, Silpachai, Damrong, Henocque, Yves, Pimoljinda, Jate Research Paper Close

• 536. [Article] Economic-based projections of future land use in the conterminous United States under alternative policy scenarios

  This is the publisher’s final pdf. The published article is copyrighted by the Ecological Society of America and can be found at: http://www.esajournals.org/toc/ecap/current. To the best of our knowledge, ...

  Citation × Citation Citation Abstract Copy Title: Economic-based projections of future land use in the conterminous United States under alternative policy scenarios Author: Withey, J. C., Lonsdorf, E., Martinuzzi, S., Radeloff, V. C., Nelson, E., Beaudry, F., Helmers, D., White, D., Lawler, J. J., Plantinga, A. J., Butsic, V., Lewis, D. J., Polasky, S. This is the publisher’s final pdf. The published article is copyrighted by the Ecological Society of America and can be found at: http://www.esajournals.org/toc/ecap/current. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Title: Economic-based projections of future land use in the conterminous United States under alternative policy scenarios Author: Withey, J. C., Lonsdorf, E., Martinuzzi, S., Radeloff, V. C., Nelson, E., Beaudry, F., Helmers, D., White, D., Lawler, J. J., Plantinga, A. J., Butsic, V., Lewis, D. J., Polasky, S. This is the publisher’s final pdf. The published article is copyrighted by the Ecological Society of America and can be found at: http://www.esajournals.org/toc/ecap/current. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Close

• 537. [Article] Twospotted spider mite, Tetranychus urticae Kock, in Oregon peppermint, Mentha piperita L. : sampling, population dynamics and economic injury

  A pest management program for Tetranychus urticae Koch in Oregon peppermint was developed based on studies of sampling, plant phenology, population dynamics and damage thresholds. A sample size of 45 leaves ...

