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• 151. [Article] The recreation resources of the Malheur National Wildlife Refuge

  Heavy use of outdoor recreation areas in the United States since World War II is endangering their quality. Demand made by a rapidly growing population with rising personal incomes and increasing leisure ...

  Citation × Citation Citation Abstract Copy Title: The recreation resources of the Malheur National Wildlife Refuge Author: Albrecht, James Conrad Heavy use of outdoor recreation areas in the United States since World War II is endangering their quality. Demand made by a rapidly growing population with rising personal incomes and increasing leisure time is expected to grow 50 percent nationally and 146 percent in Oregon by 1975. In Oregon, population, incomes, and amount of leisure time per person are all increasing more rapidly than nationally. A large influx of out-of-state visitors accelerates the demand. Eighty-five percent of outdoor recreation land in the United States and 95 percent in Oregon is owned by the Federal government. Recreation on Federal land is in general resource-based, that is, it depends upon some natural feature. The role of the Federal government is therefore pre-eminent in developing sites for resource-based recreation activities. Of the agencies involved in meeting the Federal responsibility, the possible role of the Fish and Wildlife Service is least known. Controlling approximately four percent of outdoor recreation land, the 300 refuges had only 13 million of the more than 500 million visitor-days to outdoor recreation areas in 1960. Recreation visits to refuges are increasing rapidly but apparently the quality and quantity of the remarkable wildlife resources of the National Wildlife Refuge System is little understood. As the mission of the Branch of Wildlife Refuges developed, its role involves the provision of habitat for every species of native wildlife somewhere in the System. The refuges are widely distributed over the nation, with the great majority, particularly those for migratory birds, concentrated in the four great flyways. The Service plans ultimately to include within refuge boundaries some 7.5 million acres of the 12 million acres of wetlands needed to maintain present waterfowl populations. Recreation use compatible with wildlife management is permitted on the refuges but development of facilities has been slight. Although express authorization was obtained in 1962 for such development, no funds have since been provided. The Accelerated Public Works Program and the Job Corps Program both provide an avenue for development in some areas. The Malheur National Wildlife Refuge, located in southeastern Oregon, is an excellent example of the recreation potential in the Refuge System. One of the larger refuges, its duck and geese populations number over a million during spring and fall migration. Of Oregon's 425 bird species, 226 have been observed on the Refuge; 141 of them are listed as easily seen during one or more seasons of the year. Deer, antelope, and beaver are also easily seen. The Refuge lies in the basin of the two playas, Malheur and Harney Lakes, and extends for forty miles through the marshes of the Blitzen River toward Steens Mountain, an impressive fault block with alpine vegetation. An excellent museum exhibits indigenous species, photographs, nests, and food plants. A display pool provides an opportunity to observe birds at close hand. Besides wildlife observation and photography, Refuge recreation uses include fishing, water fowl hunting, and an exceptionally high quality annual all deer archery hunt. Camping and picnicking are commonly practiced in conjunction with other recreation activities. Recreation use of the Refuge is limited by inadequate facilities. Campsites are minimally developed and Refuge roads are impassable in wet weather. Authorization for the establishment of a Job Corps Camp on the Refuge in June of 1965 has been obtained and it is expected that Corps projects will serve to alleviate the deficiencies. Development of a significant recreation resource seems assured at a time of growing need. Title: The recreation resources of the Malheur National Wildlife Refuge Author: Albrecht, James Conrad Heavy use of outdoor recreation areas in the United States since World War II is endangering their quality. Demand made by a rapidly growing population with rising personal incomes and increasing leisure time is expected to grow 50 percent nationally and 146 percent in Oregon by 1975. In Oregon, population, incomes, and amount of leisure time per person are all increasing more rapidly than nationally. A large influx