The lands of the Kingdom of Saudi Arabia are characterized by the diversity of ecosystems, which include the following:
Ecosystems of mountainous regions:
About a thousand years ago, the Hijaz Mountains, the Asir highlands and some mountainous areas in the Tuwaiq heights in the central region were distinguished by the density of their tree vegetation cover estimated at 2.7 million hectares, of which only scattered areas remain in remote sites and valleys.
Tree forests dominate the ecosystems in the mountainous regions of the Kingdom, especially the Juniper forests (Juniperus spp.) scattered in the Sarawat Mountains in the southwestern region of the Kingdom, in which other species grow, such as some Acacia spp. And wild olives (Olea europea) and others. These environments contain the highest rates of biological diversity within the Saudi terrestrial environments. In addition to their environmental importance in attracting rain and preserving the soil primarily, they also provide some products such as some medicinal and aromatic herbs and apiaries, and they contain some of the most important natural parks in the Asir, Taif and Al-Baha areas.
The Tuwaiq mountain range in the central region and the heights of the northern regions of the Kingdom is characterized by its extreme ruggedness and the presence of many wildlife species, most importantly is the Nubian ibex, and the Idmi gazelle.
One of the Kingdom's efforts in the field of preserving these environments is the work on rehabilitating the degraded forest sites, especially in the southwestern region of the Sarawat Mountains, where the ecosystem of Juniper was restored in cooperation with the Food and Agriculture Organization of the United Nations.
The natural rangelands in the Kingdom occupy an area of 171 million hectares, distributed over all regions of the Kingdom in different proportions, most of which are located in areas that receive an average rainfall of less than 200 mm per annum. The largest part of the Kingdom's rangelands are located in the northern, eastern, central and southern regions, and large areas of them are found in various sandy areas, gravel plains and rocky plateaus, and more than two-thirds of these areas is located in areas that receive an average rainfall of less than 100 mm per annum. Therefore, most of the Kingdom's rangelands are sporadic desert grasses and shrubs with little density and little coverage of the surface of the earth, they are also characterized by their low pastoral productivity and the fluctuation of pasture from year to year and from one region to another according to the fluctuation of the rainfall and the degree of uniformity of rain distribution, normally most of the pastoral production is during the rainy seasons.
Coastal and marine ecosystems:
The Kingdom includes many coastal ecosystems, the most famous of which is the Tihama Plain, which is located between the Sarawat Mountains and the Red Sea coast. It is characterized by its plants, most importantly are Acacia tortilis and Commiphora gileadensis trees and some Ziziphus spina-christi trees. And tall weeds, including the Panicum and the Lasiurus scindicus.
There is a local coastal sabkha system on the shores of the Red Sea and the Arabian Gulf, both are characterized by a vegetation cover consisting mostly of local plants with high osmotic pressure, such as the Zygophllum coccineum, the Aizoanthemum, and the Aeluropus.
The Arab marine areas constitute a vital geographic units in the northwestern part of the Indian Ocean that contains marine and coastal natural environments that are very unique in the world, and include a wide variety of ecosystems from arid coastal areas, wet coastal areas, mangrove environments, salt marshes, sea grass beds, large algae beds and coral reefs that form together the broad base for the rich marine biodiversity that supports the livelihood of a large number of coastal residents in the Kingdom.
The Red Sea Canyon, with its narrow gorge extending for 2,000 km, is one of the world's greatest extraordinary secondary seas. Its maximum depth is more than 2500 meters. It connects in the south with the Indian Ocean through the narrow Bab al-Mandab Strait, which is no more than 130 meters deep. The Red Sea extends to the northeast, forming the Gulf of Aqaba, and to the northwest, forming the Gulf of Suez, which is connected to the Mediterranean through the Suez Canal.
The Red Sea differs from other seas in the fact that its waters are well mixed in a way that makes its temperature equal throughout its depth. It is considered one of the greatest reservoirs of marine biodiversity in the world, and the most important characteristic of this tremendous diversity of coral reefs, with its uniquely complex structure and high endemicity, especially between species associated with reefs and species that live in the depths.
The Arabian Gulf resembles the Red Sea in that it is a narrow gorge and almost closed. The Arabian Gulf is a shallow northern extension of the tropical Indian Ocean, with an average depth of 35 meters and a maximum depth of no more than 120 meters, and it connects to the Indian Ocean through the Strait of Hormuz, and the rate of renewal of its waters varies Between 3 and 5.5 years. Its water temperature varies greatly throughout the year, as it falls to about 11 ° C in the winter, and rises to about 40 ° C in the summer. The high rate of sedimentation in it leads to turbidity of its waters, especially the level of light transmittance through them, which constitutes a continuous environmental stress on its ecological organisms, and makes many species live within the limits of their natural range.
The biodiversity of the Arabian Gulf contains plant and animal species that are characterized by being highly adaptive to extreme environmental conditions. The Arabian Gulf is also distinguished by its great diversity in coastal and marine ecosystems.
Coral reef ecosystems:
Coral reefs spread widely along the Saudi coast of the Red Sea. It also surrounds the scattered islands of more than 1150 islands in the form of barrier reef, which are more widespread and diverse in the northern and central regions of the Red Sea than in the southern regions. They are also found in the forms of coral barriers located far from the shore, and in the forms of coral patches in shallow areas as in Diffat al-Wajh. In the Red Sea, there are about 270 types of hard corals and 40 types of soft corals.
24 sites were surveyed in the area between Jeddah and Haql in the Saudi waters of the Red Sea, and the diversity of corals in one site ranged from 52 to 111 species, and the percentage of coral cover at one site ranged between 11-30% to 51-75. %.
In the Arabian Gulf, coral reefs are of limited spread due to the lack of hard layers and the prevalence of unsuitable environmental conditions. There are 60 species of hard coral reefs on the Saudi coast, and these reefs are spread around islands far from the coast and in a few areas close to the shore.
Ecosystems of sea grass beds:
Sea grass beds are found in shallow waters sheltered from waves in many areas, and their roots stabilize sediments. These beds are characterized by their high productivity and they provide protection and nourishment to many types of marine life, such as Polychaeta, mollusks, crustaceans, fish, turtles, and dugongs. These species also depend on sea grass beds as a source of food and as natural habitat for reproduction. Twelve species of sea grasses have been recorded in the Red Sea, 10 of which are in the Kingdom's waters, and 4 types of marine weeds have been recorded in the Arabian Gulf, all of which are found in the Kingdom's waters.