Direct estimates of CO/sub 2/ flux in Arctic environments using a spectral vegetation index

Carbon flux and spectral reflectance data were collected on the North Slope of Alaska during the 1994 growing season. Observations were made at two sites in the coastal plain and two sites in the foothills of the Brooks Mountain Range. The relationship between the normalized difference vegetation index (NDVI) and daily gross primary production (GPP) was investigated. The daily gross primary production of tussock tundra was normalized for variations in photosynthetically active radiation (PAR) and was found to be linearly related to the NDVI. Seasonal changes in the vegetation and solar elevation, and variations in cloud cover conditions during radiometric observations did not have a significant effect on the relationship between GPP/PAR and the NDVI. The contrasting landscapes of the coastal plain and foothills regions (vegetation and moisture characteristics) and experimental manipulations that included changes in soil moisture conditions, illumination and temperature also did not appear to affect the relationship.