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• 11. [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

• 12. [Article] Restoration of native upland prairies: Habitat for Fender’s blue butterfly (Icaricia icarioides fenderi)

  Our project goal is to promote the abundance of the endangered Fender’s blue butterfly (Icaricia icarioides fenderi) by recreating upland prairie habitat in former agricultural land at Finley National ...

  Citation × Citation Citation Abstract Copy Title: Restoration of native upland prairies: Habitat for Fender’s blue butterfly (Icaricia icarioides fenderi) Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Our project goal is to promote the abundance of the endangered Fender’s blue butterfly (Icaricia icarioides fenderi) by recreating upland prairie habitat in former agricultural land at Finley National Wildlife Refuge, Corvallis, Oregon. To achieve this goal we initiated the following three studies. Study One: Experimental Investigation on the Effectiveness of Restoration Treatments Our approach was to set up experimental field plots in a former agricultural field into which we sowed seeds of native grasses and dicots in the fall for two years, 2003 and 2004. Objective one: Investigate the effect of carbon banding on abundance of sowed native species and non-native species. Carbon banding is a treatment used by Willamette Valley grass seed farmers to promote seedling establishment of agricultural grasses and inhibit seedling establishment of weeds. Objective two: Investigate the effect of the sowing sequence of native dicot and grass species on the abundance and species richness of the sowed species. Our experiments were designed to test the hypothesis that our native grasses are more aggressive than the target native dicots in the initial stages of restoration. Objective three: Investigate the effect of the sowing sequence of the native dicot and grass species on the abundance of non-native species. Study Two: Monoculture Sowing of Native Species Compare the cover of non-native species and the cover of native species one and two years after sowing native species in monocultures. Study Three: Buffer Sowing of Native Grasses Monitor the abundance of the native grasses sowed in the buffer areas outside the experimental plots. Carbon banding had no significant effect on cover of non-native species or on cover and species richness of sowed native dicots or grasses after both the first and second growing seasons. However, carbon banding tended to reduce the cover of the annual Clarkia rhomboidea after the first growing season. Our results supported the hypothesis that our native grasses are more aggressive than the target native dicots in the initial stages of restoration. The sowing sequences tested did not affect cover and species richness of grasses but did affect cover and species richness of dicot species. Both dicot cover and dicot species richness were greater when sowed a year ahead of the grasses. Eriophyllum lanatum had significantly greater cover when sowed a year before the grasses. Average cover of sowed dicots was significantly greater when dicots were sowed with grasses compared to when dicots were sowed into a year-old stand of grasses. In particular, Madia gracilis and Prunella vulgaris var. lanceolata had less cover when sowed into the existing stand of grass. Species richness of all native species (grasses + dicots) was significantly less when dicots were sowed into a year-old stand of grasses. However, total cover and species richness of sowed native species (grasses + dicots) were not significantly different whether dicots were sowed a year ahead of the grasses or whether dicots and grasses were sowed together. Average cover of sowed native dicots after two years was always greater than the cover of sowed native grasses except when dicots were sowed a year after the grasses. After two growing seasons, non-native cover did not significantly vary among the three sowing sequences of sowing grasses and dicots at the same time, sowing grasses into existing dicot vegetation, and sowing grasses into existing dicot vegetation. The first year after sowing the monocultures (Study two), Collinsia grandiflora had the highest cover, greatly surpassing the next top performers, Sanguisorba occidentalis and Madia gracilis, all of which are annual species. In general, the cover of individual species sowed in monocultures decreased the second year after sowing. Only seven species, all of which were perennials, out of the 26 sowed species increased in cover. Two of these species Eriophyllum lanatum and Prunella vulgaris var. lanceolata were the top performers for 2005, but their cover did not reach the levels of the top performers in 2004. Title: Restoration of native upland prairies: Habitat for Fender’s blue butterfly (Icaricia icarioides fenderi) Author: Wilson, Mark V., Clark, Deborah Louise, 1950- Our project goal is to promote the abundance of the endangered Fender’s blue butterfly (Icaricia icarioides fenderi) by recreating upland prairie habitat in former agricultural land at Finley National Wildlife Refuge, Corvallis, Oregon. To achieve this goal we initiated the following three studies. Study One: Experimental Investigation on the Effectiveness of Restoration Treatments Our approach was to set up experimental field plots in a former agricultural field into which we sowed seeds of native grasses and dicots in the fall for two years, 2003 and 2004. Objective one: Investigate the effect of carbon banding on abundance of sowed native species and non-native species. Carbon banding is a treatment used by Willamette Valley grass seed farmers to promote seedling establishment of agricultural grasses and inhibit seedling establishment of weeds. Objective two: Investigate the effect of the sowing sequence of native dicot and grass species on the abundance and species richness of the sowed species. Our experiments were designed to test the hypothesis that our native grasses are more aggressive than the target native dicots in the initial stages of restoration. Objective three: Investigate the effect of the sowing sequence of the native dicot and grass species on the abundance of non-native species. Study Two: Monoculture Sowing of Native Species Compare the cover of non-native species and the cover of native species one and two years after sowing native species in monocultures. Study Three: Buffer Sowing of Native Grasses Monitor the abundance of the native grasses sowed in the buffer areas outside the experimental plots. Carbon banding had no significant effect on cover of non-native species or on cover and species richness of sowed native dicots or grasses after both the first and second growing seasons. However, carbon banding tended to reduce the cover of the annual Clarkia rhomboidea after the first growing season. Our results supported the hypothesis that our native grasses are more aggressive than the target native dicots in the initial stages of restoration. The sowing sequences tested did not affect cover and species richness of grasses but did affect cover and species richness of dicot species. Both dicot cover and dicot species richness were greater when sowed a year ahead of the grasses. Eriophyllum lanatum had significantly greater cover when sowed a year before the grasses. Average cover of sowed dicots was significantly greater when dicots were sowed with grasses compared to when dicots were sowed into a year-old stand of grasses. In particular, Madia gracilis and Prunella vulgaris var. lanceolata had less cover when sowed into the existing stand of grass. Species richness of all native species (grasses + dicots) was significantly less when dicots were sowed into a year-old stand of grasses. However, total cover and species richness of sowed native species (grasses + dicots) were not significantly different whether dicots were sowed a year ahead of the grasses or whether dicots and grasses were sowed together. Average cover of sowed native dicots after two years was always greater than the cover of sowed native grasses except when dicots were sowed a year after the grasses. After two growing seasons, non-native cover did not significantly vary among the three sowing sequences of sowing grasses and dicots at the same time, sowing grasses into existing dicot vegetation, and sowing grasses into existing dicot vegetation. The first year after sowing the monocultures (Study two), Collinsia grandiflora had the highest cover, greatly surpassing the next top performers, Sanguisorba occidentalis and Madia gracilis, all of which are annual species. In general, the cover of individual species sowed in monocultures decreased the second year after sowing. Only seven species, all of which were perennials, out of the 26 sowed species increased in cover. Two of these species Eriophyllum lanatum and Prunella vulgaris var. lanceolata were the top performers for 2005, but their cover did not reach the levels of the top performers in 2004. Close

