Hydrologic and Vegetation Responses Associated with Restoration of Wetlands in the Willamette Valley, Oregon PDF Download
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Author: Gregory A. Coleman
Publisher:
ISBN:
Category : Wetland ecology
Languages : en
Pages : 190
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Book Description
I examined hydrological and plant community changes associated with the implementation of a restoration management plan in two riparian meadows located within an agricultural landscape of the central Willamette Valley, Oregon. I established exclosure fencing (a form of passive restoration) in one agricultural field and established fencing and plugged a drainage ditch (active restoration) in a separate agricultural field. Permanent transects 15 m in length were established within two plant communities associated with hydrological regimes within these restored agricultural fields. Plant communities were classified as wetland meadow (inundated for more than 4 weeks/year) and mesic meadow (saturated within the upper 30 cm but not inundated) for at least 4 weeks/year. Four transects were randomly established within the wet meadow community and 6 transects were randomly situated within the mesic meadow community. Two shallow subsurface piezometers were installed to a depth of 1 m at 5 m and 10 m along each of these 15 m transects. Additionally, two shallow sub-surface piezometers were established at the outer perimeter of the agriculturally excluded fields. Shallow sub-surface and surface water table levels were measured at each piezometer after wetlands were inundated and continued until water table dropped below the piezometers (Dec. - June) for one pre-treatment and two post treatment years. The actively restored wet and mesic meadows demonstrated increased water table elevation and a decrease in water table fluctuation during both post treatment years. Increases in water table elevation were greatest in areas closest to active restoration but were significant up to 102 m. from restoration. Results indicate that filling drainage ditches induce hydrologic effects at great distances across floodplain soils. Plant community composition (species response) was quantified in both restored sites as well as the adjacent agriculturally managed (untreated) sites one year before treatment and two post-treatment years. I sampled two plant community types: wet meadow and mesic meadow. I calculated species richness and the relative abundance of wetland indicator species, nuisance weeds, and native plants. Nuisance weeds increased and native plant abundance decreased in agriculturally managed mesic meadows. Wetland plant species abundance tended to increase in agricultural sites with light grazing, and decreased in areas that were plowed and re-seeded. Native plants increased and nuisance weeds decreased in the actively restored mesic meadow. The passively restored mesic meadow exhibited no change in native plant abundance and decreases in all other categories. In the actively restored wetland there were increases in plant species richness and nuisance weed abundance with a decrease in native plant abundance. Agriculturally excluded wetlands dominated by Reed canary grass (Phalaris arundinacea) exhibited no changes for the entire study period. Results suggest that for the first few years following agricultural exclusion, nuisance weed species do not increase, but active restoration may result in increases (due to disturbance). Additionally, results indicate restored agricultural landscapes dominated by introduced grasses demonstrate minimal short-term plant community change unless initiated by intense land management practices (e g., plowing, re-seeding, or removal of dominant plant communities). Based upon results of this study, I conclude that restoration plans should repair damaged hydrological features before planting riparian plant species. Following this chronological sequence will minimize the potential destruction of planted communities by future shifts in water table elevation caused by hydrologic restoration. Furthermore, any active restoration that initiates a direct or indirect removal of the dominant plant community should be accompanied by aggressive plantings of desirable plant species and prolonged site maintenance.
