Vegetation ecology of eight Oregon freshwater wetlands was
described and net aerial primary productivity estimated in four
wetlands. Plant cover samples were used to classify 37 wetland and
11 terrestrial communities by agglomerative hierarchical clustering.
Samples and species were ordinated. Direct measurements were made
of sample relative elevation, inundation duration,...
The wetlands are distinguished from other lands of the Mid-Willamette Valley by excessive soil moisture. The wetlands, as defined for this study, consist of 20 soil series (in 22 soil mapping units) which are classified by the Soil Conservation Service as having excessive wetness as the major factor limiting their...
Wetland soils with complex stratigraphy and redoximorphic features occur on the
margin of the Willamette Valley, Oregon. In the Jackson-Frazier wetland, vertisols
show three distinct stratigraphic units that rest uncomformably upon each other and
correspond to the Bashaw series Bss, 2Bt and 3BC horizons. Holocene alluvium
deposited as distal alluvial...
The lower Columbia River (LCR) riparian zone is rich in habitat diversity. However, the natural beauty and species diversity along the river have increasingly become affected by human activity. This study quantifies the areal extent and degree of wetlands change and associated causes along the LCR over the past 44...
Relatively little is known about wintering bird communities in lowlands of the Pacific Northwest, yet, the condition of winter habitats potentially can pose a major constraint on bird populations. I initiated a study to determine: (1) Which avian species use lowland riparian and wetland habitats in the Willamette Valley during...
To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages in fifteen seasonal floodplain wetlands within four geographic regions (coastal, upper Columbia River estuary, Puget Sound and eastern Oregon/Washington) in the...
Hydrologic processes within mineral flat wetlands, along with their
connections to groundwater and downstream surface water in lowland agricultural
catchments are poorly understood, particularly under different land uses. In the three
field studies included in this thesis, we examined infiltration, wetland hydroperiod,
groundwater recharge dynamics, surface runoff generation, and water...
Understanding how wetland birds use habitat is pivotal to developing successful and
beneficial conservation strategies. Although it has been an ardent topic in forest
research for some time, how species interact with the spatial patterning of habitat
across a landscape (i.e., landscape structure) has been more or less neglected in...
Conventional natural resource management has struggled with effectively addressing dynamically complex natural resource issues. Many organizations structured in the rational-analytical paradigm of resource management are becoming increasingly aware that new management approaches are needed. Particularly in a rapidly changing environment, organizational learning is important for promoting an organization's ability to...
Coastal marsh vegetation is an important component in maintaining marsh stability that is threatened by changes in sedimentation, sea level rise, natural and anthropogenic disturbances, and competition from invasive species. Vegetation has been demonstrated to reduce wave energy, increase sedimentation, and decrease erosion in tidal environments under a range of...
