5/21/2015  |   10:30 - 10:45   |  102C

EFFECTS OF SHORT-ROTATION PINE MANAGEMENT FOR BIOENERGY ON WATER QUALITY IN THE SOUTHEASTERN UNITED STATES We are examining the effects of growing loblolly pine for bioenergy on water quality using a watershed-scale experiment. We measured nitrate, ammonium, and soluble reactive phosphorus (SRP) in stream water, groundwater, shallow subsurface flow, and throughfall in 3 adjacent, forested watersheds at the Savannah River Site (near Aiken, South Carolina). Baseline conditions were measured for 2 years (2010-2012), and in 2012, the treatments were imposed in 2 of the watersheds, with the third watershed serving as an unmanipulated control. Forty percent of the treatment watersheds were harvested in 2012, pine seedlings were planted in 2013, and herbicides and fertilizers were applied annually. Groundwater is the predominant flowpath in these low-relief watersheds, and nitrate concentrations increased in groundwater (up to 2 mg N/L) post-treatment. Nitrate concentrations have not increased in riparian zone groundwater or stream water, suggesting that elevated nitrate has not reached the streams, or has been taken up or denitrified along the flowpath. Ammonium and SRP concentrations have not increased in groundwater or stream water. Future work will estimate groundwater transit times and measure denitrification in these watersheds.

Natalie Griffiths (Primary Presenter/Author), Oak Ridge National Laboratory, griffithsna@ornl.gov;


C. Rhett Jackson (Co-Presenter/Co-Author), Warnell School of Forestry and Natural Resources, University of Georgia, RJACKSON@warnell.uga.edu;


Jeffrey J. McDonnell (Co-Presenter/Co-Author), University of Saskatchewan, jeffrey.mcdonnell@usask.ca;


Menberu Bitew (Co-Presenter/Co-Author), University of Georgia, menberu@uga.edu;


Enhao Du (Co-Presenter/Co-Author), Lawrence Berkeley National Laboratory, edu@lbl.gov;


Julian Klaus (Co-Presenter/Co-Author), Public Research Center-Gabriel Lippmann, klaus@lippmann.lu;

5/21/2015  |   10:45 - 11:00   |  102C

AN EXPLORATION OF CONVERGENT EVOLUTION IN ACADEMIA: WHY ECOSYSTEM ECOLOGISTS AND BIOGEOCHEMISTS SHOULD THINK ABOUT THE TOOLS OF SOFTWARE ENGINEERING The fundamental abstractions of computer science and ecosystem ecology have evolved to be remarkably similar, despite differences in semantics. Ecosystem ecologists study the interactions of “structure” and “function” within ecosystems, while software engineers design “attributes” and “methods” when coupling classes in object-oriented software. Engineers have established a rigorous toolkit (Unified Modeling Language, UML) for organizing hierarchical ontologies of structure and function. We suggest these tools can be effectively applied to the organization of ecological concepts, which ultimately leads to more intuitive implementations of ecological models. In this presentation, we reconcile interdisciplinary semantics and present examples of ontological descriptions of ecosystems in UML, in order to demonstrate the potential value of software engineering tools to the organization of ecologic understanding. Furthermore, we present a working prototype of a hierarchical shared-state-space software abstraction that will facilitate linking qualitative models to quantitative predictions in a hypothesis testing environment. Sharing of state space is critical to the simultaneous application of multiple interdisciplinary hypotheses in the attempt to understand the social and ecological consequences of a changing environment.

