The French SPOT satellite data (20-m resolution) were obtained on 28 July 1989 and provides a view of the mapped region from space. NDVI is an index of vegetation greenness that can be linked to plant biomass and other biophysical properties of the vegetation, such as CO2 and photosynthesis. The NDVI = (NIR - R)/(NIR + R), where NIR and R are the spectral reflectance values of the near-infrared (790-890 nm) and red (610-680 nm) bands, respectively. It is modified from an earlier version (Shippert et al. 1995). Water and barrens are generally displayed as black. Dry tundra and sparsely vegetated areas are displayed in gray. Vegetation density increases with darker shades of green.
Shippert, M. M., D. A. Walker, N. A. Auerbach, and B. E. Lewis. 1995. Biomass and leaf-area index maps derived from SPOT images for Toolik Lake and Imnavait Creek areas, Alaska. Polar Record 31:147-154. doi:10.1017/S0032247400013644.