  Citation × Citation Citation Abstract Copy Title: Twospotted spider mite, Tetranychus urticae Kock, in Oregon peppermint, Mentha piperita L. : sampling, population dynamics and economic injury Author: Hollingsworth, Craig Stephen A pest management program for Tetranychus urticae Koch in Oregon peppermint was developed based on studies of sampling, plant phenology, population dynamics and damage thresholds. A sample size of 45 leaves provided a confidence level of 90% and a confidence interval of 50%. Estimation of the sample mean was based on the relationship between the mean density of mites (x) and the number of leaves infested with 5 or more mites (INF5) in a 45 leaf sample: Log (x + 1.0) = 0.18 + 0.59(INF5 + 1.0). The coefficient of determination for the relationship was 0.92. This equation was consistent over widely separated regions and during different growing seasons. Sampling with this method was less tedious and three times faster than direct counting techniques. Plant development in commercial mint fields in the Willamette Valley and central Oregon was assessed by weekly observations of primary nodes and leaves, lateral branches, stem length and flower bud formation. Stems.were longer and more primary leaves were present in Willamette Valley fields, but the number of nodes and lateral branches were not significantly different between regions. Flower buds were present earlier in central Oregon than in the Willamette Valley. The number of primary leaves showed significant variation between fields in central Oregon, reflecting the greater range of stress present among fields in central Oregon. Studies of T. urticae populations in commercial peppermint showed wide variation in population trends. Population dispersion were examined relative to vertical strata of the plant canopy. T. urticae populations were highly aggregated in all strata at the beginning of the season, but as the population increased, dispersion became more random. Mites on the older, middle and bottom leaves became more aggregated as populations declined, but mites on the newly formed top leaves remained randomly distributed. Eighteen species of predators were identified from peppermint samples, but none were sufficiently abundant to regulate mite populations in commercial peppermint plots. Observations of a T. urticae population regulated by Amblyseius fallacis (Acari: Phytoseiidae), showed that biocontrol of T. urticae in peppermint was feasible, but probably only in less disturbed sites. T. urticae reproduction increased on mint plants subjected to water stress but not on plants stressed by Verticillium. Mite populations were reduced by fall flaming in western Oregon, and fall plowing delayed the onset of economic levels of T. urticae in central Oregon. The yield of field-grown peppermint was not reduced by mite populations reaching 50 mites per leaf at mid-season. Mite density did not affect the total concentration of terpenes from individual leaves, but changes of concentration of some terpenes indicated increased maturation of the oil. Neomenthol was higher in leaves from mite-infested plots, and the concentration of its precursor, menthone, was lower. An action threshold for T. urticae on peppermint of 10 mites per leaf was established based on the tendency for mites to undergo exponential increase once the density reaches 10 mites/leaf. Title: Twospotted spider mite, Tetranychus urticae Kock, in Oregon peppermint, Mentha piperita L. : sampling, population dynamics and economic injury Author: Hollingsworth, Craig Stephen A pest management program for Tetranychus urticae Koch in Oregon peppermint was developed based on studies of sampling, plant phenology, population dynamics and damage thresholds. A sample size of 45 leaves provided a confidence level of 90% and a confidence interval of 50%. Estimation of the sample mean was based on the relationship between the mean density of mites (x) and the number of leaves infested with 5 or more mites (INF5) in a 45 leaf sample: Log (x + 1.0) = 0.18 + 0.59(INF5 + 1.0). The coefficient of determination for the relationship was 0.92. This equation was consistent over widely separated regions and during different growing seasons. Sampling with this method was less tedious and three times faster than direct counting techniques. Plant development in commercial mint fields in the Willamette Valley and central Oregon was assessed by weekly observations of primary nodes and leaves, lateral branches, stem length and flower bud formation. Stems.were longer and more primary leaves were present in Willamette Valley fields, but the number of nodes and lateral branches were not significantly different between regions. Flower buds were present earlier in central Oregon than in the Willamette Valley. The number of primary leaves showed significant variation between fields in central Oregon, reflecting the greater range of stress present among fields in central Oregon. Studies of T. urticae populations in commercial peppermint showed wide variation in population trends. Population dispersion were examined relative to vertical strata of the plant canopy. T. urticae populations were highly aggregated in all strata at the beginning of the season, but as the population increased, dispersion became more random. Mites on the older, middle and bottom leaves became more aggregated as populations declined, but mites on the newly formed top leaves remained randomly distributed. Eighteen species of predators were identified from peppermint samples, but none were sufficiently abundant to regulate mite populations in commercial peppermint plots. Observations of a T. urticae population regulated by Amblyseius fallacis (Acari: Phytoseiidae), showed that biocontrol of T. urticae in peppermint was feasible, but probably only in less disturbed sites. T. urticae reproduction increased on mint plants subjected to water stress but not on plants stressed by Verticillium. Mite populations were reduced by fall flaming in western Oregon, and fall plowing delayed the onset of economic levels of T. urticae in central Oregon. The yield of field-grown peppermint was not reduced by mite populations reaching 50 mites per leaf at mid-season. Mite density did not affect the total concentration of terpenes from individual leaves, but changes of concentration of some terpenes indicated increased maturation of the oil. Neomenthol was higher in leaves from mite-infested plots, and the concentration of its precursor, menthone, was lower. An action threshold for T. urticae on peppermint of 10 mites per leaf was established based on the tendency for mites to undergo exponential increase once the density reaches 10 mites/leaf. Close

• 538. [Article] Development and disease of opakapaka (Pristiopomoides filamentosus) larvae in culture

  Opakapaka (Pristipomoides filamentosus) is a snapper (family Lutjanidae) native to the waters around Hawaii. Recent population declines of this commercially important species have increased interest in ...

