Mediterranean woodlands and forests

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Cedar forests of the Mediterranean woodlands and forests, Morocco. @ C.Michael Hogan

The Mediterranean woodlands and forests ecoregion stretches from the coastal plains to the hills of northern Morocco, Algeria and Tunisia, and eventually surrounds the Atlas Mountains. To the north is the Alboran Sea, the westernmost element of the Mediterranean Sea.

The variety of substrates and climates leads to a diverse mix of vegetation including holm oak forests, cork oak forests, wild olive and carob woodlands, as well as extensive Berber thuya forest. This old, endemic North African conifer species is representative of the great diversity and endemism of both flora and fauna in this ecoregion.

Reptile diversity is high and the region harbors charismatic large mammals, including the rare and endangered Barbary leopard. Unfortunately, this region contains expanding human populations and is enduring widespread deforestation.

Location and General Description

caption WWF

The Mediterranean woodlands and forests ecoregion includes the lowlands and mid-elevations of the northern half of Morocco, Algeria, and Tunisia, and two Spanish sovereign areas, Ceuta and Melilla, located in Morocco. An additional, isolated portion of the ecoregion is located in the Cyrenaic Peninsula of Libya. Coastal plains characterize this ecoregion in the northern half of the Atlantic coast of Morocco and in the eastern coast of Tunisia. Hilly land, valleys and plateaus alternate in the hinterland.

Geologically, the ecoregion is extremely diverse, and consists of a large variety of Mesozoic and Quaternary sedimentary rocks – such as sand, sandstone, conglomerate, mudstone, limestone, dolomite, marl, and evaporite sediments, formed by desiccation in endorheic and coastal areas.

Climatically, the ecoregion experiences very hot and dry summers, with relatively mild and humid winters. Mean annual temperatures range from 13ºC to 19ºC, and the mean minimum temperature ranges from 1ºC to 10ºC. The portion of this ecoregion located on the Atlantic coast of Morocco is influenced by cold offshore currents, which tend to moderate the temperatures. Annual rainfall ranges from 350 to 800 millimeters (mm). A combination of various climates and diverse geology and topography results in many different forest types. Five major forest types are found in this ecoregion:

  1. xeric pine forests;
  2. Berber thuya (Tetraclinis articulata) forests;
  3. cork oak (Quercus suber) forests;
  4. holm oak (Quercus ilex) and holly oak (Quercus coccifera) forests; and,
  5. wild olive (Olea europaea and O. europaea subsp. maroccana) and carob (Ceratonia siliqua) woodlands and maquis.

The xeric pine forests are mainly distributed in the hinterland, at low elevations and on plateaus in Algeria and Tunisia, with some forests in Morocco as well. The climate is semi-arid, with annual rainfall ranging from 300 to 600 mm. The dominant canopy tree species is the Aleppo pine (Pinus halepensis), which is broadly distributed all over the lowlands and coastal strip of the Mediterranean region.

Xeric pine forests frequently constitute mixed stands with the evergreen holm oak (Quercus ilex subsp. ballota) and xeric juniper species (Juniperus phoenicea, J. oxycedrus). The Aleppo pine forests extend over 10,000 km2 in North Africa – 8550 km2 in Algeria, 2965 km2 in Tunisia, and about 650 km2 in Morocco - and constitute the southernmost Mediterranean forest type, serving as a tree-steppe belt in the ecotone between the Mediterranean forests and the grassland steppes (Mediterranean Dry Woodland and Steppe ecoregion). The forest understory composition is mainly characterized by shrubs, many of which also characterize seral scrub communities: Spiny broom (Calicotome villosa), Cistus clusii, Cretan rockrose (C. creticus), C. monspeliensis, Genista pseudopilosa, G. microcephala, G. spartioides, Coronilla juncea, C. valentina ssp pentaphylla, Rosmarinus officinalis, Thymelaea argentata, T. tartonraira, and Anthyllis cytisoides.

caption El Feidja National Park, Tunisia. (Source: Photograph by WWF-Canon/Michel Gunther)

