Search

Search Results

• 1. [Article] Demographic analysis of Erigeron decumbens var. decumbens, an endangered plant species of the Willamette Valley, Oregon: 1999 Field Studies

  Erigeron decumbens var. decumbens, known only from the Willamette Valley of western Oregon, is listed as Endangered by the U.S. Fish and Wildlife Service and by the state of Oregon. In 1993 a long-term ...

  Citation × Citation Citation Abstract Copy Title: Demographic analysis of Erigeron decumbens var. decumbens, an endangered plant species of the Willamette Valley, Oregon: 1999 Field Studies Author: Clark, Deborah Louise, 1950- Erigeron decumbens var. decumbens, known only from the Willamette Valley of western Oregon, is listed as Endangered by the U.S. Fish and Wildlife Service and by the state of Oregon. In 1993 a long-term population monitoring program for Erigeron decumbens var. decumbens was initiated at Baskett Slough National Wildlife Refuge (Polk County). The objectives were to assess long-term population trends, particularly patterns of reproduction, recruitment, and mortality. This report presents the results of the demographic monitoring from 1993-1999. Considered together the following demographic parameters indicate that the measured population at Baskett Butte (Baskett Slough National Wildlife Refuge) is declining. 1. The population size decreased every year but one with the 1999 population only 48% of the 1993 population. 2. Increasing mortality rates exceeded recruitment rates every year but one. 3. The percentage of the population that flowered generally decreased every year. 4. The average number of heads per flowering plant decreased each year beginning in 1995 to 3.4 heads per flowering plant in 1999. 5. The pattern of average basal area per plant varied but the 1999 average basal area is only 63% of that measured in 1993. To stabilize the population, adaptive management strategies need to be developed in conjunction with experimental approaches that will determine the factors responsible for the population decline. A second approach to aid in the recovery of Erigeron decumbens var. decumbens is to increase the population by transplanting cuttings or plants grown from seed under greenhouse conditions or by sowing seeds in the field under more controlled conditions. It is strongly recommended that future efforts to stabilize the population at Baskett Slough National Wildlife Refuge be coordinated with other agencies in the Valley who are also responsible for management of Erigeron decumbens var. decumbens populations. Title: Demographic analysis of Erigeron decumbens var. decumbens, an endangered plant species of the Willamette Valley, Oregon: 1999 Field Studies Author: Clark, Deborah Louise, 1950- Erigeron decumbens var. decumbens, known only from the Willamette Valley of western Oregon, is listed as Endangered by the U.S. Fish and Wildlife Service and by the state of Oregon. In 1993 a long-term population monitoring program for Erigeron decumbens var. decumbens was initiated at Baskett Slough National Wildlife Refuge (Polk County). The objectives were to assess long-term population trends, particularly patterns of reproduction, recruitment, and mortality. This report presents the results of the demographic monitoring from 1993-1999. Considered together the following demographic parameters indicate that the measured population at Baskett Butte (Baskett Slough National Wildlife Refuge) is declining. 1. The population size decreased every year but one with the 1999 population only 48% of the 1993 population. 2. Increasing mortality rates exceeded recruitment rates every year but one. 3. The percentage of the population that flowered generally decreased every year. 4. The average number of heads per flowering plant decreased each year beginning in 1995 to 3.4 heads per flowering plant in 1999. 5. The pattern of average basal area per plant varied but the 1999 average basal area is only 63% of that measured in 1993. To stabilize the population, adaptive management strategies need to be developed in conjunction with experimental approaches that will determine the factors responsible for the population decline. A second approach to aid in the recovery of Erigeron decumbens var. decumbens is to increase the population by transplanting cuttings or plants grown from seed under greenhouse conditions or by sowing seeds in the field under more controlled conditions. It is strongly recommended that future efforts to stabilize the population at Baskett Slough National Wildlife Refuge be coordinated with other agencies in the Valley who are also responsible for management of Erigeron decumbens var. decumbens populations. Close

• 2. [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

• 3. [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

• 4. [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