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• 1. [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

• 2. [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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• 3. [Article] Progress report II: Restoring prairies: A synthesis of studies on vegetation and invasive species in support of effective management (Year two)

  Willamette Valley wetland and upland prairies are some of the most endangered ecosystems in the United States, and provide habitat for many federally listed species. Because these are dynamic systems, ...

  Citation × Citation Citation Abstract Copy Title: Progress report II: Restoring prairies: A synthesis of studies on vegetation and invasive species in support of effective management (Year two) Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Willamette Valley wetland and upland prairies are some of the most endangered ecosystems in the United States, and provide habitat for many federally listed species. Because these are dynamic systems, subject to ecological succession and invasion by aggressive non-native species, prairies require active management to maintain management goals. This is true of all Willamette Valley prairies, whether intact, degraded, or reestablished. Yet restoration and conservation efforts often lack experimental validation. Our overall objective for this project is to synthesize the scientific information now available relevant to the prairie restoration efforts of the West Eugene Wetlands project and, where there is sufficient support, develop concrete and defensible management recommendations Successful ecosystem restoration requires establishing and maintaining native plants. In turn, plant establishment hinges on having suitable environmental conditions, using species with adequate germination rates, and reducing competitive pressure from nonnative plants. In year one of this project, we synthesized the wealth of data in the West Eugene Wetlands establishment data set on plant abundance after sowing native species during wetland restoration (Wilson 2004). In year two, we will build and expand on these results in several important ways: • We are generalizing these results through the investigation of plant traits that consistently correspond to the patterns of establishment and vigor. • We are systematically compiling the results from year one and year two of this project into a public database. We are adding to this database findings from similar ecosystems, both in the Willamette Valley and elsewhere. • We are considering further the role of microsite variability on seedling establishment patterns. • We are synthesizing these results into scientific conclusions. • We are integrating these results, where there is sufficient support, into concrete and defensible management recommendations Our goal is to develop an ability to predict key aspects of prairie restoration performance, such as establishment rates, based on knowing species traits, site conditions, and maintenance. These predictions can then be converted into management recommendations, such as which species to sow and which site preparation and maintenance regimes should be followed to maximize native plant abundance and minimize non-native plant abundance at a given site. The two components of our project –plant traits and the database– are crucial to this goal. • Without the generalization that traits allow, understanding of wetland restoration increases slowly and expensively, one case study at a time. • The organization of the database will increase the power and efficiency of revealing the relationships between plant traits and plant performance. Perhaps even more important is the role of the database as a first step in developing a Web-based expert system for managers wishing to plan wetland restorations Title: Progress report II: Restoring prairies: A synthesis of studies on vegetation and invasive species in support of effective management (Year two) Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Willamette Valley wetland and upland prairies are some of the most endangered ecosystems in the United States, and provide habitat for many federally listed species. Because these are dynamic systems, subject to ecological succession and invasion by aggressive non-native species, prairies require active management to maintain management goals. This is true of all Willamette Valley prairies, whether intact, degraded, or reestablished. Yet restoration and conservation efforts often lack experimental validation. Our overall objective for this project is to synthesize the scientific information now available relevant to the prairie restoration efforts of the West Eugene Wetlands project and, where there is sufficient support, develop concrete and defensible management recommendations Successful ecosystem restoration requires establishing and maintaining native plants. In turn, plant establishment hinges on having suitable environmental conditions, using species with adequate germination rates, and reducing competitive pressure from nonnative plants. In year one of this project, we synthesized the wealth of data in the West Eugene Wetlands establishment data set on plant abundance after sowing native species during wetland restoration (Wilson 2004). In year two, we will build and expand on these results in several important ways: • We are generalizing these results through the investigation of plant traits that consistently correspond to the patterns of establishment and vigor. • We are systematically compiling the results from year one and year two of this project into a public database. We are adding to this database findings from similar ecosystems, both in the Willamette Valley and elsewhere. • We are considering further the role of microsite variability on seedling establishment patterns. • We are synthesizing these results into scientific conclusions. • We are integrating these results, where there is sufficient support, into concrete and defensible management recommendations Our goal is to develop an ability to predict key aspects of prairie restoration performance, such as establishment rates, based on knowing species traits, site conditions, and maintenance. These predictions can then be converted into management recommendations, such as which species to sow and which site preparation and maintenance regimes should be followed to maximize native plant abundance and minimize non-native plant abundance at a given site. The two components of our project –plant traits and the database– are crucial to this goal. • Without the generalization that traits allow, understanding of wetland restoration increases slowly and expensively, one case study at a time. • The organization of the database will increase the power and efficiency of revealing the relationships between plant traits and plant performance. Perhaps even more important is the role of the database as a first step in developing a Web-based expert system for managers wishing to plan wetland restorations Close

• 4. [Article] Progress report [I]: Restoring prairies: A synthesis of studies on vegetation and invasive species in support of effective management (Year two)

  Willamette Valley wetland and upland prairies are some of the most endangered ecosystems in the United States, and provide habitat for many federally listed species. These are dynamic systems, subject ...