Author: Gregory A. Coleman
Publisher:
ISBN:
Category : Wetland ecology
Languages : en
Pages : 190
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Book Description
I examined hydrological and plant community changes associated with the implementation of a restoration management plan in two riparian meadows located within an agricultural landscape of the central Willamette Valley, Oregon. I established exclosure fencing (a form of passive restoration) in one agricultural field and established fencing and plugged a drainage ditch (active restoration) in a separate agricultural field. Permanent transects 15 m in length were established within two plant communities associated with hydrological regimes within these restored agricultural fields. Plant communities were classified as wetland meadow (inundated for more than 4 weeks/year) and mesic meadow (saturated within the upper 30 cm but not inundated) for at least 4 weeks/year. Four transects were randomly established within the wet meadow community and 6 transects were randomly situated within the mesic meadow community. Two shallow subsurface piezometers were installed to a depth of 1 m at 5 m and 10 m along each of these 15 m transects. Additionally, two shallow sub-surface piezometers were established at the outer perimeter of the agriculturally excluded fields. Shallow sub-surface and surface water table levels were measured at each piezometer after wetlands were inundated and continued until water table dropped below the piezometers (Dec. - June) for one pre-treatment and two post treatment years. The actively restored wet and mesic meadows demonstrated increased water table elevation and a decrease in water table fluctuation during both post treatment years. Increases in water table elevation were greatest in areas closest to active restoration but were significant up to 102 m. from restoration. Results indicate that filling drainage ditches induce hydrologic effects at great distances across floodplain soils. Plant community composition (species response) was quantified in both restored sites as well as the adjacent agriculturally managed (untreated) sites one year before treatment and two post-treatment years. I sampled two plant community types: wet meadow and mesic meadow. I calculated species richness and the relative abundance of wetland indicator species, nuisance weeds, and native plants. Nuisance weeds increased and native plant abundance decreased in agriculturally managed mesic meadows. Wetland plant species abundance tended to increase in agricultural sites with light grazing, and decreased in areas that were plowed and re-seeded. Native plants increased and nuisance weeds decreased in the actively restored mesic meadow. The passively restored mesic meadow exhibited no change in native plant abundance and decreases in all other categories. In the actively restored wetland there were increases in plant species richness and nuisance weed abundance with a decrease in native plant abundance. Agriculturally excluded wetlands dominated by Reed canary grass (Phalaris arundinacea) exhibited no changes for the entire study period. Results suggest that for the first few years following agricultural exclusion, nuisance weed species do not increase, but active restoration may result in increases (due to disturbance). Additionally, results indicate restored agricultural landscapes dominated by introduced grasses demonstrate minimal short-term plant community change unless initiated by intense land management practices (e g., plowing, re-seeding, or removal of dominant plant communities). Based upon results of this study, I conclude that restoration plans should repair damaged hydrological features before planting riparian plant species. Following this chronological sequence will minimize the potential destruction of planted communities by future shifts in water table elevation caused by hydrologic restoration. Furthermore, any active restoration that initiates a direct or indirect removal of the dominant plant community should be accompanied by aggressive plantings of desirable plant species and prolonged site maintenance.
Author:
Publisher:
ISBN:
Category : Wetland conservation
Languages : en
Pages : 80
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Author: Rachel A. Schwindt
Publisher:
ISBN:
Category : Invasive plants
Languages : en
Pages : 180
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Book Description
Invasion by exotic species can pose a major challenge for developing native plant communities in wetland restoration projects. Often native plant communities do not develop as anticipated in restored wetlands due to colonization by exotic species that dominate the native plant community. Despite the time and expense to restore wetlands, there has been little long term research to compare plant communities in restored and natural wetland sites. Research into plant community diversity across several wetland sites over several years can provide a broader perspective into how these ecosystems recover from long-term disturbance. The objective of this study was to compare plant community change from 2000 to 2005 between restored and remnant wetland prairie sites in the southern Willamette Valley in Oregon to determine if exotic species abundance was consistent between these groups. Specific objectives included 1) comparing the diversity and abundance of all species in remnant and restored wetland prairie sites, 2) evaluate the trajectory of community change between remnant and restored wetland prairie sites to determine if there was rapid change in restored sites, and 3) describe the plot level heterogeneity of the plant community in all sites to determine how microsites influence diversity. In 2005, species abundance was re-measured in four remnant wetland prairies and four restored wetland prairies that had been selected for an unrelated vegetation survey in 2000. Species were characterized by life form, origin, and wetland indicator status. Species abundance between groups of remnant and restored sites were compared using a multi-response permutation procedure (MRPP). The plant community trajectory was evaluated with nonmetric multidimensional scaling (NMS) and tested for significance with multivariate analysis of variance (MANOVA). Species area curves were compared between sites and within remnant and restored groups of plots. Within-year and between-year significance tests indicated that remnant and restored sites were similar in exotic species abundance, graminoid abundance, and wetland species abundance with no significant difference between these remnant and restored wetland prairie sites. Individual sites in both groups experienced changes in exotic species abundance which confounded the statistical results. Species heterogeneity was no more spatially diverse across the remnant site plots than restored site plots. Species area curves did not show significant differences between remnant and restored plots but individual plots did show homogeneous community characteristics at smaller spatial scales. Restoration sites had developed high graminoid cover by the 2000 survey which was conducted two to three years after restoration was initiated. All sites were equally likely to contain exotic species. Exotic species common across all sites included Centaurium umbellatum, Holcus lanatus, and Hypericum perforatum. Native species common across sites included Deschampsia cespitosa, Danthonia californica and Juncus tenuis. These results suggested that differences between remnant and restored Willamette Valley wetland prairie sites were not generalizable at the landscape scale and were more dependent on site specific management activities and local barriers to colonization. Five years may not be enough time to see evidence that suggests if restored plant communities will develop spatial characteristics of the remnant sites. This research does suggest that multi-site comparisons help distinguish individual sites that are not developing characteristics of remnant wetland plant communities.
