Some situations in Africa

Due to periodic burning, a large area of plateau land has been covered by tall weeds, occasionally mixed with a small number of primitive trees. The tall and rough grass of Hyparrhenia can form a conspicuous patch, which is not suitable for feeding livestock and often hides insects that spread diseases. Herdsmen had better plant Themeda grass.

For centuries, human beings have selectively kept tree species with certain economic value in cultivated fields, and the result is a "cultivated sparse grassland" where some people like trees can grow. For example, shea butter trees are very common in Ghana and Ivory Coast. In addition, Senegal and Zambia also have Albizia Albizia, and Adansonia digitata, which is really carefully cultivated, is probably the most widely distributed.

(5) Thorn woodland, grassland and semi-desert vegetation. The vegetation on the tropical edge becomes short and thin when it gradually changes to desert type. The southern edge of the Sahara, between 15 and 20 latitude, is called the Sahel (Arabic Sahel, meaning "edge"), and the meaning of this word can also be used for the undulating desert edge of the northern Sahara. Kalahari desert in the south is also covered with this kind of vegetation. Although Kalahari is called desert, it should be called dry land.

Thorn woodland is mainly xerophyte, sometimes succulent or semi-succulent trees such as acacia, myrrh or Persian summer (evergreen hardwood tree). Striated desert dates (barnacle shells) always seem to be associated with barren land. There is a rather lush shrub, which often forms a dense bush, and is combined with succulent plants, such as aloe, Huwei Lan (fibrous species) and glandular grass, or desert rose (a succulent shrub with smooth bark, gray color, large base and beautiful flowers, red or pink) and smaller Euphorbia plants.

Closer to the desert, trees and perennial grasses that survive in narrow areas along the waterway separate large sparse annual grasses from scattered shrubs (mainly acacia). Shrubs are usually salt-tolerant. These shrubs may wither for lack of water, but they are rarely affected by rare fires.

(6) Desert vegetation. The density of plant species in the Sahara desert is one of the lowest in the world. Only on mounds or oases can there be vegetation, either trees or shrubs. Vegetation in other places is discontinuous, and there are two main types: perennial plants with large but sparse roots above ground, which are often protected by waxy cuticles, thorns and epidermis; The other is a short-lived plant system with few roots and thin leaves, but occasionally it can blossom and bear fruit immediately after a storm.

Namibi Desert is one of the driest deserts in the world. However, there is often fog in coastal areas, and succulent shrubs, such as aloe, try to survive in humidity. In the desert, there is also a kind of strange and exotic Cymbidium, which can survive 100 years.

(7) Karoo-Namibi shrub land. In this arid land, the soil is shallow, even salty. The low shrubs growing here can be divided into two kinds: woody plants, such as acacia, golden dragon with five claws and atriplex; The succulent plants are Aloe Vera, Euphorbia Euphorbia and Araceae. Aristide and Sedum are unique grasses. Every year, the color of bulbous plants is like a flash in the pan, fleeting. Many shrubs are drought-tolerant and contain high minerals, so they can provide useful food for goats and sheep.

(8) Mediterranean vegetation. The climate in this area is characterized by very dry summer and mild and rainy winter, and its vegetation mainly depends on this climate. However, for a long time, human habitation has caused great changes in vegetation conditions, and large areas have become shrubbery, calcareous wasteland or arid semi-desert (grassland) vegetation. There are xerophytes and hardwoods, shrubs and small trees in the bush jungle, which are often fire-proof. Calcareous wasteland only appears on calcareous soil, and many trees grow, including evergreen trees and Quercus variabilis. There used to be a large area of pine and cedar on the high slope of Atlas Mountain, but now it has been greatly reduced. From the coast to the desert, typical grasses are vines and Stipa.

(9) Shrubs, bushes and plants in the headland. This area is the corresponding part of the southern Mediterranean, but it has great vegetation potential (except the Atlas Mountains). There used to be a considerable real evergreen shrub here, which was unique, but now it has become a shrub belt. There are many hardwood trees and ever-changing trees. Although there is a lot of grass on the mountain, it is rare in low-lying places. Outside the Cape Mountains, the alpine hard-leaved shrub community gradually turned into a dry platform wet-season grassland.

(10) Madagascar. From the natural and biological point of view, Madagascar has long formed an independent group. The trees in its rainforest are short, the climate is slightly drier than that in the equatorial region, and it has its own short palm trees and bamboo. Deciduous forests in the west grow in the shadow of rain, some of which are similar to oak trees in the Mediterranean. There are important Euphorbia plants and local pediatric plants in the flora of South China. There are severely degraded secondary forests on the east coast and north coast of the island (known locally as Savoca).

