Arctic soil respiration: Effects of climate and vegetation depend on season

Arctic ecosystems are important in the context of global climate change because the most rapid rises in air temperature are expected at high northern latitudes during winter. The presence of extensive soil carbon reserves in the Arctic suggests that substantial feedbacks to CO2-induced climate change could occur if warming alters carbon cycling belowground. Characterization of the controls on regional patterns of belowground CO2 release through the annual cycle is an important step towards evaluating potential feedbacks from arctic ecosystems to climate change. In this study, we assess seasonal control over the influences by climate and vegetation-type on CO2 efflux from belowground in the Alaskan tundra. Our results indicate that climate had strong effects on belowground CO2 release in both seasons. By contrast, vegetation-type had little impact on CO2 efflux from belowground in winter but was the principal control in summer. Together, these results demonstrate that seasonality is a critical factor regulating climate and vegetation-type effects on belowground CO2 release, which should be included in regional models of net carbon balance in arctic ecosystems.