  Citation × Citation Citation Abstract Copy Title: Progress report [I]: Restoring prairies: A synthesis of studies on vegetation and invasive species in support of effective management (Year two) Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Willamette Valley wetland and upland prairies are some of the most endangered ecosystems in the United States, and provide habitat for many federally listed species. These are dynamic systems, subject to ecological succession and invasion by aggressive non-native species, and require active management to maintain management goals. This is true of all Willamette Valley prairies, whether intact, degraded, or reestablished. Yet restoration and conservation efforts often lack experimental validation. Our overall objective is to synthesize the scientific information now available pertinent to the prairie restoration efforts of the West Eugene Wetlands Program (WEWP) and, where there is sufficient support, develop concrete and defensible management recommendations. Successful ecosystem restoration requires establishing and maintaining native plants. In turn, plant establishment hinges on having suitable environmental conditions, using species with adequate germination and growth rates, and reducing competitive pressure from non-native plants (Figure 1). In year one of this project, we synthesized the wealth of plant establishment data during wetland restoration in the West Eugene Wetlands Program. In year two, we are building and expanding on these results in several important ways: • We are generalizing these results through the investigation of plant traits (Table 1) that consistently correspond to the patterns of establishment and vigor (Figure 1). • We are systematically compiling the results from year one and year two of this project into a public database. We are adding to this database findings from similar ecosystems, both in the Willamette Valley and elsewhere. • We are considering further the role of microsite variability on seedling establishment patterns. • We are synthesizing these results into scientific conclusions. • We are integrating these results, where there is sufficient support, into concrete and defensible management recommendations Our goal is to develop an ability to predict key aspects of prairie restoration performance, such as establishment rates, based on species traits, site conditions, and maintenance. These predictions can then be restated as management recommendations, such as which species to sow and site preparation and maintenance regimes to follow to maximize native plant abundance and minimize non-native plant abundance at a given site. The two components of our project–plant traits and the database–are crucial to this goal. • Without the generalization that traits allow, understanding of wetland restoration increases slowly and expensively, one case study at a time. • The organization of the database will increase the power and efficiency of revealing the relationships between plant traits and plant performance. Perhaps even more important is the role of the database as a first step in developing a Web-based expert system for managers wishing to plan wetland restorations. Title: Progress report [I]: Restoring prairies: A synthesis of studies on vegetation and invasive species in support of effective management (Year two) Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Willamette Valley wetland and upland prairies are some of the most endangered ecosystems in the United States, and provide habitat for many federally listed species. These are dynamic systems, subject to ecological succession and invasion by aggressive non-native species, and require active management to maintain management goals. This is true of all Willamette Valley prairies, whether intact, degraded, or reestablished. Yet restoration and conservation efforts often lack experimental validation. Our overall objective is to synthesize the scientific information now available pertinent to the prairie restoration efforts of the West Eugene Wetlands Program (WEWP) and, where there is sufficient support, develop concrete and defensible management recommendations. Successful ecosystem restoration requires establishing and maintaining native plants. In turn, plant establishment hinges on having suitable environmental conditions, using species with adequate germination and growth rates, and reducing competitive pressure from non-native plants (Figure 1). In year one of this project, we synthesized the wealth of plant establishment data during wetland restoration in the West Eugene Wetlands Program. In year two, we are building and expanding on these results in several important ways: • We are generalizing these results through the investigation of plant traits (Table 1) that consistently correspond to the patterns of establishment and vigor (Figure 1). • We are systematically compiling the results from year one and year two of this project into a public database. We are adding to this database findings from similar ecosystems, both in the Willamette Valley and elsewhere. • We are considering further the role of microsite variability on seedling establishment patterns. • We are synthesizing these results into scientific conclusions. • We are integrating these results, where there is sufficient support, into concrete and defensible management recommendations Our goal is to develop an ability to predict key aspects of prairie restoration performance, such as establishment rates, based on species traits, site conditions, and maintenance. These predictions can then be restated as management recommendations, such as which species to sow and site preparation and maintenance regimes to follow to maximize native plant abundance and minimize non-native plant abundance at a given site. The two components of our project–plant traits and the database–are crucial to this goal. • Without the generalization that traits allow, understanding of wetland restoration increases slowly and expensively, one case study at a time. • The organization of the database will increase the power and efficiency of revealing the relationships between plant traits and plant performance. Perhaps even more important is the role of the database as a first step in developing a Web-based expert system for managers wishing to plan wetland restorations. Close

• 5. [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

• 6. [Article] Increasing the abundance of rare native wetland prairie species

  Native prairies of the Willamette Valley are considered among the rarest of Oregon’s ecosystems and are in critical need of conservation. Management strategies for increasing the abundance of native species ...

