This section describes each Land Unit according to the Landscape Systems and the Landforms it belongs to.
The description refers to the unit’s "reference" facet, defined as the dominant facet (as percentage of the total area) among the ones identified and described in the field-forms. Since a good, and thus complete, knowledge of a land unit can only be achieved elaborating the total amount of acquired information, the "other facets in the unit" description (if present) is the best item to obtain that knowledge; and this must be always taken into account.
Each Land Unit is provided with the following information:
- area (km2);
- relevé/s belonging to the unit being described;
- land cover;
- vegetation (if present);
- land use;
- soil type;
- morphology;
- geology;
- other facets in the unit (if present);
Total area: 87.41km2.
Land Unit: 1.
Land Unit 1 (87.41km2).
Relevés - 104 and 111.
Land use - rainfed agriculture.
Soils - Vertisol.
Morphology - flat unit located in the middle of the study area. Any presence of erosional process close to the border of the plateau is due to the incoherence of these areas.
Geology - Black soils (tirs), calcarenites (Moghrebien, superior and middle of the Pliocene), and triassic basalts.
Note - the area is highly suitable for agriculture but, in some partsto improve land capability class, a stone removal intervention should be done. Mostly unsuitable for forestry.
Total area: 6.66km2.
Land Units: 2 and 3.
Land Unit 2 (2.88km2)
No data available.
Land Unit 3 (3.78km2)
Relevés - 123 and 408.
Land use - rainfed agriculture.
Soils - Solonetz.
Morphology - typical of the Ben Slimane plateau, these closed depressions have sub-circular shapes. The bottom part is flat and substratum materials can occasionally outcrop. Generally the erosional processes are stopped.
Geology - Gray black soils of dayas above the calcarenite (Moghrebien, superior and middle of the Pliocene).
Note - in most of the cases extensive grazing can be the only solution for land exploitation due to the insufficient soil drainage that induces long periods of waterlogging. Salinity is another limiting factor.
Total area: 271.29km2.
Land Units: 4, 6, 5, 7, 10, 12, 13, 8, 9, and 11.
Land Unit 4 (7.78km2)
Relevés - 213 and 118.
Land use - rainfed fallow agriculture.
Soils - Kastanozem.
Morphology - this unit, 3-10% sloping, is composed by dune calcarenites that give to the area an undulating morphology. The parent material is weak and presents some erosional active process. The rills are 30cm deep and moderately spaced.
Geology - Sandstones calcareous of the Soltanien-Villafranchien (Pleistocene).
Note - area with limitation in soil characteristic (alkaline soil) that doesn’t allow a wide range of crop choices.
Moderately suitable for afforestation.
Land Unit 5 (133.26km2)
Relevés - 310, 117, 301, 304, 317, 418, 216, 222, and 313.
Land use - rainfed fallow agriculture.
Soils - Plinthosol-Kastanozem-Vertisol-Cambisol.
Morphology - undulating unit of the plateau of Ben Slimane with occasional erosional processes. The slope classes varies from 1 to 3%.
Geology - Sandstones, rock outcrops of quartzites.
Other facets in the unit - gently sloping areas on siltstones covered with vineyards (9% of the unit area), gently sloping agricultural areas on limestones (8% of the unit area), very gently surfaces on quartzites covered with tree crops (3% of the unit area).
Note - area cultivated mainly with graminoids and vineyards. Fruit tree cultivation can be expanded.
Highly suitable for Eucalyptus camaldulensis plantation.
Land Unit 6 (24.62km2)
Relevés - 206, 201, 202, 218, 204 and 110.
Land use - rainfed fallow agriculture.
Soils - Luvisol-Plinthosol-Vertisol-Kastanozem.
Morphology - It represents the changing part between two land systems. It is represented by an homogeneous geomorphology, more or less undulating according to the geological substratum units. The erosional processes are not very strong.
Geology - Silty claystones, schists of the Devonian.
Other facets in the unit - gently sloping vertisols on limestones (15% of the unit area), very gently sloping surfaces on alluvial deposits covered with Olea spp. (5% of the unit area).