  Citation × Citation Citation Abstract Copy Title: Development and disease of opakapaka (Pristiopomoides filamentosus) larvae in culture Author: Keafer, Briana Opakapaka (Pristipomoides filamentosus) is a snapper (family Lutjanidae) native to the waters around Hawaii. Recent population declines of this commercially important species have increased interest in the culture of this fish. Survival of this fish through the larval period in culture has been consistently low, usually not exceeding 2%. The aim of this thesis was to provide an extensive diagnostic report of diseases affecting opakapaka larvae in culture. Opakapaka larvae mortality was found to be the result of a synergy of factors including larvae development stage, larvae nutrition, environmental conditions, and the presence of infectious agents. During culture, high larval mortalities occur around first feeding and around a period of rapid development. Crucial periods of development in both the digestive system and the respiratory system coincided with these catastrophic mortality events. It is therefore suspected that failure to complete the progression of development from one stage to the next is partially responsible for low larvae survival. A large proportion of opakapaka surviving to the juvenile stage had deformed jaws and/or vertebral columns. Therefore, the development of the jaw and other skeletal elements was investigated. Lower jaw deformities were found to occur as early as 2 days post hatch and larvae with some deformity represented roughly 30% of the population. Given the severity of these deformities, it is likely that this results in increased larvae mortality. Due to the identified risk of ammonia toxicity, experiments were designed to determine the concentration of ammonia lethal to opakapaka larvae. The 50% lethal dose for post-hatch opakapaka larvae was found to be 1.4 mg/L total nitrogen. Ammonia toxicity could have been a factor in opakapaka larvae mortality, because this concentration was lower than that observed in larvae rearing tanks. The evaluation of the role of infectious disease in opakapaka culture showed that current infections are primarily opportunistic. Observed infections included bacterial gill disease and external lungal infection. Although infectious disease is not currently a significant cause of mortality, continued surveillance for infectious disease introduction is recommended. The success of intensive opakapaka culture hinges on the ability to culture a large number of opakapaka to the juvenile stage. As a result of this study, major issues of concern in opakapaka culture were identified. This information could provide direction for culturists in the refinement of opakapaka culture and subsequent improvement of larvae survival. Title: Development and disease of opakapaka (Pristiopomoides filamentosus) larvae in culture Author: Keafer, Briana Opakapaka (Pristipomoides filamentosus) is a snapper (family Lutjanidae) native to the waters around Hawaii. Recent population declines of this commercially important species have increased interest in the culture of this fish. Survival of this fish through the larval period in culture has been consistently low, usually not exceeding 2%. The aim of this thesis was to provide an extensive diagnostic report of diseases affecting opakapaka larvae in culture. Opakapaka larvae mortality was found to be the result of a synergy of factors including larvae development stage, larvae nutrition, environmental conditions, and the presence of infectious agents. During culture, high larval mortalities occur around first feeding and around a period of rapid development. Crucial periods of development in both the digestive system and the respiratory system coincided with these catastrophic mortality events. It is therefore suspected that failure to complete the progression of development from one stage to the next is partially responsible for low larvae survival. A large proportion of opakapaka surviving to the juvenile stage had deformed jaws and/or vertebral columns. Therefore, the development of the jaw and other skeletal elements was investigated. Lower jaw deformities were found to occur as early as 2 days post hatch and larvae with some deformity represented roughly 30% of the population. Given the severity of these deformities, it is likely that this results in increased larvae mortality. Due to the identified risk of ammonia toxicity, experiments were designed to determine the concentration of ammonia lethal to opakapaka larvae. The 50% lethal dose for post-hatch opakapaka larvae was found to be 1.4 mg/L total nitrogen. Ammonia toxicity could have been a factor in opakapaka larvae mortality, because this concentration was lower than that observed in larvae rearing tanks. The evaluation of the role of infectious disease in opakapaka culture showed that current infections are primarily opportunistic. Observed infections included bacterial gill disease and external lungal infection. Although infectious disease is not currently a significant cause of mortality, continued surveillance for infectious disease introduction is recommended. The success of intensive opakapaka culture hinges on the ability to culture a large number of opakapaka to the juvenile stage. As a result of this study, major issues of concern in opakapaka culture were identified. This information could provide direction for culturists in the refinement of opakapaka culture and subsequent improvement of larvae survival. Close

• 539. [Article] Areal distribution, change, and restoration potential of wetlands within the lower Columbia River riparian zone, 1948-1991

  The lower Columbia River (LCR) riparian zone is rich in habitat diversity. However, the natural beauty and species diversity along the river have increasingly become affected by human activity. This study ...

