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• 1. [Article] Traits, neighbors, and species performance in prairie restoration

  Questions: Are traits related to the performance of plant species in restoration? Are the relationships between traits and performance consistent across the functional groups of annual forbs, perennial ...

  Citation × Citation Citation Abstract Copy Title: Traits, neighbors, and species performance in prairie restoration Author: Roberts, R. E., Wilson, Mark V., Clark, Deborah Louise, 1950- Questions: Are traits related to the performance of plant species in restoration? Are the relationships between traits and performance consistent across the functional groups of annual forbs, perennial forbs, and grasses? Do the relationships between traits and performance depend on neighboring functional groups? Location: A former agricultural field, being restored to native upland prairie, in the Willamette Valley of western Oregon USA. Methods: Twenty-eight native species, representing three functional groups, were sown in seven different combinations. The following summer the performance of each species was measured. Eleven functional traits were measured from plants in the laboratory and in the field. Correlations between individual traits and performance variables were measured and stepwise regression techniques were used to determine which sets of traits were most strongly related to performance. Results: Sets of traits explained up to 56% of variation in cover, and up to 48% of variation in establishment frequency. The relationships between traits and performance were influenced by functional group identity, and the functional group identity of neighboring species also influenced species’ cover and the relationships between traits and cover. Species’ establishment rate in monoculture was the trait most strongly correlated to both establishment and cover in mixtures. In multi-trait models, annual forb functional group identity was strongly related to establishment in mixtures, and height, leaf weight ratio at 7 days, and seed mass were strongly related to cover. Conclusions: Based on the strength of the statistical models, multiple-trait models should be a useful way of predicting the performance of species prior to sowing in restoration. The functional group identity of each species as well as the other species being sown may need to be taken into account when making predictions. Title: Traits, neighbors, and species performance in prairie restoration Author: Roberts, R. E., Wilson, Mark V., Clark, Deborah Louise, 1950- Questions: Are traits related to the performance of plant species in restoration? Are the relationships between traits and performance consistent across the functional groups of annual forbs, perennial forbs, and grasses? Do the relationships between traits and performance depend on neighboring functional groups? Location: A former agricultural field, being restored to native upland prairie, in the Willamette Valley of western Oregon USA. Methods: Twenty-eight native species, representing three functional groups, were sown in seven different combinations. The following summer the performance of each species was measured. Eleven functional traits were measured from plants in the laboratory and in the field. Correlations between individual traits and performance variables were measured and stepwise regression techniques were used to determine which sets of traits were most strongly related to performance. Results: Sets of traits explained up to 56% of variation in cover, and up to 48% of variation in establishment frequency. The relationships between traits and performance were influenced by functional group identity, and the functional group identity of neighboring species also influenced species’ cover and the relationships between traits and cover. Species’ establishment rate in monoculture was the trait most strongly correlated to both establishment and cover in mixtures. In multi-trait models, annual forb functional group identity was strongly related to establishment in mixtures, and height, leaf weight ratio at 7 days, and seed mass were strongly related to cover. Conclusions: Based on the strength of the statistical models, multiple-trait models should be a useful way of predicting the performance of species prior to sowing in restoration. The functional group identity of each species as well as the other species being sown may need to be taken into account when making predictions. Close

• 2. [Article] Final Report 1994-1997: Effects of Fire, Mowing, and Mowing with Herbicide on Native Prairie of Baskett Butte, Baskett Slough NWR

  We report results from a field experiment evaluating the effectiveness of mowing, mowing and herbicides, and burning on woody plants, key native and non-native grasses and forbs, and the Fender’s blue ...

