Abstract: The high altitude area in Arctic is one of important global seabird active regions. Seabird guano provides rich nutrients for tundra soils, thus affects carbon cycle in tundra ecosystem. However, effects of seabird activity on CO2 fluxes from Arctic tundra have not been reported. During the summertime of 2009, CO2 fluxes were investigated in the bird sanctuary and non-bird region from Ny-?lesund using a static chamber technique. To evaluate temporal variations and daily variations of CO2 fluxes from the bird sanctuary, bird-intensive areas (HB), fewer activities area (MB) and the edge region with little seabirds activities（LB）were investigated. Net CO2 fluxes and photosynthetic rates were (-107.6±19.2),（21.7±9.7）and（67.5±12.4）mg/(m2.h) and（-243.6±25.5）,（-105.5±7.6）and（-45.6±12.0）mg/(m2.h ), respectively. They were both significantly different between the observation sites, and photosynthetic rates reduced in order, indicating bird activities significantly increased atmosphere CO2 uptake. The respiratory rates were（136.0±16.5）,（127.2±15.6）and（113.0±6.8）mg/(m2.h) had no significant differences between the observation sites, indicating the effect of bird activities may be insignificant. The average NEE of non-bird region (seaside and mining tundra) were (6.91±4.8）and（17.5±41.6）mg/(m2.h), respectively. The data suggested the non-bird tundra was the CO2 sink. Temporal variations of CO2 fluxes during summertime in the non-bird region showed it was a source for atmospheric CO2. The CO2 fluxes were positively related to air temperature and ground temperature, with no significant correlation with precipitation and air humidity. Our results from 23 observation sites in three types of tundra indicated seabird activity had a major impact on carbon fluxes and significantly enhanced the sink of carbon in Arctic tundra.

Key words: CO₂ fluxes, Arctic, tundra, seabirds, wetland