Note - stony subacid soil suitable for agricultural crops, even if with some limitation.
Highly suitable for Eucalyptus camaldulensis plantation.
Note - since the following land units belong to the same morphological type, Morphology description is reported only in land unit 5.
Land Unit 7 (0.71km2)
Relevé - 306.
Land cover - sparse shrubs.
Vegetation - Chamaerops humilis L., Asphodelus microcarpus Viv.
Land use - extensive grazing.
Soils - Kastanozem.
Geology - Sandstones with rock outcrops of calcareous (Soltanien, Villafranchian-Pleistocene).
Other facets in the unit - Flat agricultural surfaces on limestones (10% of the unit area).
Note - shallow soil; grazing should be forbidden. Onions could be grown.
Highly suitable for Eucalyptus camaldulensis and Pinus halepensis.
Land Unit 8 (7.78km2)
Relevé - 221.
Land cover - open forest with no undergrowth.
Vegetation - Quercus suber L.
Land use - extensive grazing, wood and cork collection.
Soils - Plinthosol.
Geology - Brown silt with pisolithes of the Soltanien, Villafranchian (Pleistocene).
Note - same as land unit 10.
Land Unit 9 (36.13km2)
Relevés - 215, 106, 410, 411, 305, 319, and 114.
Land cover - open forest with a second layer of shrubs.
Vegetation - Quercus suber L., Pistacia lentiscus L., Cistus (monspeliensis L. and salvifolius L.).
Land use - extensive grazing, wood and cork collection.
Soils - Plinthosol
Geology - Brown silts with pisolithes of the Soltanien, Villafranchian (Pleistocene).
Other facets in the unit - very gently sloping areas on schists covered with Quercus suber and Cistus monspeliensis (10% of the unit area).
Note - Moderately suitable for forestry. The cover of Quercus suber should be developed and the cork exploitation implemented in a proper way.
Land Unit 10 (33.71km2)
Relevés - 115, 311, and 412.
Land cover - open forest with a second layer of low shrubs.
Vegetation - Quercus suber L., Cistus monspeliensis L.
Land use - extensive grazing, wood and cork collection.
Soils - Plinthosol.
Geology - Sandstones, limestones, and schists of the Carboniferous.
Note - Quercus suber L. is highly suitable for natural management; its cover should be developed and cork exploitation implemented in a proper way. Highly suitability also for Eucalyptus camaldulensis for wood production.
Land Unit 11 (5.61km2)
Relevés - 409.
Land cover - open forest with a second layer of shrubs.
Vegetation - Quercus suber L., Pistacia lentiscus L., Cistus monspeliensis L., Arbutus unedo L.
Land use - hunting reserve.
Soils - Plinthosol.
Geology - Brown silts with pisolithes of the Soltanien, Villafranchian (Pleistocene) above sandstones, limestones, and schists (Carboniferous).
Note - same as land unit 9.
Land Unit 12 (3.53km2)
Relevés - 309 and 312.
Land cover - open forest with a second layer of low shrubs.
Vegetation - Quercus suber L., Cistus monspeliensis L.
Land use - hunting reserve.
Soils - Plinthosol.
Geology - Brown silts with pisolithes of the Villafranchian, Pleistocene above the sandstones, limestones and schists (Carboniferous).
Note - tree cover should be increased because it is suffering from Lymantrya dispar and drought. In spite of the exclusion of grazing animals, cork oak condition appear weakened. Reasons for this contradiction should be further investigated.
Land Unit 13 (18.15km2)
Relevés - 214, 314, 105, and 318.
Land cover - artificial forest.
Vegetation - Eucalyptus camaldulensis Dehnh., E. gomphocephala A.DC., Pinus halepensis Mill.
Land use - afforestation.
Soils - Plinthosol.
Geology - Sandstones, limestones, and schists of the Carbonifeours.
Note - Highly suitable for Eucalyptus camaldulensis for wood production.
Total area: 4.99km2.
Land Unit: 14.
Land Unit 14 (4.99km2)
Relevé - 223.
Land cover - very open forest with a second layer of shrubs.