  Citation × Citation Citation Abstract Copy Title: Final Report 1994-1997: Effects of Fire, Mowing, and Mowing with Herbicide on Native Prairie of Baskett Butte, Baskett Slough NWR Author: Wilson, Mark V., Clark, Deborah Louise, 1950- We report results from a field experiment evaluating the effectiveness of mowing, mowing and herbicides, and burning on woody plants, key native and non-native grasses and forbs, and the Fender’s blue butterfly. The goal was to find a technique that controlled woody pest plants without harming native species or promoting non-native species. Three years after the initial manipulations, all treatments significantly reduced woody plant cover. Mowing promoted the group of measured native grasses without promoting non-native species. In contrast, burning had mixed effects on herbaceous species, promoting growth for some species and decreasing growth for others. Each treatment, particularly mowing, caused local increases in numbers of Fender’s blue butterfly egg masses, probably because lupines invigorated by treatments attracted ovipositing females. Although prescribed burning seemed to kill larvae, treated areas still accumulated more eggs masses than in controls. Three years after the start of manipulations, mowing was the most effective overall treatment for controlling woody plants, increasing native species abundance without promoting non-native species, and increasing Fender’s blue butterfly numbers. We recommend mowing for restoring similar habitats. Prescribed burning would also be an effective choice for habitat restoration. Title: Final Report 1994-1997: Effects of Fire, Mowing, and Mowing with Herbicide on Native Prairie of Baskett Butte, Baskett Slough NWR Author: Wilson, Mark V., Clark, Deborah Louise, 1950- We report results from a field experiment evaluating the effectiveness of mowing, mowing and herbicides, and burning on woody plants, key native and non-native grasses and forbs, and the Fender’s blue butterfly. The goal was to find a technique that controlled woody pest plants without harming native species or promoting non-native species. Three years after the initial manipulations, all treatments significantly reduced woody plant cover. Mowing promoted the group of measured native grasses without promoting non-native species. In contrast, burning had mixed effects on herbaceous species, promoting growth for some species and decreasing growth for others. Each treatment, particularly mowing, caused local increases in numbers of Fender’s blue butterfly egg masses, probably because lupines invigorated by treatments attracted ovipositing females. Although prescribed burning seemed to kill larvae, treated areas still accumulated more eggs masses than in controls. Three years after the start of manipulations, mowing was the most effective overall treatment for controlling woody plants, increasing native species abundance without promoting non-native species, and increasing Fender’s blue butterfly numbers. We recommend mowing for restoring similar habitats. Prescribed burning would also be an effective choice for habitat restoration. Close

• 3. [Article] Plant traits – a tool for restoration?

  Question: Most results of restoration efforts are species-specific and/or site-specific and therefore are not general enough to be easily applied to other species and other sites. Our research addresses ...

