Spatial variability of organic matter properties determines methane fluxes in a tropical forested peatland.

N T Girkin, C H Vane, H V Cooper, V Moss-Hayes, J Craigon, B L Turner, N Ostle, S Sjögersten
Author Information
  1. N T Girkin: 1School of Biosciences, University of Nottingham, Nottingham, NG7 2RD UK. ORCID
  2. C H Vane: British Geological Survey, Centre for Environmental Geochemistry, Keyworth, NG12 5GG UK.
  3. H V Cooper: 1School of Biosciences, University of Nottingham, Nottingham, NG7 2RD UK.
  4. V Moss-Hayes: British Geological Survey, Centre for Environmental Geochemistry, Keyworth, NG12 5GG UK.
  5. J Craigon: 1School of Biosciences, University of Nottingham, Nottingham, NG7 2RD UK.
  6. B L Turner: 3Smithsonian Tropical Research Institute, Apartado, 0843-03092 Balboa, Ancon Republic of Panama.
  7. N Ostle: 4Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ UK.
  8. S Sjögersten: 1School of Biosciences, University of Nottingham, Nottingham, NG7 2RD UK.

Abstract

Tropical peatland ecosystems are a significant component of the global carbon cycle and feature a range of distinct vegetation types, but the extent of links between contrasting plant species, peat biogeochemistry and greenhouse gas fluxes remains unclear. Here we assessed how vegetation affects small scale variation of tropical peatland carbon dynamics by quantifying in situ greenhouse gas emissions over 1 month using the closed chamber technique, and peat organic matter properties using Rock-Eval 6 pyrolysis within the rooting zones of canopy palms and broadleaved evergreen trees. Mean methane fluxes ranged from 0.56 to 1.2 mg m h and were significantly greater closer to plant stems. In addition, pH, ranging from 3.95 to 4.16, was significantly greater closer to stems. A three pool model of organic matter thermal stability (labile, intermediate and passive pools) indicated a large labile pool in surface peat (35-42%), with equivalent carbon stocks of 2236-3065 g m. methane fluxes were driven by overall substrate availability rather than any specific carbon pool. No peat properties correlated with carbon dioxide fluxes, suggesting a significant role for root respiration, aerobic decomposition and/or methane oxidation. These results demonstrate how vegetation type and inputs, and peat organic matter properties are important determinants of small scale spatial variation of methane fluxes in tropical peatlands that are affected by climate and land use change.

Keywords

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