of out-of-state visitors accelerates the demand. Eighty-five percent of outdoor recreation land in the United States and 95 percent in Oregon is owned by the Federal government. Recreation on Federal land is in general resource-based, that is, it depends upon some natural feature. The role of the Federal government is therefore pre-eminent in developing sites for resource-based recreation activities. Of the agencies involved in meeting the Federal responsibility, the possible role of the Fish and Wildlife Service is least known. Controlling approximately four percent of outdoor recreation land, the 300 refuges had only 13 million of the more than 500 million visitor-days to outdoor recreation areas in 1960. Recreation visits to refuges are increasing rapidly but apparently the quality and quantity of the remarkable wildlife resources of the National Wildlife Refuge System is little understood. As the mission of the Branch of Wildlife Refuges developed, its role involves the provision of habitat for every species of native wildlife somewhere in the System. The refuges are widely distributed over the nation, with the great majority, particularly those for migratory birds, concentrated in the four great flyways. The Service plans ultimately to include within refuge boundaries some 7.5 million acres of the 12 million acres of wetlands needed to maintain present waterfowl populations. Recreation use compatible with wildlife management is permitted on the refuges but development of facilities has been slight. Although express authorization was obtained in 1962 for such development, no funds have since been provided. The Accelerated Public Works Program and the Job Corps Program both provide an avenue for development in some areas. The Malheur National Wildlife Refuge, located in southeastern Oregon, is an excellent example of the recreation potential in the Refuge System. One of the larger refuges, its duck and geese populations number over a million during spring and fall migration. Of Oregon's 425 bird species, 226 have been observed on the Refuge; 141 of them are listed as easily seen during one or more seasons of the year. Deer, antelope, and beaver are also easily seen. The Refuge lies in the basin of the two playas, Malheur and Harney Lakes, and extends for forty miles through the marshes of the Blitzen River toward Steens Mountain, an impressive fault block with alpine vegetation. An excellent museum exhibits indigenous species, photographs, nests, and food plants. A display pool provides an opportunity to observe birds at close hand. Besides wildlife observation and photography, Refuge recreation uses include fishing, water fowl hunting, and an exceptionally high quality annual all deer archery hunt. Camping and picnicking are commonly practiced in conjunction with other recreation activities. Recreation use of the Refuge is limited by inadequate facilities. Campsites are minimally developed and Refuge roads are impassable in wet weather. Authorization for the establishment of a Job Corps Camp on the Refuge in June of 1965 has been obtained and it is expected that Corps projects will serve to alleviate the deficiencies. Development of a significant recreation resource seems assured at a time of growing need. Close

• 152. [Article] Expansion of scouringrush (Equisetum spp. L.) : crop interference and control options in winter wheat (Triticum aestivum L.) and chemical fallow cropping cropping systems

  Scouringrushes (Equisetum hyemale L.; E. xferrissii Clute; E. laevigatum L.) are ancient perennial seedless vascular plants historically associated with wetlands, low-lying roadsides or field margins with ...

  Citation × Citation Citation Abstract Copy Title: Expansion of scouringrush (Equisetum spp. L.) : crop interference and control options in winter wheat (Triticum aestivum L.) and chemical fallow cropping cropping systems Author: Kerbs, Blake D. Scouringrushes (Equisetum hyemale L.; E. xferrissii Clute; E. laevigatum L.) are ancient perennial seedless vascular plants historically associated with wetlands, low-lying roadsides or field margins with more plant available water. There has been little research conducted on scouringrush species in the context of agricultural production because traditional farming practices confined them to field margins and roadside depressions. An increasing amount of dryland winter wheat (Triticum aestivum L.) hectares in the inland Pacific Northwest have replaced summer tilled-fallow rotations with chemical fallow. Where chemical fallow rotations have become the standard practice, scouringrush has expanded out of its historical habitat into production fields and established at high