  Citation × Citation Citation Abstract Copy Title: Plant traits – a tool for restoration? Author: Wilson, Mark V., Kaye, Thomas N., Roberts, Rachel, Dunwiddie, Peter W., Clark, Deborah Louise, 1950-, Stanley, Amanda Question: Most results of restoration efforts are species-specific and/or site-specific and therefore are not general enough to be easily applied to other species and other sites. Our research addresses the issue of species-specific results by investigating the feasibility of using plant traits instead of taxonomic species to characterize species responses to restoration treatments. Specifically, we test the explanatory power of plant traits, one necessary prerequisite for the development of predictive and general plant trait models. Location: Ten remnant bunchgrass prairie sites in the Pacific Northwest of North America (Oregon and Washington, USA; British Columbia, Canada). Methods: We developed two types of quantitative models for each of 10 prairie restoration sites: 1) plant trait models, which related plant traits to species field responses following restoration management treatments, and 2) species identity models, which related species taxonomic identity to species field responses following restoration management treatments. Species identity models determined the maximum amount of variability of field responses that can be explained by differences in individual species’ responses to management treatments. Plant trait models determined what proportion of this explanatory power can be attributed to plant traits. This approach contrasts with approaches often used in other plant trait studies that describe how traits vary with environmental conditions. Specifically, we used these two models to address the following questions: 1) How much of the variability in field responses of plants to restoration management treatments is explained by plant traits? 2) How well do plant traits explain the variability of field responses following restoration management treatments compared to models relating field responses to species identity? Our approach was to measure two aspects of explanatory power: R2 (variability explained) and AIC (a measure of model fit that accounts for parsimony, i.e., how well a model fits the data with relatively few explanatory variables). Results: 1) The plant trait models (relating plant traits with plant field responses) explained much of the variability within each of the ten restoration sites, with R2 values ranging between 31% and 69%. 2) The species identity models (relating species taxonomic identity with plant field responses) explained between 47% and 74% of variability in field performance (R2). Thus, the plant trait models explained nearly as much variability as the species identity models. In seven out of nine sites, the plant trait models were superior to the species identity models as measured by AIC; that is, the trait models did well at explaining variability with less model complexity (i.e., fewer explanatory variables). Conclusion: Development of general and predictive plant trait models is a multi-step process. Strong explanatory power by plant trait models, both on an absolute scale and as compared to species identity models, supports the feasibility of using plant traits instead of species taxonomic identity as a common language to characterize plant field responses to restoration treatments. Such high explanatory power is one necessary pre-requisite for the development of predictive and general plant trait models. Our results also indicate that the plant trait models are site-specific even though all sites were upland bunchgrass remnant prairies. We discuss the next steps in the development of more general and predictive models: incorporating environmental factors into the plant trait models to address the issue of site-specificity and testing the power of these models to predict vegetation responses. Title: Plant traits – a tool for restoration? Author: Wilson, Mark V., Kaye, Thomas N., Roberts, Rachel, Dunwiddie, Peter W., Clark, Deborah Louise, 1950-, Stanley, Amanda Question: Most results of restoration efforts are species-specific and/or site-specific and therefore are not general enough to be easily applied to other species and other sites. Our research addresses the issue of species-specific results by investigating the feasibility of using plant traits instead of taxonomic species to characterize species responses to restoration treatments. Specifically, we test the explanatory power of plant traits, one necessary prerequisite for the development of predictive and general plant trait models. Location: Ten remnant bunchgrass prairie sites in the Pacific Northwest of North America (Oregon and Washington, USA; British Columbia, Canada). Methods: We developed two types of quantitative models for each of 10 prairie restoration sites: 1) plant trait models, which related plant traits to species field responses following restoration management treatments, and 2) species identity models, which related species taxonomic identity to species field responses following restoration management treatments. Species identity models determined the maximum amount of variability of field responses that can be explained by differences in individual species’ responses to management treatments. Plant trait models determined what proportion of this explanatory power can be attributed to plant traits. This approach contrasts with approaches often used in other plant trait studies that describe how traits vary with environmental conditions. Specifically, we used these two models to address the following questions: 1) How much of the variability in field responses of plants to restoration management treatments is explained by plant traits? 2) How well do plant traits explain the variability of field responses following restoration management treatments compared to models relating field responses to species identity? Our approach was to measure two aspects of explanatory power: R2 (variability explained) and AIC (a measure of model fit that accounts for parsimony, i.e., how well a model fits the data with relatively few explanatory variables). Results: 1) The plant trait models (relating plant traits with plant field responses) explained much of the variability within each of the ten restoration sites, with R2 values ranging between 31% and 69%. 2) The species identity models (relating species taxonomic identity with plant field responses) explained between 47% and 74% of variability in field performance (R2). Thus, the plant trait models explained nearly as much variability as the species identity models. In seven out of nine sites, the plant trait models were superior to the species identity models as measured by AIC; that is, the trait models did well at explaining variability with less model complexity (i.e., fewer explanatory variables). Conclusion: Development of general and predictive plant trait models is a multi-step process. Strong explanatory power by plant trait models, both on an absolute scale and as compared to species identity models, supports the feasibility of using plant traits instead of species taxonomic identity as a common language to characterize plant field responses to restoration treatments. Such high explanatory power is one necessary pre-requisite for the development of predictive and general plant trait models. Our results also indicate that the plant trait models are site-specific even though all sites were upland bunchgrass remnant prairies. We discuss the next steps in the development of more general and predictive models: incorporating environmental factors into the plant trait models to address the issue of site-specificity and testing the power of these models to predict vegetation responses. Close

• 4. [Article] Final report [year one]: Control of Brachypodium sylvaticum and restoration of rare native upland prairie habitat at Butterfly Meadows, Benton County ODA 1342 GR

  Our project goal is to protect and restore rare Willamette Valley upland prairie habitat at Butterfly Meadows (Benton County) from invasion by the noxious weed Brachypodium sylvaticum (false brome). Native ...

