LINKING ENERGY FLOW AND NUTRIENT CYCLING IN STREAMS
Carbon and nutrients are the energetic currency of ecosystems, and their respective cycles drive metabolic and biogeochemical processes in streams. While stoichiometric limitations can have significant effects on coupled element transformations, carbon and nutrient cycles are often studied in isolation from each other. To what extent are dynamics of carbon and other element cycles in streams linked? Using ecosystem metabolism and nitrogen cycling data collected for the Lotic Intersite Nitrogen eXperiment (LINX-II), we compared spiraling metrics for both organic carbon (OC) and nitrate (NO3-) in headwater streams across a variety of land uses and biomes. Mineralization velocities of OC (vf-OC) and NO3- uptake velocities (vf-NO3) were of similar magnitude (6.1*10-6 to 4.5*10-3 m/min and 2.5*10-5 to 1.8*10-2 m/min, respectively). vf-OC and vf-NO3- were weakly positively correlated across all sites (r=0.23, p=0.06). The strongest relationships between OC turnover and NO3- uptake were in streams that were more metabolically balanced (steppe sites, r=0.81, p=0.03, GPP/ER=0.81; tallgrass sites, r=0.72, p=0.03, GPP/ER=0.91; urban streams, r=0.45, p=0.03, GPP/ER=0.54). This study highlights the promise of investigating coupled carbon-nitrogen cycles, and how the balance between productivity and respiration may be a universal driver of coupled carbon-nutrient behavior.
Stephen Plont (Primary Presenter/Author), Virginia Tech, email@example.com;
Brynn ODonnell (Co-Presenter/Co-Author), Virginia Tech, firstname.lastname@example.org;
Morgan Gallagher (Co-Presenter/Co-Author), Department of Crop and Soil Environmental Sciences, Virginia Tech, email@example.com;
Erin Hotchkiss (Co-Presenter/Co-Author), Virginia Tech, firstname.lastname@example.org;