Biological diversity in the Mediterranean Basin
Biological diversity in the Mediterranean Basin has been significantly reduced since prehistoric times due to the steady accession of humans in conversion of coastal lands to agriculture and urban uses.
The largest of the world's five Mediterranean-climate regions, the Mediterranean Basin stretches west to east from Portugal to Jordan and north to south from northern Italy to Morocco. Surrounding the Mediterranean Sea, the hotspot's 2,085,292 km2 also include parts of Spain, France, the Balkan states, Greece, Turkey, Syria, Lebanon, Israel, Egypt, Libya, Tunisia and Algeria, as well as around five thousand islands scattered around the Mediterranean Sea. West of the mainland, the hotspot includes the Macaronesian Islands of the Canaries, Madeira, the Selvages (Selvagens), the Azores, and Cape Verde.
The basin's location at the intersection of two major landmasses, Eurasia and Africa, has contributed to its high diversity and spectacular scenery. The region boasts mountains as high as 4500 metres, peninsulas, and one of the largest archipelagos in the world. The climate of the Mediterranean Basin is dominated by cool, wet winters and hot, dry summers, and rainfall ranges from as little as 100 millimeters to as much as 3000 millimeters.
Although much of the hotspot was once covered in evergreen oak forests, deciduous and conifer forests, eight thousand years of human settlement and habitat modification have distinctly altered the characteristic vegetation. Today, the most widespread vegetation type is hard-leafed or sclerophyllus shrublands called maquis or matorral, which include representatives from the plant genera Juniperus, Myrtus, Olea, Phillyrea, Pistacia, and Quercus. This vegetation is similar in appearance to the chaparral vegetation of California and the matorral of Chile. Some important components of Mediterranean vegetation (species of the genera Arbutus, Calluna, Ceratonia, Chamaerops, and Laurus) are relicts from the ancient forests that dominated the Basin two million years ago. Frequent burning of maquis results in depauperate vegetation dominated by Kermes oak (Quercus coccifera), Cistus spp. or Sarcopoterium spinosum, all of which regenerate rapidly after fire by sprouting or mass germination. Shrublands, including maquis and the aromatic, soft-leaved and drought-tolerant vegetation of Rosmarinus, Salvia, and Thymus, persist in the semi-arid, lowland, and coastal regions of the Basin.
Unique and Threatened Biodiversity
Like other Mediterranean-type ecosystems, the Mediterranean Basin has high levels of plant diversity and endemism but relatively poor representation of mammals and birds compared to other hotspots. The mammal and bird faunas are largely derived from extra-Mediterranean biogeographical zones, with Eurasian and African elements dominating the mammal fauna, whereas Eurasian and semi-arid southern elements dominate the avifauna. The North African mammal fauna has closer affinities with tropical Africa than with the Mediterranean Basin. On the other hand, the reptile and amphibian faunas comprise mainly Mediterranean species, and have higher levels of endemism.
Of the 22,500 species of vascular plants in this hotspot, approximately 11,700 (52 percent) are found nowhere else in the world. The endemics are mainly concentrated on islands, peninsulas, rocky cliffs, and mountain peaks. Endemism at the higher level is very reduced, with only two endemic families (Aphyllanthaceae and Drosophyllaceae), both represented by single species, Aphyllanthes monspeliensis and Drosophyllum lusitanicum.
The Mediterranean region harbors a high degree of tree richness and endemism (290 indigenous tree species with 201 endemics). A number of trees are important flagships, including the cedars (such as the famous cedar of Lebanon, Cedrus libani, which has been exploited since the rise of civilization in the Fertile Crescent); the argan tree (Argania spinosa), a species in the Souss region of southwest Morocco; oriental sweet gum (Liquidambar orientalis); and Cretan date palm (Phoenix theophrasti) in Greece and western Turkey. One of only two palms native to Mediterranean Europe, Phoenix theophrasti, is found in a tiny part of Crete and on Turkey's Datca Peninsula, two areas of the Mediterranean Basin experiencing substantial tourism development.
The principal foci in the Mediterranean are 10 regional mini-hotspots within the larger hotspot, characterized by areas of high plant richness and narrow endemism of more than 10 percent: the Atlas Mountains in North Africa; the Rif-Betique range in southern Spain and two coastal strips of Morocco and Algeria; Maritime and Ligurian Alps of the French-Italian border; Tyrrhenian Islands; southern and central Greece; Crete; southern Turkey/Cyprus; Israel and Lebanon; Cyrenaica in Libya; and the Canary/Madeira Islands. These 10 areas cover about 22 percent of the Basin’s total area, yet account for almost 5500 endemic plants, i.e., about 47 percent of total Mediterranean endemics.