• 13. [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

• 14. [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

• 15. [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

• 16. [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. Close

• 17. [Article] Post-dispersal seed fates in a Western Oregon native prairie

  Knowledge of post-dispersal seed fates and other regeneration characteristics is crucial for predicting abundances and distributions of populations and, ultimately, community species composition and diversity. ...

  Citation × Citation Citation Abstract Copy Title: Post-dispersal seed fates in a Western Oregon native prairie Author: Clark, Deborah Louise, 1950- Knowledge of post-dispersal seed fates and other regeneration characteristics is crucial for predicting abundances and distributions of populations and, ultimately, community species composition and diversity. Seed fate studies, however, are rare primarily due to the difficulty of determining seed fates and causes of mortality. This thesis investigated post-dispersal seed fates for four species common to western Oregon native prairies: Bromus carinatus Hook and Am. var. carinatus, Cynosurus echinatus L., Daucus carota L., and Prunella vulgaris var. lanceolata (Barton) Fern. The general approach was to sow seeds of these species into experimentally manipulated field plots for each of two years, and to recover these seeds from the soil one year later to determine their fates (persistence, death, or establishment as seedlings). The effect of mowing on seedling establishment was also addressed. Additional studies focused on the effects of a single mortality factor, fungal disease, on seed and seedling deaths. The fate of most seeds was death (44%-80%). Few seeds established as seedlings (4%-17%), and mowing did not significantly increase seedling establishment. Only Daucus carota formed a persistent seed bank. Fungal disease generally caused less than 10% mortality. Pot studies corroborated these field results. Other investigators have suggested higher levels of disease in natural vegetation. Vertebrate predation significantly reduced seed numbers for only Bromus carinatus (21%). The largest cause of death for all species for both years was the combined group of other mortality causes (invertebrate predation, interference, and abiotic factors) (52%-73%). The components of this combined group, however, differed among species. The most likely components for Bromus carinatus and Cynosurus echinatus were interference (competition plus allelopathy) and abiotic factors, although invertebrate predation cannot be ruled out for Bromus carinatus. Seedling death due to abiotic factors was most likely the largest component for Daucus carota. The most probable components for Prunella vulgaris were invertebrate predation and abiotic factors. Implications of these findings for population patterns and for restoration of native prairies are discussed. Title: Post-dispersal seed fates in a Western Oregon native prairie Author: Clark, Deborah Louise, 1950- Knowledge of post-dispersal seed fates and other regeneration characteristics is crucial for predicting abundances and distributions of populations and, ultimately, community species composition and diversity. Seed fate studies, however, are rare primarily due to the difficulty of determining seed fates and causes of mortality. This thesis investigated post-dispersal seed fates for four species common to western Oregon native prairies: Bromus carinatus Hook and Am. var. carinatus, Cynosurus echinatus L., Daucus carota L., and Prunella vulgaris var. lanceolata (Barton) Fern. The general approach was to sow seeds of these species into experimentally manipulated field plots for each of two years, and to recover these seeds from the soil one year later to determine their fates (persistence, death, or establishment as seedlings). The effect of mowing on seedling establishment was also addressed. Additional studies focused on the effects of a single mortality factor, fungal disease, on seed and seedling deaths. The fate of most seeds was death (44%-80%). Few seeds established as seedlings (4%-17%), and mowing did not significantly increase seedling establishment. Only Daucus carota formed a persistent seed bank. Fungal disease generally caused less than 10% mortality. Pot studies corroborated these field results. Other investigators have suggested higher levels of disease in natural vegetation. Vertebrate predation significantly reduced seed numbers for only Bromus carinatus (21%). The largest cause of death for all species for both years was the combined group of other mortality causes (invertebrate predation, interference, and abiotic factors) (52%-73%). The components of this combined group, however, differed among species. The most likely components for Bromus carinatus and Cynosurus echinatus were interference (competition plus allelopathy) and abiotic factors, although invertebrate predation cannot be ruled out for Bromus carinatus. Seedling death due to abiotic factors was most likely the largest component for Daucus carota. The most probable components for Prunella vulgaris were invertebrate predation and abiotic factors. Implications of these findings for population patterns and for restoration of native prairies are discussed. Close