(1 1) Large floating vegetation. In addition to the main vegetation described above, there is also a special vegetation called sudd (literally "obstacle"), which can be found in the Great Nile, Niger River and Zambezi River in the inland plateau of Africa. This plant floating along the white Nile in Sudan and Uganda is very unique. Cypress (especially papyrus), reed and other aquatic plants (including floating Nile cabbage) form a large area of waterlogged plants, which is not only useless, but also an obstacle to fishing and navigation. Pistia became an unwelcome invader of Kariba Lake, which was formed around Zambezi River in 1959.

Human influence

Most of the decrease of natural plants in Africa occurred in the past 2000 years (for tropical plants, it may have started from the late19th century), which was the most active period of human beings. The explosion of animal husbandry, agriculture, human beings and livestock, the expansion of cities and towns, and the external demand for original resources have all put forward unprecedented demands for means of subsistence and raised extravagant hopes for improving the economy.

In tropical forests and woodlands, fire is undoubtedly a tool used by human beings to clean up and degrade woodlands, which is much more effective than logging, peeling bark or uprooting, at least before the introduction of modern agronomy and mining operations. For centuries, hunters, shepherds and cultivators have been burning this land, where they collect wild food and wood for building and burning.

Africa is famous for its wide variety and large number of wildlife. There are more large ungulate mammals (about 90 species) and freshwater fish (2000 species) than other continents.

mammal

The main herbivore is African antelope, which belongs to 4 subfamilies of Bovine. The first subfamily is bovine subfamily, which is similar to cattle. This subfamily is further divided into African buffalo and pronghorn, including impala (the largest of all antelopes), pronghorn, impala and South African antelope. The second subfamily is oryx, a primitive calf that lives in bushes, bushes and forests. The third subfamily is called "Red Antelope", which is further divided into sable antelope, red antelope and big antelope. Deer antelope, East African red deer antelope, elk antelope, wildebeest, wildebeest and South African white-faced antelope are all animals mainly living in the vast plains, as well as swamp antelope, African water antelope, short-nosed water antelope, water antelope, curved-toothed water antelope and small water antelope. The fourth subfamily is orthodox antelope, which is divided into two clans. The first clan includes dwarf antelope, dog antelope, rock antelope, Jurassic antelope, small rock antelope and black-eared stone antelope. The second clan includes antelope, impala, springbok and gazelle. Other well-known African herbivores include zebras, giraffes, hippos, rhinoceroses and African elephants.

Perhaps no other animal can identify with Africa more than carnivores. There are about 60 kinds of them. In addition to the famous big cats such as lions, leopards and cheetahs, there are wild dogs, hyenas, serval cats (a kind of long-legged cat), wild cats, wolves, foxes, ferrets, civets and mongooses. These carnivores and scavengers are very important to maintain the ecological balance in their living areas.

Primates include about 45 species of Old World monkeys and two kinds of great apes in the world: chimpanzees and the largest ape-like gorillas in the world. Primates of pre-anthropoid monkeys, such as tree bear monkeys (African lemurs), young monkeys (small arboreal lemurs in young animals or bushes) and lazy monkeys ([loridae, crawling slowly and gently in trees), are mostly small and nocturnal, but Madagascar has no real monkeys, but there are the most diverse pre-anthropoid lemurs in the world, big or small, or nocturnal.

Marine mammals include a Mediterranean seal and a South African seal (Cape seal) and two kinds of manatees (aquatic herbivores)-dugong and manatee. In addition, whales, porpoises and dolphins often visit the coastal waters of Africa.

A large number of mammals endemic to Africa are second only to South America. These mammals include giraffes and hippos. The little relatives of civets are hyenas, mainly African breeds. The jumping rabbit, a rodent, is endemic to this area, and there is also a giant nocturnal cave-dwelling aardvark (〔tubulidintata) endemic to Africa. Madagascar also has a perverted insectivorous family called the hedgehog (an animal with a long, pointed mouth, some with thorns and no tail).

bird

There are nearly 65,438+0,500 resident birds in sub-Saharan Africa, and 275 are non-resident birds in northwest China or winter migratory birds in Palaearctic world. The number of migratory birds once reached 2 billion, but due to severe drought, human use of land and predation, the number decreased sharply. Birds mainly belong to the old world family, but they belong to those endemic species. The most valuable are ostriches, baleen, hammerhead birds (a brown bird resembling herons), herons (a large carnivorous bird with long legs) and banana cuckoos (with beautiful feathers and some helmet-shaped crowns). Other families such as bustard, sand chicken, honey? Larks are common in Africa. Many birds prey on land mammals, including eagles, eagles and owls; There are fish-eating birds such as storks and wading birds and a few kingfishers; There are many insect-eating animals, which are usually very beneficial to human beings. Scavengers include vultures and vultures.

