The Blurred Line Between Form and Process: A Comparison of Stream Channel Classification Frameworks

Stream classification provides a means to understand the diversity and distribution of channels and floodplains that occur across a landscape while identifying links between geomorphic form and process. Accordingly, stream classification is frequently employed as a watershed planning, management, and restoration tool. At the same time, there has been intense debate and criticism of particular frameworks, on the grounds that these frameworks classify stream reaches based largely on their physical form, rather than direct measurements of their component hydrogeomorphic processes. Despite this debate surrounding stream classifications, and their ongoing use in watershed management, direct comparisons of channel classification frameworks are rare. Here we implement four stream classification frameworks and explore the degree to which each make inferences about hydrogeomorphic process from channel form within the Middle Fork John Day Basin, a watershed of high conservation interest within the Columbia River Basin, U.S.A. We compare the results of the River Styles Framework, Natural Channel Classification, Rosgen Classification System, and a channel form-based statistical classification at 33 field-monitored sites. We found that the four frameworks consistently classified reach types into similar groups based on each reach or segment’s dominant hydrogeomorphic elements. Where classified channel types diverged, differences could be attributed to the (a) spatial scale of input data used, (b) the requisite metrics and their order in completing a framework’s decision tree and/or, (c) whether the framework attempts to classify current or historic channel form. Divergence in framework agreement was also observed at reaches where channel planform was decoupled from valley setting. Overall, the relative agreement between frameworks indicates that criticism of individual classifications for their use of form in grouping stream channels may be overstated. These form-based criticisms may also ignore the geomorphic tenet that channel form reflects formative hydrogeomorphic processes across a given landscape

Effects of large-scale and local anthropogenic habitat modifications on aquatic bird communities in an urban estuary

The abundance of several marine bird and waterfowl species in Puget Sound and adjacent waters has declined markedly in recent decades. The causes of these declines are not well understood, but they likely include a variety of local and large-scale influences. While individual species and species groups are monitored throughout the greater Puget Sound, few analyses of local natural and anthropogenic influences on taxonomic composition have been done. We combined data from annual winter aerial bird surveys and GIS layers of physical shoreline structure and land cover to explore changes in marine bird and waterfowl assemblage composition across years, oceanographic sub-basins, and simple urbanization metrics in Puget Sound. Twenty-one years of annual winter surveys (1994-2014) were combined with data layers of land use/land cover adjacent to the shoreline. The best models using large-scale factors (year, oceanographic sub-basin), and local factors (% armoring or % urbanization) were generated through multiple model comparisons. Declines over time in some key groups (diving invertivores, diving piscivores, opportunistic omnivores) had added effects of sub-basin and local urbanization. These results document declining diversity in marine bird and waterfowl assemblages across greater Puget Sound and demonstrate that local anthropogenic factors can also influence bird density, presumably by affecting availability of food, foraging areas, or nesting sites. Examining these relationships will not only improve our understanding of local bird populations, but will also improve our understanding of the greater Puget Sound ecosystem and assist in the development of improved monitoring and assessment tools

Science for integrative management of a diadromous fish stock: interdependencies of fisheries, flow, and habitat restoration

Fish face many anthropogenic stressors. Authorities in marine, estuarine, and freshwater realms often share interdependent fisheries management goals, but address singular stressors independently. Here, we present a case study suggesting that coordinating stressor relief across management realms may synergize conservation efforts, especially to actualize restoration benefits. Major efforts are underway to restore juvenile salmon habitat across California’s Central Valley landscape, but it is unclear how fisheries and flow management will influence juvenile salmon occupancy of restored sites. Leveraging monitoring data, we find that for juvenile salmon (<55 mm) to actualize benefits of restored habitats will likely require maintaining spawner abundances and flows at or above intermediate values, especially in less-connected portions of the landscape. Furthermore, restoration efforts may prioritize more connected regions to promote use of restored areas, considering that less connected areas are often uninhabited when water and spawners are scarcer. This ecosystem-based framework that evaluates interdependencies of management decisions may be applied to realize natural productivity and enhance conservation in many systems.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Insights into estuary habitat loss in the western United States using a new method for mapping maximum extent of tidal wetlands.

Effective conservation and restoration of estuarine wetlands require accurate maps of their historical and current extent, as well as estimated losses of these valued habitats. Existing coast-wide tidal wetland mapping does not explicitly map historical tidal wetlands that are now disconnected from the tides, which represent restoration opportunities; nor does it use water level models or high-resolution elevation data (e.g. lidar) to accurately identify current tidal wetlands. To better inform estuarine conservation and restoration, we generated new maps of current and historical tidal wetlands for the entire contiguous U.S. West Coast (Washington, Oregon, and California). The new maps are based on an Elevation-Based Estuary Extent Model (EBEEM) that combines lidar digital elevation models (DEMs) and water level models to establish the maximum historical extent of tidal wetlands, representing a major step forward in mapping accuracy for restoration planning and analysis of wetland loss. Building from this new base, we also developed an indirect method for mapping tidal wetland losses, and created maps of these losses for 55 estuaries on the West Coast (representing about 97% of historical West Coast vegetated tidal wetland area). Based on these new maps, we estimated that total historical estuary area for the West Coast is approximately 735,000 hectares (including vegetated and nonvegetated areas), and that about 85% of vegetated tidal wetlands have been lost from West Coast estuaries. Losses were highest for major river deltas. The new maps will help interested groups improve action plans for estuarine wetland habitat restoration and conservation, and will also provide a better baseline for understanding and predicting future changes with projected sea level rise