Methane oxidation in contrasting soil types:responses to experimental warming with implication for landscape-integrated CH 4 budget

• Published in: Global Change Biology
• Main Authors: D'Imperio, Ludovica, Nielsen, Cecilie Skov, Westergaard-Nielsen, Andreas, Michelsen, Anders, Elberling, Bo
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Arctic; bare soil; dry heath; Greenland; methane budget; methane uptake; soil moisture; warming; Climate change; Tundra
• Online Access: https://curis.ku.dk/portal/da/publications/methane-oxidation-in-contrasting-soil-types(450dec64-7f8e-478a-b803-8a0ac2726305).html; https://doi.org/10.1111/gcb.13400; https://curis.ku.dk/ws/files/172272485/Methane_oxidation_in_contrasting_soil_types_responses_to_experimental_warming_with_implication_for_landscape_integrated_CH4_budget.pdf

Arctic ecosystems are characterized by a wide range of soil moisture conditions and thermal regimes and contribute differently to the net methane (CH 4 ) budget. Yet, it is unclear how climate change will affect the capacity of those systems to act as a net source or sink of CH 4 . Here, we present results of in situ CH 4 flux measurements made during the growing season 2014 on Disko Island (west Greenland) and quantify the contribution of contrasting soil and landscape types to the net CH 4 budget and responses to summer warming. We compared gas flux measurements from a bare soil and a dry heath, at ambient conditions and increased air temperature, using open-top chambers (OTCs). Throughout the growing season, bare soil consumed 0.22 ± 0.03 g CH 4 -C m −2 (8.1 ± 1.2 g CO 2 -eq m −2 ) at ambient conditions, while the dry heath consumed 0.10 ± 0.02 g CH 4 -C m −2 (3.9 ± 0.6 g CO 2 -eq m −2 ). These uptake rates were subsequently scaled to the entire study area of 0.15 km 2 , a landscape also consisting of wetlands with a seasonally integrated methane release of 0.10 ± 0.01 g CH 4 -C m −2 (3.7 ± 1.2 g CO 2 -eq m −2 ). The result was a net landscape sink of 12.71 kg CH 4 -C (0.48 tonne CO 2 -eq) during the growing season. A nonsignificant trend was noticed in seasonal CH 4 uptake rates with experimental warming, corresponding to a 2% reduction at the bare soil, and 33% increase at the dry heath. This was due to the indirect effect of OTCs on soil moisture, which exerted the main control on CH 4 fluxes. Overall, the net landscape sink of CH 4 tended to increase by 20% with OTCs. Bare and dry tundra ecosystems should be considered in the net CH 4 budget of the Arctic due to their potential role in counterbalancing CH 4 emissions from wetlands – not the least when taking the future climatic scenarios of the Arctic into account.