Reptiles and amphibians

There are almost no endemic species of reptiles, and the main species are related to the Old World. The most common are lizards, skinks (characterized by overlapping scales), crocodiles and turtles. The local reptiles have lizards with their tails wrapped around ropes. In Africa, only Madagascar has flying lizards and pythons that hang their prey. There are many kinds of poisonous snakes, and the number is not small: some kinds of poisonous snakes are extremely poisonous, but they are rare. Many snakes (with fangs on the back of the upper palate) and cobras (with fixed fangs on the front of the upper palate) in the family Serpentidae also include highly toxic cobra species, such as mamba snakes.

Amphibians also mainly belong to the Old World. Newts and Ranidae (Ranidae, Bufonidae; Toothed upper jaw) is confined to the northwest of Palaearctic realm. A large number of common frogs and toads include the eccentric Cameroonian hairy frog, whose hair is an auxiliary respiratory organ. The frog (Phrynomerinae) is endemic to Africa.

arthropod

Africa has a large number of arthropods (including insects and other classified invertebrates). Among them are butterflies, stick insects and mantises belonging to Charaxes and papilio, locusts, root-eating ants or spear ants, ants (tropical ants swim in the vast and dense jungle), termites and dung beetles. There are many spiders on the whole continent. There are many scorpions and migratory locusts in some areas. Large swarms of migratory locusts regularly sweep across vast areas, causing great damage to vegetation. Other serious pests include mosquitoes and tsetse flies. The former is the vector of malaria and other diseases, while the latter spreads parasites that cause African trypanosomiasis. People and livestock will be infected with this disease.

aquatic animal

Freshwater fish have both obvious primitive forms and modern examples of rapid evolution. There are lungfish (1230: 〔Protopterus〕), polypterus and Calamoichthys, which belong to ancient types. These fish can breathe air, and some catfish ([Clariidae [12300]] also have this characteristic, and they can cross the land in wet weather. About 200 newly evolved fish species appear in Nyasha Lake, and 4/5 of them grow here.

An ancient marine fish, coelacanth, was thought to have been extinct for more than 60 million years, but it was still found on the east coast of South Africa in 1938, and was later found in other places. There are rich and diverse invertebrates, including marine microorganisms, on the east and west coasts, which are typical creatures in the Indian Ocean-Pacific Ocean and Atlantic Ocean. Coral reefs and attached microorganisms mainly exist in the warm current on the east coast of Africa, and the southwest and west coast washed by the cold Benjira and Canary currents are rich in fish.

conservation of natural resources

Many countries now set aside large areas of land as national parks, wildlife reserves or forest reserves. Only a few of these parks are large enough to be called ecosystems that are not affected by the outside world, and most of them are inhabited by large mammals. There is also a protected area for birds and marine microorganisms in East Africa. Vegetation reserves are mainly located in forest reserves and national parks. In addition, some countries try to protect wild animals by refusing to issue export licenses for certain animal skins, especially leopard skins, cheetah skins and zebra skins.

The oldest and most famous national park is Kruger National Park in South Africa, where most treeless grassland species are preserved. Botswana's Kalahari Antelope National Park in South Africa has reserved a dry-fed antelope species such as springbok and East African antelope. Smaller protected areas and parks retain special species. Only one large mammal, the antelope, has been extinct, and several subspecies are close to extinction; For example, the white zebra, a subspecies of zebra, has become extinct. There are large national parks in East and Central African countries, and their scale and number have expanded due to the profits of tourism. Tsavo National Park is one of the largest parks in Kenya, covering an area of 20,700 square kilometers (8,000 square miles). Lake Nakuru National Park with red storks; Several mountain forest parks and an ocean park. There are three national parks in Uganda. Tanzania has a famous Serengeti National Park, and its unparalleled animals are ungulates on the plains. There are Ngorongoro, Lake Manyala, Arusha and other parks. Other countries with famous national parks and game reserves include Botswana, Malawi, Namibia, Zambia and Zimbabwe. In all parks in these countries, typical natural habitats and woodland, thorn bushes, grasslands and desert species are protected.