Vegetation - Quercus suber L., Olea europaea var. oleaster DC., Cistus salvifolius L.
Land use - extensive grazing, wood, and cork collection.
Soils - Cambisol.
Morphology - The unit is mainly composed by quartzite rocks forming a very gentle morphology (slope 3%). Sometimes bedded structures are present but not always recordable. Sheet erosion only but rocks show atmospheric and chemical alteration phenomena.
Geology - Schists, psammites, micaceous quartzites with a level of iron ooliths of the Ordovician.
Note - the land capability class (III) is related to rock outcrops and superficial stones that limit the possibility of cultivation if not removed; still the area can be suitable for a wide range of crops. No soil data were available. Moderately suitable for forestry; goat grazing should be forbidden to protect the present cork oak regeneration.
Total area: 0.57km2.
Land Unit: 15.
Land Unit 15 (0.57km2)
Relevé - 316.
Land cover - rocks and sparse low shrubs.
Vegetation - Chamaerops humilis L., Cistus salvifolius L.
Soils - Cambisol.
Morphology - it represents the substratum of Ben Slimane city. The steep slopes of elongated and very dissected quartzite are the main features of the study area. They are the witnesses of the strong tectonic and erosional past processes, which have occurred in the whole area.
Geology - Quartzites and conglomerates of the Carboniferous-Devonian.
Other facets in the unit - very gently sloping areas covered with Quercus suber and Cistus monspeliensis on quartzite (15% of the unit area).
Note - the area, due to the shallow soil and to the surface and soil stoniness, is not suitable for any kind of exploitation except marginally for forestry.
- Accumulation footslope
Total area: 6.39km2.
Land Units: 16, 17, and 18.
Land Unit 16 (2.64km2)
Relevé - 103.
Land use - rainfed fallow agriculture.
Soils - Cambisol.
Morphology - this land unit represents the footslope in the bottom of Ben Slimane quartzite, with slope between 10 and 32%. On the slope diffuse erosional sheet processes were recognised. Highly suitable for Eucalyptus camaldulensis plantation.
Geology - Gray silts of lower fluvial terraces and mass of fallen rocks of quartzites (Carboniferous-Devonian).
Note - the soil needs careful management to prevent erosion processes. A permanent grass cover with olive trees plantation can be suggested.
Land Unit 17 (1.41km2)
Relevé - 124.
Land cover - very open high shrubs.
Vegetation - Rhus pentaphylla (Jacq.) Desf., Cistus salvifolius L., Chamaerops humilis L.
Land use - extensive grazing.
Soils - CAMBISOL
Morphology - this land unit represents the footslope in the bottom of Ben Slimane quartzite, with slope between 10 and 32%. On the slope we can recognise diffuse erosional sheet processes. Geology - Gray silts of lower fluvial terraces (Holocene) and mass of fallen rocks of quartzites and conglomerates (Carboniferous-Devonian).
Other facets in the unit - moderately inclined bare surfaces on quartzite (15% of the unit area).
Note - the soil is very stony and shallow, so limiting the exploitation to extensive grazing. Highly suitable for Pinus halepensis plantation.
Land Unit 18 (2.34km2)
Relevés - 125, and 217.
Land cover - open forest with a second layer of shrubs.
Vegetation - Quercus suber L. forest, Cistus salvifolius L., Rhus pentaphylla (Jacq.) Desf.
Land use - extensive grazing, wood, and cork collection.
Soils - LUVISOL-CAMBISOL.
Morphology - this land unit represents the footslope in the bottom of Ben Slimane quartzite, with slope between 10 and 32%. On the slope diffuse erosional sheet processes were recognised.
Geology - Quartzites and conglomerates of the Carboniferous-Devonian.
Other facets in the unit - steep surfaces with shrubs on quartzite (10% of the unit area).
Note - the area presents a good loamy texture, but due to coarse fragment presence and to the shallow soil it is more suitable for forestry purposes. Quercus suber cover should be improved, for naturalistic forestry’s purposes.
Total area: 49.42km2.
Land Units: 19, 20, and 21.
