Plants in Africa

(1) lowland rainforest. There are lowland rainforests in Guinea coast and Congo basin in West Africa. The all-round development of this tropical rain forest needs a continuous warm climate and an annual rainfall of more than 1 270? 1.520cm, evenly distributed throughout the year.

Tropical rain forests are characterized by bottom, middle and upper layers. The bottom layer is about 1.8? 3 meters high bushes, ferns and mosses; The middle layer is trees and up to 6? Palm tree18m; There is a tree at the top, with a straight trunk, 46 meters high, no bifurcation, a wide bottom and a stretched evergreen leaf crown at the top. These crown branches provide a small niche for parasitic plants such as orchids, ferns and mosses. Lianas bind trees together, while parasites are tied to trunks and branches, and fig plants take aerial roots.

In a real rainforest, grass appears occasionally. Elephant grass can flourish in places where other vegetation is difficult to stand, and can provide good feed for herbivorous livestock when it is young, but it soon becomes rough and spreads, becoming a hiding place for insects. LMPERATA cylindrica is an annoying weed that grows on barren and charred land.

(2) Forests and bushes in East Africa. Lowland forests and evergreen shrubs form a narrow strip of about 200 kilometers along the Indian Ocean. In places with good terrain, such as the edge of the harbor, the seaward side of Zanzibar Island and Pemba Island, and the hilly areas across the southeast rainy season, forests and broad-leaved forests are still dominant. In areas with poor geographical location (such as prominent coral reefs) and close to cities and small harbors, the land in the rain shadow is dominated by spiny shrubs, cactus shrubs and sparse vegetation. However, there are some domestic trees that play an important role in the economy, such as coconut trees, cashew trees, mango trees and lilac trees (especially in Sanjiba Island and Pemba Island).

(3) Mangrove swamp land. There are many kinds of mangroves, including broadleaf shrubs, and how long they are beside muddy rivers and tidal harbors. They need warm salt water, so they are mostly scattered along the tropical coastline. They often form almost impenetrable clusters and can only be accessed from the sea. Trunks and roots are termite-proof, so they have long been good building materials and good materials for making charcoal.

(4) Broad-leaved forest land and grassland. This classification constitutes the most comprehensive category that has been confirmed, including many areas originally marked as savanna. The structure and floristic distribution change greatly with the increase of latitude (north and south). The average annual rainfall is 889? 1 143 cm has obvious seasonality, and both the total rainfall and the start date of rainy season have considerable changes every year. Woodlands in West Africa are very similar to those south of the equator. In these two areas, undulating wooded beaches and soft and humid clay-based canyon grasslands appear alternately on light soil.

9? Trees with a height of15m are typical deciduous trees, which are often fireproof, because most of them are burned once a year. Common tree species in West Africa are Leguminosae, Daniela (Leguminosae with white bark) and African oak (with banded leaves, which is said to produce the most durable wood in this area). Other tree species, Combretum and Elemene, form different hardwood groups, which are more suitable for arid areas. The equivalent species in the south are Brachystegia (a leguminous hardwood whose bark was once used for weaving) and Jubenadia (another leguminous tree). In many arid and barren inland areas of Tanzania, there is a sparse and persistent forest called Miombo Forest, which grows on a rather thin and barren soil layer. This is an excellent habitat for bees, and people have come here for a long time to collect honey.

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 aboveground roots, 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 are not only useless, but also cause obstacles to fishing and navigation. Pistia became an unwelcome invader of Kariba Lake, which was formed around Zambezi River in 1959.