The Berber thuya is a very old and endemic North African conifer species, whose closest relatives (Callitris sp.) are currently found in South Africa and Australia. The Berber thuya is one of only two Mediterranean conifer species that can be transformed into coppice woodlands (the Canary pine species (Pinus canariensis), endemic to some Macronesian Atlantic islands is the other). Berber thuya forests and woodlands are mainly distributed in the dry and mild lowlands and hills of the northern half of the Atlantic and Mediterranean coasts of Morocco, the western half of the Algerian coast, and some mountain areas along the northeastern coast of Tunisia. These forests extend over almost 10,000 km2 in North Africa – 7500 km2 in Morocco, 1600 km2 in Algeria, and about 220 km2 in Tunisia - mainly on limestone substrates. Low temperatures and especially frosts in the high hinterland areas confine the Berber thuya forests to the milder lowlands. The forest understory composition is mainly characterized by very thermophilous shrubs species, which also characterise seral scrub communities: Calycotome infesta, Rhus pentaphylla, Lavandula dentata, Periploca angustifolia, Globularia alypum, Cistus clusii, C. monspeliensis, C. munbyi, Genista tricuspidata, G. erioclada, Cytisus arboreus, Rosmarinus officinalis, Ceratonia siliqua, Quercus coccifera, and Erica multiflora.

Cork oak forests are widely distributed in the entire western Mediterranean along the coast from low and medium elevations on siliceous substrates. In this ecoregion, they are found in northern Morocco along the coastal plains between Casablanca and the Rif, and in several hinterland areas around the Rif and Middle Atlas. They are in northern Algeria along the Tellien Atlas, and in northern Tunisia along the Kroumerie-Mogod mountain ranges. Cork oak forests grow from sea level up to 1,500 m in humid and warm climates. The annual rainfall here ranges from 600 to 800 mm and there is no frost appearance. These forests extend over almost 4,400 km2 in Algeria, 350 km2 in Morocco, and about 455 km2 in Tunisia. Cork oak forests are characterized by a very rich evergreen and subtropical-like mixing of small trees and high shrubs such as Laurus nobilis, Arbutus unedo, Erica arborea, Ilex aquifolium, Phillyrea latifolia, P. angustifolia, Viburnum tinus, Cytisus villosus, and Myrtus communis. There is also with a very representative liana layer, including Lonicera periclymenum subsp. hispanica, Smilax aspera subsp. mauretanica, Rubia peregrina var. longifolia, Hedera helix, and H. algeriensis.

Holm oak and holly oak forests extend in North Africa over 20,000 km2: 14,320 km2 in Morocco, 6,800 km2 in Algeria, and 15 km2 in Tunisia. They are widely distributed from the coast to the high altitudes (2,500 to 2,900 m) of the main mountain ranges. Holm oak is the most abundant tree species over the entire Mediterranean region. This widespread distribution occurs because the holm oak is an euryecious species which can withstand large temperature and rainfall ranges, and grow on a variety of substrates. The holm oak once covered extensive areas with deep and humid soils, which have mostly been transformed into agricultural land today. Only the holm oak forests and woodlands at lower altitudes are considered part of this ecoregion. Holly oak normally constitutes dense maquis and small forest stands under humid and warm climate on all types of substrates. A dense evergreen tree and high shrub layer containing Myrtus communis, Arbutus unedo, Chamaerops humilis, Pistacia lentiscus, Erica arborea, Phillyrea latifolia, as well as many liana species, characterize the holly oak formations.

Wild olive and carob woodlands and maquis were once widely spread along the fertile soil of the dry coastal and inland plains. Now, much of the region has been transformed into agricultural land. Only a few remnants – small stands of trees kept in sacred areas called "marabout"- maintain the natural structure of this forest type. Human impacts, mainly grazing, fires, and firewood collection, have transformed the majority of the remaining wild olive and carob plant communities into secondary dense shrubs, known as "maquis," and into agro-forestry landscapes comprised of scattered trees on grasslands or crops. Furthermore, wild olive and carob have been widely domesticated to produce olive oil and food/fodder, respectively. A large number of high shrubs or small trees characterize these woodlands and maquis such as the small palm tree Chamaerops humilis, Pistacia lentiscus, P. atlantica, Phillyrea latifolia, P. angustifolia, Myrtus communis, Ziziphus lotus, Withania frutescens, Rhus tripartita, Acacia gummifera, Ephedra fragilis, and E. altissima. Lianas such as Clematis cirrhosa, C. flammula, Smilax aspera, Dioscorea communis, Rubia peregrina, Bryonia dioica- and herbaceous species, including Arisarum vulgare, A. simorrhinum, Vinca difformis, Allium triquetrum, Acanthus mollis, Ballota hispanica frequently appeared within the dense and shady tree layer. The open woodlands and more degraded shrublands are characterized by small shrub species: Lavandula dentata, Lycium intricatum, Calicotome infesta, Osyris lanceolata, Jasminum fruticans, and Rhamnus lycioides ssp. oleoides.