  Citation × Citation Citation Abstract Copy Title: Final report [year one]: Control of Brachypodium sylvaticum and restoration of rare native upland prairie habitat at Butterfly Meadows, Benton County ODA 1342 GR Author: Johnson, Deborah, Pfund, Fred, Hammond, Paul, Wilson, Mark V., Vomocil, Marc, Kaye, Tom, Clark, Deborah Louise, 1950-, Kelpsas, Bruce Our project goal is to protect and restore rare Willamette Valley upland prairie habitat at Butterfly Meadows (Benton County) from invasion by the noxious weed Brachypodium sylvaticum (false brome). Native prairies, which once dominated the landscape of the Willamette Valley, are considered among the rarest of Oregon’s ecosystems and are in critical need of conservation. One of the largest remaining parcels of native upland prairie, Butterfly Meadows (Benton County), is being invaded by Brachypodium sylvaticum. This site is one of the three most important remaining habitats for the Fender’s blue butterfly and Kincaid’s lupine, listed as Endangered and Threatened respectively. We propose to develop and implement herbicide treatments that control Brachypodium sylvaticum without harming native prairie vegetation. We will also develop and implement measures to reestablish native species from seed after removal of Brachypodium sylvaticum. Conifers and mature shrubs that have encroached on the meadow, both on the edge and in the complex, will be removed by mechanical means or girdling. We propose to construct a buffer zone between the boundary of Butterfly Meadows and the neighboring intact forest and recently clear-cut areas, which are continuing sources of seed of Brachypodium sylvaticum invading Butterfly Meadows. This buffer zone will extend into both Starker Forest owned portions and OSU owned portions. To determine the success of control of Brachypodium sylvaticum and woody species and restoration of native vegetation, we will monitor changes in abundance of Brachypodium sylvaticum, woody species, and native vegetation. We will use monitoring results to adjust future Brachypodium sylvaticum control measures and native vegetation restoration measures as needed. Title: Final report [year one]: Control of Brachypodium sylvaticum and restoration of rare native upland prairie habitat at Butterfly Meadows, Benton County ODA 1342 GR Author: Johnson, Deborah, Pfund, Fred, Hammond, Paul, Wilson, Mark V., Vomocil, Marc, Kaye, Tom, Clark, Deborah Louise, 1950-, Kelpsas, Bruce Our project goal is to protect and restore rare Willamette Valley upland prairie habitat at Butterfly Meadows (Benton County) from invasion by the noxious weed Brachypodium sylvaticum (false brome). Native prairies, which once dominated the landscape of the Willamette Valley, are considered among the rarest of Oregon’s ecosystems and are in critical need of conservation. One of the largest remaining parcels of native upland prairie, Butterfly Meadows (Benton County), is being invaded by Brachypodium sylvaticum. This site is one of the three most important remaining habitats for the Fender’s blue butterfly and Kincaid’s lupine, listed as Endangered and Threatened respectively. We propose to develop and implement herbicide treatments that control Brachypodium sylvaticum without harming native prairie vegetation. We will also develop and implement measures to reestablish native species from seed after removal of Brachypodium sylvaticum. Conifers and mature shrubs that have encroached on the meadow, both on the edge and in the complex, will be removed by mechanical means or girdling. We propose to construct a buffer zone between the boundary of Butterfly Meadows and the neighboring intact forest and recently clear-cut areas, which are continuing sources of seed of Brachypodium sylvaticum invading Butterfly Meadows. This buffer zone will extend into both Starker Forest owned portions and OSU owned portions. To determine the success of control of Brachypodium sylvaticum and woody species and restoration of native vegetation, we will monitor changes in abundance of Brachypodium sylvaticum, woody species, and native vegetation. We will use monitoring results to adjust future Brachypodium sylvaticum control measures and native vegetation restoration measures as needed. Close

• 5. [Article] Final Report: Controlling Tall Oatgrass in Fender’s Blue Butterfly Habitats

  We report final results from a five-year field experiment evaluating the effects of different mowing regimes on groups of native and non-native grasses and forbs. The study site was a degraded prairie ...

