This type of environment is characterized by warm dry summers and mild rainy winters. This remarkably influences the vegetation, which is therefore characterized by low, woody, evergreen plants with a sclerophytic type of structure, that is, with small and hard leaves that are suited to resist the summer draught. For this reason the Mediterranean scrub is also called “sclerophyl forest” (skleros = hard, phyllon = leaf). Total annual rainfall is approximately 250-500 millimetres and occurs mainly in the winter months. In summer the mean monthly temperature is often higher than 20°C and in this biome, in winter it very rarely freezes.
The most typical Mediterranean scrub area is the Mediterranean basin, but it can also be found in other regions of the world: California, Central Chile, the southern tip of South-Africa and Southern Australia.
The Mediterranean. In the Mediterranean basin, the scrub has been remarkably attacked by tamed animals. In particular, goats do not have a specialised diet, so they can feed on any type of vegetation, supplying milk, wool, meat and hides. They need very little water and can even climb on trees to reach for food. In the Mediterranean region, there are areas with an exceptional concentration of biodiversity and a high density of endemic species, the so-called hot spots. In Italy, these areas are in Sicily and Sardinia. The problem with all these areas is that in the dry season there is nothing to protect plants from indiscriminate pasturing. Farmers do not stock up on fodder for the season and so animals keep pasturing even when the plants are not in their growing season, which results in the formation of poor and sparse vegetation. This vegetation is further affected by fires, since during the dry season everything is dry and easily flammable because of many species containing high amounts of volatile oils.
California. In California, the Mediterranean scrub is called chaparral and is an area of thorny shrubs rich in birds and other vertebrates, especially in the rainy season; during the hot summer, many birds and the largest herbivores migrate to more favourable areas. The mammals living in the chaparral are: terricolous squirrels and kangaroo rats, animals that store seeds in their lairs. The important function of these seeds is to preserve water since they take up the steam sent out by these small mammals as they breathe in their lairs. Largest animals include collared peccaries, that look like pigs but are smaller and also omnivores; common antelopes, which are very good runners; mule deer, which are very numerous, while the number of wolves, grizzlies and mountain lions is decreasing with time. Number one among birds is the runner cock, related to cuckoo, although without the latter’s parasitic habit of the nest; it is not good at flying but runs fast and feeds on reptiles and rodents.
Australia. In southern Australia, the scrub is called mallee and consists of half-dry scrubland. This habitat houses many granivorous birds and a few frugivorous ones (i.e. that feed on fruits). Granivorous birds include Australian pheasants, birds that do not hatch their eggs by sitting on them, but build up a mound of earth and lay their eggs onto it. The cock-pheasant is in charge of checking the temperature of the eggs by adding or removing soil from the mound. There are also many carnivorous birds, such as many species of falcons, goshawks, owls, little owls and butcher birds.
Chile. In Chile, there is the matorral, inhabited by such small mammals as the degu, a rodent which is as the same size as a mouse and has sharp nails with which it digs the ground in search of roots and tubers. Guanacos seem to have been living here once.
Plants of the Mediterranean scrub
The Mediterranean scrub may be divided into tall scrub, with well-developed trees that can provide shade and humidity to the undergrowth, and short scrub, made up of impassable shrubs and bushes, called garrigue. This biome contains evergreen broad-leaved and aciform trees, including: holm oaks, arbutuses, olive trees, laurels, carob trees, pine trees, junipers, cypresses and others. It also includes shrubby plants, for instance rock roses, mastic trees, myrtle and rosemary.
Animals in the scrub
At present, the scrub that surrounds the Mediterranean basin certainly hosts fewer animals because of the long history of man’s local activities: in other parts of the world, this biome houses, instead, many animals. Here one can find wild boars, roe deer, deer, squirrels, wolves, foxes, badgers, rodents, tortoises, lizards and many species of birds. Animals living on ground include snails, insects and earthworms, and twice a year they have to cope with two seasons in which they have to stop all activity: the winter cold (hibernation) and the summer dryness (aestivation).
Mediterranean vegetation is very important as the habitat of a wide variety of wild and farm animals. Particularly important in the Mediterranean is its high number of endemic vegetal species which make up approximately 50% of the total number of plants living in this environment. Southern Italy is the southernmost limit for many species living all over Europe, for instance beeches, oaks and silver firs. During the ice age, the southern regions must have acted as “sheltering areas” for these species, from which they spread again to the rest of Europe.
Origins of the Mediterranean basin
In the Cainozoic age, the area of the Mediterranean sea was a huge ocean that slowly shrank into a few secondary basins. The main one then turned into the Mediterranean Sea. This was caused by the African and Eurasian continental plate moving closer to each other. The powerful thrusts coming from the south caused the sediments built up at the bottom of the ocean to raise, thus originating the mountain ridges of the Atlantis, the Pyrenees, the Alps, the Balkans and Asia minor.