enough densities to cause concern from growers. Research was conducted to identify control options that fit chemical fallow cropping systems, evaluate the magnitude of crop interference by scouringrush, and address how soil pH affects scouringrush growth and establishment, as soil acidification is another agronomic issue caused by intensive wheat production in the Pacific Northwest. Field studies located in Reardan, WA, and near The Dalles, OR, were established in commercial wheat production fields that evaluated 10 herbicide treatments for efficacy on scouringrush. An additional factor in the trials was to determine if pre-herbicide mowing affected herbicide efficacy. At both locations pre-herbicide mowing had no effect on efficacy and only chlorsulfuron plus MCPA-ester controlled scouringrush though the subsequent winter wheat rotation. A third herbicide trial determined that triclopyr or increased rates of chlorsulfuron plus 2,4-D and dicamba or asulam were able to effectively control scouringrush seven and 10 months after treatment at a non-crop site in eastern Oregon. Under field conditions wheat yield reductions were correlated with increasing scouringrush density, but in a controlled study scouringrush density had no effect on winter wheat development or grain yield. Disagreement between these results is hypothesized to be a function of nutrient deficiencies within production fields. Results from three greenhouse studies showed that scouringrush biomass production increased as soil pH increased from ≈4.6 to ≈8.0 and that scouringrush was able to establish and survive in soil pH conditions that are unsuitable for winter wheat production. Title: Expansion of scouringrush (Equisetum spp. L.) : crop interference and control options in winter wheat (Triticum aestivum L.) and chemical fallow cropping cropping systems Author: Kerbs, Blake D. Scouringrushes (Equisetum hyemale L.; E. xferrissii Clute; E. laevigatum L.) are ancient perennial seedless vascular plants historically associated with wetlands, low-lying roadsides or field margins with more plant available water. There has been little research conducted on scouringrush species in the context of agricultural production because traditional farming practices confined them to field margins and roadside depressions. An increasing amount of dryland winter wheat (Triticum aestivum L.) hectares in the inland Pacific Northwest have replaced summer tilled-fallow rotations with chemical fallow. Where chemical fallow rotations have become the standard practice, scouringrush has expanded out of its historical habitat into production fields and established at high enough densities to cause concern from growers. Research was conducted to identify control options that fit chemical fallow cropping systems, evaluate the magnitude of crop interference by scouringrush, and address how soil pH affects scouringrush growth and establishment, as soil acidification is another agronomic issue caused by intensive wheat production in the Pacific Northwest. Field studies located in Reardan, WA, and near The Dalles, OR, were established in commercial wheat production fields that evaluated 10 herbicide treatments for efficacy on scouringrush. An additional factor in the trials was to determine if pre-herbicide mowing affected herbicide efficacy. At both locations pre-herbicide mowing had no effect on efficacy and only chlorsulfuron plus MCPA-ester controlled scouringrush though the subsequent winter wheat rotation. A third herbicide trial determined that triclopyr or increased rates of chlorsulfuron plus 2,4-D and dicamba or asulam were able to effectively control scouringrush seven and 10 months after treatment at a non-crop site in eastern Oregon. Under field conditions wheat yield reductions were correlated with increasing scouringrush density, but in a controlled study scouringrush density had no effect on winter wheat development or grain yield. Disagreement between these results is hypothesized to be a function of nutrient deficiencies within production fields. Results from three greenhouse studies showed that scouringrush biomass production increased as soil pH increased from ≈4.6 to ≈8.0 and that scouringrush was able to establish and survive in soil pH conditions that are unsuitable for winter wheat production. 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• 153. [Article] The influence of prescribed fire on the rare endemic plant Delphinium pavonaceum (Peacock larkspur)

  In the wetland prairie of William L. Finley National Wildlife Refuge (FNWR) in western Oregon, we investigated the response of Delphinium pavonaceum Ewan (peacock larkspur, Ranunculaceae), an endangered ...

