Increased CO 2 loss from vegetated drained lake tundra ecosystems due to flooding

• Published in: Global Biogeochemical Cycles
• Main Authors: Zona, Donatella, Lipson, David A., Paw U, Kyaw T., Oberbauer, Steve F., Olivas, Paulo, Gioli, Beniamino, Oechel, Walter C.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2012
• Subjects: Arctic; Climate change; Thermokarst; Tundra
• Online Access: https://oro.open.ac.uk/38776/; https://oro.open.ac.uk/38776/1/oechel%201.pdf; https://doi.org/10.1029/2011GB004037

Tundra ecosystems are especially sensitive to climate change, which is particularly rapid in high northern latitudes resulting in significant alterations in temperature and soil moisture. Numerous studies have demonstrated that soil drying increases the respiration loss from wet Arctic tundra. And, warming and drying of tundra soils are assumed to increase CO 2 emissions from the Arctic. However, in this water table manipulation experiment (i.e., flooding experiment), we show that flooding of wet tundra can also lead to increased CO 2 loss. Standing water increased heat conduction into the soil, leading to higher soil temperature, deeper thaw and, surprisingly, to higher CO 2 loss in the most anaerobic of the experimental areas. The study site is located in a drained lake basin, and the soils are characterized by wetter conditions than upland tundra. In experimentally flooded areas, high wind speeds (greater than ~4 m s −1 ) increased CO 2 emission rates, sometimes overwhelming the photosynthetic uptake, even during daytime. This suggests that CO 2 efflux from C rich soils and surface waters can be limited by surface exchange processes. The comparison of the CO 2 and CH 4 emission in an anaerobic soil incubation experiment showed that in this ecosystem, CO 2 production is an order of magnitude higher than CH 4 production. Future increases in surface water ponding, linked to surface subsidence and thermokarst erosion, and concomitant increases in soil warming, can increase net C efflux from these arctic ecosystems.