  Citation × Citation Citation Abstract Copy Title: Increasing the abundance of rare native wetland prairie species Author: Goodridge, Jennifer, Wilson, Mark V., Clark, Deborah Louise, 1950- Native prairies of the Willamette Valley are considered among the rarest of Oregon’s ecosystems and are in critical need of conservation. Management strategies for increasing the abundance of native species are urgently needed, particularly those strategies that promote the regeneration of native species from seed. Fire may be an important factor in promoting regeneration of native species from seed because of its historical role in maintaining the prairie landscape. The study objectives were (1) to determine the effect of prescribed burning on regeneration of native species from seed, and (2) to establish predictive relationships between easily measured plant traits and seedling establishment rates in the field. The general approach was to sow seeds of target wetland prairie species during the fall into experimental field plots already established at the Danebo Wetland, Eugene, OR. Seedling establishment rates were then compared between burned and unburned plots the following spring. To establish predictive relationships these seedling establishment rates were related to selected seed and seedling traits measured under laboratory conditions. Overall seedling establishment rates showed no significant differences between burned (7.0%) and unburned plots (8.7%), although for the seven species showing positive responses to prescribed burning, the increase was approximately doubled in the burned plots. Burning significantly increased the seedling establishment rates of three species, Wyethia angustifolia, Grindelia integrifolia, and Danthonia californica. Seedling establishment significantly decreased with burning for one species, Sidalcea campestris. For three of the four endangered, threatened or rare species, Aster curtus, Horkelia congesta, and Sidalcea cusickii var. purpurea, seedling establishment rates were smaller in the burned plots compared to the unburned plots, although the differences were not significant. Lomatium bradshawii had no seedlings establish in either the burned or the unburned plots. Plant weight 7 days after germination was the best trait at predicting field seedling establishment rates for both the burned plots and the unburned plots, explaining a significant amount of variation in establishment rates: 70% for the burned plots and 45% for the unburned plots. This model could be used by managers to choose species for sowing in burned and unburned prairies or to estimate seeding rates at burned and unburned sites. Title: Increasing the abundance of rare native wetland prairie species Author: Goodridge, Jennifer, Wilson, Mark V., Clark, Deborah Louise, 1950- Native prairies of the Willamette Valley are considered among the rarest of Oregon’s ecosystems and are in critical need of conservation. Management strategies for increasing the abundance of native species are urgently needed, particularly those strategies that promote the regeneration of native species from seed. Fire may be an important factor in promoting regeneration of native species from seed because of its historical role in maintaining the prairie landscape. The study objectives were (1) to determine the effect of prescribed burning on regeneration of native species from seed, and (2) to establish predictive relationships between easily measured plant traits and seedling establishment rates in the field. The general approach was to sow seeds of target wetland prairie species during the fall into experimental field plots already established at the Danebo Wetland, Eugene, OR. Seedling establishment rates were then compared between burned and unburned plots the following spring. To establish predictive relationships these seedling establishment rates were related to selected seed and seedling traits measured under laboratory conditions. Overall seedling establishment rates showed no significant differences between burned (7.0%) and unburned plots (8.7%), although for the seven species showing positive responses to prescribed burning, the increase was approximately doubled in the burned plots. Burning significantly increased the seedling establishment rates of three species, Wyethia angustifolia, Grindelia integrifolia, and Danthonia californica. Seedling establishment significantly decreased with burning for one species, Sidalcea campestris. For three of the four endangered, threatened or rare species, Aster curtus, Horkelia congesta, and Sidalcea cusickii var. purpurea, seedling establishment rates were smaller in the burned plots compared to the unburned plots, although the differences were not significant. Lomatium bradshawii had no seedlings establish in either the burned or the unburned plots. Plant weight 7 days after germination was the best trait at predicting field seedling establishment rates for both the burned plots and the unburned plots, explaining a significant amount of variation in establishment rates: 70% for the burned plots and 45% for the unburned plots. This model could be used by managers to choose species for sowing in burned and unburned prairies or to estimate seeding rates at burned and unburned sites. Close