Author: Sara M. Taylor
Publisher:
ISBN:
Category : Endemic plants
Languages : en
Pages : 147
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Native prairies of the Willamette Valley are considered among the rarest of Oregon's ecosystems (Clark and Wilson, 2001). As a result of agriculture conversion, urban development and cessation of native burning, Willamette Valley prairies have become highly fragmented and invaded by non-native species, leaving little room for native plant diversity. Even though wetland prairie conservation and restoration has been a priority for many government agencies there is a need for research on what restoration techniques and management are necessary for increasing native species richness and abundance in remnant and restored wet prairie sites. In this research project, two studies were conducted. In the first study, data were collected on species presence and abundance from three 100m2 randomized plots within three remnant wet prairies (Green Mountain, Gotter Prairie South, Knez) and three restored wet prairies (Hutchinson, Gotter Prairie North, Lovejoy) to answer the following research question, 'Are there differences between remnant and restored prairie plant communities with respect to the diversity and abundance of native species?' Analysis of variance and multivariate ordination techniques were used to assess the ecological differences between uncultivated, minimally-managed remnant wet prairies and newly-restored, highly managed wet prairies. Data on soils collected from agricultural sites (Westbrook, Zurcher, Gotter Prairie Ag), as well as the remnant and restored wet prairies mentioned above, were also used to compare soil quality and processes with the remnant and restored wetlands. Restored wet prairie had 23% higher native species cover than remnant prairie (p-value=0.089, N=6). Remnant and restored sites did not differ in native species richness (p-value=0.949, N=6). The relatively high per cent cover of native species at restored sites, (significant at the 10% level), suggests that land managers have successfully restored agricultural properties with an abundance of native species. The lack of significant difference in native species richness between remnant and restored sites also suggests that land managers have also been able to restore native plant diversity into former agricultural properties equivalent to some of the best intact remnant prairies within the Northern Willamette Valley in a short period of time (8 years or less). However, a non-metric scaling (NMS) ordination of the species matrix separated the remnant sites from the restored sites, suggesting that community composition distinguishes restored sites from remnants. The NMS results, which include environmental data in the analysis, also suggest that there is a positive correlation of percent soil moisture and percent soil organic matter associated with the remnant prairies and a positive correlation of management practices such as yearly chemical use, mowing, and clean crops, associated with the restored prairies. The location of Gotter Prairie North restoration within the ordination, between the remnant and restored sites, suggests an intermediate plant composition and soil quality. This could be attributed to intensive weed suppression and soil organic matter build up over time (8 years) in comparison to younger restored sites (3 and 4 years). Indicator species analysis identified many species with high indicator values (IVs) in the remnant prairies; Holcus lanatus, Deschampsia cespitosa, Carex densa and Phalaris arundinacea being the highest. The use of fire as a management tool produced only one species with a high IV (Camassia quamash). In the second study, three seeding treatments (Grass first, Grass and Forb together, Forb first) were compared within a 4 hectare experimental wet prairie unit to answer the research question 'Which of the three seeding treatments used leads to the highest native species abundance and species richness?' Results from an analysis of variance indicated significant differences between treatments in native species richness for 2009 and 2010 (p-values=0.002 & 0.004 respectively) at the 5% level and native species abundance in 2010 only (p-value=0.099) at the 10% level. The Grass and Forb and Forb first treatments were highest in native species richness for 2009 and 2010, whereas the Grass and Forb and Grass first treatments were highest in native species abundance in 2010. A NMS ordination suggests that Juncus tenuis is one of the dominant species, in all seeding treatments, after one year of growth.