Land Unit 19 (38.86km2)
Relevés - 402, 403, and 205.
Land use - rainfed fallow agriculture.
Soils - Vertisol-Kastanozem.
Morphology - the land unit is located in the bottom of the plateau and it is composed by the materials coming from the high surfaces. It is moderately inclined (about 13-20%) and mainly composed by tirs and basaltic formation. Locally erosional processes are present but non very intense.
Geology - In this part the predominant lithology is the doleritic basalts of the Trias above the red siltstones (Trias).
Other facets in the unit - moderately inclined vertisols on calcarenite (35% of the unit area); moderately inclined cultivated fields on basaltic rocks (15% of the unit area).
Note - the land unit is affected by rock outcrops and surface stoniness that limits the agricultural utilisation for fruit trees like olive trees and vineyards. Unsuitable for forestry, moderately suitable for Eucalyptus camaldulensis plantation.
Land Unit 20 (4.18km2)
Relevés - 112 and 113.
Land cover - sparse shrubs.
Vegetation - Rhus pentaphylla (Jacq.) Desf., Chamaerops humilis L..
Land use - extensive grazing.
Soils - Luvisol And Regosol.
Morphology - the surface of this unit is characterised by 40% steep slopes. In some cases moderate erosional processes, that model the area, are evident.
Geology - Schists, flyschs, and graptolithic limestones intercalations of Silurian,
Other facets in the unit - moderately inclined bare surfaces on claystones (15% of the unit area); steep surfaces with Eucaliptus spp. plantations on schists (10% of the unit area).
Note - the area is not suitable for agriculture; it needs to be excluded from grazing (to limit the erosion processes) and covered with forest plantations, for example of Tetraclinis articulata.
Land Unit 21 (6.37km2)
Relevés - 404 and 405.
Land cover - bare soil.
Soils - Kastanozem And Regosol.
Morphology - moderately inclined unit (40%). In some cases moderate erosional processes, that model the area, are evident.
Geology - Silty claystones and weathered rocks of Devonian schists.
Other facets in the unit - moderately inclined surfaces on limestones covered with dwarf shrubs, mainly Chamaerops spp. (40% of the unit area).
Note - same as land unit 20, but with more severe erosion dynamics. It could be afforested with Tetraclinis articulata, highly suitable for soil conservation.
Total area: 5.41km2.
Land Units: 22 and 23.
Land Unit 22 (4.68km2)
Relevé - 406.
Land use - rainfed agriculture.
Soils - Kastanozem.
Morphology - flat area corresponding to the alluvial terraces of the valley bottom of Oued Nefifikh.
Geology - Gray silts of oued and lower fluvial terraces of Holocene.
Note - the area, presenting deep soil and no coarse fragment on the surface, is suitable for a wide range of crops (especially safflower) and can be converted to fruit tree plantations.
Land Unit 23 (0.73km2)
Relevé - 208.
Land use - rainfed agriculture, tree crops.
Soils - Kastanozem.
Morphology - flat area corresponding to the alluvial terraces of the valley bottom of Oued Nefifikh. Alluvial deposits fill these units.
Geology - Gray silts of oued and lower fluvial terraces on top of the doleritic basalts of the Trias,
Note - same as land unit 22.
Total area: 41.6km2
Land Units: 24, 25, 26, 27, and 28
Note - since all the following Land Units belong to the same morphological type, this feature’s description was reported only in land unit 24.
Land Unit 24 (8.76km2)
Relevé - 122.
Land use - rainfed fallow agriculture.
Soil - Plinthosol.
Morphology - very steep unit influenced by past strong tectonic activity. These land units are also strongly influenced by geology and human activities. Erosional processes are partially stopped by the abundant vegetation cover.
Geology - Limestones interbedded with clay (Devonian).
Other facets in the unit - moderately sloping areas on quartzites covered with dwarf shrubs, mainly Chamaerops spp. (20% of the unit area).
Note - due to the steep slope, the area should be managed to prevent erosion processes and to limit agricultural areas development to detriment of forest plantations. Safflower could be suitable.
Land Unit 25 (5.18km2)
Relevé - 423
Land cover - open shrubs.
