International Polar Year (IPY) 2012: From Knowledge to Action
Air temperature has been increasing in the Arctic at much faster rates than the rest of the globe. Low temperatures limit the growth and reproduction of arctic plants, so an increase in temperature could greatly affect the plant community. The objective of this analysis was to determine if the response of graminoids to warming is consistent across species and locations. Sites were established at Barrow in 1994 and Atqasuk in 1996. Each location consists of a dry heath site and a wet meadow site. Plots of vegetation (1m2) were warmed 1°C to 3°C using open-top fiberglass chambers, following protocols of the International Tundra Experiment (ITEX). Each study site contains 24 warmed plots and 24 control plots. Growth and reproductive effort for all graminoid species at each site were analyzed. In general, species showed increased leaf length with warming at all sites. For inflorescence height and the number of inflorescences, graminoids at the dry sites generally showed a positive response to warming, while responses at the wet sites were inconsistent (significantly larger or smaller depending on the species). Overall, the response of graminoids to warming at the dry sites is more consistent than at the wet sites. The dry sites are more open communities with presumably less competition, and are dominated by prostrate shrubs and forbs. At the wet sites, graminoids are the most abundant growth form. This analysis suggests that at the dry sites graminoids are out-competing the other growth forms, resulting in a more consistent positive response to warming. At the wet sites, however, graminoid species are being forced to compete with each other, thus resulting in a more inconsistent response.