Biodiversity Features

Few quantified data exist on the endemic vascular plant species of the ecoregion. Nevertheless, endemism rates are thought to be very high. One of the dominant tree species that characterizes this ecoregion, the Berber thuya, is an endemic Tertiary relict, whose living relatives are now found in South Africa and Australia. Many plant taxa related to these forest ecosystems have a very restricted distribution range, and are regarded as threatened species.

The faunal diversity of the ecoregion is very similar to the rest of the North African terrestrial ecoregions, and amongst the most significant in the Palearctic realm. The ecoregion is rich in mammal species, both smaller mammals such as Atelerix algirus, Elephantulus rozeti, Atlantoxerus getulus, Gerbillus campestris and large mammals including the red fox (Vulpes vulpes), common jackal (Canis aureus), caracal (Caracal caracal), Genetta genetta, Herpestes ichneumon, the wild boar (Sus scrofa) and the polecat ferret (Mustela putorius). This ecoregion may also harbor Barbary leopards (Panthera pardus panthera CR), although these rare cats are mostly confined to remote montane and rugged foothill areas. Barbary macaques (Macaca sylvanus VU) and Barbary sheep (Ammotragus lervia VU) may be found in this ecoregion as well.

This ecoregion hosts an outstanding bird community, with more than 120 species present, including an endemic subspecies of great spotted woodpecker, Dendrocopos major numidus, an endemic subspecies of grey shrike, Lanus meridionalis algeriensis, the endangered Algerian nuthatch (Sitta ledanti), and raptors such as golden eagle (Aquila chrysaetos), black-shouldered kite (Elanus caeruleus), short-toed eagle (Circaetus gallicus), booted eagle (Hieratus pennatus), and the vulnerable lesser kestrel (Falco naumanni).

Reptiles are also well represented in these forest ecosystems, including the spurred tortoise (Testudo graeca VU), common chameleon (Chamaeleo chamaeleon), North African ocellated lizard (Lacerta pater), Atlas mountain viper (Macrovipera mauritanica), Olivier’s desert-racer (Mesalina olivieri), Eumeces algeriensis, Chalcides mauretanicus, Lataste’s viper (Vipera latasti), Acanthodactylus maculatus, A. savigni, A. lineomaculatus. A significant number of endemic species are also found here, such as the banded lizard-fingered gecko (Saurodactylus fasciatus), Macrovipera transmediterranea, Koelliker’s glass lizard (Ophisaurus koellikeri) (the only anguid in North Africa), Trogonophis wiemanni, three cylindrical skinks (Chalcides colosii, C. ebneri, C. mauritanicus) and two fringe-fingered lizards (Acanthodactylus blanci, A. savignyi).

There are also a similar number of near-endemic reptiles that are shared only with other North African Mediterranean ecoregions. The amphibian community is represented by Discoglossus pictus and D. scovazzi, anurans that hide under rocks in the daytime summer heat and are found in Quercus suber forests near surface waters. Amietophrynus mauritanicus  is a toad found across most of this ecoregion.

Insect diversity is especially high in the ecoregion’s evergreen broadleaf forest ecosystem. An endemic amphibian of the ecoregion is the Moroccan spadefoot toad (Pelobates varaldii), an endangered fossorial anuran found on the sandy coastal plains, often near cork oak woodlands.