Vegetation - Pistacia lentiscus L., Olea europaea var. oleaster.
Land use - extensive grazing.
Soils - Kastanozem.
Geology - Schists, flyschs, and graptolithic limestones of the Devonian-Silurian.
Other facets in the unit - moderately sloping areas on limestones covered with dwarf shrubs, mainly Chamaerops spp. (40% of the unit area).
Note - the area is not suitable for agriculture due to a high susceptibility to erosion. Forest plantation should be planned.
Land Unit 26 (9.53km2)
Relevés - 121, 321, 413, and 415
Land cover - open forest with a second layer of open shrubs.
Vegetation - Tetraclinis articulata (Vahl.) Masters, Pistacia lentiscus L., Phillyrea latifolia L., Olea europaea var. oleaster.
Land use - extensive grazing
Soils - Luvisol-Cambisol.
Geology - Silty claystones of the Devonian.
Other facets in the unit - moderately sloping areas on schists covered with shrubs (30% of the unit area), very gently sloping surfaces on schists covered with Eucalyptus spp. plantation (10% of the unit area).
Note - forest cover should be preserved to protect this sloping area.
Land Unit 27 (12.99km2)
Relevés - 116, 315, 320, 416, and 417.
Land cover - very open forest with a second layer of shrubs.
Vegetation - Tetraclinis articulata (Vahl.) Masters, Pistacia lentiscus L., Phillyrea latifolia L., Olea europaea var. oleaster, Cistus monspeliensis L.
Land use - extensive grazing.
Soils - Luvisol-CambisoL-Kastanozem-Leptosol.
Geology - Sandstones, limestones, and schists of the Carboniferous.
Other facets in the unit - moderately sloping areas on limestones covered with Tetraclinis spp. and shrubs (20% of the unit area), moderately sloping areas on limestones covered with shrubs (10% of the unit area).
Note - the soil is very stony and does not allow agricultural activity. The area should be left with natural vegetation trying to increase the tree cover with new plantations of Tetraclinis ariculata.
Land Unit 28 (5.13km2)
Relevés - 108, 109, and 302.
Land cover - artificial forest.
Vegetation - Pinus halepensis Mill., Cistus monspeliensis L., Pistacia lentiscus L..
Land use - afforestation.
Soils - Cambisol-Leptosol.
Geology - Brown silt with pisolithes above the conglomerates and quartzite of the Carboniferous Devonian.
Other facets in the unit - steep sloping areas on schists covered with shrubs (25% of the unit area).
Note - the area is highly susceptible to erosion.
Total area: 131.69km2.
Land Units: 32, 35, 33, 29, 36, 37, 34, 30 and 31.
Note - since all the following land units belong to the same morphological type, Morphology description is reported only in land unit 32.
Land Unit 29 (32.78km2)
Relevés - 120 and 219.
Land use - rainfed fallow agriculture.
Soils - Luvisol-Cambisol.
Geology - Calcareous schists of the Devonian, rock outcrops of vertically bedded limestones.
Other facets in the unit - gently sloping cultivated fields on siltstones (35% of the unit area), moderately sloping areas covered with dwarf shrubs mainly Chamaerops spp. on schists (15% of the unit area), gently sloping surfaces on limestones covered with dwarf shrubs mainly Chamaerops spp. (10% of the unit area).
Note - not suitable for agriculture (soil is too shallow) and marginally suitable also for forestry. Eucalyptus camaldulensis could be used.
Land Unit 30 (5.40km2)
Relevé - 207.
Land use - rainfed fallow agriculture.
Soils - KASTANOZEM.
Geology - Black soils (tirs) above the calcarenite (Moghrebien, superior and middle Pliocene))
Other facets in the unit - gently sloping areas covered with tree crops (10% of the unit area).
Note - this land unit is suitable for agricultural crops such as wheat, barley, sorghum, safflower, vineyard, and Eucayptus camaldulensis plantation for wood production.
Land Unit 31 (6.17km2)
Relevés - 308, 126, and 212.
Land use - rainfed fallow agriculture.
