Process‐Oriented Modeling of a High Arctic Tundra Ecosystem: Long‐Term Carbon Budget and Ecosystem Responses to Interannual Variations of Climate. Issue 4 (6th April 2018)

• Record Type: Journal Article
• Authors: Zhang, Wenxin; Jansson, Per‐Erik; Schurgers, Guy; Hollesen, Jørgen; Lund, Magnus; Abermann, Jakob; Elberling, Bo
• Is Part Of: Journal of geophysical research. Volume 123:Issue 4(2018)
• Page Start: 1178
• Page End: 1196
• Publication Date: 2018-04-06
• Subjects: carbon budget -- CoupModel -- high Arctic -- permafrost -- interannual variations -- nongrowing season; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2017JG003956
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Terrestrial carbon (C) cycling in high Arctic tundra depends on ecosystem responses to climatic warming and concurrent changes in environmental conditions. There are very few studies to quantify long‐term C budget in high Arctic tundra due to lack of sufficient measurements. Here based on well‐established multiyear measurements, we calibrated a process‐oriented model (CoupModel) to quantify various components of the C budget at a Cassiope tetragona heath ecosystem in northeast Greenland. Net ecosystem exchange of CO2 (NEE) for 2000–2014 was estimated at −15 ± 10 g C m −2 yr −1 . Ecosystem respiration (ER) for nongrowing seasons was estimated at 10.3 ± 5.3 g C m −2 yr −1, representing around 13% of the annual ER. Significant trends for interannual variations of aboveground and belowground C fluxes and stocks were found for the subperiods (i.e., 2000–2008 and 2008–2014) but not for the entire period. Interannual variations of NEE largely relied on the response of gross primary production (GPP) and ER to seasonal changes in climate. Moreover, the model showed that interannual variations of GPP, ER, and NEE had a much higher linear correlation with July temperature and annual maximum thawing depth (ALDmax ) than other climatic and site characteristics. ALDmax had the highest correlation with the decomposition rate of humus C. Overall, this modeling study suggests that a sink‐source transition of the studied ecosystem depends on ecosystem responses to interannual variations of climate and that the net C balance may be sensitive to summer warmth and active layer thickness. Key Points: The CoupModel is constrained using 15 year eddy covariance measurements to estimate long‐term C budget for a high Arctic heath ecosystem Significant trends for ecosystem functioning as a stronger or weaker sink are found at subperiod intervals but not for the entire period The CoupModel implies that summer warmth and annual maximum thawing depth are key factors to explain interannual variations of C fluxes