6/05/2017  |   11:00 - 11:15   |  302B

SHORT- AND LONG-TERM STREAMFLOW VARIABILITY OF RIVERS IN THE GREAT BASIN, USA Rivers of the Great Basin, USA, are a heterogeneous group of rivers subject to a multitude of flow alteration. In this study, short- and long-term streamflow variabilities of three major rivers in the Great Basin were described. Fourteen years (2002-2016) of continuous daily streamflow data were analyzed for the Carson, Humboldt and Bear River drainages. Hydrological indicators were generated using daily stream-flow records. Subsequently, Principal Component Analyze and hierarchical clustering analysis were used to identify which indicators explain best the variance. Of these, 36 hydrological indicators were selected to describe two scales of streamflow variabilities. As a result, 14 indices for short- and long-term scales were determined. Lowland stream sites of the Carson River were positively correlated to minimum, maximum and variation of mean monthly flows on the long-term scale, and mean and median of daily mean flow on the short-term scale. In contrast, upland sites of three rivers were negatively correlated to these same indicators. The scale of study significantly affects the observation of hydrological similarities among rivers of the Great Basin. Therefore, significant differences in scale-dependent responses of biological communities are expected across the studied drainages.

Bolortsetseg Erdenee (Primary Presenter/Author), Department of Biodiversity, Earth and Environmental Science, Drexel University, be83@drexel.edu;


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6/05/2017  |   11:15 - 11:30   |  302B

TAILS FROM THE HYPORHEIC ZONE: DESCRIBING SOLUTE TURNOVER WITH 3D GEOPHYSICAL IMAGING The hyporheic zone (HZ) plays a large role in nutrient transformation, but it has proven difficult to fully describe both its temporal dynamics and hydrologic extent. Historically, field experiments have relied on a combination of well sampling and breakthrough curve analysis to describe the HZ. The incorporation of geophysical imaging, like electrical resistivity tomography (ERT), with tracer additions has allowed researchers to directly view the HZ in 2D. We conducted a series of constant-rate tracer additions in a small headwater mountain stream while collecting ERT images downstream yielding a 3D model of the HZ. We were able to measure the tracer downwelling deep into the subsurface and monitor how it flushed out over the course of several days following the addition. We calculated the volume of the HZ at each time step (about 2 hour intervals) and applied decay models describing solute turnover time similar to those used to describe breakthrough curve tails in the main channel. Moreover, we found the flushing behavior to be consistent with mobile and less-mobile zones where solutes exit the HZ at two distinct rates.

Brady Kohler (Primary Presenter/Author), University of Wyoming, kohlerbrady@gmail.com;


Robert O. Hall ( Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana, bob.hall@flbs.umt.edu;


Brad Carr ( Co-Presenter/Co-Author), University of Wyoming, bcarr1@uwyo.edu;


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6/05/2017  |   11:30 - 11:45   |  302B

THE FORCE OF FLOW: HYDROLOGY CONTRIBUTES TO THE INTER-ANNUAL VARIABILITY OF LITTER DECOMPOSITION IN TEMPERATE FORESTED STREAMS Hydrology influences litter decomposition in low-order streams through physical abrasion and by affecting detritivorous invertebrate abundance. The degree to which the hydrological regime – mediated by precipitation changes – may contribute to the temporal variability of litter decomposition is not well studied. We determined shredder- (10-mm mesh) and microbial-mediated (500 µm) litter decomposition, and litterbag-associated shredder abundance and fungal biomass, in forested streams during three consecutive and hydrologically different autumns in British Columbia and Ontario, Canada. Overall, the ratio of shredder- and microbial-mediated decomposition rate at any given year to the three-year mean ranged from 0.78-1.39 and 0.75-1.30, respectively. This variation of decomposition was explained by differences in hydrological regime. In the low-flow years, decomposition was similar to or faster than the higher-flow year, as under reduced flow, the increase in shredder abundance and hence decomposition likely approximated or surpassed the reduction in the physical fragmentation of litter. The ranges we found slightly exceeded the range of natural variability (0.75-1.33) in a recommended assessment framework for stream functional integrity, and could indicate ‘impaired’ ecosystem functioning. Therefore, the utility of litter decomposition assays in bioassessment should deserve caution when covering hydrologically distinct years.

