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Soil Greenhouse Gas Fluxes, Environmental Controls, and the Partitioning of N 2 O Sources in UK Natural and Seminatural Land Use Types
Author(s) -
Sgouridis Fotis,
Ullah Sami
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg003783
Subject(s) - greenhouse gas , environmental science , denitrification , peat , ecosystem , water content , flux (metallurgy) , methane , atmospheric sciences , hydrology (agriculture) , soil water , terrestrial ecosystem , nitrogen , environmental chemistry , soil science , ecology , chemistry , geotechnical engineering , biology , geology , organic chemistry , engineering
Natural and seminatural terrestrial ecosystems (unmanaged peatlands and forests and extensive and intensive grasslands) have been under‐represented in the UK greenhouse gas (GHG) inventory. Mechanistic studies of GHG fluxes and their controls can improve the prediction of the currently uncertain GHG annual emission estimates. The source apportionment of N 2 O emissions can further inform management plans for GHG mitigation. We have measured in situ GHG fluxes monthly in two replicated UK catchments and evaluated their environmental controlling factors. An adapted 15 N‐gas flux method with low addition of 15 N tracer (0.03–0.5 kg 15 N ha −1 ) was used to quantify the relative contribution of denitrification to net N 2 O production. Total N 2 O fluxes were 40 times higher in the intensive grasslands than in the peatlands (range: −1.32 to 312.3 μg N m −2 h −1 ). The contribution of denitrification to net N 2 O emission varied across the land use types and ranged from 9 to 60%. Soil moisture was the key parameter regulating the partitioning of N 2 O sources ( r 2 = 0.46). Total N 2 O fluxes were explained by a simple model ( r 2 = 0.83) including parameters such as total dissolved nitrogen, organic carbon, and water content. A parsimonious model with the soil moisture content as a single scalar parameter explained 84% of methane flux variability across land uses. The assumption that 1% of the atmospherically deposited N on natural ecosystems is emitted as N 2 O could be overestimated or underestimated (0.3–1.6%). The use of land use‐specific N 2 O emission factors and further information on N 2 O source partitioning should help constrain this uncertainty.