Fig. 4. Map of the magnitude of change in amplitude after a disturbance. Image differencing is a spatially explicit method to visualize change in a landscape. The subtraction of the vegetation index (VI) reference year (initial conditions in 1972) from the disturbance year (the 1984 drought) is a measure of amplitude. The white areas that did not change are located in bofedal (wet meadow) areas of the study site.