Biome Context and Lotic Ecosystem Rates

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Walter K Dodds1, Janine Rüegg1, Ken Sheehan2, Chao Song3, Ford Ballantyne3, Christina Baker4, William B Bowden5, Kaitlin Farrell3, Michael B Flinn6, Erica Garcia7, Tamara Harms8, Jeremy Jones8, Lauren Koenig9, John Stephen Kominoski10, William H McDowell9, Damien McMaster7, Samuel Parker5, Matt T Trentman1, Matt Whiles11, Wilfred M Wollheim9, Alba Argerich12 and Brooke Penaluna12, (1)Kansas State University, Manhattan, KS, United States, (2)Institute for the Study of Earth, Oceans and Space (EOS), University of New Hampshire (UNH), Durham, NH, United States, (3)University of Georgia, Athens, GA, United States, (4)University of Alaska, Biology and Wildlife, Fairbanks, AK, United States, (5)University of Vermont, Burlington, VT, United States, (6)Murray State University, Murray, KY, United States, (7)Charles Darwin University, Research Institute for the Environment and Livelihoods, Darwin, Australia, (8)University of Alaska Fairbanks, Fairbanks, AK, United States, (9)University of New Hampshire Main Campus, Durham, NH, United States, (10)Florida International University, Miami, FL, United States, (11)Southern Illinois University Carbondale, Zoology, Carbondale, IL, United States, (12)Oregon State University, Corvallis, OR, United States
The stream biome gradient concept suggests that the biome in which a stream is embedded influences stream community structure and key ecosystem functions including primary production, community respiration, and nutrient uptake. We measured these key processes with whole-stream reach methods and smaller-scale incubations in numerous locations within stream networks across two years as part of a project on scaling ecosystem rates. Measurements were repeated across 7 biomes (tropical forest, tropical savanna, temperate deciduous forest, temperate rain forest, tallgrass prairie, boreal forest, and tundra). We found strong effects of light on primary production within and among biomes as a function of variable canopy among reaches and biomes. Community respiration and ammonium uptake were decoupled from light relative to gross primary production. Ammonium uptake rarely exhibited saturation with elevated concentrations, regardless of background concentrations or biome. We hypothesize that even though biomes exhibit major differences in gross primary production, the overall variation in community respiration and ammonium uptake is similar across biomes because respiration and uptake depend on carbon irrespective if it is derived from allochthonous or autochthonous inputs. Respiration and uptake are expected to vary depending upon factors not as tightly connected to the biome a stream is embedded in.