This procedure reduced the number of classes from 45 to 27. The resulting mean NDVI time profiles of the final agricultural classes are shown in Fig. 3. Fig. 4 shows only natural land cover classes. These NDVI time profiles reflect the mean values for each individual class. A three period moving average filter is used to smooth the profile as described by Reed et al. (1994). It can introduce time lag which is avoided by using one period before and one period next from the time of analysis.