  Citation × Citation Citation Abstract Copy Title: The influence of prescribed fire on the rare endemic plant Delphinium pavonaceum (Peacock larkspur) Author: McKernan, Brie-Anne In the wetland prairie of William L. Finley National Wildlife Refuge (FNWR) in western Oregon, we investigated the response of Delphinium pavonaceum Ewan (peacock larkspur, Ranunculaceae), an endangered perennial forb, to four unreplicated dormant season fire regimes of 0, 2, 4, or 10 fires that were applied over a 12-year period. Additionally, an unexpected removal of woody plants by refuge staff within some portions of our control area offered an unplanned opportunity for study. In 2002 we measured the density and vigor of reproductive plants, and performed seed germination trials. In 2003 we repeated previous field measurements, sampled immature plant density, and recorded observations of the insects visiting D. pavonaceum in burned and unburned habitats. We hypothesized that this rare endemic species and its insect visitors would respond positively to prescribed burning or the removal of woody species. Low seedling density was found in the unburned and hand-removal areas, likely due to interference from litter and/or taller, shading plants. We also found low seedling density in sites burned the previous year, implying that fire consumes or damages unprotected seeds in the litter layer or exposed on the soil surface. Seedling density was greater in a site burned three seasons previously, suggesting that fire ultimately leads to the enhancement of seedling density following the replenishment of the seed bank. The largest density of recruits was detected in a subunit recently returned to fire management in 1999, and also burned in 2002 following our first field season. However, the other, more-frequently burned sites did not exhibit an increased density of recruits, possibly due to a reduction of the seed bank following repeated bums, and increased intraspecific competition with mature plants. The elevated density of seedlings and recruits we observed in some burned areas may lead to population growth, as we observed a greater density of reproductive plants in the two most-frequently burned subunits during both years of study. Our results also suggest that fewer plants enter summer dormancy in burned areas, and that increases in flowering plant density may decline after 3 years. Plants in the burned and hand-removal sites were shorter, likely resulting from water stress following the removal of shading plants and litter. Additionally, plants in unburned areas might have experienced greater stem elongation due to competition with tall and dense vegetation. Plants in the burned and hand-removal areas were generally similar to the unburned control site for flower and fruit production, fruit set, seed production and seed mass. However, plants in the burned and hand-removal areas produced more flowers per centimeter of height, indicating that they allocated more energy to reproduction than plants in the unburned area. We suggest that the decreased productivity we observed in some vigor traits is not problematic to D. pavonaceum conservation goals and may be ameliorated after 3 years. Bombus ca1ifornicus, B. appositus, and several large moths were the only insects we observed visiting D. pavonaceum during the two years of this study. We did not detect a difference in bumblebee abundance between a frequently burned and unburned study plot during the peak flowering time of D. pavonaceum. However, our small sample size requires that this result be cautiously interpreted and further studied, as it is possible that our visitation data would change appreciably with a broader range of observations. Our results indicate that the current FNWR fire management plan is not in conflict with D. pavonaceum conservation. The choice of fire-return interval seems to influence D. pavonaceum populations and plant vigor, but because the fire-schedule at FNWR was altered in 1997, our ability to recommend an appropriate fire-regime for this species is limited. Although not directly investigated, we suggest that annual fires, when applied for more than five consecutive years, might lead to population declines for this species because fire appears to consume the seed bank and reduce seedling density. If annual fires are returned to FNWR, the potential for this undesirable result should be investigated for at least 10 years by population monitoring. Title: The influence of prescribed fire on the rare endemic plant Delphinium pavonaceum (Peacock larkspur) Author: McKernan, Brie-Anne In the wetland prairie of William L. Finley National Wildlife Refuge (FNWR) in western Oregon, we investigated the response of Delphinium pavonaceum Ewan (peacock larkspur, Ranunculaceae), an endangered perennial forb, to four unreplicated dormant season fire regimes of 0, 2, 4, or 10 fires that were applied over a 12-year period. Additionally, an unexpected removal of woody plants by refuge staff within some portions of our control area offered an unplanned opportunity for study. In 2002 we measured the density and vigor of reproductive plants, and performed seed germination trials. In 2003 we repeated previous field measurements, sampled immature plant density, and recorded observations of the insects visiting D. pavonaceum in burned and unburned habitats. We hypothesized that this rare endemic species and its insect visitors would respond positively to prescribed burning or the removal of woody species. Low seedling density was found in the unburned and hand-removal areas, likely due to interference from litter and/or taller, shading plants. We also found low seedling density in sites burned the previous year, implying that fire consumes or damages unprotected seeds in the litter layer or exposed on the soil surface. Seedling density was greater in a site burned three seasons previously, suggesting that fire ultimately leads to the enhancement of seedling density following the replenishment of the seed bank. The largest density of recruits was detected in a subunit recently returned to fire management in 1999, and also burned in 2002 following our first field season. However, the other, more-frequently burned sites did not exhibit