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Interannual variability of net ecosystem CO 2 exchange at a subarctic fen
Author(s) -
Griffis T. J.,
Rouse W. R.,
Waddington J. M.
Publication year - 2000
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/1999gb001243
Subject(s) - subarctic climate , environmental science , ecosystem respiration , ecosystem , carbon sink , wetland , phenology , growing season , sink (geography) , snowmelt , carbon cycle , atmospheric sciences , climatology , primary production , hydrology (agriculture) , ecology , oceanography , geography , surface runoff , geology , cartography , geotechnical engineering , biology
Landscape‐scale net ecosystem CO 2 exchange (NEE) and the energy balance of a subarctic fen were studied during five growing seasons near Churchill, Manitoba. Interannual variability in NEE was large and ranged from a net sink of −235 g CO 2 m −2 in 1996 to a net source of +76 g CO 2 m −2 in 1994. Annual estimates of CO 2 exchange indicate that during the present period the fen is losing carbon nearly 3 times faster than its long‐term historical gain of about −11 g CO 2 m −2 yr −1 . Our estimates suggest that gross ecosystem photosynthesis may be more variable than ecosystem respiration on diurnal, seasonal, and interannual timescales. Our data strongly indicate that an early snowmelt combined with wet and warm conditions during the spring period lead to large carbon acquisition even when drier conditions were experienced over the majority of the growing season. The phenological stage of the vegetation relative to the climatic conditions experienced is an important cause of the interannual variability in NEE. An accurate representation of phenology in climate models is, therefore, critical to the success of forecasting the carbon budgets of northern wetlands.