  Citation × Citation Citation Abstract Copy Title: Final Report: Controlling Tall Oatgrass in Fender’s Blue Butterfly Habitats Author: Wilson, Mark V., Clark, Deborah Louise, 1950- We report final results from a five-year field experiment evaluating the effects of different mowing regimes on groups of native and non-native grasses and forbs. The study site was a degraded prairie at Baskett Slough National Wildlife Refuge dominated by the pest plant Arrhenatherum elatius (tall oatgrass). Mowing treatments differed in time of year they were applied, mowing height, and removal of cut material. Treatments started in 1994 and continued through 1998. Title: Final Report: Controlling Tall Oatgrass in Fender’s Blue Butterfly Habitats Author: Wilson, Mark V., Clark, Deborah Louise, 1950- We report final results from a five-year field experiment evaluating the effects of different mowing regimes on groups of native and non-native grasses and forbs. The study site was a degraded prairie at Baskett Slough National Wildlife Refuge dominated by the pest plant Arrhenatherum elatius (tall oatgrass). Mowing treatments differed in time of year they were applied, mowing height, and removal of cut material. Treatments started in 1994 and continued through 1998. Close

• 6. [Article] Final report: Restoration of Fender’s blue butterfly and its prairie ecosystem: Management applications of fire to Baskett Slough NWR

  We tested the recolonization ability of the Fender’s blue butterfly and monitored the vegetation response to a management-scale prescribed fire at the Baskett Slough National Wildlife Refuge, western Oregon. ...

  Citation × Citation Citation Abstract Copy Title: Final report: Restoration of Fender’s blue butterfly and its prairie ecosystem: Management applications of fire to Baskett Slough NWR Author: Wilson, Mark V., Clark, Deborah Louise, 1950- We tested the recolonization ability of the Fender’s blue butterfly and monitored the vegetation response to a management-scale prescribed fire at the Baskett Slough National Wildlife Refuge, western Oregon. The prescribed fire successfully cut shrub cover in half, but also reduced the size of Festuca roemeri, a dominant native grass. Although the fire killed all Fender’s blue butterfly larvae, as expected, adult females were able to recolonize the burned area from a nearby, unburned patch. These results support predictions that the Fender’s blue butterfly can recolonize burned areas for a distance of at least 100 m. Title: Final report: Restoration of Fender’s blue butterfly and its prairie ecosystem: Management applications of fire to Baskett Slough NWR Author: Wilson, Mark V., Clark, Deborah Louise, 1950- We tested the recolonization ability of the Fender’s blue butterfly and monitored the vegetation response to a management-scale prescribed fire at the Baskett Slough National Wildlife Refuge, western Oregon. The prescribed fire successfully cut shrub cover in half, but also reduced the size of Festuca roemeri, a dominant native grass. Although the fire killed all Fender’s blue butterfly larvae, as expected, adult females were able to recolonize the burned area from a nearby, unburned patch. These results support predictions that the Fender’s blue butterfly can recolonize burned areas for a distance of at least 100 m. Close

• 7. [Article] Recommendations for Control of Tall Oatgrass, Poison Oak, and Rose in Willamette Valley Upland Prairies