A total of nearly 500 bird species are found in the Mediterranean Basin hotspot, and many more migrate through the region, crossing the Mediterranean at Gibraltar, Sicily, the Balearic Islands, Corsica, Sardinia, Crete, and Cyprus. About 25 of these species are endemic, and several are threatened, including: the Spanish Imperial eagle (Aquila adalberti, EN), thought to number around 350 mature individuals, Raso Island lark (Alauda razae, CR), which occurs only on the uninhabited Raso Island in the Cape Verdes; Balearic shearwater (Puffinus mauretanicus, CR), which breeds in the Balearic Islands; and the Madeira or Zino’s petrel (Pterodroma madeira, CR), which has an estimated breeding population of 20-30 pairs in the central mountain massif of Madeira.
The destruction and degradation of Mediterranean wetlands threaten widespread species occurring in the hotspot such as the Dalmatian pelican (Pelecanus crispus, VU), which winters in the eastern parts of the hotspot, as well as marbled teal (Marmaronetta angustirostris, VU) and ferruginous duck (Aythya nyroca). These wetlands are also important for wintering and migrating species like the slender-billed curlew (Numenius tenuirostris, CR), which travels between Africa and its breeding grounds somewhere in Siberia each year.
Portions of the hotspot also appear as priorities in BirdLife International’s global analysis of Endemic Bird Areas (EBAs), namely Cyprus, Madeira, and the Canary Islands, and Cape Verde. The Canary Islands and Madeira are home to eight endemic species, including three Columba pigeons: the white-tailed laurel pigeon (C. junoniae, EN), dark-tailed laurel pigeon (C. bolli), and Madeira laurel pigeon (C. trocaz).
The Mediterranean Basin hotpsot is the home of more than 220 terrestrial mammal species, of which 25 are endemic (11 percent). A number of large mammal species, like the lion (Panthera leo, VU) and the scimitar-horned oryx (Oryx dammah, EW), have been extirpated from the region in the last few thousand years as the result of human habitat alteration and hunting pressure.
Among notable flagship species are the Mediterranean monk seal (Monachus monachus, CR), of which less than 400 individuals remain in the wild; the Barbary macaque (Macaca sylvanus, VU), the only native monkey known from Europe confined to several small, disparate fragments of habitat in the mountain ranges of Morocco and Algeria and on the island of Gibraltar; the Barbary deer (Cervus elaphus barbarus), actually a race of the red deer (Cervus elaphus), and represented by a few hundred individuals in a small forest on the Algerian/Tunisian border; and the Iberian lynx (Lynx pardinus, CR), the most threatened felid in the world, with no more than 250 individuals remaining in the wild.
There are more than 225 reptile species in the Mediterranean hotspot, nearly 80 (34 percent) of which are endemic. There are also four endemic genera, namely Algyroides, Trogonophis, Macroscincus, and Gallotia (the last being a genus of lizard unique to the Canary Islands).
The family Lacertidae, characterized by small, long-tailed lizards, is represented in the hotspot by more than 60 species, a quarter of the world total, while the family Viperidae, stocky venomous snakes, is represented by nearly 20 species. The family Testudinidae is represented by five tortoises: spur-thigh or Greek tortoise (Testudo graeca, VU); Hermann's tortoise (Testudo hermanni); marginated tortoise (Testudo marginata); the Endangered Egyptian tortoise (Testudo kleinmanni, CR), and Weissinger’s tortoise (Testudo weissingeri), an endemic species.
There are nearly 80 amphibian species in the Mediterranean Basin hotspot; nearly 30 of these are endemic (31 percent). The hotspot is a center of endemism for two amphibian families: the Discoglossidae and the Salamandridae. Eleven of the world's 12 recognized species of disc-tongued frogs (Discoglossidae) are found here, seven of which are endemic. The Palestinian painted frog (Discoglossus nigriventer, EX), known from Israel, has not been recorded since 1955, although there are recent tantalizing reports of the species having been seen in Lebanon. The hotspot's 23 species of Salamandridae account for over a third of the world's representatives from this family. The fire salamander (Salamandra salamandra) is one of the largest species of salamander in the world; its range includes most of Europe, a portion of North Africa, and the Mediterranean Middle East. Of the 17 species of threatened amphibians present in the region, the most at risk is probably Rana holtzi (CR), which is endemic to two lakes (Karagol and Cinegol), no more than 500 meters apart, in the Taurus Range of Turkey.