Robert Payn (Primary Presenter/Author), Montana State University, Montana Institute on Ecosystems, rpayn@montana.edu;


Clemente Izurieta (Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, clemente.izurieta@cs.montana.edu;


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

5/21/2015  |   11:00 - 11:15   |  102C

USING STRUCTURAL EQUATION MODELING TO DETERMINE EFFECTS OF FISH PRESENCE AND ENVIRONMENTAL FACTORS ON STREAM BENTHIC BIOGEOCHEMICAL RATES Biogeochemical fluxes within streams can vary with local environmental conditions as well as variations in the distribution of fishes. We used structural equation modeling to elucidate direct and indirect effects of fish and other environmental factors (e.g. canopy cover, substrate size) on fine scale (300 cm2) benthic rates of ecosystem respiration (ER), gross primary production (GPP), and ammonium uptake in a prairie stream. We manipulated fish presence over some substrata with mesh exclosures prior to incubation. We measured biogeochemical rates of stream-equilibrated substrata (n=49) by monitoring fluxes of dissolved O2 (in light and dark) and ammonium inside sealed acrylic chambers with internal circulation systems. Total model-explained variance was highest for ER and lowest for GPP. Fish presence directly increased ammonium uptake and GPP, while all rates were indirectly affected through changes in either FBOM or chlorophyll a standing stocks. Significant paths of environmental factors varied with each model; however, wetted width was important for all rates. Separate analyses of fish exclusions and SEM models both agree that fish presence likely affects ammonium uptake, with less evidence for GPP.

Matt Trentman (Primary Presenter/Author), Flathead Lake Biological Station, University of Montana, matt.trentman@flbs.umt.edu;


Walter Dodds (Co-Presenter/Co-Author), Kansas State University, wkdodds@ksu.edu;


Keith Gido (Co-Presenter/Co-Author), Kansas State University, kgido@ksu.edu;


Janine Rüegg (Co-Presenter/Co-Author), University of Lausanne, janine.ruegg@unil.ch;


Claire Ruffing (Co-Presenter/Co-Author), University of British Columbia, ruffing.cathcart@ubc.ca;

5/21/2015  |   11:15 - 11:30   |  102C

VARIATION IN DISSOLVED NUTRIENTS AND GREENHOUSE GASES ALONG STREAM NETWORKS IN TWO WATERSHEDS OF CONTRASTING LAND USE Human activity has increased atmospheric greenhouse gasses, and streams may be important sources of carbon dioxide (CO2), methane (CH4), and nitrous oxide, which are responsible for the majority of heat trapping capacity in the modern atmosphere. Using 24hr synoptic sampling, we measured dissolved nutrients and gasses at 80 stream/river sites within two watersheds: the Manistee (MI) and the Tippecanoe Rivers (IN), which have contrasting agricultural land use (~17% vs 82% of area, respectively). During summer, dissolved nutrients varied spatially both within and among watersheds, ranging from 5-2490 µgNO3-N/L, 6-73 µgNH4-N/L and 4-41 µgSRP/L in the Manistee, and from 10-4321 µgNO3-N/L, 2-590 µgNH4-N/L and 1-607 µgSRP/L in the Tippecanoe. Additionally, dissolved CO2 and CH4 in the Tippecanoe were generally supersaturated, but the degree of saturation was significantly higher and more variable in tributaries (n=54) compared to the river mainstem (n=26). Based on preliminary data, we suggest that rivers may integrate spatial variation in nutrients and gasses from watershed tributaries. These data will be used to parameterize a watershed model linking dissolved nutrients to gas emissions as a function of land use.

Martha M. Dee (Primary Presenter/Author), University of Notre Dame, mdee@nd.edu;


Jennifer L. Tank (Co-Presenter/Co-Author), University of Notre Dame, tank.1@nd.edu;


Jake J. Beaulieu (Co-Presenter/Co-Author), United States Environmental Protection Agency, beaulieu.jake@epa.gov;


Alessandra Marzadri (Co-Presenter/Co-Author), Center for Ecohydraulics Research, University of Idaho , marzadri@ing.unitn.it;


Daniele Tonina (Co-Presenter/Co-Author), Center for Ecohydraulics Research, University of Idaho, dtonina@uidaho.edu ;


Alberto Bellin (Co-Presenter/Co-Author), University of Trento, Trento, Italy, Alberto.Bellin@unitn.it ;