Current Status

The original forest cover of this ecoregion has been dramatically reduced and converted into agriculture and pastureland. Intense land clearance has occurred since since Classical times, when favorable weather conditions and fertile soils suited the development of important human settlements. This ecoregion is the most populated one in the Maghreb, containing 80 to 90 percent of the population. The holm oak forests and the wild olive and carob forests once covered 50,000 km2 each, representing the largest forest cover within the ecoregion. Today in Algeria, only 1,000 km2 of the original 10,000 km2 of wild-olive and carob forests remain, and only 6,800 km2 of the original 18,000 km2of holm oak forest remains. In Morocco, 5,000 km2 of the estimated 36,240 km2 original wild-olive and carob forests remain, and 14,320 km2 of the original 24,500 km2 holm oak forest remains. Degraded shrub-like communities represent the majority of this forest coverage, and the area of good forest remaining is much smaller.

The original extent of the cork oak forests in North Africa is estimated as 30,000 km2, but less than one third of this exists today (3,500 km2 in Morocco, 4,500 km2 in Algeria, and 455 km2 in Tunisia). The southernmost cedar stands in the Eastern High Atlas are facing extinction. Holly oak forests have never been inventoried due to their intense degradation and low forestry interest. Nonetheless, most of the original cover has been converted into agricultural land. Degraded shrub-like communities dominate elsewhere as a result of intense overgrazing and fire management on pasture land, intense pruning and uprooting for firewood collection, and tannin production.

There are several national parks in this region, although resources and funding are low. Al Hoceima N.P. in Morocco includes a large marine area, but also contains some holm oak woodlands. Boukournine, Chaambi, and Ichkeul N.P.s in Tunisia conserve holm oak and aleppo pine forests, as do the Tlemcen and Gouraya N.P.s in Algeria.

Conservation and development work is ongoing in the region: a forest gap analysis exercise to target Important Forest Areas (well preserved forest stands with high biodiversity values, in urgent need of protection) was carried out by regional experts from research and governmental institutions and NGOs. The Moroccan government has recently launched a WB/GEF project on biodiversity conservation, intending to enlarge the national protected areas network, create new National Parks, and declare a number of Nature Reserves, and improve management systems, by establishing management plans, improving local capacity, and involving local populations. Finally, a number of development initiatives are addressing major problems related to unsustainable management of natural resources by mountain Berber communities by investigating energy alternatives to firewood and promoting subsistence agriculture of local cereal varieties.

Types and Severity of Threats

As discussed above, extensive deforestation has occurred throughout the ecoregion. Human impact in the region is very high, because this ecoregion hosts most of the human settlements within North Africa, and those countries are generally facing strong socio-economic instability. The high population growth results in rapid and intense land conversion, mainly for agriculture, urban development, industries, and quarries. Tannin production from the cork oak trunk, which occurred at the end of the 19th century and beginning of the 20th century, contributed to the destruction of significant forests areas (as can be seen in the Cadiz province of Spain where more than 1,000,000 trees were lost in only 20 years).

The Northern Africa evergreen oak forests may be extremely threatened by climate change. The intensified summer drought season and the increasing average annual temperatures strongly modify the bioclimatic conditions needed for the survival of these forest types. Furthermore, human impact (mainly the overexploitation of the sylvopastoral systems and soil degradation) has considerably reduced the forest’s resilience to natural disturbances; during periods of intense drought, extensive tree stands suddenly die.

Generally speaking, there is a lack of resources including worker capacity and knowledge, financial backing, equipment, and knowledge of species, habitat distributions, and ecology to help implement adequate conservation and sustainable development programs. The large rural population in this ecoregion is still growing in and around protected areas. People’s needs normally conflict with protected areas under the existing legislation, and people’s rights of use are not clearly established, resulting in many illegal activities such as logging and overgrazing. Finally, habitats and populations of certain species are not adequately represented in protected areas to ensure their long-term survival and the maintenance of the ecological processes related to them.

Justification of Ecoregion Delineation

The Mediterranean woodlands and forests ecoregion forms part of the Mediterranean sclerophyll biogeographic province of Udvardy. The boundaries of this ecoregion are taken directly from the Mediterranean sclerophyllous forest vegetation unit of White, with the addition of White’s ‘Mediterranean anthropic landscape.’ The latter was added since the potential vegetation of this region prior to cultivation is likely to have been sclerophyllous forest. The ecoregion contains high numbers of endemic plants and some endemic animals, including relict species and others with Palearctic and Afrotropical affinities.

Further Reading

  • BirdLife International. 2000. Threatened birds of the world. Lynx Editions and BirdLife International. Barcelona and Cambridge, UK.
  • A.Benabid. 1985, Les écosystèmes forestiers, préforestiers et présteppiques du Maroc : Diversité, répartition biogéographiques et problèmes posés par leur aménagement. Forêt Méditerranéenne, 7 (1) Pages 53-64.
  • J.Charco. 1999. El Bosque Mediterraneo en El Norte de Africa. Biodoversita y lucha contra la desertificacion. Agencia espagnola de cooperatioon internacional. Madrid.
  • M.Dahmani. 1984. Contribution à l’étude des groupements à chêne vert (Quercus rotundifolia Lamk) des monts de Tlemcen (ouest algérien). Approche phytocoenologique et phytosociologique. Thèse 3ème cycle USTHB. Alger, 238 p + annexes.
  • S.Djebaili. 1978. Recherches phytosociologiques et écologiques sur la végétation des hautes plaines steppiques et de l’Atlas saharien algérien. Thèse Doc. Univ. Montpellier. 266 pages.
  • S.Djebaili. 1990. Syntaxonomie des groupements prèforetsiers et steppiques de l’Algérie aride, Ecologia Mediterranea, XVI, Pages 231-244.
  • M.Fennane. 1989. Esquisse des séries du thuya de Bérbérie au Maroc. Bulletin de l’Institut Scientifique, Rabat, 13: 77-83
  • C.Hilton-Taylor. 2000. The IUCN 2000 Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, United Kingdom. ISBN: 2831705657
  • C.Michael Hogan. 2012. Pelobates varaldii Pasteur and Bons, 1959. African Amphibians. ed. B.Zimkus
  • IUCN. 1997. Red List of Threatened Plants. Ed. Kerry Walter and Harriet J. Gillet The Red Data Book of plants.
  • Kaabache, M. 1993. Les forêts de pin d’Alep de l’Atlas Saharien (Algérie). Essai de synthèse sur la végétation steppique du Maghreb. Thèse Doct. Univ. Paris-Sud
  • Mediouni, K. 2000. Bilan, Straégie et plan d’action d’utilisation durable de la diversité biologique algérienne, 1080 p. Direction Générale de l’Environnement/PNUD-GEF.
  • Nabli, M.A. 1995. Essai de synthèse sur la végétation et la phyto-écologie tunisienne. I. Eléments de Botanique et Phytoécologie. Programme Flore et végétations tunisiennes. Vols 5 et 6. Faculté des Sciences de Tunis.
  • Nowell, K., P. Jackson and IUCN/SSC Cat Specialist Group, editors. 1996. Wild cats: Status survey and conservation action plan. IUCN, Gland, Switzerland. 406 pages.
  • Oldfield, S., C. Lusty, and A. MacKinven. 1998. World List of Threatened Trees. World Conservation Press, Cambridge.
  • Sadki, N. 1995. Etude des groupments à olivier et lentisque de la région d’Annaba (nord-est algérien). Essai phytosociologique. Documents phytosociologiques XVPp 253-271
  • Udvardy, M.D.F. A classification of the biogeographical provinces of the world. IUCN Occasional Paper No. 18 (International Union of Conservation of Nature and Natural Resources, Morges, Switzerland, 1975).
  • White, F. 1983. The vegetation of Africa: a descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa. UNESCO, Paris, France. ISBN: 9231019554
  • WWF Mediterranean Programme Office, 2001. The Mediterranean Forests. A new conservation strategy.
  • WWF Mediterranean Programme Office, 2001. The major forest types in the Mediterranean. Map.
  • For a more terse summary of this subject, see the WWF WildWorld profile of this ecoregion.

Disclaimer: This article contains certain information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.


 

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Fund, W., & Hogan, C. (2014). Mediterranean woodlands and forests. Retrieved from http://www.eoearth.org/view/article/154554

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