Estimating CO 2 exchange at two sites in Arctic tundra ecosystems during the growing season using a spectral vegetation index

Measurements of carbon ̄ uxes in Arctic tundra landscapes are generally obtained through intensive ® eld work and involve the use of chamber and/or micrometeorological tower techniques. However, ® ndings in a variety of nonArctic ecosystems have demonstrated the potential of remote sensing-based techniques (particularly spectral vegetation indices) to provide estimates of CO2 exchange in amore timely and e cient manner. As the ® rst step towards modelling Arctic regional and circumpolar ̄ uxes of CO2 using remotely sensed data, we investigated the relationships between plot-level ̄ uxes of CO2 and a vegetation spectral re ̄ ectance index derived from hand-held radiometric data at two sites. These relationships were evaluated for variations in vegetation cover type and environmental factors using data collected during the short Arctic growing season. Overall, this study demonstrated a relationship between the Normalized Di€ erence Vegetation Index (NDVI) and measurements of mean site gross photosynthesis and ecosystem respiration at two sites in Arctic tundra ecosystems on the North Slope of Alaska.