A Multi-Scale Assessment of the Relationship Between the Riparian Landscape and the Health of Streams in Portland, Oregon PDF Download
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Author: Publisher: ISBN: Category : Riparian areas Languages : en Pages : 0
Book Description
The riparian areas adjacent to streams are sensitive and important environments that have a great deal of influence on the overall health of the streams they border. In cities, riparian areas are routinely impacted and degraded by property developments, urban infrastructure, and other alterations to the natural environment. In this study, I worked with the City of Portland to determine how a wide range of landscape features occurring in riparian areas affect the overall health of streams at multiple scales. Data were collected from buffer areas of widths ranging from 15 ft to 500 ft that were digitally generated around 1-km reaches upstream of 59 long term monitoring stations. In these buffer areas, I aggregated information on 20 variables relating to land use, impervious surfaces, transportation, vegetation, and hydrologic control structures. Using a random forest variable selection algorithm and regression analysis tools, I created models that described the health of the urban streams (represented by macroinvertebrate IBI) as a function of the urban landscape variables in the multiple riparian buffer areas surrounding the 59 study reaches. In the process of model refinement and analysis, I determined that the 50 ft and 500 ft buffer models were sufficient at describing the spatial variability in the datasets. I found that the length of piped stream in both of the buffer areas was negatively correlated with stream health but that it had an especially strong influence in the 50 ft buffer areas. In these same buffer areas, the mean canopy height was positively correlated with stream health, but its effect was much more pronounced in 50 ft buffer areas. Additionally, my analysis showed that impervious surfaces in riparian areas within 50 ft of streams had a strong, negative impact on the health of the 59 stream reaches studied. These findings suggest that health of streams in the study area could be improved by planting more trees in riparian zones, daylighting piped waterways, and by removing impervious surfaces from areas within 50 ft of streams.
Author: Publisher: ISBN: Category : Riparian areas Languages : en Pages : 0
Book Description
The riparian areas adjacent to streams are sensitive and important environments that have a great deal of influence on the overall health of the streams they border. In cities, riparian areas are routinely impacted and degraded by property developments, urban infrastructure, and other alterations to the natural environment. In this study, I worked with the City of Portland to determine how a wide range of landscape features occurring in riparian areas affect the overall health of streams at multiple scales. Data were collected from buffer areas of widths ranging from 15 ft to 500 ft that were digitally generated around 1-km reaches upstream of 59 long term monitoring stations. In these buffer areas, I aggregated information on 20 variables relating to land use, impervious surfaces, transportation, vegetation, and hydrologic control structures. Using a random forest variable selection algorithm and regression analysis tools, I created models that described the health of the urban streams (represented by macroinvertebrate IBI) as a function of the urban landscape variables in the multiple riparian buffer areas surrounding the 59 study reaches. In the process of model refinement and analysis, I determined that the 50 ft and 500 ft buffer models were sufficient at describing the spatial variability in the datasets. I found that the length of piped stream in both of the buffer areas was negatively correlated with stream health but that it had an especially strong influence in the 50 ft buffer areas. In these same buffer areas, the mean canopy height was positively correlated with stream health, but its effect was much more pronounced in 50 ft buffer areas. Additionally, my analysis showed that impervious surfaces in riparian areas within 50 ft of streams had a strong, negative impact on the health of the 59 stream reaches studied. These findings suggest that health of streams in the study area could be improved by planting more trees in riparian zones, daylighting piped waterways, and by removing impervious surfaces from areas within 50 ft of streams.
Author: Daniel Allen Sarr Publisher: ISBN: Category : Forest regeneration Languages : en Pages : 276
Book Description
I studied riparian forests of four western Oregon watersheds (dry south to wet north) to determine the multiscale controls on woody riparian vegetation. I conducted separate analyses of controls on plant distribution, diversity, and tree regeneration using vegetation and environmental data collected in two related field studies: (1) a multiscale riparian forest inventory; (2) a comparative study of natural forest gaps and interiors. Climatic moisture, indexed by vapor pressure deficit in summer, was the primary correlate of compositional change between riparian sites at all scales analyzed, demonstrating that the majority of riparian species responded directly or indirectly to the landscape scale climate gradient. Additional variation in composition was explained by measures of local topography and disturbance. Climate, as indexed by modeled gross primary productivity (GPP), explained the majority of the variation in multiple regression models of plant diversity that included local and landscape scale variables. As GPP increased from dry to wet climates, understory light and moisture heterogeneity decreased, coincident with declines in alpha, beta, and hectare scale diversity, suggesting that climate controls diversity indirectly through its effects on local conditions. Tree regeneration varied sharply across the climate gradient; seedling frequency and diversity declined and nurse log use increased from the driest to wettest climates. Life history attributes of riparian tree species provided important clues to their regeneration success in different environments. These relationships were explored in a model that linked species shade and drought tolerance with expected variation in the environment caused by climate and disturbance. The model accurately predicted regeneration patterns for four of five functional groups of tree species. The studies in this dissertation provided compelling evidence of regional variation in riparian vegetation composition, diversity, and dynamics, illustrating that these communities are strongly shaped by landscape scale as well as local scale factors. Moreover, climate-related differences among riparian sites were at least as important as the local variation within them in explaining spatial vegetation patterns. These findings argue for a multiscale perspective of riparian forest ecology that closely integrates larger scale controls, such as climate, with local hydrologic processes.
Author: National Research Council Publisher: National Academies Press ISBN: 0309082951 Category : Science Languages : en Pages : 449
Book Description
The Clean Water Act (CWA) requires that wetlands be protected from degradation because of their important ecological functions including maintenance of high water quality and provision of fish and wildlife habitat. However, this protection generally does not encompass riparian areasâ€"the lands bordering rivers and lakesâ€"even though they often provide the same functions as wetlands. Growing recognition of the similarities in wetland and riparian area functioning and the differences in their legal protection led the NRC in 1999 to undertake a study of riparian areas, which has culminated in Riparian Areas: Functioning and Strategies for Management. The report is intended to heighten awareness of riparian areas commensurate with their ecological and societal values. The primary conclusion is that, because riparian areas perform a disproportionate number of biological and physical functions on a unit area basis, restoration of riparian functions along America's waterbodies should be a national goal.
Author: Marcus W. Griswold Publisher: ISBN: Category : Languages : en Pages :
Book Description
This reflected the higher biomass of chlorophyll a in macrophytes and bacteria in leaf packs. This was supported during a behavioral study utilizing a habitat specialist and generalist where the availability of both macrophytes and leaf packs was preferred by both groups and decreased emigration rates from landscapes. Increased diversity of habitats created by harvest potentially balanced the effects of habitat fragmentation and isolation. Evidence from this study indicates that properly managed riparian zones effectively maintain water quality in small coastal plain streams. However, managers should consider the consequences of reducing habitat specialists and its potential effects on food-web structure.
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Author: Tamara Heartsill Scalley
Author: United States. Environmental Protection Agency
Author: Daniel Allen Sarr
Author: American Water Resources Association. Summer Specialty Conference
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Author: National Research Council
Author: Marcus W. Griswold
Author: Michele Eloise Bakacs
Author: