The five countries of North Africa included in the project (Algeria, Egypt, Libya, Morocco and Tunisia) cover a total area of 5,738,390 km2. There is a high degree of demographic pressure in these lands: in 1990 the population was 115.3 million, giving an average density of 20 inhabitants per km2, with an annual growth rate of 2.7 per cent between 1981 and 1990. The total area of natural forests is 5,655,000 ha, or only 1 per cent of the total land area, while their potential area is 14 per cent.
North Africa's woody formations (texts taken from H. Marchand's report on the forest resources of North Africa, 1986) may be characterised to a greater degree than other Mediterranean basin countries by two main features: their floristic and sociological heterogeneity and their instability, both of which stem from several factors:
the region's geographical and geomorphological diversity;
the variety in climatic conditions, in time and space, and particularly the combination of temperature and humidity;
man's ancestral presence and his impact on the development of forest formations.
The harshness of most of the ecological factors, the archaic nature and isolation of certain species, the persistence over time of a negative effect of man and animals have destabilised the formations in a consistently negative way. At the beginning of man's era the forest mantle covered a much larger area than it does today. More than three-quarters of this mantle has since disappeared, the rate of contraction accelerating with the increase in human and animal numbers. The more or less rapid transformation of forests into bushy formations, then into steppes and grassland, continues to this day. Competition between dominant species, whether or not favoured by human influences continues imperceptibly, and the original climatic climax vegetation is hardly perceptible.
This results in a certain difficulty in classifying the various plant associations against bioclimatic stages, all the more so since most of the principal species are relatively flexible with respect to the ecological conditions. This leads one to differentiate woody formations by their general shape morphology, and according to the dominant species, by putting them in three main phytogeographical areas: Mediterranean, sub-Mediterranean and Saharan.
A. MEDITERRANEAN AREA
1. Mediterranean broad leaved forests
Holm oak forest: Quercus ilex is found at all altitudes, between 400 m up to the limits of forest vegetation, but it is more a tree of cold mountain regions, in the semi-arid, sub-humid and moist layers. Its ecology is very varied. It is good at resisting adverse factors such as being cut, pasture or fire since it grows again vigorously from a stump.
Cork oak forest: Quercus suber inhabits distinct but large areas throughout the Maghreb, in the semi-arid, sub-humid and moist layers. It extends lower down and is found at higher altitudes than the Holm oak. It is calcifugous.
Kermes oak forest: Quercus coccifera is only found in small stations near the coast in Morocco and Tunisia. It is a small tree (1 to 3m), often bushy, and associated with Phoenician juniper, lentiscus, oleaster, yew and a variety of bushes.
The degradation of sclerophyllous evergreens leads successively to the following formations:
|on chalky soils:||sparse vegetation of Kermes oak or rosemary, followed by a turf of brachypodes;|
|on silica soils:||mixed Holm oak/cork oak forest, followed by high matorral, arborescent heather and arbutus, then cistus, and finally a turf of helianthus.|
2. Broad leaved forests of Mediterranean oaks
Zeen oak forest: Quercus faginea is found in the three Maghreb countries. It is a tree of the moist level, growing at altitude on cool and shaded slopes. Stands are often pure and dense. They re-seed themselves in abundance.
Afares oak forest: Quercus afares only occurs in Algeria. It is a species closely related to the Zeen oak, but it favours relatively dry slopes.
The degradation of deciduous forests leads successively to a wood made up of chewed shoots, an open wood with abundant under-storey, a bushy formation of secondary species containing a few oaks, themselves also bushy, and finally a turf of fern, diss and asphodel.
3. Mediterranean coniferous forests
Aleppo pine forest: Pinus halepensis grows in semi-arid and sub-humid layers: it a typical low altitude xerophilous and thermophilous species.
Degradation of Aleppo pine leads to a low vegetation such as rosemary garrigue in the north, to alfa grass steppe and then artemisia (Artemisia herba alta) in the south.
Phoenician juniper: Juniperus phoenica is frequently associated with the Aleppo pine and the Holm oak under good conditions. When the forest is degraded, it subsists alone.
Thurifer juniper forest: Juniperus thurifera is a tree of the high semi-arid and cold regions of Algeria and Morocco (Aurès). It is generally only found in a dispersed and disfigured state. It is often the final witness of cedar forests since disappeared.
Atlas cedar forest: Cedrus atlantica is North Africa's most beautiful tree; it rises to a height of 60 m. It is only found in Morocco and in the Algerian Aurès, in the mountains of moist and sub-humid layers.
Degradation of cedar forests produces thickets of Q. ilex with Juniperus oxycedrus, Crataegus sp., followed by a Fescue turf grass in a dispersed state. At upper mountain levels, after J. thurifera, one finds communities of prickly bushes.
Maritime pine forest: Pinus pinaster is a moist and sub-humid mountain tree. In total it only covers a few thousand hectares. It may consist of pure or mixed populations.
Berber thuja forest: Tetraclinis articulata is a xerophilous and thermophilous species which is extremely sensitive to moist cold. Nevertheless it is widespread in the semi-arid south-west of Morocco influenced by the sea. It grows in highly populated regions and has been extensively cleared and degraded. It is replaced by rosemary (Rosmarinus officinalis) and heather (Erica multiflora).