an increased density of recruits, possibly due to a reduction of the seed bank following repeated bums, and increased intraspecific competition with mature plants. The elevated density of seedlings and recruits we observed in some burned areas may lead to population growth, as we observed a greater density of reproductive plants in the two most-frequently burned subunits during both years of study. Our results also suggest that fewer plants enter summer dormancy in burned areas, and that increases in flowering plant density may decline after 3 years. Plants in the burned and hand-removal sites were shorter, likely resulting from water stress following the removal of shading plants and litter. Additionally, plants in unburned areas might have experienced greater stem elongation due to competition with tall and dense vegetation. Plants in the burned and hand-removal areas were generally similar to the unburned control site for flower and fruit production, fruit set, seed production and seed mass. However, plants in the burned and hand-removal areas produced more flowers per centimeter of height, indicating that they allocated more energy to reproduction than plants in the unburned area. We suggest that the decreased productivity we observed in some vigor traits is not problematic to D. pavonaceum conservation goals and may be ameliorated after 3 years. Bombus ca1ifornicus, B. appositus, and several large moths were the only insects we observed visiting D. pavonaceum during the two years of this study. We did not detect a difference in bumblebee abundance between a frequently burned and unburned study plot during the peak flowering time of D. pavonaceum. However, our small sample size requires that this result be cautiously interpreted and further studied, as it is possible that our visitation data would change appreciably with a broader range of observations. Our results indicate that the current FNWR fire management plan is not in conflict with D. pavonaceum conservation. The choice of fire-return interval seems to influence D. pavonaceum populations and plant vigor, but because the fire-schedule at FNWR was altered in 1997, our ability to recommend an appropriate fire-regime for this species is limited. Although not directly investigated, we suggest that annual fires, when applied for more than five consecutive years, might lead to population declines for this species because fire appears to consume the seed bank and reduce seedling density. If annual fires are returned to FNWR, the potential for this undesirable result should be investigated for at least 10 years by population monitoring. Close

• 154. [Article] Biological control of purple loosestrife Lythrum salicaria by two chrysomelid beetles Galerucella pusilla and G. calmariensis

  In the first part of this study we monitored the development of biological control of purple loosestrife Lythrum salicaria over a six-year period at Morgan Lake in western Oregon. In 1992, two beetles, ...

  Citation × Citation Citation Abstract Copy Title: Biological control of purple loosestrife Lythrum salicaria by two chrysomelid beetles Galerucella pusilla and G. calmariensis Author: Schooler, Shon In the first part of this study we monitored the development of biological control of purple loosestrife Lythrum salicaria over a six-year period at Morgan Lake in western Oregon. In 1992, two beetles, Galerucella pusilla and G. calmariensis (Coleoptera: Chrysomelidae), were released to control the wetland weed at this test site. Our purpose was to estimate quantitative performance parameters that might be generally applied in monitoring biological weed control. Our six performance measures were: 1) biological control agent establishment, 2) the rate of increase of the agents, 3) the rate of spread of the agents, 4) the effect of the agents on individual target plants, 5) the effect of the agents on the population of the target plants, and 6) the indirect impact of the biological control agents on the local plant community. The beetles established viable populations that increased during the study with an intrinsic rate of increase (r), based on the growth rate in damage, estimated at 2.24/year. Within six years after introduction, the beetles spread to saturate the entire purple loosestrife habitat (4100 m²) around the lake. The rate of spread, estimated by calculating a diffusion coefficient (D), was 57.5 m²/year. Adult beetles made seasonal, exploratory movements up to 30 m away from the host plant stand into surrounding crop fields, which suggests a disturbance-free buffer should be established in the habitat surrounding the loosestrife stand. By 1997, both flowering success and median stem density (per 0.125 m² plot) of purple loosestrife declined to zero. Mean above-ground biomass decreased to 8.4% of its 1994 level. Biomass of native plant species increased by only 3% between 1996 and 1997. Overall, G. pusilla and G. calmariensis reduced the abundance of the target plant at our site. Our monitoring methods were effective at quantitatively measuring the establishment, increase, spread, and damage of the biological control agent, the subsequent decline of the target plant, and the impact on the local plant community. The second part of our study used field and greenhouse experiments to assess non-target effects of two introduced biological control organisms (Galerucella pusilla Duftschmid and G. calmariensis L.: Chrysomelidae) on the economically important ornamental plant, crape myrtle (Lagerstroemia indica L: Lythraceae). Prior host specificity tests performed in the laboratory found that beetles fed, but were unable to complete their life cycle, on this non-target plant. However, there was concern over damage that might occur when the two plant species existed together. This study extended prior tests into a field environment in order to compare the physiological host range revealed in greenhouse tests with the ecological host range revealed in the field. We assumed, based on prior evidence, that the control agents would not complete development on the non-target plant, and therefore, when the non-target organism was isolated from populations of the target organism the direct effects of the biological control