SYMP 17 - Nitrogen in Terrestrial Ecosystems: New Paradigms

Thursday, August 10, 2017: 8:00 AM-11:30 AM
Portland Blrm 251, Oregon Convention Center
Rachel C. Wooliver, University of Tennessee
Jennifer Schweitzer, University of Tennessee
Jennifer Schweitzer, University of Tennessee
The role of nitrogen in primary productivity, community interactions, and ecosystem processes has been studied for decades, but recent work has provided evidence against current paradigms in our understanding of nitrogen in natural systems. The goal of this symposium is to highlight those paradigms and how they are shifting. Working to better understand nitrogen, in particular nitrogen cycling and nitrogen limitation of primary productivity, has implications for community and ecosystem responses to continued increases in global nitrogen deposition. For example, with increases in nitrogen inputs to soils we may see a dampening of productivity increases due to phosphorus- or water-limitation, which contradicts the paradigm that ecosystem productivity is primarily limited by nitrogen. Or, we may see that increased nitrogen inputs to soils will extend the duration of the land carbon sink in response to rising atmospheric CO2. The research presented in this symposium appeals to a broad audience of ESA members as it 1) integrates the fields of community and ecosystem ecology, biogeochemistry, and global change biology and 2) addresses the role of nitrogen in above- and belowground processes. Presentations in this symposium span a range of perspectives, from the origins of nitrogen in the nitrogen cycle to the responses of plants to nitrogen and nitrogen cycling belowground. Specifically, presentations will address how nitrogen inputs to ecosystems can originate from parent material, negating the paradigm that nitrogen come from the atmosphere alone; how nitrogen limitation of plants can be mediated by phosphorus limitation and soil microbes and how nitrogen limitation varies widely across plant species, a combination of ideas that shift how we think about nitrogen limitation of primary productivity; how nitrogen availability in tropical soils can be lower than previously thought due to losses via denitrification; and how nitrogen availability in soils is limited by the ability of soil microbial enzymes to depolymerize nitrogen-containing polymers rather than competition for nitrogen between plants and soil microbes.
8:00 AM
 Global ecological significance of rock nitrogen weathering
Benjamin Z. Houlton, University of California, Davis; Scott L. Morford, University of California, Davis; Randy A. Dahlgren, University of California, Davis; Ying-Ping Wang, CSIRO Marine and Atmospheric Research; Pawlok Dass, University of California, Davis; Scott Mitchell, University of California, Davis; Katherine A. Dynarski, University of California, Davis
8:30 AM
 Nitrogen losses during fire and the emergence of fire-plant-soil feedbacks across individual, community, and ecosystem scales
Adam F.A. Pellegrini, Stanford University; Lars O. Hedin, Princeton University; Sarah E. Hobbie, University of Minnesota; Peter B. Reich, University of Minnesota; Robert B. Jackson, Stanford University
9:00 AM
 Phylogeny and soil fungi explain tradeoffs in plant growth responses to nitrogen enrichment
Rachel C. Wooliver, University of Tennessee; Alix A. Pfennigwerth, University of Tennessee; Christopher R. Peterson, University of Texas; Zachary H. Marion, University of Nevada; Brad M. Potts, University of Tasmania; John K. Senior, University of Tasmania; Joseph Bailey, University of Tennessee; Jennifer Schweitzer, University of Tennessee
9:30 AM
9:40 AM
 Nitrogen limitation of decomposition and decay: How can it occur?
Colin Averill, Boston University; Bonnie Waring, Utah State University
10:10 AM
 Belowground responses to nitrogen and phosphorus addition in a regenerating tropical dry forest
Bonnie Waring, Utah State University; Jennifer S. Powers, University of Minnesota
10:40 AM
 Nitrogen mineralization versus depolymerization: What drives the soil N cycle?
Joshua Schimel, University of California - Santa Barbara
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