The freshwater fishes of the Mediterranean Basin are small subsets of the rich Eurasian and African fish faunas from which they are isolated. Although there are less than 220 species, more than 60 are endemic, including six endemic genera. There is also one endemic family, the Valenciidae (tooth carps) coming from the Iberian and Greek peninsulas. These two peninsulas contain about 86 % of the entire hotspot’s endemic fishes.
The Mediterranean Basin has experienced intensive human development and impact on its ecosystems for thousands of years, significantly longer than any other hotspot. Significant human settlements of have existed in the area for at least 10,000 years. The greatest impacts of human civilization have been deforestation, intensive grazing and fires, and infrastructure development, especially on the coast. Historically, Mediterranean forests were burned to make way for agriculture, the intensification of which has particularly affected European countries. The agricultural lands, evergreen woodlands and maquis that dominate the region today are the result of these anthropogenic disturbances over several millennia. Paradoxically, grazing and fire can maintain species richness, while in their absence, closed forests are often less diverse.
There are now roughly 300 million people living in the Mediterranean Basin. In Northern Africa, rapid population growth and the spread of mechanized agriculture have driven the replacement of biodiversity-friendly means of cultivation with more intensive land management systems. Water shortages and desertification are serious problems in this area. An increased demand from northern Europe for products such as strawberries and carnations year-round is further intensifying agriculture.
Habitat fragmentation is a serious problem in the basin; what original vegetation does remain exists in small scattered patches. Furthermore, many of the endemic plant species in the basin are narrow endemics: that is, they are confined to very small areas, in some cases individual rock outcrops, and thus are extremely vulnerable to habitat destruction, overgrazing, and urban expansion.
Development for tourism has placed significant pressure on the region's coastal ecosystems. The shores of the Mediterranean are one of the major large-scale tourist attractions in the world, with 110 million visitors arriving per year, a figure that is expected to double in the next two decades. The construction of infrastructure and the direct impacts of people using and trampling sensitive dune ecosystems remains a key threat to coastal areas in Turkey, Cyprus, Tunisia, Morocco, and Greece, as well as smaller Mediterranean Islands such as the Balearics, Corsica, Sardinia, Sicily, Crete, and the Atlantic island archipelagos of the Canaries and Madeira Islands.
Today, a mere five percent of the original extent of the hotspot contains relatively intact vegetation, placing the Mediterranean Basin among the four most significantly altered biodiversity hotspots on Earth.
Conservation Action and Protected Areas
The Mediterranean Basin has a long history of land conservation, even though the conservation outcome has not been successful. As early as 2000 years ago, the Romans and Greeks set aside areas for the protection of natural resources. Nonetheless, today, protected areas still only cover 90,000 km2, or 4.3 percent of the total land area, of which only 29,000 km2 (1.4 percent) are in IUCN categories I to IV.
In recognition of the valuable, but extremely threatened, natural heritage of the Mediterranean Basin, most countries within the region are planning significant expansion of their protected area systems, especially Turkey, Lebanon and Syria. However, widespread development and human land-use means that many of the new protected areas will be too small to adequately support animal populations. Many existing and proposed protected areas suffer from pollution and water shortages, problems that will only intensify as the human population increases in the Basin.
The establishment of biosphere reserves, which allow for the sustainable use of land and resources within reserve borders, has proved successful in areas where state authorities recognize their value. Achieving a balance between biodiversity conservation and human development is an important conservation strategy for the Mediterranean. Other important conservation efforts in the area include the European Union’s Habitats Directive (Natura 2000), which requires the Mediterranean countries of the European Union to identify the more important natural sites and to formulate conservation responses.
Regional cooperative programs are also an important factor for conservation in the Mediterranean Basin. One process that has established mechanisms for regional action on pollution control and conservation of the shared marine environment is the Mediterranean Action Plan, a cooperative effort established under the aegis of the United Nations in the mid-1970s, in response to the pollution-driven death of the Mediterranean Sea.
Future conservation efforts need to address population pressures on the land, especially in the coastal zone, issues of infrastructure impact and connectivity, and above all, how to maintain traditional rural livelihoods in a way that benefits biodiversity. This will require achieving sustainable levels of grazing, as well as forest and fire management.
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