agents would be negligible. When the target and non-target organisms existed together, the magnitude of indirect effect of the target organism on the non-target organism via the control agent was expected to increase with: 1) decreasing distance between the target and non-target organisms, and 2) increasing dispersal capability of the control agents. As expected from prior studies beetle feeding and oviposition occurred on crape myrtle but the beetles could not complete development on this non-target plant in our greenhouse and field tests. Leaf damage inflicted by the beetle was lower on crape myrtle than on purple loosestrife plants used as controls and extensive defoliation to the non-target plant was limited to within 30 m from the edge of the purple loosestrife stand. Biomass of crape myrtle was significantly reduced near the stand compared with plants that remained relatively untouched at greater distances. Purple loosestrife biomass exhibited a greater reduction with decreasing distance from the source of beetle colonization. In this thesis we construct and implement strategies for quantitatively assessing success of biological control programs and risk of introduced biological agents to non-target organisms. Through these observations and experiments we hope to increase the predictability and safety of biological control programs. Title: Biological control of purple loosestrife Lythrum salicaria by two chrysomelid beetles Galerucella pusilla and G. calmariensis Author: Schooler, Shon In the first part of this study we monitored the development of biological control of purple loosestrife Lythrum salicaria over a six-year period at Morgan Lake in western Oregon. In 1992, two beetles, Galerucella pusilla and G. calmariensis (Coleoptera: Chrysomelidae), were released to control the wetland weed at this test site. Our purpose was to estimate quantitative performance parameters that might be generally applied in monitoring biological weed control. Our six performance measures were: 1) biological control agent establishment, 2) the rate of increase of the agents, 3) the rate of spread of the agents, 4) the effect of the agents on individual target plants, 5) the effect of the agents on the population of the target plants, and 6) the indirect impact of the biological control agents on the local plant community. The beetles established viable populations that increased during the study with an intrinsic rate of increase (r), based on the growth rate in damage, estimated at 2.24/year. Within six years after introduction, the beetles spread to saturate the entire purple loosestrife habitat (4100 m²) around the lake. The rate of spread, estimated by calculating a diffusion coefficient (D), was 57.5 m²/year. Adult beetles made seasonal, exploratory movements up to 30 m away from the host plant stand into surrounding crop fields, which suggests a disturbance-free buffer should be established in the habitat surrounding the loosestrife stand. By 1997, both flowering success and median stem density (per 0.125 m² plot) of purple loosestrife declined to zero. Mean above-ground biomass decreased to 8.4% of its 1994 level. Biomass of native plant species increased by only 3% between 1996 and 1997. Overall, G. pusilla and G. calmariensis reduced the abundance of the target plant at our site. Our monitoring methods were effective at quantitatively measuring the establishment, increase, spread, and damage of the biological control agent, the subsequent decline of the target plant, and the impact on the local plant community. The second part of our study used field and greenhouse experiments to assess non-target effects of two introduced biological control organisms (Galerucella pusilla Duftschmid and G. calmariensis L.: Chrysomelidae) on the economically important ornamental plant, crape myrtle (Lagerstroemia indica L: Lythraceae). Prior host specificity tests performed in the laboratory found that beetles fed, but were unable to complete their life cycle, on this non-target plant. However, there was concern over damage that might occur when the two plant species existed together. This study extended prior tests into a field environment in order to compare the physiological host range revealed in greenhouse tests with the ecological host range revealed in the field. We assumed, based on prior evidence, that the control agents would not complete development on the non-target plant, and therefore, when the non-target organism was isolated from populations of the target organism the direct effects of the biological control agents would be negligible. When the target and non-target organisms existed together, the magnitude of indirect effect of the target organism on the non-target organism via the control agent was expected to increase with: 1) decreasing distance between the target and non-target organisms, and 2) increasing dispersal capability of the control agents. As expected from prior studies beetle feeding and oviposition occurred on crape myrtle but the beetles could not complete development on this non-target plant in our greenhouse and field tests. Leaf damage inflicted by the beetle was lower on crape myrtle than on purple loosestrife plants used as controls and extensive defoliation to the non-target plant was limited to within 30 m from the edge of the purple loosestrife stand. Biomass of crape myrtle was significantly reduced near the stand compared with plants that remained relatively untouched at greater distances. Purple loosestrife biomass exhibited a greater reduction with decreasing distance from the source of beetle colonization. In this thesis we construct and implement strategies for quantitatively assessing success of biological control programs and risk of introduced biological agents to non-target organisms. Through these observations and experiments we hope to increase the predictability and safety of biological control programs. Close

• 155. [Article] Multivariate analysis of a tidal marsh ecosystem at Netarts Spit, Tillamook County, Oregon

  Variability of plant species distributions, plant connunities, soil and hydrological factors in an area of the Netarts Spit tidal marsh are examined. The purpose is to advance general understanding of ...

