Provenance & quality
Each site consisted of a polygon of roughly 400 x 500 m to 1000 x 1000 m in size, dependent upon site length (parallel to shore) and width (perpendicular to shore). Twenty two 1 x 1 m quadrats were randomly placed within each site polygon using R (R Development Core Team, 2014) to specify placement at four different spatial scales (A = 1 quadrat only, B = 3 quadrats at 1 m to 10 m apart, C = 6 quadrats at 10 m to 100 m apart, D = 12 quadrats at 100 m to 1000 m or site maximum). Only the quadrat from scale A, two quadrats from scale B and four quadrats from scale C were sampled for greenhouse gas fluxes. Light and dark incubations were performed using a benthic chamber connected to an infrared gas analyser. This allowed direct measurements of CO2. CH4 and N2O fluxes were measured from gas samples collected at five time points during the dark incubation and stored in glass Exetainer bottles for later processing. The samples were analysed using a gas chromatograph.