An automated dual chamber system to partition the Net Ecosystem Exchange of CO­2 in arctic tundra

Abstract:

Long arctic photoperiods hamper the partitioning of NEE into photosynthesis (GEE) and ecosystem respiration (ER). We developed an automated dual chamber (a clear and dark chamber) system to partition NEE and assess errors in commonly used NEE partitioning techniques in arctic tundra. Measurements in the clear chamber reflected NEE, measurements in the dark chamber and nighttime clear chamber measurements reflected ER. The difference between dark and clear measurements equaled GEE and was compared with the inferred partitioned GEE. Inferred GEE and ER in the clear chamber was determined with a daytime light response curve in the clear chamber, and with an exponential relationship with soil and air temperature on nighttime clear chamber measurements. Different flux partitioning methods influenced the estimation of GEE and some approaches overestimated GEE. Our chamber design provides high frequency GEE, ER, and NEE measures that can reveal novel insights on arctic carbon cycling.