Premium
Climatic variability, hydrologic anomaly, and methane emission can turn productive freshwater marshes into net carbon sources
Author(s) -
Chu Housen,
Gottgens Johan F.,
Chen Jiquan,
Sun Ge,
Desai Ankur R.,
Ouyang Zutao,
Shao Changliang,
Czajkowski Kevin
Publication year - 2015
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12760
Subject(s) - carbon sink , environmental science , marsh , sink (geography) , ecosystem , ecosystem respiration , total organic carbon , hydrology (agriculture) , carbon fibers , carbon dioxide , carbon sequestration , carbon cycle , methane , atmospheric sciences , ecology , environmental chemistry , primary production , wetland , chemistry , geology , biology , geography , materials science , cartography , geotechnical engineering , composite number , composite material
Freshwater marshes are well‐known for their ecological functions in carbon sequestration, but complete carbon budgets that include both methane ( CH 4 ) and lateral carbon fluxes for these ecosystems are rarely available. To the best of our knowledge, this is the first full carbon balance for a freshwater marsh where vertical gaseous [carbon dioxide ( CO 2 ) and CH 4 ] and lateral hydrologic fluxes (dissolved and particulate organic carbon) have been simultaneously measured for multiple years (2011–2013). Carbon accumulation in the sediments suggested that the marsh was a long‐term carbon sink and accumulated ~96.9 ± 10.3 (±95% CI ) g C m −2 yr −1 during the last ~50 years. However, abnormal climate conditions in the last 3 years turned the marsh to a source of carbon (42.7 ± 23.4 g C m −2 yr −1 ). Gross ecosystem production and ecosystem respiration were the two largest fluxes in the annual carbon budget. Yet, these two fluxes compensated each other to a large extent and led to the marsh being a CO 2 sink in 2011 (−78.8 ± 33.6 g C m −2 yr −1 ), near CO 2 ‐neutral in 2012 (29.7 ± 37.2 g C m −2 yr −1 ), and a CO 2 source in 2013 (92.9 ± 28.0 g C m −2 yr −1 ). The CH 4 emission was consistently high with a three‐year average of 50.8 ± 1.0 g C m −2 yr −1 . Considerable hydrologic carbon flowed laterally both into and out of the marsh (108.3 ± 5.4 and 86.2 ± 10.5 g C m −2 yr −1 , respectively). In total, hydrologic carbon fluxes contributed ~23 ± 13 g C m −2 yr −1 to the three‐year carbon budget. Our findings highlight the importance of lateral hydrologic inflows/outflows in wetland carbon budgets, especially in those characterized by a flow‐through hydrologic regime. In addition, different carbon fluxes responded unequally to climate variability/anomalies and, thus, the total carbon budgets may vary drastically among years.