• 18. [Article] Promoting regeneration of native species In Willamette Valley upland prairies

  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: Promoting regeneration of native species In Willamette Valley upland prairies Author: 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. The focus of this investigation was to address this need. The general approach was to sow seeds of native species into experimental field plots, which had been burned once, burned repeatedly, mowed, or unmanaged at three sites at Baskett Slough National Wildlife Refuge. Seedling numbers were then counted one growing season after sowing. To investigate mechanisms for the regeneration responses of species to management treatments, selected abiotic and biotic factors potentially important for seed regeneration were measured in the field plots. Seedling establishment rates in unmanaged plots were relatively small, averaging 9.7% for all three sites. Only one species, Danthonia californica, showed a positive response to the mowing treatment. Of the 13 species sowed in the burn plots, six species (Bromus carinatus, Elymus glacus, Festuca roemeri/rubra, Clarkia quadrivulera, Prunella vulgaris, Sidalcea campestris) had significant more seedlings in the burn plots compared to the unmanaged plots. Seedling establishment of two species, Danthonia californica and Potentilla gracilis, was significantly lower with burn treatments. The other five species showed no significant responses to the burn treatments: Carex tumicola, Calochortus tolmiei, Zygadensus venenosus, Balsamorhiza deltoidea, and Agoseris grandilflora. The strongest fire effects were generally in plots that had been burned only once, rather than plots burned more than once. Abundance of litter and vegetation were the factors that were most often related, both positively and negatively, with seedling establishment rates. Based on the results of this investigation, prescribed burning, rather than mowing, is a more viable management option to promote regeneration of native species from seed in upland prairies. However, prescribed burning must be used with caution as it can reduce seedling establishment rates for some species. Sowing seeds in unmanaged sites is an option, but sowing rates need to be high to compensate for the small seedling establishment rates in unmanaged prairies. Title: Promoting regeneration of native species In Willamette Valley upland prairies Author: 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. The focus of this investigation was to address this need. The general approach was to sow seeds of native species into experimental field plots, which had been burned once, burned repeatedly, mowed, or unmanaged at three sites at Baskett Slough National Wildlife Refuge. Seedling numbers were then counted one growing season after sowing. To investigate mechanisms for the regeneration responses of species to management treatments, selected abiotic and biotic factors potentially important for seed regeneration were measured in the field plots. Seedling establishment rates in unmanaged plots were relatively small, averaging 9.7% for all three sites. Only one species, Danthonia californica, showed a positive response to the mowing treatment. Of the 13 species sowed in the burn plots, six species (Bromus carinatus, Elymus glacus, Festuca roemeri/rubra, Clarkia quadrivulera, Prunella vulgaris, Sidalcea campestris) had significant more seedlings in the burn plots compared to the unmanaged plots. Seedling establishment of two species, Danthonia californica and Potentilla gracilis, was significantly lower with burn treatments. The other five species showed no significant responses to the burn treatments: Carex tumicola, Calochortus tolmiei, Zygadensus venenosus, Balsamorhiza deltoidea, and Agoseris grandilflora. The strongest fire effects were generally in plots that had been burned only once, rather than plots burned more than once. Abundance of litter and vegetation were the factors that were most often related, both positively and negatively, with seedling establishment rates. Based on the results of this investigation, prescribed burning, rather than mowing, is a more viable management option to promote regeneration of native species from seed in upland prairies. However, prescribed burning must be used with caution as it can reduce seedling establishment rates for some species. Sowing seeds in unmanaged sites is an option, but sowing rates need to be high to compensate for the small seedling establishment rates in unmanaged prairies. Close

• 19. [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