Soils - Luvisols.
Geology - Silty clays with schists and limestones rock outcrops.
Other facets in the unit - gently sloping areas on limestones covered with dwarf shrubs, mainly Chamaerops spp. (30% of the unit area).
Note - the area is suitable for all the herbaceous crops analysed, with an S1 rating for sorghum; it is also suitable for Eucalyptus camaldulensis plantation for wood production.
Land Unit 32 (4.69km2)
Relevé - 210.
Land cover - sparse low shrubs.
Vegetation - Cistus salvifolius L.
Land use - extensive grazing.
Soils - Luvisol.
Morphology - this land unit belongs to the "Flat Topped Rolling Southern Hills" land system. It is characterised by several morphological processes that give the area its typical land, dissected and flat on the tops. The slopes vary from flat (0-1%) to steep (32-56%). Erosional processes are more or less heavy, according to geology formations.
Geology - Claystones with schists, and limestones rock outcrops.
Other facets in the unit - gently sloping bare surfaces on quartzite (10% of the unit area).
Note - this areas should be afforested with Pinus halepensis, highly suitable for wood production.
Land Unit 33 (2.81km2)
Relevés - 120 and 219.
Land cover - very open low shrubs.
Vegetation - Pistacia lentiscus L., Olea europaea var. oleaster, Chamaerops humilis L.
Land use - extensive grazing.
Soils - Luvisol-Leptosol.
Geology - Brown silt with pisolithes and limestones rock outcrops.
Note - This area should be afforested with Pinus halepensis for soil conservation.
Land Unit 34 (36.51km2)
Relevés - 420, 419, 102, and 421.
Land cover - sparse forest with a second layer of open low shrubs.
Vegetation - Quercus suber L., Cistus monspeliensis L.
Land use - extensive grazing, wood, and cork collection.
Soils - Luvisol-Cambisol.
Geology - Calcareous schists of the Devonian.
Other facets in the unit - moderately sloping surfaces on claystones with Eucaliptus spp. and Pinus halepensis plantations (20% of the unit area).
Note - not suitable for agriculture; forest plantation should be planned to prevent erosional process.
Land Unit 35 (10.71km2)
Relevés - 211 and 422.
Land cover - closed medium to high shrubs.
Vegetation - Pistacia lentiscus L., Olea europaea var. oleaster, Philyrea latifolia L.
Land use - extensive grazing.
Soils - Luvisol.
Geology - Calcareous schists of the Devonian.
Other facets in the unit - moderate sloping surfaces covered by Quercus suber and shrubs on sandstones (40% of the unit area).
Note - High suitability for Pinus halepensis, for wood production and soil conservation.
Land Unit 36 (6.91km2)
Relevé - 119.
Land cover - open forest.
Vegetation - Tetraclinis articulata (Vahl.) Masters.
Land use - wood collection, extensive grazing.
Soils - Leptosol.
Geology - Black limestones of the Devonian.
Other facets in the unit - moderately sloping areas on sandstones mainly covered with Tetraclinis spp. (20% of the unit area).
Note - shallow soil, not appropriate for agriculture; moderately suitable for forestry.
Land Unit 37 (25.70km2)
Relevés - 303 and 307.
Land cover - artificial forest.
Vegetation - Pinus halepensis Mill, Cistus monspeliensis L., Pistacia lentiscus L.
Land use - afforestation.
Soils - Cambisol.
Geology - Shifts with graptolithic limestone intercalations.
Other facets in the unit - steep sloping areas with shrubs, mainly Cistus monspeliensis, on sandstones (20% of the unit area).
Note - in the last 15 years the forest plantation reduced the erosion processes. Pinus halepensis and Tetraclinis articulata should be adopted instead of Eucalyptus camaldulensis.
Recreational and urban areas, depurator, military airport and quarries
- Golf, quarries and town
Total area: 12.04km2.
Land Units: Q, U, and R.
Land Unit Q (1.41km2)
Land use - quarry.
Land Unit U (8.63km2)
Land use - urban area, military airport, and depurator.
Land Unit R (2.00km2)
Land use - recreational area.