  Citation × Citation Citation Abstract Copy Title: Areal distribution, change, and restoration potential of wetlands within the lower Columbia River riparian zone, 1948-1991 Author: Allen, Tracy Hunter The lower Columbia River (LCR) riparian zone is rich in habitat diversity. However, the natural beauty and species diversity along the river have increasingly become affected by human activity. This study quantifies the areal extent and degree of wetlands change and associated causes along the LCR over the past 44 years. This research examines the distribution of wetland types and their patterns of change, developing regional models which rank areas most conducive to potential wetland recovery or restoration efforts. The length of the study area totals 234 river kilometers, from the mouth of the Columbia River to Bonneville Dam. The width includes the active channel and an approximately three-kilometer swath on either side of the river. Aerial photography was the primary means for interpreting historical extent of wetlands, using five photo dates (1948, 1961, 1973, 1983, and 1991), based upon their time interval, coverage, and photo quality. For each photo throughout the entire study site, land uses and wetland habitats greater than one hectare were identified and classified. Each classified polygon was digitized and spatially analyzed using a Geographic Information System. This study indicates that wetland habitats which were once contiguously draped upon the linear features of the river are decreasing in size and becoming fragmented. There have been both increases and decreases in specific wetland habitat areas which vary by river reach, even though wetlands have diminished overall. The estuarine section of the LCR experienced a 25% net decrease in wetland area between 1948 and 1991, while the riverine tidal section fostered a 1% increase. The riverine lower perennial section sustained the greatest loss of wetlands, which decreased by 37%. Causes for wetland losses in the estuarine section were largely related to in-water activities, such as channelization, while the causes for declines in the riverine lower perennial section were correlated with rapid urbanization. Wetland increases in the riverine tidal section were generally influenced by significant growth in palustrine and forested wetlands associated with the establishment of wildlife refuges and the incremental increase of upstream flood storage capacity. This research provides a template for identifying degraded or displaced wetlands. Through the use of a GIS, each historical wetland was ranked in either low, moderate, or high categories for restoration potential. GIS technology permits focused, sequentially-refined queries to identify potential restoration or recovery sites. In the estuarine section, 74 historical wetland sites were ranked high for restoration potential, while in the riverine tidal and riverine lower perennial sections, there were 178 and 105, respectively. Overall, these sites represent only 25% of the area occupied by wetlands in 1948. While this study advocates restoration potential, restoration is not a surrogate for responsible ecosystem-wide stewardship of the riparian zone. Restoration will not succeed unless degrading factors are mitigated or eliminated. Title: Areal distribution, change, and restoration potential of wetlands within the lower Columbia River riparian zone, 1948-1991 Author: Allen, Tracy Hunter The lower Columbia River (LCR) riparian zone is rich in habitat diversity. However, the natural beauty and species diversity along the river have increasingly become affected by human activity. This study quantifies the areal extent and degree of wetlands change and associated causes along the LCR over the past 44 years. This research examines the distribution of wetland types and their patterns of change, developing regional models which rank areas most conducive to potential wetland recovery or restoration efforts. The length of the study area totals 234 river kilometers, from the mouth of the Columbia River to Bonneville Dam. The width includes the active channel and an approximately three-kilometer swath on either side of the river. Aerial photography was the primary means for interpreting historical extent of wetlands, using five photo dates (1948, 1961, 1973, 1983, and 1991), based upon their time interval, coverage, and photo quality. For each photo throughout the entire study site, land uses and wetland habitats greater than one hectare were identified and classified. Each classified polygon was digitized and spatially analyzed using a Geographic Information System. This study indicates that wetland habitats which were once contiguously draped upon the linear features of the river are decreasing in size and becoming fragmented. There have been both increases and decreases in specific wetland habitat areas which vary by river reach, even though wetlands have diminished overall. The estuarine section of the LCR experienced a 25% net decrease in wetland area between 1948 and 1991, while the riverine tidal section fostered a 1% increase. The riverine lower perennial section sustained the greatest loss of wetlands, which decreased by 37%. Causes for wetland losses in the estuarine section were largely related to in-water activities, such as channelization, while the causes for declines in the riverine lower perennial section were correlated with rapid urbanization. Wetland increases in the riverine tidal section were generally influenced by significant growth in palustrine and forested wetlands associated with the establishment of wildlife refuges and the incremental increase of upstream flood storage capacity. This research provides a template for identifying degraded or displaced wetlands. Through the use of a GIS, each historical wetland was ranked in either low, moderate, or high categories for restoration potential. GIS technology permits focused, sequentially-refined queries to identify potential restoration or recovery sites. In the estuarine section, 74 historical wetland sites were ranked high for restoration potential, while in the riverine tidal and riverine lower perennial sections, there were 178 and 105, respectively. Overall, these sites represent only 25% of the area occupied by wetlands in 1948. While this study advocates restoration potential, restoration is not a surrogate for responsible ecosystem-wide stewardship of the riparian zone. Restoration will not succeed unless degrading factors are mitigated or eliminated. Close

• 540. [Article] The effects of burning in mountain big sagebrush on key sage grouse habitat characteristics in southeastern Oregon

  Sage grouse are a species of concern because their abundance, distribution, and productivity have declined during the past century. Sage grouse productivity has been linked to specific habitat components ...

