Monitoring fire danger of northern boreal forests with NOAA-AVHRR NDVI images

The objective of this study was to assess the potential of remote sensing from satellites for monitoring forest fire danger in northern Canadian boreal forests. In Canada, daily forest fire danger is rated by the Canadian Forest Fire Danger Rating System (CFFDRS). One of its components is the Fire Weather Index (FWI) system. FWI variables were computed from weather records of the 1994 fire season. They were correlated to NDVI and cumulative NDVI (Sigma NDVI) data computed from NOAA-AVHRR red and near-infrared bands in the case of coniferous stands located in the Northwest Territories, Canada. NDVI and Sigma NDVI data were more strongly correlated to FWI variables corresponding to slow-drying fuels, i.e. duff moisture code (DMC), drought code (DC) and buildup index (BUI), than to those related to fast-drying fuels, i.e. fine fuel moisture code (FFMC) and fire weather index (FWI). The correlations between spectral data and FWI variables were explained by the fact that both kinds of variables have a similar seasonal variation, but not by an eventual direct relationship between NDVI and fuel moisture conditions, since NDVI is more directly related to chlorophyllian activity of the vegetation than to droughtness conditions.