Olive trees are the native arboreal species that is most commonly grown in the region of the Mediterranean scrub and is of remarkable importance in its inhabitants’ economy. Nevertheless, another two originally native species should be mentioned for their use: cork oaks and carob trees.
Other important plants that are grown here are cereals, pulse vegetables, fruit trees, vegetables and salads. Oil and wine are the most important produce on which the economy of scrub areas is based.
Cork oak. Cork oak forests are closely related to the climatic conditions of some Mediterranean areas. These forests have scattered populations forming agro-silvi-pastoral systems which are extremely rich in flora and fauna. In particular, the native flora, very rich in aromatic and medicinal species, may increase the value of cork oaks. Many vegetal species growing in this forest, because of their variety and long blooming period, supply bees with excellent supplies. Cork is collected only from trunks, and its production has remarkably increased over the last few years; the new cork oak forests actually cover almost 120,000 hectares.
Olive trees. Olive trees, probably native to Syria, were brought to Asia minor, Egypt, Greece, Italy and other Mediterranean countries. By growing this tree, man has remarkably expanded the geographical distribution of this plant, which can now be found from the centre-south of France to pre-Saharan areas. The Mediterranean species, Olea europea, consists of two subspecies: oleaster or wild olive (Olea oleaster) and cultivated olive (Olea sativa). Cultivated olive trees are bigger than wild olive trees, approximately 4 to 12 metres tall, and can reach 20 metres tall if they find their ideal climate and soil. Their trunk is big, their branches are rounded, smooth and thorn-less, their foliage is generally well developed and soaring. Olive twigs are flexible and sometimes dangling, their leaves are lanceolate, green and hairless on top, bright white at the bottom. Cultivated olives are big, fleshy, rich in oil, but fewer than in wild olive trees and in any case much fewer than their flowers.
Carob trees (Ceratonia siliqua) also live in the scrub. Carob trees can be used to control erosion, preserve the soil and reclaim lands, while supplying carobs as fodder. Carobs have always been used in many different ways: as animal fodder (especially horses), brewed into alcohol drinks or as thickeners (carob flour) in the food industry. Carobs can also be eaten as picked; sometimes, they have been toasted and used as ersatz coffee. A peculiarity of this plant is that its seeds are extremely hard and, above all, all have the same shape and weight. The people of the eastern basin of the Mediterranean know about this peculiarity of the seeds and so they used them as units of weight for gold and gems; basically they put gold or gems on one scale pan and the seeds of the keration (as the Greeks called them) on the other. This is why gold, diamonds or other precious stones are still weighed in carats and not in grams. Because plants grow slowly, the wood is mainly used as firewood and for crafts. A particular woody product is heather log, used to make pipes.
In Mediterranean scrub areas, there generally is a marked difference between harsh winters and long hot summers. This natural condition forces shepherds to use high pastures during the summer and to move to milder climates, which are therefore closer to the sea, during the winter. This migration led to the development of a peculiar breeding culture: transhumance. Even if there are many historical and geographical differences among the different breeding systems, transhumant culture is common and similar in all those countries that are related to the Mediterranean.
A source of wealth that is becoming more and more important is tourism. The climate and beauty of the sights of this ecosystem attract many holiday-makers, especially in the warmest months. The tourism sector is developing so much as to become a potential danger for the environment.
One of the main causes for the drying of the soil is excess pasturing. It occurs when the pressure of the pasturing activity on an area exceeds what that area can bear. The soil, deprived of its vegetal covering, is more sensitive to atmospheric agents. As a consequence, it dries up in the summer and is washed away by winter rains. Unfortunately, people often resort to fire as a quick way to obtain pasturelands. This involves the deterioration of the garrigue and steppe Mediterranean scrub areas.
Climate change, the destruction of temperate and tropical forests, intensive agricultural practices, and hydrogeological instability are among the causes leading to desertification and flooding. As early as 1992, during the United Nations World Summit on Environment and Development in Rio de Janeiro, it was stated that desertification is 'land degradation in arid, semi-arid and sub-humid areas, resulting from various factors, including climatic variations and human activities'. Desertification takes the form of the progressive reduction of the surface layer of the soil and its reproductive capacity, and is a much larger phenomenon than the expansion of sandy deserts.
In these regions, where the summer climate is dry and parched, fires are frequent and natural; fires may be caused by spontaneous combustion or by a flash of lightning of a summer storm. Because of the many fires, the vegetation contains many fire-resistant plants, such as cork oaks, or plants whose germination is even promoted by fires (pyrophitic plants, such as, for instance, plants of the genus Tuberaria) or plants that quickly recover after fires, such as holm-oaks. Animals have also adjusted to live in different habitats and can quickly repopulate recently burnt areas.