Alex Yeung (Primary Presenter/Author), Department of Forest and Conservation Sciences, University of British Columbia, Canada, yeungcheeyu@gmail.com;


David Kreutzweiser ( Co-Presenter/Co-Author), Great Lakes Forestry Centre, Canadian Forest Service, dave.kreutzweiser@canada.ca;


John Richardson ( Co-Presenter/Co-Author), Department of Forest and Conservation Sciences, University of British Columbia, john.richardson@ubc.ca;


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6/05/2017  |   11:45 - 12:00   |  302B

SMALL FLOW OBSTRUCTIONS IMPLICATED IN ACCELERATING WHOLE-FLOODPLAIN SIDE-CHANNEL LOSS Side-channel extents influence the diversity and structure of riverine communities. Side channels are dynamic geomorphic features that persist in floodplain landscapes when gross rates of side-channel creation and loss are balanced. Although riprap and other linear structures are well-recognized impediments to side-channel creation, we hypothesized that other types of “anthropogenic plugs” (flow obstructions such as dikes or berms) built across side channels facilitate side-channel loss at a whole-river scale. We quantified longitudinal patterns of gross creation and loss of side-channel areas between the 1950s and 2001 using digitized aerial photographs along >500 km of the Yellowstone River. We then related these patterns to the longitudinal variation in the frequency of anthropogenic side-channel plugs. Consistent with our hypothesis, the frequency of anthropogenic plugs was positively correlated with gross side-channel loss, but not with gross side-channel creation. Because they are relatively inconspicuous, anthropogenic plugs may be a largely overlooked but important management concern for the evolution and maintenance of channel habitats.

Ann Marie Reinhold (Primary Presenter/Author), Montana State University, Montana Institute on Ecosystems, reinhold@montana.edu;


Geoffrey Poole ( Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, gpoole@montana.edu ;


Robert Bramblett ( Co-Presenter/Co-Author), Montana State University, bbram@montana.edu;


Alexander Zale ( Co-Presenter/Co-Author), U.S. Geological Survey, Montana Cooperative Fishery Research Unit, zale@montana.edu;


David Roberts ( Co-Presenter/Co-Author), Montana State University, droberts@montana.edu;


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6/05/2017  |   12:00 - 12:15   |  302B

REMOTE SENSING TO CHARACTERIZE STRUCTURE AND PROCESSES IN DYNAMIC GRAVEL-BED RIVERS Dynamic processes shape the riverine landscape resulting in a shifting mosaic of both aquatic and riparian/floodplain habitats. During the past two decades, the development of remote sensing tools has dramatically increased capacity to link ecological structure and processes across spatial and temporal scales from centimeters to kilometers and from minutes to decades. We present a summary of methodologies to quantitatively assess habitats that support aquatic and terrestrial biota and the processes of geomorphic work necessary to maintain the river and floodplain shifting habitat mosaic. Spatially explicit modeling of water depth, flow velocity, shear stress, and stream power derived from surface hydraulic measurements can be combined with airborne multispectral remote sensing for detailed modeling of channel, back water, and wetland habitats. LiDAR and multispectral imaging allow researchers to spatially evaluate floodplain vegetation complexity and patch quality and dynamics over tens of square kilometers. Model results of aquatic and terrestrial habitats, within a GIS framework, demonstrate the utility of remote sensing data coupled with ground-based measures to integrate a suite of tools and delineate critical elements from evaluation of habitat quantity and quality to river assessment or evaluation of restoration plans.

Richard Hauer (Primary Presenter/Author), University of Montana, ric.hauer@umontana.edu;


Mark Lorang ( Co-Presenter/Co-Author), Freshwatermap, mark@freshwatermap.com;


Diane Whited ( Co-Presenter/Co-Author), University of Montana, diane.whited@umontana.edu;


Phil Matson ( Co-Presenter/Co-Author), University of Montana, phil.matson@umontana.edu;


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6/05/2017  |   12:15 - 12:30   |  302B

COUPLING BIOPHYSICAL COMPLEXITY AND FOREST METABOLISM IN FLOODPLAIN LANDSCAPES Floodplains are biophysically complex systems that are considered among the most productive and biodiverse ecosystems on Earth. Until recently, quantitative assessment of these relationships have been constrained by technological limitation. To address how floodplain biophysical complexity and ecosystem function are related, we employed remote sensing, GIS, and spatial analyses to quantify and couple complexity and terrestrial production. The study site is a 7-km by 2-km portion of the Bitterroot River floodplain upon which 551 sample plots were delimited via segmentation classification. Biophysical complexity characterized by topographic heterogeneity and connectivity were represented in each plot by mean standard deviation ground height (0.13m - 0.92m), mean standard deviation canopy height (0.01m -2.96m) and percent inundation (0.0% -97.5%) metrics computed from Light Detection and Ranging (LiDAR) data and HEC-RAS inundation modeling. Potential primary production was addressed as Normalized Difference Vegetation Index (NDVI) values generated from aerial imagery. NDVI values ranged from -0.25 to 0.39, and were robustly related to the explanatory variables that together explained 59% of variation in NDVI, indicating that areas of the floodplain with greater biophysical complexity exhibited greater productivity.

Peter Davis (Primary Presenter/Author), University of Montana- Division of Biological Sciences, Systems Ecology Graduate Program, petedavis327@gmail.com;


Marc Peipoch ( Co-Presenter/Co-Author), Stroud Water Research Center, mpeipoch@stroudcenter.org;


H. Maurice Valett ( Co-Presenter/Co-Author), University of Montana, Division of Biological Sciences, maury.valett@umontana.edu;


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