PARENT SESSION
Oral Session #44: Global Change and Climate Change.
Presiding: C. Wessman
Tuesday, August 6. 1:00 PM to 4:45 PM. Grand Ballroom West, Radisson.
Tundra carbon fluxes in response to experimental warming along moisture and climate gradients in Northern Alaska.
OBERBAUER, STEVEN*,1, TWEEDIE, CRAIG2, WEBBER, PATRICK2, KUCHY, ANDREA1, ELMORE, ELIZABETH1, HOLLISTER, ROBERT2, STARR, GREG3, 1 Florida International University, Miami, FL2 Michigan State University, East Lansing, MI3 University of Florida, Gainesville, FL
ABSTRACT- As part of the International Tundra Experiment, we compared ecosystem CO2 exchange from experimentally-warmed and control plots in both wet and dry tundra communities at two locations in Northern Alaska, Barrow and Atqasuk. Measurements were made during the growing seasons of both 2000 and 2001. Fluxes were assessed using static chamber techniques conducted over 24 hr sample periods sampled regularly throughout the summer. Net ecosystem exchange (NEE) from the wet tundra at both sites were largely positive (carbon uptake) during the growing season. Warming tended to increase carbon uptake on the wet sites. In contrast, NEE from the dry tundra at both Barrow and Atqasuk were largely negative (carbon losses) throughout the growing season. Warming exacerbated carbon losses on the dry sites. The effects of warming were stronger during 2000 than in 2001 at both sites and in both habitat types. Fluxes of controls were similar between the two sites but warming had a stronger impact on the dry site at Barrow than Atqasuk. Measurements of ecosystem dark respiration were used to estimate gross ecosystem uptake in 2001. These findings indicate that warming tends to increase photosynthetic uptake on all sites, but on dry sites the corresponding increase in respiration was even greater. The results of this study suggest that climate warming will enhance carbon uptake on wet sites but will increase the rate of carbon losses from dry sites.
KEY WORDS: itex, open top chamber, experimental warming