Crau

The Crau is a stone steppe in the south of France, northeast of the Camargue. Until the last century, it was one of many stone steppes that ran on the Mediterranean coast. All created by deposition of sediments of large rivers, such as the Tet, lez, Arc, Gapeau and the Durance. After the last ice age, the gravel plains were dry and the steppe-like landscapes that Craus arisen. Today, after the ongoing destruction of these areas just left the Crau d' Arles as large, contiguous area. A large part of today's range extends into the triangle between Arles, Salon-de -Provence and Fos -sur -Mer.

• 3.1 sheep industry
• 3.2 irrigation
• 3.3 Agriculture

Formation

Until about two million years ago the area of ​​the Crau was still below the sea surface of today's Mediterranean Sea. The area was covered during this phase with water- gray clays. After the sea had retreated, led the Durance with a large delta into the sea, the " Vieille Crau " was created by slow embankment of gravel and pebbles, which the Durance resulted from the Alps with it. Through this gravel the Durance built the road and shifted its course to the southeast. There the river enlarged its delta and poured, as before, again crushed stone and gravel from siliceous rocks from the Alps to the " de Crau Luquier " and " de Crau miramas " arise ( 120,000 and 70,000 years ago ). 12,000 years ago, the Durance changed for the last time take its course and flows, until today, in the Rhône. This " migration " of the river, and the embankment of rock material formed over a long period of 600 km ² Crau.

Ecology

There are several environmental factors which significantly affect the Crau.

Water

From the beginning, the water is an important factor. It has applied for the Crau so typical, very well drained, gravel. A special feature in the Crau, however, which forms the gravel and cobbles in the 40 to 60 cm depth by a calcareous binder is a partial meter thick concrete hard conglomerate ( Taparas ). This geological feature is very important for the particular water balance in the Crau. It means that the water from the ground water reservoir for the plants and animals of the Crau is unreachable. Through this limited water supply hardly tree growth is possible only where the conglomerate layer is naturally weathered and holes arise. This " Laurons " can then reach the surface of the ground water. Even outside the Crau seen this geological feature. Where the Taparas ceases arise strongly Dividend Payment sources that cause large-scale in northern swamps. This is also reflected in the vegetation changes abruptly. The dry Crau is more steppe -like, wet Crau, however, is covered with trees and bushes, as there the Taparas lies deeper in the soil and more water can hold in the soil.

Climate

A second important factor in the Crau is the climate. The Crau is in the Mediterranean climate zone, the mean for this landscape hot summers and mild winters. The temperature is 14-15 ° C throughout the year, some are available in the Crau year-round frost -free zones. A special feature in the summer is that the Crau is warmer than the surrounding areas, as the sun heats the stones during the day. Thus they serve as heat storage and release the stored heat at night again. This particular microclimate is important for plants and animals as well as for agriculture. Nevertheless, there are due to the cold north winds at least one cold month of the year, which is colder than 7 ° C on average.

Wind

The wind is also a big factor for the Crau. Dominating here is the Mistral. It is formed by channeling effects in the Rhone valley is a cool, dry north wind, the 50-150 km / h can be fast. It blows up to 110 days a year and can cause temperature drops of up to 10 ° C. He also sells the clouds and thereby increases the number of sunshine hours (3000 hrs. / Year ) as opposed to Paris with 1780 hours of sunshine per year. The Mistral also shapes the cultural landscape, as farmers planted to protect fields hedgerows that are to the wind break.

Precipitation

The precipitate has, by the lack of groundwater, an important role in the Crau. The 500-600 mm of precipitation per year mainly fall in autumn and winter, outside the growing season. In the summer falls only low precipitation and there is a high evaporation rate, which partially exceeds precipitation. Therefore, 3-4 months a year arid. This water is a limiting factor for animals, especially when in some years, fall only 300-400 mm of precipitation per year.

Use by humans

Sheep industry

The principal management of the Crau is the sheep industry. The Crau was early used by man as a sheep pasture. This began 10,000 years ago and is occupied by bone finds. However, the shepherds remained in the peripheral areas of the Crau, as they felt the stone desert as threatening. Therefore, the Crau was hardly used until the 11th century. The sheep farming has then more and more efficiency. Especially after caused by watering green areas in the Crau. Since it's too hot for the sheep in the summer, they were driven to pastures in the Alps. For this buoyancy of the still existing sheep drive between the Crau and the Alps, transhumance was born. Today, sheep farming is largely abandoned, the former shepherd now operate agriculture in the Crau, which they promote their destruction. Grazing by sheep is the Crau but still important to keep the grass in the steppe short and so to preserve the habitat of the stone curlew. Where the sheep are not, or barely graze the grass grows high. There you will find the habitat of the little bustard.

