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1.
Abstract: Surface water resources in urban areas serve multiple functions ranging from recreation to wildlife habitat. As a result, diverse values influence people’s views about resource protection, potentially leading to conflicting interests. In metropolitan Portland, Oregon, natural resource planning has recently focused on habitat restoration as well as stormwater and pollution mitigation, especially through the protection of riparian areas. Due to opposition over proposed regulations in the study region, this research examines public attitudes about an array of resource management efforts. The primary research question is: what is the extent of positive–negative attitudes about water resource protection, and what theoretical dimensions underlie diverse judgments? After empirical survey results are presented, I outline a conceptual approach for future assessments of environmental attitudes while highlighting important value‐based dimensions of judgments. Although flexible, the framework allows broad comparisons to advance knowledge about the social acceptability of varied water resource management approaches across diverse places and contexts.  相似文献   
2.
The hydrogeomorphic (HGM) approach to wetland classification and functional assessment is becoming more widespread in the United States but its use has been limited by the length of time needed to develop appropriate data sets and functional assessment models. One particularly difficult aspect is the transferability among geographic regions of specific models used to assess wetland function. Sharing of models could considerably shorten development and implementation of HGM throughout the United States and elsewhere. As hydrology is the driving force behind wetland functions, we assessed the comparability of hydrologic characteristics of three HGM subclasses (slope, headwater floodplain, mainstem floodplain) using comparable long-term hydrologic data sets from different regions of the United States (Ridge and Valley Province in Pennsylvania and the Willamette Valley in Oregon). If hydrology by HGM subclass were similar between different geographic regions, it might be possible to more readily transfer extant models between those regions. We found that slope wetlands (typically groundwater-driven) had similar hydrologic characteristics, even though absolute details (such as depth of water) differed. We did not find the floodplain subclasses to be comparable, likely due to effects of urbanization in Oregon, regional differences in soils and, perhaps, climate. Slight differences in hydrology can shift wetland functions from those mediated by aerobic processes to those dominated by anaerobic processes. Functions such as nutrient cycling can be noticeably altered as a result. Our data suggest considerable caution in the application of models outside of the region for which they were developed.  相似文献   
3.
ABSTRACT: Armored stream segments may affect the suspended sediment regime of small mountain streams in western Oregon by the release of fine sediments stored in the bed gravels. Sieve analysis of bed materials indicated that at least 30 percent of the suspended sediment yield for the 1975–76 winter had been stored in the streambed. Suspended sediment concentrations during storm-generated runoff were influenced by stream discharge and hydrograph characteristics. Sediment-discharge relations for individual storms were characterized by hysteresis loops. A seasonal flushing of fines was shown by a progressive decrease in the ratio of suspended sediment to stream discharge during the winter runoff period.  相似文献   
4.
Simple plankton models serve as useful platforms for testing our understanding of the mechanisms underlying ecosystem dynamics. A simple, one-dimensional plankton model was developed to describe the dynamics of nitrate, ammonium, two phytoplankton size-classes, meso-zooplankton, and detritus in the Oregon upwelling ecosystem. Computational simplicity was maintained by linking the biological model to a one-dimensional, cross-shelf physical model driven by the daily coastal upwelling index. The model sacrificed resolution of regional-scale and along-shore (north to south) processes and assumed that seasonal productivity is primarily driven by local cross-shelf Ekman transport of surface waters and upwelling of nutrient-rich water from depth.Our goals were to see how well a simple plankton model could capture the general temporal and spatial dynamics of the system, test system sensitivity to alternate parameter set values, and observe system response to the effective scale of potential retention mechanisms. Model performance across the central Oregon shelf was evaluated against two years (2000-2001) of chlorophyll and copepod time-series observations. While the modeled meso-zooplankton biomass was close in scale to the observed copepod biomass, phytoplankton was overestimated relative to that inferred from the observed surface chlorophyll concentration. Inshore, the system was most sensitive to the nutrient uptake kinetics of diatom-size phytoplankton and to the functional grazing response of meso-zooplankton. Meso-zooplankton was more sensitive to alternate parameter values than was phytoplankton. Reduction of meso-zooplankton cross-shelf advection rates (crudely representing behavioral retention mechanisms) reduced the scale of model error relative to the observed seasonal mean inshore copepod biomass but had little effect of the modeled meso-zooplankton biomass offshore nor upon phytoplankton biomass across the entire shelf.  相似文献   
5.