The situation in other places is not satisfactory. After the independence of Congo (DRC), the number of national parks has been seriously reduced. There are seven national parks in China, including Virunga National Park, covering an area of 8,000 square kilometers (3 100 square mile). Although Sudan is one of many countries with a large number of ungulate mammals, the situation is little known and there is not enough park network in this country. There are nine parks in Ethiopia, which developed greatly during the period of1970s. However, there is only one underdeveloped park system in Somalia, most of which are wildlife reserves, and a place called Luc Badana fails to meet the standards of the United Nations as a park. "W" Park is owned by Burkina Faso, Nigeria and Benin, but most West African countries have national parks, but they are all small.

Unprotected animals in the park have no such demand. There are still many large animal species in forests or game reserves or control game reserves. Well-managed forest reserves provide a safe living environment for many unprotected small animals.

[Edit this paragraph] Natural resources

Africa is rich in mineral resources, which are not only varied, but also rich in reserves. At present, the known reserves of petroleum, copper, gold, diamond, bauxite, phosphate, niobium and cobalt account for a large proportion in the world. Oil is mainly distributed in North Africa and Atlantic countries. Libya, Algeria, Egypt and Nigeria are important oil producers and exporters in Africa. It is estimated that it accounts for about 1.2% of the world's total reserves. Copper is mainly distributed in Sabah, Zambia and Zaire. South Africa ranks first in the world in terms of gold and diamond reserves and output. Gold is mainly distributed in South Africa, Ghana, Zimbabwe and Zaire, while diamonds are mainly distributed in Zaire, South Africa, Botswana, Ghana and Namibia. In addition, there are manganese, antimony, chromium, vanadium, uranium, platinum, carp, iron, tin, asbestos and so on. The forest area accounts for about 2 1% of the whole continent.

[Edit this paragraph] Economic overview

The economies of African countries have long been controlled by imperialism. After independence, many countries have adopted policies and measures that are beneficial to their own economic interests in order to safeguard national sovereignty and national interests, and have achieved certain results. On the road of developing national economy, it is changing the state of "single economy" caused by colonial rule in the past. The agricultural population of the whole continent accounts for about 2/3 of the total population of the whole continent, and the output of many cash crops occupies an important position in the world; Coffee and peanuts each account for about 25% of the world's total output, cocoa, cloves, palm oil and palm kernel each account for 50-80%, as well as cotton and sisal. Most industries are agricultural products and livestock products processing. South Africa, Egypt and Algeria have developed heavy industries. The exploitation of major minerals in Africa occupies an important position in the world. Crude oil accounts for about 10% of the world's total output, copper ore accounts for about 20%, and diamonds and gold account for about 70%. The output of manganese, antimony, cobalt, chromium, phosphate, asbestos, uranium, platinum, lithium, tantalum, beryllium and niobium often ranks first and second on all continents.

North-South economy with wide gap

People used to divide Africa into North Africa and sub-Saharan Africa. The population of North Africa accounts for about 1/4 of Africa, while the gross national product accounts for more than 1/3, and the per capita possession is more than half of the national average. The region belongs to middle-income countries. In sub-Saharan Africa, the economy is relatively backward. South Africa is the country with the most developed modern industry in sub-Saharan Africa.

[Edit this paragraph] Geographical area

Geographically, it is customarily divided into five regions: North Africa, East Africa, West Africa, Central Africa and South Africa.

North Africa: It usually includes Egypt, Sudan, Libya, Tunisia, Algeria, Morocco, Azores and Madeira. Among them, Egypt, Sudan and Libya are sometimes called Northeast Africa. The rest of the countries and regions are called Northwest Africa. North Africa covers an area of more than 8.2 million square kilometers, with a population of about/kloc-0.2 billion, and Arabs account for about 70%. Atlas Mountain is in the northwest, part of Sudan grassland in the southeast, narrow plains along the Mediterranean and Atlantic coasts, and most of the rest are Sahara desert. Many agricultural products and minerals in this area occupy an important position in the world. Crude oil accounts for 5% of the world's total output, phosphate accounts for 22%, cotton accounts for about 5%, gum Arabic accounts for more than 80%, and others include cork, olives, oranges, grapes, dates and figs.