  Citation × Citation Citation Abstract Copy Title: The effects of burning in mountain big sagebrush on key sage grouse habitat characteristics in southeastern Oregon Author: McDowell, Michelle K. D. Sage grouse are a species of concern because their abundance, distribution, and productivity have declined during the past century. Sage grouse productivity has been linked to specific habitat components including particular forbs and native bunchgrasses. Studies on the effects of fire were conducted in Southeastern Oregon in mountain big sagebrush communities to better understand the effects of fire on key sage grouse habitat components. The short-term study was conducted at South Steens Mountain during 1997 and 1998. Habitat components (medium shrub cover; perennial grass cover; hen and chick food forb cover, frequency, and availability; chick food forb nutrition; insect abundance; and sagebrush reproductive branch abundance) were compared between preburn or unburned, 1- year post-bum, and 2-years post-burn areas. The long-term effects of fire on essential sage grouse habitat components were studied during 1997 at Hart Mountain National Antelope Refuge (Lake County), and during 1998 at South Steens Mountain (Harney County). Habitat components (medium height mountain big sagebrush, tall grass, hen and chick food forb, and other forb cover) were measured at burned and adjacent unburned control sites and compared with recommended cover amounts. Burned sites ranged in age from 5 to 43 years. In the short-term fire effects study, prescribed burning increased the amount of sage grouse hen and chick foods, the quality of some chick foods, and increased the amount of time of these foods were available. Sagebrush cover was essentially eliminated in burned areas. Perennial grass cover was significantly higher in a comparison of the 2-years post burn to the 1-year post burn samples. In the long-term fire effects study, all key vegetative and structural components needed for successful sage grouse reproduction became available in burned areas from 25-35 years old. Sagebrush cover was the only habitat component tested that was substantially affected by burning in the long term. Prescribed burning would be most beneficial to sage grouse habitat if used as a management tool to create a mosaic of needed habitat components. Title: The effects of burning in mountain big sagebrush on key sage grouse habitat characteristics in southeastern Oregon Author: McDowell, Michelle K. D. Sage grouse are a species of concern because their abundance, distribution, and productivity have declined during the past century. Sage grouse productivity has been linked to specific habitat components including particular forbs and native bunchgrasses. Studies on the effects of fire were conducted in Southeastern Oregon in mountain big sagebrush communities to better understand the effects of fire on key sage grouse habitat components. The short-term study was conducted at South Steens Mountain during 1997 and 1998. Habitat components (medium shrub cover; perennial grass cover; hen and chick food forb cover, frequency, and availability; chick food forb nutrition; insect abundance; and sagebrush reproductive branch abundance) were compared between preburn or unburned, 1- year post-bum, and 2-years post-burn areas. The long-term effects of fire on essential sage grouse habitat components were studied during 1997 at Hart Mountain National Antelope Refuge (Lake County), and during 1998 at South Steens Mountain (Harney County). Habitat components (medium height mountain big sagebrush, tall grass, hen and chick food forb, and other forb cover) were measured at burned and adjacent unburned control sites and compared with recommended cover amounts. Burned sites ranged in age from 5 to 43 years. In the short-term fire effects study, prescribed burning increased the amount of sage grouse hen and chick foods, the quality of some chick foods, and increased the amount of time of these foods were available. Sagebrush cover was essentially eliminated in burned areas. Perennial grass cover was significantly higher in a comparison of the 2-years post burn to the 1-year post burn samples. In the long-term fire effects study, all key vegetative and structural components needed for successful sage grouse reproduction became available in burned areas from 25-35 years old. Sagebrush cover was the only habitat component tested that was substantially affected by burning in the long term. Prescribed burning would be most beneficial to sage grouse habitat if used as a management tool to create a mosaic of needed habitat components. Close