  Native upland prairies, which once dominated the landscape of the Willamette Valley, are considered among the rarest of Oregon's ecosystems. Even though only remnants remain today, they harbor many rare ...

  Citation × Citation Citation Abstract Copy Title: Recommendations for Control of Tall Oatgrass, Poison Oak, and Rose in Willamette Valley Upland Prairies Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Native upland prairies, which once dominated the landscape of the Willamette Valley, are considered among the rarest of Oregon's ecosystems. Even though only remnants remain today, they harbor many rare and endangered species such as the Fender's blue butterfly and its host plant, Kincaid’s lupine. Invasion of remnant prairies by woody plants and weedy non-native herbaceous species is of great concern to agencies and managers responsible for conserving these native ecosystems. Available methods for the control of these pests include herbicides, biological control, prescribed burning, and mowing. This report first reviews the literature on the control of tall oatgrass and the shrubs poison oak and rose. Each of these species is an important threat to Willamette Valley upland prairies. We then presents recommendations. For control of tall oatgrass, we recommend for most situations mowing in late spring or early summer. Mowing height should be just above most of the foliage of native plants to be protected (typically 10 cm - 15 cm). In areas with Kincaid’s lupine and Fender’s blue butterfly, mowing should be delayed until July, after the flowering and flight seasons. For control of prairie shrubs, we recommend further studies to evaluate herbicide effectiveness against the target shrubs and safety for non-target native plants and animals. If herbicide use is unavailable, we recommend burning or mowing. All burning or mowing treatments should be repeated, perhaps indefinitely, to maintain pest plant control. Title: Recommendations for Control of Tall Oatgrass, Poison Oak, and Rose in Willamette Valley Upland Prairies Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Native upland prairies, which once dominated the landscape of the Willamette Valley, are considered among the rarest of Oregon's ecosystems. Even though only remnants remain today, they harbor many rare and endangered species such as the Fender's blue butterfly and its host plant, Kincaid’s lupine. Invasion of remnant prairies by woody plants and weedy non-native herbaceous species is of great concern to agencies and managers responsible for conserving these native ecosystems. Available methods for the control of these pests include herbicides, biological control, prescribed burning, and mowing. This report first reviews the literature on the control of tall oatgrass and the shrubs poison oak and rose. Each of these species is an important threat to Willamette Valley upland prairies. We then presents recommendations. For control of tall oatgrass, we recommend for most situations mowing in late spring or early summer. Mowing height should be just above most of the foliage of native plants to be protected (typically 10 cm - 15 cm). In areas with Kincaid’s lupine and Fender’s blue butterfly, mowing should be delayed until July, after the flowering and flight seasons. For control of prairie shrubs, we recommend further studies to evaluate herbicide effectiveness against the target shrubs and safety for non-target native plants and animals. If herbicide use is unavailable, we recommend burning or mowing. All burning or mowing treatments should be repeated, perhaps indefinitely, to maintain pest plant control. Close