East Africa: It usually includes Ethiopia, Eritrea, Somalia, Djibouti, Kenya, Tanzania, Uganda, Rwanda, Burundi and Seychelles. Sometimes Sudan is considered as a part of East Africa. East Africa covers an area of about 3.7 million square kilometers with a population of 65.438+0.3 million, mainly Bantu blacks, distributed in the south; Followed by Amhara, Gera and Somalis, distributed in the north. The Ethiopian Plateau is the roof of Africa in the north, the East African Plateau in the south, and the long and narrow plains along the Indian Ocean coast. The Great Rift Valley runs through the central and western parts of the East African Plateau. Coffee produced in this area accounts for about 1.4% of the world's total output, sisal accounts for more than 25%, and clove supply accounts for more than 80% of the world's clove supply. Tea, sugar cane and cotton also occupy an important position in Africa.

West Africa: Mauritania, Western Sahara, Senegal, Gambia, Mali, Burkina Faso, Guinea, Guinea-Bissau, Cape Verde, Sierra Leone, Liberia, C? te d 'Ivoire, Ghana, Togo, Benin, Niger, Nigeria and Canary Islands. The area is about 6.56 million square kilometers. The population exceeds 654.38+05 million, of which blacks account for about 85% of the total population, and the rest are mostly Arabs. The northern part of this area belongs to the Sahara desert, the middle part is the Sudan grassland, the southern part is the Upper Guinea Plateau, and there are long and narrow plains along the coast. Diamonds produced in this region account for about 1.2% of the world's total output, bauxite accounts for more than 90% of Africa's total output, cocoa and palm kernel account for more than 50% of the world's total output, palm oil accounts for about 38%, peanuts account for about 1.654+0.38%, and coffee and natural rubber also occupy a certain position in the world.

Central Africa: It usually includes Chad, Central Africa, Cameroon, Equatorial Guinea, Gabon, Li Gang, Zaire, Sao Tome and Principe, and sometimes Zambia, Zimbabwe and Malawi are regarded as part of Central Africa. It covers an area of more than 5.36 million square kilometers and has a population of more than 56 million, of which Bantu blacks account for about 80% and are distributed in the south. The rest are black Sudanese, distributed in the north. The northern part of the region belongs to the Sahara desert, the central part belongs to the Sudan grassland, the southern part belongs to the Congo basin, and the southwestern part belongs to the Guinea Plateau. The Congo basin covers an area of about 3.37 million square kilometers, with the lowest point in the middle only 200m above sea level, and the surrounding plateaus and mountains generally reach an altitude of 65,438+0,000m. Diamond production accounts for about 30% of the world's total output, and manganese ore accounts for 1.2%. The output of copper, cobalt, uranium, tin, radium, niobium and tantalum all occupy an important position in the world. Palm oil, palm kernel, natural rubber and cocoa are also important.

South Africa: It usually includes Zambia, Angola, Zimbabwe, Malawi, Mozambique, Botswana, Namibia, South Africa, Swaziland, Lesotho, Madagascar, Comoros, Mauritius, reunion island, Saint Helena and Ascension. It covers an area of 6,665,438+1 00000 square kilometers and a population of about1000000, among which Bantu blacks account for 8.5%, Madagascar-Polynesian Malagasy people account for 9% and European whites account for more than 5%. The South African Plateau is the main terrain in this area. The middle of the plateau is the Kalahadi Basin, surrounded by highlands and mountains. The gold produced in this area accounts for about 7 1.83% of the world's total output.

[Edit this paragraph] Africa is short of water.

According to the statistics of UNESCO, the water crisis in Africa causes 6000 deaths every year, and about 300 million Africans live in poverty because of lack of water. In the next 20 years, at least 500 million people in Africa will live in trouble because of lack of water. This will further lead to their agricultural output will continue to decrease due to the lack of water to irrigate crops. Experts believe that in the next 23 years, due to the lack of sufficient water resources, Africa's grain output will be reduced by 23%, while some experts believe that Africa is not short of natural water resources, but poor Africa has not managed these precious water resources well, thus making the situation of water crisis increasingly severe. At present, one third of the population in Africa lacks drinking water, and nearly half of Africans suffer from drinking unclean water. Analysts believe that if the current situation of drinking water shortage is not improved, at least 17 African countries will be seriously short of water by 2065,438+07, and the water resource problem is likely to become the fuse of disputes or conflicts in some African countries.

According to statistics, in order to solve the water shortage problem of African population, it needs to invest 20 billion US dollars every year. At present, water supply investment in some African countries only accounts for 1% of the financial budget. Experts pointed out that the shortage of water resources will be a potential factor leading to social contradictions and political conflicts, and the difficulty of water supply will bring great crisis to the economic development and life health of African people.