All the data, collected as previously stated, were input in a database and pre-processed in order to correct the preliminary legend and map. As for the landscape system, the subdivision made in the first phase was modified distinguishing four main land systems: plateau of Ben Slimane, Western scarp of plateau, Eastern scarp of plateau and Southern reliefs. According to the field observations, the landforms of the preliminary legend were not modified while the land cover description for "Open to the close forests" and "Bushes" was additionally subdivided in seven classes because it was deemed necessary to give a greater importance to the spectral answer of undergrowth in the areas with natural vegetation. Also the "Agricultural" land cover description of the preliminary legend was subdivided in: "Rainfed agriculture", "Rainfed agriculture-tree crops", and "Rainfed fallow agriculture" and three new classes were added in the final legend: "Bare soil", "Grassland (dayas)" and "Recreational area" (Table 7). We proceeded to modify the preliminary map according to the above mentioned field observations, correcting the land unit boundaries and relating them to the attributes of different facet percentages. For the Ben Slimane forest, where greater differences related to the land cover description were found, in order to modify the preliminary map, a methodology based on the variation of NDVI’s value between April and August 2000 was performed (paragraph 2.4).
The final land unit map was therefore realised differentiating the various polygons with relevés according to the main facet represented and associating the same identification code to each unit with the same attributes (Figure 4).
Figure 4 - Final map and relevés location. The background image is obtained by fusion of multispectral bands 4,3,2 (RGB) with panchromatic band of August 2000
|
LAND SYSTEM |
LAND FORM |
LAND UNIT |
LAND COVER / LAND USE |
VEGETATION |
SOIL |
|
PLATEAU OF BEN SLIMANE |
Flat planation surface |
1 |
Rainfed agriculture |
Vertisols |
|
|
Closed depressions (dayas) |
2 |
Grassland |
|||
|
3 |
Rainfed agriculture |
Solonetz |
|||
|
Undulating planation surface |
4 |
Rainfed fallow agriculture |
Kastanozems |
||
|
5 |
Association of Plinthosols, Kastanozems, Vertisols, Cambisols |
||||
|
6 |
Association of Luvisols, Plinthosols, Vertisols, Kastanozems |
||||
|
7 |
Sparse shrubs |
Kastanozems |
|||
|
8 |
Open forest with no undergrowth |
Quercus suber L. |
Plinthosols |
||
|
9 |
Open forest with a second layer of shrubs |
Quercus suber L. and Mediterranean shrubs |
|||
|
10 |
Open forest with a second layer of low shrubs |
Quercus suber L. and Cistus monspeliensis L. |
|||
|
11 |
Open forest with a second layer of shrubs – hunting reserve |
Quercus suber L. and Mediterranean shrubs |
|||
|
12 |
Open forest with a second layer of low shrubs - hunting reserve |
Quercus suber L. and Cistus monspeliensis L. |
|||
|
13 |
Afforestation |
Eucalyptus (camaldulensis Dehnh., gomphocephala A.DC.) and Pinus halepensis Mill. |
|||
|
Low residual crests |
14 |
Very open forest with a second layer of shrubs |
Quercus suber L. and Mediterranean shrubs |
||
|
High residual crest (skhour) |
15 |
Rocks and sparse low shrubs |
Mediterranean shrubs |
Cambisols |
|
|
Accumulation footslope |
16 |
Rainfed fallow agriculture |
|||
|
17 |
Very open high shrubs |
Rhus pentaphylla (Jacq.) Desf., Cistus salvifolius L., Chamaerops humilis L. |
|||
|
18 |
Open forest with a second layer of shrubs |
Quercus suber L. and Mediterranean shrubs |
Association of Luvisols and Cambisols |
||
|
WESTERN SCARP OF PLATEAU |
Accumulation slopes |
19 |
Rainfed fallow agriculture |
Association of Vertisols and Kastanozems |
|
|
20 |
Sparse shrubs |
Mediterranean shrubs |
Luvisols |
||
|
21 |
Bare soil |
Kastanozems |
|||
|
Alluvial valley bottom |
22 |
Rainfed agriculture |
|||
|
23 |
Rainfed agriculture - tree crops |
||||
|
EASTERN SCARP OF PLATEAU |
Dissected sloping area |
24 |
Rainfed fallow agriculture |
Plinthosols |
|
|
25 |
Open shrubs |
Mediterranean shrubs |
Kastanozems |
||
|
26 |
Open forest with a second layer of open shrubs |
Tetraclinis articulata (Vahl.) Masters and Mediterranean shrubs |
Association of Luvisols and Cambisols |
||
|
27 |
Very open forest with a second layer of shrubs |
Tetraclinis articulata (Vahl.) Masters and Mediterranean shrubs |
Association of Luvisols, Cambisols, Kastanozems and Leptosols |
||
|
28 |
Afforestation |
Pinus halepensis Mill. |
Association of Cambisols and Leptosols |
||
|
SOUTHERN RELIEFS |
Flat topped hills |
29 |
Rainfed fallow agriculture |
Association of Luvisols and Cambisols |
|
|
30 |
Kastanozems |
||||
|
31 |
Luvisols |
||||
|
32 |
Sparse low shrubs |
Cistus salvifolius L. |
|||
|
33 |
Very open low shrubs |
Chamaerops humilis L., Olea europaea var. oleaster DC., Pistacia lentiscus L. |
Association of Luvisols and Leptosols |
||
|
34 |
Sparse forest with a second layer of open low shrubs |
Quercus suber L. and Cistus monspeliensis L. |
Association of Luvisols and Cambisols |
||
|
35 |
Closed and medium to high shrubs |
Mediterranean shrubs |
Luvisols |
||
|
36 |
Open forest |
Tetraclinis articulata (Vahl.) Masters |
Leptosols |
||
|
37 |
Afforestation |
Pinus halepensis Mill. |
Cambisols |
||
|
U |
Urban area, depurator, military airport |
||||
|
R |
Recreational area |
||||
|
Q |
Quarry |
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Table 7 - Final legend