• 8. [Article] Fire effects on wetland prairie species: final report

  Project No. 14-48-0001-96749

  Citation × Citation Citation Abstract Copy Title: Fire effects on wetland prairie species: final report Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Project No. 14-48-0001-96749 Title: Fire effects on wetland prairie species: final report Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Project No. 14-48-0001-96749 Close

• 9. [Article] Controlling woody vegetation in wetland prairies, 1994-1999

  Wetland prairies of the Willamette Valley, among the rarest of Oregon’s ecosystems, are threatened by invasion of woody species and non-native pest species. Because fire has been important in maintaining ...

  Citation × Citation Citation Abstract Copy Title: Controlling woody vegetation in wetland prairies, 1994-1999 Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Wetland prairies of the Willamette Valley, among the rarest of Oregon’s ecosystems, are threatened by invasion of woody species and non-native pest species. Because fire has been important in maintaining Willamette Valley prairies for at least 1000 years, prescribed burning is a top choice of managers for preventing encroachment of woody species. However, the effects of prescribed burning on present day wetland prairie communities, with their mix of native and non-native species, are not clear. Moreover, because strict governmental requirements for smoke management hinder prescribed burning, natural-area managers are considering alternatives to fire, like mowing and hand removal of woody plants. The present study explored the ecological interactions of a wetland prairie by experimentally testing the responses of burning, hand-removal of woody species, and mowing with removal of cut material on woody plants and key native and non-native grasses and forbs. We evaluated these perturbations for their effectiveness in meeting management objectives of reducing abundance of woody species, reducing or preventing an increase in abundance of nonnative pest species, and increasing or at least maintaining native species’ abundance. After three treatments periods (1994, 1996, and 1998) the following patterns emerged: • Woody species Burning and hand-removal consistently caused the greatest reduction in cover of woody species. Mowing with removal of cut material did not reduce the abundance of woody species compared to the control. As woody plant cover decreased, plant mortality increased, indicating that treatments influenced woody plant cover at least partially through changes in survival. • Native herbaceous species All management treatments consistently failed to significantly increase the cover of Deschampsia cespitosa, while burning decreased the number of inflorescences. As a group, native graminoid flowering consistently showed no significant responses to the management treatments. Although burning and hand-removal significantly increased the cover of native forbs as group after the second treatment period in 1997, native forbs showed no significant responses to treatments in 1999. • Non-native herbaceous species Response of non-native forb cover to management treatments has been inconsistent during the five year study period with no significant differences in 1995, significant reductions by burning and hand-removal in 1997, and increases with mowing in 1997. Mowing consistently increased flowering of nonnative graminoids as a group. Overall no treatment was clearly superior in fulfilling restoration objectives. Burning was effective in reducing woody cover and did not promote non-native herbaceous, but it reduced the flowering the dominant native grass, Deschampsia cespitosa. Hand-removal woody species was also effective at reducing woody cover and sometimes promoted the abundance of some native species at different times, but it also at times promoted non-native herbaceous species. Because mowing with removal of cut material was ineffective in reducing woody cover and tended to promote non-native herbaceous species, this treatment is not a recommended management strategy. Title: Controlling woody vegetation in wetland prairies, 1994-1999 Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Wetland prairies of the Willamette Valley, among the rarest of Oregon’s ecosystems, are threatened by invasion of woody species and non-native pest species. Because fire has been important in maintaining Willamette Valley prairies for at least 1000 years, prescribed burning is a top choice of managers for preventing encroachment of woody species. However, the effects of prescribed burning on present day wetland prairie communities, with their mix of native and non-native species, are not clear. Moreover, because strict governmental requirements for smoke management hinder prescribed burning, natural-area managers are considering alternatives to fire, like mowing and hand removal of woody plants. The present study explored the ecological interactions of a wetland prairie by experimentally testing the responses of burning, hand-removal of woody species, and mowing with removal of cut material on woody plants and key native and non-native grasses and forbs. We evaluated these perturbations for their effectiveness in meeting management objectives of reducing abundance of woody species, reducing or preventing an increase in abundance of nonnative pest species, and increasing or at least maintaining native species’ abundance. After three treatments periods (1994, 1996, and 1998) the following patterns emerged: • Woody species Burning and hand-removal consistently caused the greatest reduction in cover of woody species. Mowing with removal of cut material did not reduce the abundance of woody species compared to the control. As woody plant cover decreased, plant mortality increased, indicating that treatments influenced woody plant cover at least partially through changes in survival. • Native herbaceous species All management treatments consistently failed to significantly increase the cover of Deschampsia cespitosa, while burning decreased the number of inflorescences. As a group, native graminoid flowering consistently showed no significant responses to the management treatments. Although burning and hand-removal significantly increased the cover of native forbs as group after the second treatment period in 1997, native forbs showed no significant responses to treatments in 1999. • Non-native herbaceous species Response of non-native forb cover to management treatments has been inconsistent during the five year study period with no significant differences in 1995, significant reductions by burning and hand-removal in 1997, and increases with mowing in 1997. Mowing consistently increased flowering of nonnative graminoids as a group. Overall no treatment was clearly superior in fulfilling restoration objectives. Burning was effective in reducing woody cover and did not promote non-native herbaceous, but it reduced the flowering the dominant native grass, Deschampsia cespitosa. Hand-removal woody species was also effective at reducing woody cover and sometimes promoted the abundance of some native species at different times, but it also at times promoted non-native herbaceous species. Because mowing with removal of cut material was ineffective in reducing woody cover and tended to promote non-native herbaceous species, this treatment is not a recommended management strategy. Close

• 10. [Article] Controlling woody vegetation in wetland prairies, 1994-2001

  Wetland prairies of the Willamette Valley, among the rarest of Oregon’s ecosystems, are threatened by invasion of woody species and non-native pest species. Because fire has been important in maintaining ...

  Citation × Citation Citation Abstract Copy Title: Controlling woody vegetation in wetland prairies, 1994-2001 Author: Clark, Deborah Louise, 1950- Wetland prairies of the Willamette Valley, among the rarest of Oregon’s ecosystems, are threatened by invasion of woody species and non-native pest species. Because fire has been important in maintaining Willamette Valley prairies for at least 1000 years, prescribed burning is a top choice of managers for preventing encroachment of woody species. However, the effects of prescribed burning on present day wetland prairie communities, with their mix of native and non-native species, are not clear. Moreover, because strict governmental requirements for smoke management hinder prescribed burning, natural-area managers are considering alternatives to fire, like mowing and hand-removal of woody plants. The present study explored the ecological interactions of a wetland prairie by experimentally testing the responses of burning, hand-removal of woody species, and mowing with removal of cut material on woody plants and key native and non-native grasses and forbs. We evaluated these perturbations for their effectiveness in meeting management objectives of reducing abundance of woody species, reducing or preventing an increase in abundance of nonnative pest species, and increasing or at least maintaining native species’ abundance. After four treatments periods (1994, 1996, 1998, and 2000) the following patterns emerged: • Woody species Burning and hand-removal of woody plants every two years consistently decreased the cover of woody species, even with a gradual increase in the controls to over double 1994 levels. The change in woody cover after mowing with removal of cut material was not significantly different from that in the control. As woody plant cover decreased, plant mortality increased, indicating that treatments influenced woody plant cover at least partially through changes in survival. • Native herbaceous species None of the treatments had a significant effect after four treatment periods on the proportional change in cover or in number of inflorescences of Deschampsia cespitosa, although the change in number of inflorescences was consistently less than that in the control, including a significant decrease with burning in 1997. As a group, native graminoid species showed no significant differences in flowering response to treatments during any of the four treatment periods. However, burning and mowing consistently promoted flowering of Juncus tenuis. The cover of native forbs as a group was not significantly different from that of the control, with the exception of 1997, where cover increased with burning and hand-removal. Even though native forbs as a group have generally not shown significant differences, individual native forb species have shown positive responses to treatments: Sidalcea cusickii, spp. purpurea, Eriophyllum lanatum, and Sisyrinchium idahoensis. • Non-native herbaceous species Both hand-removal and mowing promoted flowering of non-native graminoids as a group. In contrast, burning maintained levels of flowering of non-native graminoids similar to that of the controls. Cover of non-native forbs as a group showed no significant treatment differences except for 1997, in which significant reductions in cover occurred after burning and hand-removal. The results to date show that prescribed burning is the best option of the three tested management treatments for achieving the restoration goals for native wetland prairies. Because mowing with removal of cut material was ineffective in reducing woody cover and tended to promote non-native herbaceous species, this treatment should be avoided. Title: Controlling woody vegetation in wetland prairies, 1994-2001 Author: Clark, Deborah Louise, 1950- Wetland prairies of the Willamette Valley, among the rarest of Oregon’s ecosystems, are threatened by invasion of woody species and non-native pest species. Because fire has been important in maintaining Willamette Valley prairies for at least 1000 years, prescribed burning is a top choice of managers for preventing encroachment of woody species. However, the effects of prescribed burning on present day wetland prairie communities, with their mix of native and non-native species, are not clear. Moreover, because strict governmental requirements for smoke management hinder prescribed burning, natural-area managers are considering alternatives to fire, like mowing and hand-removal of woody plants. The present study explored the ecological interactions of a wetland prairie by experimentally testing the responses of burning, hand-removal of woody species, and mowing with removal of cut material on woody plants and key native and non-native grasses and forbs. We evaluated these perturbations for their effectiveness in meeting management objectives of reducing abundance of woody species, reducing or preventing an increase in abundance of nonnative pest species, and increasing or at least maintaining native species’ abundance. After four treatments periods (1994, 1996, 1998, and 2000) the following patterns emerged: • Woody species Burning and hand-removal of woody plants every two years consistently decreased the cover of woody species, even with a gradual increase in the controls to over double 1994 levels. The change in woody cover after mowing with removal of cut material was not significantly different from that in the control. As woody plant cover decreased, plant mortality increased, indicating that treatments influenced woody plant cover at least partially through changes in survival. • Native herbaceous species None of the treatments had a significant effect after four treatment periods on the proportional change in cover or in number of inflorescences of Deschampsia cespitosa, although the change in number of inflorescences was consistently less than that in the control, including a significant decrease with burning in 1997. As a group, native graminoid species showed no significant differences in flowering response to treatments during any of the four treatment periods. However, burning and mowing consistently promoted flowering of Juncus tenuis. The cover of native forbs as a group was not significantly different from that of the control, with the exception of 1997, where cover increased with burning and hand-removal. Even though native forbs as a group have generally not shown significant differences, individual native forb species have shown positive responses to treatments: Sidalcea cusickii, spp. purpurea, Eriophyllum lanatum, and Sisyrinchium idahoensis. • Non-native herbaceous species Both hand-removal and mowing promoted flowering of non-native graminoids as a group. In contrast, burning maintained levels of flowering of non-native graminoids similar to that of the controls. Cover of non-native forbs as a group showed no significant treatment differences except for 1997, in which significant reductions in cover occurred after burning and hand-removal. The results to date show that prescribed burning is the best option of the three tested management treatments for achieving the restoration goals for native wetland prairies. Because mowing with removal of cut material was ineffective in reducing woody cover and tended to promote non-native herbaceous species, this treatment should be avoided. 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