It is generally accepted that recreation use in natural environments results in some degree of negative social and environmental impact. Environmental managers are tasked with mitigating the impact while providing beneficial recreation opportunities. Research on the factors that influence visitors' perceptions of environmental and social conditions is necessary to inform sound environmental management of protected natural areas. This study examines the effect of prior experience with the setting and two dimensions of place attachment (i.e., place identity and place dependence) on visitors' perceptions of three types of recreation impacts (i.e., depreciative behavior, environmental impacts, and recreation conflict). Principal components analysis, confirmatory factor analysis, and structural equation modeling were used to test the study hypotheses using data collected from 351 visitors through on-site questionnaires (response rate of 93 percent). The results show that prior experience exhibited a moderate and significant direct positive effect on place identity, place dependence, and visitors' perceptions of recreation impacts. Contrary to study hypotheses and prior research, neither place dependence nor place identity exhibited a significant effect on the dependent variables. The results show that prior experience causes visitors to be more sensitive to depreciative behaviors, environmental impacts, and recreation conflict. These findings raise concerns over potential visitor displacement and deterioration of site conditions. Implications for resource managers are discussed, which include education, modifying visitor use patterns, and site design strategies.  相似文献   
6.
Rangeland Fire Protection Associations (RFPAs) are volunteer-based groups of trained private landowners who are authorised to respond to events in partnership with governmental agencies. This study analysed the functioning and structure of RFPAs in Idaho and Oregon in the western United States to characterise this under-researched model of disaster response. RFPAs represent an expanding type of disaster response organisation that interfaces with established fire suppression entities, yet ‘emergent behaviour’ manifested in some RFPA response actions. This appeared to lessen and mediate with time, as well as due to recognition of the issues, increased experience of fires, and training that fostered new mutual understandings. There is a need for continued examination of the effect of repeat experience in developing the characteristics of disaster response organisations. In addition, it is crucial to know how the interface between established and other types of organisations may be enhanced to make cooperative disaster response more effective.  相似文献   
7.
ABSTRACT: Collaborative watershed groups have formed at a significant rate throughout the United States in the last decade. Data on these groups, however, has been largely anecdotal and lacking in rigorous examination of the relationship between group formation, membership, process, and group effectiveness. Using a mail survey, Oregon watershed group participants were asked to identify who initiated the formation of the group, how efficiently the group formed, how the group determines membership, what decision making method the group uses, and how members perceive the group's effectiveness. Findings indicated that a majority believe that, because of their participation in a watershed group, they better understand issues in the watershed and the perspectives of others, but less than half believe that relationships with government decision makers or physical conditions in the watershed have improved. Members of citizen initiated groups rated their groups higher than government initiated groups on addressing difficult or controversial issues. Members of groups that use consensus responded most positively on whether the group gives fair consideration to dissenting opinions. Overall, groups with restricted membership systems rated themselves lowest on involving key decision making groups, timeliness in addressing issues, and overall effectiveness. These results raise concerns about this type of group membership system.  相似文献   
8.
ABSTRACT: Two modifications to automated pumping samplers improve discrete sampling during high flow events in small mountain streams. One modification entails mounting the intake nozzle on a bent, free-swinging metal rod supported in midstream. This allows sampling in midstream yet prevents the buildup of floatable organic debris that otherwise would cause the intake to fail. On the lower end of the rod, dynamic forces exerted by the stream keep the intake submerged over diverse flow conditions. The second modification consists of a magnetic switching device that automatically activates the pumping sampler at any preset stage on the rising limb of a storm hydrograph. The pumping sampler then remains on to collect one sample per hour which allows field crews sufficient time to change bottles before the sampler fills its 28-bottle capacity. This device improves the capability to sample frequently at fixed intervals, yet with minimal maintenance between runoff events. It also ensures sample collection during the rising limb of the hydrograph when flow and sediment concentrations are rapidly changing. Both modifications have improved data collection during periods of storm runoff.  相似文献   
9.
ABSTRACT: The Salmon Creek Watershed drains 325 km2 of forested terrain in the Cascade Mountains of western Oregon. Over a 30–year period (from 1955 to 1984) average daily maximum and minimum stream temperatures, calculated from the 10 warmest days of each year, have risen 6°C and 2°C, respectively. In contrast, a small decrease in maximum air temperatures was found over the same period. Regression analysis indicated a highly significant (p < 0.01) relationship between a cumulative index of forest harvesting and maximum stream temperatures. Maximum temperatures also tended to increase for several years following major peak flow events. The interaction between harvest activity (logging and road construction), changing forest and riparian management practices and the occurrence of natural hydrologic events (peak flows and associated mass soil movements) tend to obscure specific cause-and-effect relationships regarding long-term changes in maximum stream temperature.  相似文献   
10.
ABSTRACT: One-hundred-and-sixty step pools were examined that have developed in andesitic, basaltic, or dacitic lavas or in glaciofluvial sediments along several reaches of Soda Creek in the Three Sisters Wilderness of the Oregon High Cascades to determine whether such systems exhibit similar morphology. Pool shapes, sizes, and spacing were measured, and the hydraulic head loss calculated for each pool surface. Lithologic variations among 15 shape categories were not significant, but size attributes - length, depth, and area - of pools were systematically different by rock type. The energy lost at hydraulic jumps did not differ significantly among the four lithologies, suggesting that perhaps step pools represent similar stream channel adjustments in steep terrain.  相似文献   
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