Carbon dioxide fluxes of tundra vegetation communities on an esker top in the low-Arctic
Peter M. LAFLEUR1*, A. Brett CAMPEAU2 & Sohee KANG3
1 School of the Environment, Trent University, Peterborough, Ontario, Canada;
2 Geography Department Trent University, Peterborough, Ontario, Canada;
3 Department of Computer and Mathematical Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
Corresponding author, E-mail: firstname.lastname@example.org
Abstract: Previous studies have shown that carbon dioxide fluxes vary considerably among Arctic environments and it is important to assess these differences in order to develop our understanding of the role of Arctic tundra in the global carbon cycle. Although many previous studies have examined tundra carbon dioxide fluxes, few have concentrated on elevated terrain (hills and ridge tops) that is exposed to harsh environmental conditions resulting in sparse vegetation cover and seemingly low productivity. In this study we measured carbon dioxide (CO2) exchange of four common tundra communities on the crest of an esker located in the central Canadian low-Arctic. The objectives were to quantify and compare CO2 fluxes from these communities, investigate responses to environmental variables and qualitatively compare fluxes with those from similar communities growing in less harsh lowland tundra environments. Measurements made during July and August 2010 show there was little difference in net ecosystem exchange (NEE) and gross ecosystem production (GEP) among the three deciduous shrub communities, Arctous alpina, Betula glandulosa and Vaccinium uliginosum, with means ranging from −4.09 to −6.57 µmol·m−2·s−1 and −7.92 to −9.24 µmol·m−2·s−1, respectively. Empetrum nigrum communities had significantly smaller mean NEE and GEP (−1.74 and −4.08 µmol·m−2·s−1, respectively). Ecosystem respiration (ER) was similar for all communities (2.56 to 3.03 µmol·m−2·s−1), except the B. glandulosa community which had a larger mean flux (4.66 µmol·m−2·s−1). Overall, fluxes for these esker-top communities were near the upper range of fluxes reported for other tundra communities. ER was related to soil temperature in all of the communities. Only B. glandulosa GEP and ER showed sensitivity to a persistent decline in soil moisture throughout the study. These findings may have important implications for how esker tops would be treated in construction of regional carbon budgets and for predicting the impacts of climate change on Arctic tundra future carbon budgets.
Keywords: tundra carbon exchange, net ecosystem exchange, gross ecosystem productivity, ecosystem respiration, low-Arctic, esker top, xerophytes