  Citation × Citation Citation Abstract Copy Title: Multivariate analysis of a tidal marsh ecosystem at Netarts Spit, Tillamook County, Oregon Author: Liverman, Marc C. Variability of plant species distributions, plant connunities, soil and hydrological factors in an area of the Netarts Spit tidal marsh are examined. The purpose is to advance general understanding of Oregon's tidal marsh ecosystems in terms of plant coninunities and functio'nal habitat conditions and make a contribution to the conceptual and technical framework used by regulatory agencies to manage wetlands. Vegetation, soil and hydrological attributes were measured periodically from May, 1978 to March, 1979 along three transects extending parallel to the elevation gradient. Each transect began at point bayward of the lower limit of marsh vegetation and continued to a point shoreward of the perceived upper limit of the marsh on the narrow, stabilized dune ridge separating Netarts Spit from the ocean. Plant species distribution and abundance by cover class was recorded in microplots located at increments of five meters or less along each transect. Soil and hydrological observations at intervals of approximately six weeks were made at 29 primary sampling sites located at increments of 15 meters or less along the transects. Water table fluctuations and soil moisture tension were examined in situ. Soil cores were extracted from the marsh for analysis of interstitial soil moisture content and salinity, soil texture, pH, organic matter content, cation exchange capacity, magnesium, calcium, phosphorus, potassium and sodium content. Data on tidal inundation frequency and duration were provided by the National Ocean Survey from a tide gauge located at Netarts public boat dock. Weather data were obtained from continuously recording hygrothermographs and an accumulating rain gauge located in the ecotone between marsh and upland. Comparative climatic data were obtained from published National Oceanic and Atmospheric Administration Environmental Data Center Bulletins. Analysis of individual environmental gradients was initiated by arranging the data matrix into a composite transect ordered by elevation. Each attribute was then plotted against elevation using graphically comparable scales. Data synthesis was accomplished using a combination of reciprocal averaging ordination (to identify coimlunity gradients) and cluster analysis (for sampling site classification) applied to hierarchical data sets composed of combinations of physical, chemical, and vegetative sampling site attributes. Habitat at lower elevations of the study area (0.70 m below mean high water) is dominated by tidal factors which decrease steadily as one approaches extreme higher high water (0.52 m above mean high water). Fine textured sediments are saturated near the middle elevations of the study area (-0.25 to 1.00 m above mean high water), with the lower and higher elevations dominated by sand. Hydrologic factors (water table depth and soil moisture tension) dominate the highest elevations of the study area but decrease steadily as one approaches mean high water. The remaining environmental factors (interstitial soil moisture content and salinity, cation exchange capacity, specific ion concentrations, organic matter, and pH) may each be interpreted as variants of one or more of the three primary environmental gradients: tides, sediment texture, and hydrology. Interstitial soil moisture salinity, soil moisture tension, and water table depth all show maxima during months with high daily temperatures and low precipitation (Aug.-Sep.,) and minima during months with low daily temperatures and high precipitation (Dec.-Mar.). Interstitial soil moisture content shows the reverse relationship with minima during Aug.-Sep. and maxima during Dec.- Mar. Plant community structure of the tidal marsh may be best understood as a species continuum beginning at about 0.60 m below mean high water characterized by snecies dominance at low elevation (_0.51) to 0.40 m above mean hiah water) givinG way to soecies diversity at higher elevations. This continuum may be locally qraduated into three or more subdivisions or plant communities by the dynamic reltionshi of intertidal deposition and erosion processes. Community structure of the associated dune upland is distinguishable environmentally and floristically as distinct from the tidal marsh at about 0.90 m above mean hich water although no attempt is made to resolve finer details of urland community structure beyond