Author: Jon A. Kusler
Publisher:
ISBN:
Category : Restoration ecology
Languages : en
Pages : 180
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Author: Jon A. Kusler
Publisher:
ISBN:
Category : Restoration ecology
Languages : en
Pages : 690
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Book Description
Author: James W. Good
Publisher: Oregon Sea Grant
ISBN:
Category : Business & Economics
Languages : en
Pages : 126
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Book Description
Author: Jennifer C. Rowe
Publisher:
ISBN:
Category : Bullfrog
Languages : en
Pages : 97
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Book Description
Wetland restoration success in attaining wildlife conservation goals can be confounded by the presence of multiple biological invaders. Wetland management activities typically target invasive plants, but bottom-up responses of higher trophic levels in novel communities are difficult to predict. We surveyed plant and amphibian assemblages at 26 sites enrolled in the Wetlands Reserve Program (WRP) in the Willamette Valley, Oregon to determine the relative importance of plant management, non-native species presence, and surrounding landscape for amphibians across multiple life history stages. Explanatory variables negatively associated with native anuran counts included percent invasive plant cover, invasive bullfrog counts, non-native fish presence, and area of urban land cover. In addition, native anurans were positively associated with WRP site age, suggesting that the benefits of restored wetlands may increase over time. Although invasive plant management provided indirect benefits to native amphibians, the most effective way to enhance native amphibian populations may be through eliminating the strong top-down forces exerted by non-native vertebrates. We also explored the impact of restoration activities on predator/prey dynamics by analyzing bullfrog diet contents. We sampled vegetation and analyzed bullfrog diet contents from 10 WRP wetlands categorized by management intensity and hydrology to determine whether prey consumption patterns (abundance, richness, and % large prey), diet breadth, and dietary community (based on taxonomic and prey size composition) differed among wetlands categorized by management regime and hydroperiod. We found disparities in the diet breadth with respect to wetland categories, with bullfrogs consuming a disproportionate abundance of few prey orders at actively managed sites. Diet breadth could have been influenced by frequent applications of restoration treatments, as invertebrate species richness and abundance is often negatively linked to habitat disturbance. Dietary taxonomic composition also differed between wetland groups, but prey size composition did not. Instead, prey size was strongly influenced by site-level vegetation covariates; large-bodied prey consumption was positively associated with plant species richness. However, diet dry mass was highest in wetlands with high invasive plant cover, suggesting that other factors, such as foraging activity rates, should be considered to fully understand how bullfrogs meet energy demands in managed wetlands. Variation in native and invasive amphibian responses to wetland restoration efforts may provide important information on how habitat structure and composition influence trophic dynamics. Given that the outcomes of plant control on wildlife may not follow planned trajectories in invasive-dominated systems, this research addresses the need for a community approach to assessments of restoration success.
Author:
Publisher:
ISBN:
Category : Biotic communities
Languages : en
Pages : 58
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As part of the Willamette Basin Geographic Initiative Program, the Environmental Protection Agency (EPA) funded The Nature Conservancy of Oregon to inventory, classify, and map native wetland and riparian plant communities and their threatened biota in the Willamette Valley. Between October 1994 and September 1996, we evaluated 172 wetland and riparian sites throughout the Willamette Valley. A site is a stream or river reach or wetland area that was inventoried at one to many locations. Of these sites, 21 are high-quality remnants important for future protection and restoration efforts. We identified 153 natural communities as occurring in native wetland and riparian habitats, of which 101 are new to the plant community classification of the Oregon Natural Heritage Program. Twenty-six species of rare animals and 23 species of rare plants occur in the Willamette Valley. Thirty-two species of rare plants and animals appear to be directly dependent on wetland and riparian communities in the Willamette Valley, and twenty-two species are dependent on upland upland communities in the Willamette Valley. Mapping of presettlement vegetation in the Willamette Valley indicates that 456,119 hectares (1,127,071 ac) of wetland and riparian habitat have been lost overall, with 12 communities impacted in particular. As for uplands, 732,432 hectares (1,809,841 ac) of habitat have been lost overall, with 7 natural communities impacted in particular. We recommend local citizen involvement, land purchases and restoration as means of protecting and restoring remnant ecosystems and their biota in the Willamette Valley.
Author: Elizabeth Orr
Publisher: Arcadia Publishing
ISBN: 1439666474
Category : History
Languages : en
Pages : 272
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Book Description
Western Oregon's Willamette Basin, once a vast wilderness, became a thriving community almost overnight. When Oregon territory was opened for homesteading in the early 1800s, most of the intrepid pioneers settled in the valley, spurring rapid changes in the landscape. Heralded as fertile with a mild climate and an abundance of natural resources, the valley enticed farmers, miners and loggers, who were quickly followed by the construction of rail lines and roads. Dams were built to harness the once free-flowing Willamette River and provide power to the growing population. As cities rose, people like Portland architect Edward Bennett and conservationist governor Tom McCall worked to contain urban sprawl. Authors Elizabeth and William Orr bring to life the changes that sculpted Oregon's beloved Willamette Valley.
