4th UF Water Institute Symposium Abstract

Submitter's Name Anna Normand
Session Name Poster Session: Impact of changing drivers on water resources
Poster Number 3
Author(s) Anna Normand,  Wetland Biogeochemistry Laboratory, Soil and Water Science Department (Presenting Author)
  Adam Smith,  Department of Chemistry
  Mark Clark, Wetland Biogeochemistry Laboratory, Soil and Water Science Department
  K. Ramesh Reddy, Wetland Biogeochemistry Lab, University of Florida
  Comparison of organic matter composition from shifting vegetation communities due to increased inundation of a subarctic mire in Abisko, Sweden
  Climate change over the next century will affect vegetation communities in peatlands. External drivers such as precipitation and temperature may influence diversity of vegetation species composition. Particularly in the subarctic region, the temperature will increase more rapidly than the global mean, annual mean precipitation will likely intensify, and permafrost is projected to decrease by 37 to 81%. This will result in increased inundation of peatlands and consequently shift vegetation communities. These changes have already been observed in a subarctic mire ecosystem near Abisko, Sweden. Three vegetation community types dominate the system: 1) permafrost sites consisting of drained palsa areas with woody herbaceous vegetation; 2) intermediate thaw features with Sphagnum spp. where the water table is close to the surface; 3) wet fen dominated by Eriophorum spp. where the ground completely thaws. Over 40 years, the wet fen communities have established in former Sphagnum areas, and Sphagnum has recruited at degraded palsa hummocks. The altered hydrologic regime selecting for vegetative communities will dictate the quantity and quality of litter inputs. In this study, we examined the varying organic matter quality of the vegetation and litter from the community types. When present, live, standing dead, below ground biomass, and detritus were collected from fen, Sphagnum, and palsa communities across a 26 m transect. Total carbon (C), nitrogen (N), and phosphorus (P) and C and N isotopes determined differences in the vegetation composition. Solid State 13C Nuclear Magnetic Resonance (NMR) identified the relative abundance of C functional groups: carbonyl, O-aromatic, aromatic, O-alkyl, N-alkyl-methoxy, and alkyl. The ratio of alkyl/O-alkyl and aromatic peak area inferred differences in stability of the vegetative inputs. The molecular properties and stability of the vegetation inputs will ultimately dictate decomposition and stability of the resulting soil organic matter which is important for nutrient cycling and greenhouse gas (GHG) emissions.