5/21/2015  |   11:30 - 11:45   |  102C

A NEW METHANE DATABASE AND A REVISED GLOBAL ESTIMATE OF METHANE EFFLUX FROM FLUVIAL ECOSYSTEMS Historical wisdom has been that CH4 should be scarce in streams and rivers, yet it is often present at supersaturated concentrations. To better understand CH4 dynamics and generate a global estimate of fluvial efflux, we assembled a database of 398 concentration and 222 diffusive flux measurements from >90 articles. Published values spanned >6 orders of magnitude (0-1260 uM and 10-383 mmol m-2 d-1). Nearly all concentrations were supersaturated and only 4 sites reported negative mean fluxes. Global CH4 emissions were estimated using (1) a simple bootstrapping approach and (2) molar ratios of CH4:CO2 diffusive efflux from papers that also reported CO2 flux. These conservative calculations resulted in estimates of 35.7 ± 81.9 and 49.8 ± 131 Tg CH4/yr- an order of magnitude greater than a prior estimate (1.5 Tg/yr). This indicates that fluvial CH4 efflux is larger than the most recent estimates for reservoirs and ca. 20-50% of that from wetlands and lakes and respectively. While uncertainty is substantial, this suggests that streams and rivers are globally significant CH4 sources and should no longer be excluded from global methane budgets.

Emily Stanley (Primary Presenter/Author), University of Wisconsin - Madison, ehstanley@wisc.edu;


Nora Casson (Co-Presenter/Co-Author), University of Winnipeg, n.casson@uwinnipeg.ca;


Samuel Christel (Co-Presenter/Co-Author), University of Wisconsin-Madison , schristel@wisc.edu;


John Crawford (Co-Presenter/Co-Author), U.S. Geological Survey, jtcrawford@usgs.gov;


Corinna Gries (Co-Presenter/Co-Author), University of Wisconsin, cgries@wisc.edu;


Luke Loken (Co-Presenter/Co-Author), University of Wisconsin-Madison, lloken@wisc.edu;


Samantha K Oliver (Co-Presenter/Co-Author), University of Wisconsin Madison, skoliver@wisc.edu;

5/21/2015  |   11:45 - 12:00   |  102C

HIGH AUTOCHTHONOUS SUPPORT OF AQUATIC INVERTEBRATES DESPITE EXTREMELY LOW RATES OF GROSS PRIMARY PRODUCTION IN BOREAL STREAMS Terrestrial support of aquatic food webs is pervasive, with terrestrial subsidies responsible for significant fractions of biomass production and widespread heterotrophy (ecosystem respiration > gross primary production; ER>GPP) in freshwater ecosystems. Despite this, aquatic GPP may disproportionately fuel consumer production and respiration relative to the quantity of terrestrial organic carbon (OC) potentially available for consumption. We used diet and consumer d²H to quantify the relative contributions of autochthonous (algal) and terrestrial OC to invertebrates from five boreal streams draining different catchment areas and compositions. We compared consumer autochthony with OC concentrations and fluxes, including stream metabolism (GPP, ER). Invertebrate autochthony ranged from 11-100% in a second-order stream despite low GPP (<0.5 gCm^-2d^-1), high dissolved OC (18-45 mg/L), and pronounced net heterotrophy (GPP:ER = 0.04). Using taxa-specific biomass and stable isotopes sampled from June-October, we will calculate site-specific relative autochthony for further comparison with in-stream OC sources and fluxes. Invertebrates appear to preferentially consume autochthonous OC in streams with low GPP and high terrestrial OC, suggesting a crucial, but often overlooked role for in-stream primary production in boreal stream food webs.

Erin R. Hotchkiss (Primary Presenter/Author), Virginia Tech, ehotchkiss@vt.edu;


Emelie Landström (Co-Presenter/Co-Author), Umeå University, emmelie.landstrom@gmail.com;


Ryan Sponseller (Co-Presenter/Co-Author), Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden, ryan.sponseller@umu.se;


Jan Karlsson (Co-Presenter/Co-Author), Umeå University, jan.p.karlsson@emg.umu.se;