The carbon balance of a managed boreal landscape measured from a tall tower in northern Sweden

• Published in: Agricultural and Forest Meteorology
• Main Authors: Chi, Jinshu, Nilsson, Mats B., Kljun, Natascha, Wallerman, Jörgen, Fransson, Johan E.S., Laudon, Hjalmar, Lundmark, Tomas, Peichl, Matthias
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2019
• Subjects: Northern Sweden
• Online Access: https://repository.hkust.edu.hk/ir/Record/1783.1-119387; https://doi.org/10.1016/j.agrformet.2019.04.010; http://lbdiscover.ust.hk/uresolver?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rfr_id=info:sid/HKUST:SPI&rft.genre=article&rft.issn=0168-1923&rft.volume=274&rft.issue=&rft.date=2019&rft.spage=29&rft.aulast=Chi&rft.aufirst=Jinshu&rft.atitle=The+carbon+balance+of+a+managed+boreal+landscape+measured+from+a+tall+tower+in+northern+Sweden&rft.title=Agricultural+and+Forest+Meteorology; http://www.scopus.com/record/display.url?eid=2-s2.0-85067982099&origin=inward; http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=LinksAMR&SrcApp=PARTNER_APP&DestLinkType=FullRecord&DestApp=WOS&KeyUT=000471356600004

Boreal forests exchange large amounts of carbon dioxide (CO 2 ) with the atmosphere. A managed boreal landscape usually comprises various potential CO 2 sinks and sources across forest stands of varying age classes, clear-cut areas, mires, and lakes. Due to this heterogeneity and complexity, large uncertainties exist regarding the net CO 2 balance at the landscape scale. In this study, we present the first estimate of the net CO 2 exchange over a managed boreal landscape (∼68 km 2 ) in northern Sweden, based on tall tower eddy covariance measurements. Our results suggest that from March 1, 2016 to February 28, 2018, the heterogeneous landscape was a net CO 2 sink with a 2-year mean uptake of −87 ± 6 g C m −2 yr −1 . Due to an earlier and warmer spring and sunnier autumn, the landscape was a stronger CO 2 sink during the first year (−122 ± 8 g C m −2 ) compared to the second year (−52 ± 9 g C m −2 ). Footprint analysis shows that 87% of the CO 2 flux measurements originated from forests, whereas mires, clear-cuts, lakes, and grassland contributed 11%, 1%, 0.7%, and 0.2%, respectively. Altogether, the CO 2 sink strength of the heterogeneous landscape was up to 38% lower compared to the sink strength of a mature stand surrounding the tower. Overall, this study suggests that the managed boreal landscape acted as a CO 2 sink and advocates tall tower eddy covariance measurements to improve regional carbon budget estimates.