REQUE ils 
  
Fig. 6 Overlay LANDSAT MSS Imagery and 
Physiographic Map by SPECK et al. (1982) Geometry 
not corrected, scene approx. 50 km x 50 km, for 
numbers and comment see text 
    
50 km 
i 
[C 
Fig. 7 Area Maquinchao-Jacobacci (Fig. 6) as 
recorded by NOAA (March 9th, 1987), bands 1, 2, 
9 used for colour output 
155 
It turns out that multispectral classification would 
not allow to extract fully the information offered 
by LANDSAT MSS imagery for desertification 
monitoring. Interpretation of imagery by a skilled 
expert based on ground truth seems to be the best 
method for segmentation of object classes. 
Small features may be very useful for the 
desertification expert and serve as an important 
indicator for degradation. This is studied in large scale 
like explained in Fig. 6. However, the project has to 
consider Patagonia as a whole. 
Consequently, monitoring of desertification in Pa- 
tagonia presents a lot of organisational challenges, 
because it refers to a very large area while individual 
plants may serve as indicators for the degradation 
process. Therefore the procedure „from large to 
small“ is applied: starting from intensively checked 
areas (like Jacobacci-Maquincao) the knowledge 
acquired there - including ground truth - is used 
in the transects and from there interpolated for the 
whole country. This process represents a particular 
regionalisation scheme.