4. Arboreal Oleolenticetum formations
These formations are sometimes viewed as a climax but instead they appear to be the first stage of degradation of forests from the semi-arid layer. In any event they are the ones which have suffered most from man's activities, cultivation and grazing, because they grow on compact clayey but generally fertile soils in the semi-arid layers. The characteristic species is the Oleaster (Olea europea) which is found mixed with the Atlas pistachio tree, the carob tree, the jujube and the monogynous hawthorn.
5. Mediterranean shrub and bush formations
Bushy high mountain formations: these exist above the limits of forest vegetation, and consequently almost exclusively in Morocco. They consist of spiny vegetation in the form of dwarf cushions and bushes, and are of no forestry interest.
Mediterranean brushland and garrigue: their very varied appearance is similar to that of Oleolenticetum. However they are fairly well advanced forms of forest formation degradation, coming between forest formations and turf grass. The wood volume is not negligible, but it is no longer a wood of significant volume.
B. SUB-MEDITERRANEAN DOMAIN
Argania bush formations: Argania spinosa is a tree from the semi-arid and arid levels influenced by the sea which only exists in the south-west of Morocco. Its under-storey is bushy when the formation has not altered; however, the areas where it is found are nearly always degraded or intensively grazed.
Acacia bush formations: Acacia gummifera and Ziziphus lotus meet in the arid part of the Mediterranean layer, or in the transition layer between the Sahara and the Mediterranean. In the salty sectors within this zone trees disappear and are replaced by atriplex halimus.
Steppe formations: these formations are generally asylvatic. However, in high plain regions occasional trees or bushes are found on rocky points, such as Juniperus phoenicea, and Olea europea, which would tend to show that the various forms of bushy and grassy vegetation of theses steppes constitute the final stage in the degradation of dry evergreen forests of Holm oak, Aleppo pine or juniper.
C. SAHARAN DOMAIN
Along the wadi beds in the moist non salty sectors at the beginning of the desert one finds sub-desertic vegetation associations, composed of herbaceous vegetation or shrubs and dominated by sparse trees. Several trees and bushes subsist in the mountains of the Sahara above an altitude of 1800 m, and in gorges between 1200 m and 1800 m, vestiges of an ancient Mediterranean vegetation. The last natural specimens of Cupressus duprezziana may be found in the Tassili and Ajjer.
The group of countries making up the Near East 1 included in this study cover a total area of 6,008,510 km2. Its population in 1990 was 141.7 million inhabitants, giving an average density of 24 inhabitants per square kilometre. This figure, while low in absolute terms, is actually considerable when one takes into account the region's immense desert, or at least arid areas. Natural forests only cover 3,339,000 ha, i.e. only 0.6 per cent of the total area of the lands, and the wooded land per inhabitant is therefore 0.02 ha/inhabitant, significantly lower than the world average of 0.60 ha/inhabitant, all the more so since the state of these wooded lands is significantly below the average.
Natural woody formations in the Near East range from desert, including some low vegetation with woody stems, to dense temperate broad leaved high forest (Iran) or coniferous forest (Afghanistan). At the two extremes of the range, classification is relatively easy, since access by man and his herds is difficult and consequently his influence is very limited. Everywhere else, man's influence on his environment is marked; more or less continuous developments occur ever more rapidly, and truly typical situations exist only very rarely.
Most forestry formations may be classified by their climatic complex category, as a result of man and livestock. The type of vegetation in the Near East depends, more than elsewhere, on the climate. For this reason the following vegetation formation summaries are split by climate and in particular by bioclimate.
Tropical and sub-tropical climates correspond to:
more or less dense forest and forest-savanna formations of Juniperus procera (Yemen) associated at altitude with Podocarpus gracilior;
pseudo-steppe and shrub or wooded savanna, thickets and dry forests of Olea chrysophylla and Dodonea viscosa (Saudi Arabia, Yemen);
pseudo-steppe and bushy shrub or wooded savanna and thickets of Euphorbia amac and Themeda triandra (mountains of Saudi Arabia, Yemen).
Accentuated sub-desertic and hot and temperate desert climates correspond to several perennial formations of scrub, bushes, succulent, graminaceous species, etc.
Attenuated Mediterranean and sub-desertic climates correspond to several types of wooded and non-wooded shrubby or bushy steppe or pseudo steppe.
Cold climates with dry temperate summers correspond to several categories of more or less wooded steppe, and real forests;
steppe and high mountain turf grass above the limits of forest vegetation (Afghanistan, Iran);
plateau and medium mountain steppe of Artemisia, devoid of trees and scrub (Afghanistan, Iran);
wooded and non-wooded steppe of Pistacia sp., Juniperus sp., Amygdalus sp. (Afghanistan);
formations over the layer of oak and juniper forests of varying degrees of degradation, the advanced stage of degradation of which consists of grasslands devoid of trees and scrub;
formations over the layer of semi-deciduous and deciduous forests;
formations over the layer of oaks and sub-Mediterranean eastern pines. (Quercus baloot, Pinus gerardiana);
formations over the layer of firs and cedars, which may end in steppe through degradation (Syria).
Temperate and cold desert climates at high mountain altitudes correspond to forms of grassland degradation.
Cold and temperate to cold desert and sub-desertic climates with hot summers steppe (northern Afghanistan) or more or less salty semi-deserts.
1 Afghanistan, Bahrain, Iran (Islamic Republic of), Iraq, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syrian Arab Republic, United Arab Emirates, Yemen.