the marsh interface. Title: Multivariate analysis of a tidal marsh ecosystem at Netarts Spit, Tillamook County, Oregon Author: Liverman, Marc C. Variability of plant species distributions, plant connunities, soil and hydrological factors in an area of the Netarts Spit tidal marsh are examined. The purpose is to advance general understanding of Oregon's tidal marsh ecosystems in terms of plant coninunities and functio'nal habitat conditions and make a contribution to the conceptual and technical framework used by regulatory agencies to manage wetlands. Vegetation, soil and hydrological attributes were measured periodically from May, 1978 to March, 1979 along three transects extending parallel to the elevation gradient. Each transect began at point bayward of the lower limit of marsh vegetation and continued to a point shoreward of the perceived upper limit of the marsh on the narrow, stabilized dune ridge separating Netarts Spit from the ocean. Plant species distribution and abundance by cover class was recorded in microplots located at increments of five meters or less along each transect. Soil and hydrological observations at intervals of approximately six weeks were made at 29 primary sampling sites located at increments of 15 meters or less along the transects. Water table fluctuations and soil moisture tension were examined in situ. Soil cores were extracted from the marsh for analysis of interstitial soil moisture content and salinity, soil texture, pH, organic matter content, cation exchange capacity, magnesium, calcium, phosphorus, potassium and sodium content. Data on tidal inundation frequency and duration were provided by the National Ocean Survey from a tide gauge located at Netarts public boat dock. Weather data were obtained from continuously recording hygrothermographs and an accumulating rain gauge located in the ecotone between marsh and upland. Comparative climatic data were obtained from published National Oceanic and Atmospheric Administration Environmental Data Center Bulletins. Analysis of individual environmental gradients was initiated by arranging the data matrix into a composite transect ordered by elevation. Each attribute was then plotted against elevation using graphically comparable scales. Data synthesis was accomplished using a combination of reciprocal averaging ordination (to identify coimlunity gradients) and cluster analysis (for sampling site classification) applied to hierarchical data sets composed of combinations of physical, chemical, and vegetative sampling site attributes. Habitat at lower elevations of the study area (0.70 m below mean high water) is dominated by tidal factors which decrease steadily as one approaches extreme higher high water (0.52 m above mean high water). Fine textured sediments are saturated near the middle elevations of the study area (-0.25 to 1.00 m above mean high water), with the lower and higher elevations dominated by sand. Hydrologic factors (water table depth and soil moisture tension) dominate the highest elevations of the study area but decrease steadily as one approaches mean high water. The remaining environmental factors (interstitial soil moisture content and salinity, cation exchange capacity, specific ion concentrations, organic matter, and pH) may each be interpreted as variants of one or more of the three primary environmental gradients: tides, sediment texture, and hydrology. Interstitial soil moisture salinity, soil moisture tension, and water table depth all show maxima during months with high daily temperatures and low precipitation (Aug.-Sep.,) and minima during months with low daily temperatures and high precipitation (Dec.-Mar.). Interstitial soil moisture content shows the reverse relationship with minima during Aug.-Sep. and maxima during Dec.- Mar. Plant community structure of the tidal marsh may be best understood as a species continuum beginning at about 0.60 m below mean high water characterized by snecies dominance at low elevation (_0.51) to 0.40 m above mean hiah water) givinG way to soecies diversity at higher elevations. This continuum may be locally qraduated into three or more subdivisions or plant communities by the dynamic reltionshi of intertidal deposition and erosion processes. Community structure of the associated dune upland is distinguishable environmentally and floristically as distinct from the tidal marsh at about 0.90 m above mean hich water although no attempt is made to resolve finer details of urland community structure beyond the marsh interface. Close