Irrigation

The irrigation of the Crau began in 1559 with the first major irrigation canal leading from the Durance in the Crau. It was planned by engineer Adam de Craponne. A little later they built extensions to east and west. Until the 19th century, the expansion of the Crau by irrigation was reduced only very slowly, there were still 500 km ² of the original 600 km ² Crau available. At the end of the 19th century, which still exists today Compagnie Agricole de la Crau is founded. She had to dry out the goal of 4000 ha Marshes at Fos -sur -Mer and to make the Crau fertile nutrient rich waters of the Durance. But it turned out that it was too expensive, the fan-shaped to pull Crau with channels; the plan was discarded. The irrigation has advantages and disadvantages for the Crau. The range of species of plants increases, they can grow better. Due to the growth of plants, new habitats for other species, which thus also benefit from the irrigation. In addition, the new green areas increased the profitability of sheep farming.

Agriculture

Already in 1965 began the first experiments with intensive agriculture. The farmers built large melon fields in the Crau and watered them with nutrient-poor groundwater. The soil was washed through it, and the farmers had to move again and again their fields. Thus, these surfaces of the natural Crau are destroyed, since the partially blown away Taparas to reach the ground water. 1970 26.000 ha of irrigated 53,000 hectares have been irrigated. Since the early 60s the irrigation of the Crau is no longer positive. The sheep farmers are increasingly displaced by intensively managed fruit growers. This massive destruction of only 150 km ² of the original area in 1980 were available. These remaining area is still at risk because today instead of melons peaches are grown. Another problem is the dryland. It serves the growing of feed grain for sheep meat and is limited to temporary crops. In this type of agriculture is not irrigated, but the stones are removed and plowed the ground. The microclimate of the soil, the soil structure and the water balance are severely disturbed. The only known dryland farming in the Crau, which has worked without major damage, and this was provided habitat for birds, were almond tree plantations.

Destruction of the Crau

There are many different aspects that are driving the destruction of the Crau. In addition to the irrigation and agriculture, there are many other causes of problems. For example, the adjacent industrial areas. Directly south includes the industrial area of ​​Fos -sur- Mer on the Crau. Since land prices are low in the Crau, many writers see the Crau as land reserve. An example of this is the BMW test track, which was built in the Crau. The area, which was used for this was the breeding ground of a Kalanderlerchenkolonie, which now no longer exists.

It looks similar to the landfill Marseilles. It is located in the Crau, since there is the site cheap and is far away from the city. It is not known whether the toxins from the leachate from landfills contaminate ground water. In addition, the waste by the mistral is widely flown in the Crau and dirty this over a wide area. Also problematic is that the surface of the Crau cut off by road from the surrounding areas, is sometimes even cut. Thus, the animals can no longer move freely in the Crau. They are also disturbed by the noise of the construction of the roads and by the noise of traffic. In addition, the construction of roads, the Taparas is destroyed, the water balance is destroyed along the road route forever, even if the road is no longer used. Problems for the animals also arise from the Hunting. Traps that are actually placed against marten and rats are also dangerous for the protected species in the Crau. Tourism is also disturbing, especially in the breeding season. The well-camouflaged eggs of ground- birds are virtually indistinguishable from their surroundings; the clutch can be easily trampled.

Conservation

After a long work of various institutions, the Crau is now under the protection of UNESCO. Since 2001, shall be ¾ of the still 10,000 acres remaining area as a "reserve naturelle ". The Crau is important as a transit area for many migratory birds and habitat for endangered species such as the chicken skewer flight, the Little Bustard, Stone Curlew of, the lesser kestrel and the Ocellated. The nature reserve was created by using the donor of EUR nature, donors from France as well as the nature conservation organization on site, the CEEP The care is provided by the C.E.E.P. and ecologically sound economic end farmers in the region. The conservation activities are coordinated by the ECOMUSEE in Saint -Martin -de- Crau from.