Plant communities emerge in natural surroundings with the interaction of relief, climate, and soil. There are different types of natural vegetation: forest, grassland, and desert.
What Is Natural Vegetation
Plant communities emerge in natural surroundings with the interaction of relief, climate, and soil. There are different types of natural vegetation: forest, grassland, and desert. Vegetation is the plant cover of the earth it includes trees, shrubs, grasses, lianas vines that climb up trees, and mosses. These trees are the most important because they supply timber, firewood, leaves, bark, resins, and other things. They also help reduce runoff soil erosion and air pollution.
For a balanced economy, a country should have 20 to 25 percent of its land covered with forests. Over the years man has been clearing these various types of natural vegetation for purposes such as farming, mining, transportation, and industrial and economic development. In the more densely populated parts of the world such as western Europe, there is very little left of the natural vegetation.
Even in the less populated parts of the tropics, long periods of shifting cultivation, overgrazing, and commercial lumbering have reduced the natural vegetation to some kind of secondary vegetation locally known as a beluga.
It is only in the interior of big continents such as Siberia, and the least accessible uplands and mountain ranges that there are big areas of the original vegetation. We can divide the world into natural regions based on geographical location, characteristics of vegetation, and appearance.
Types of natural vegetation
There are different types of natural vegetation in the world of these the most important major types of natural vegetation are as follows:
A- Forests
There are three important types of forests are:
1-Tropical Rainforest
2- Temperate Deciduous Forest
3- Coniferous Forest
B- Grasslands
There are two important types of Grasslands are:
4- Tropical Grasslands (Savanna)
5- Temperate Grasslands (Steppes)
C- Deserts
6- Hot Desert
7- Cold Desert
1: Tropical Rainforests
Distribution:
The tropical rainforest is most extensively found within the tropics, especially in the equatorial region. It includes the Selvas of the Amazon, Zaire Basin, Southeast Asia, and scattered areas of Central America, northern Australia, and West Africa.
Characteristics:
The forest is thick, with plants that grow to great heights. There is also much foliage.
A tropical rainforest has a distinct three-layered arrangement.
a- The top layer consists of tall trees up to 50 meters, spreading wide apart, with buttress roots to support the heavy crown above.
b- The middle layer is made up of a canopy of trees with tree ferns, lianas, and climbers, and epiphytes (anchored to trunks or branches). Most of the trees are around 30 meters high. The top of the trees forms a wave-like canopy when seen from an airplane.
c- The bottom layer consists of numerous small trees, bushes, ferns, and herbs. Most of these young trees will eventually replace the taller trees as they strive to reach for sunlight.
On the ground, there is little undergrowth, with only a few shady plants and ferns, as little sunlight reaches here. Where there are clearings and the sun comes through a great variety of small trees, shrubs, and lalang begins to grow and become some kind of beluga or secondary forest.
The trees are broad-leaved and evergreen and have small flowers. The bark is thin and smooth and the trunk grows tall and straight. There are many varieties of trees but some species are seldom found together making commercial lumbering more difficult. Along the sandy shores are swaying coconut palms and conifer-shaped casuarina or rue trees. Where the coast is muddy, there are mangrove swamps, Nipah palms, and other mud-loving plants with hanging stilt roots.
Plant Varieties and Tree Species
The tropical rainforest with its wealth of vegetation such as trees, palms, ferns, herbs, creepers, climbers, lianas, epiphytes, orchids, and lalang, yields a great range of useful products: timber, charcoal, firewood, nuts, flowers, and medical herbs. Most of the trees yield tropical hardwood such as mahogany, chengal, meranti, ebony, and green heart.
2- Temperate Deciduous Forest
Distribution:
Large areas of the original temperate deciduous forest have been removed to make way for modern civilization and industrial development. As such, only in the least accessible areas of western Europe are found large stretches of these forests. In some parts of Europe, deciduous forests are found together with the evergreen coniferous forests. Such a forest is known as a mixed forest.
Outside Europe, deciduous forests are found in the southeastern USA, southern Chile, Tasmania, New Zealand, and the far east.
Characteristics:
1- The temperate deciduous forest has developed its distinct features, thriving on a moderate annual rainforest between 1000 and 1500 millimeters with warm summers and cold winters.
2- The forests are not so thick as the tropical rainforest. The trees are more widely spaced with low shrubs and herbs in between them.
3- The undergrowth is on the other hand denser than that of the tropical rainforest as there are no thick canopies to shield the ground from the sun.
4- The deciduous trees have thin and delicate leaves with remain on them only in the warmer parts of the year. They bear fruits called acorns which are used for feeding animals in some countries.
5- All deciduous trees shed leaves in the autumn when the temperature falls below 6°C. This is to prevent the loss of water from the leaves as most winters are dry.
Vegetation Species
Deciduous forests have a variety of species of trees scattered through them. These are found in pure stands the same type clustered together making lumbering much easier. The trees yield strong and very durable hardwood which is of great commercial value. The most common deciduous trees include oak, ash, and maple. Other species found in Europe, the USA, and the Far East include elm, willow, poplar, hickory, birch, horse chestnut, and beech.
3- Coniferous Forest
Distribution:
Coniferous forests are mainly found in the temperate areas of the northern hemisphere e.g. northern Europe, northern Eurasia, the Taiga of Siberia, Russia, and northern Canada. In the southern hemisphere, coniferous forests are found only in a few scattered areas such as the uplands of southern Chile and New Zealand.
Characteristics:
1- One of the toughest trees known are the conifers which can survive in the rugged uplands and interiors of continents where winters are long and severe. Conifers survive in places with thin soil and frozen ground and those with an annual rainfall of only 600 millimeters. They have many features to adapt to such a harsh environment.
2- Conifers are also known as needle leaf trees which remain evergreen throughout the year. When old needles turn yellow and brown and drop off, young fresh needles take their place. Their growth is not hampered by either cold or drought in any season.
3- Conifers grow tall, straight, and close to one another. Coniferous forests are not very thick and have sparse undergrowth as leaves do not drop so much as to enrich the soil.
4- Trees are conical in shape and take the name from the cones in which they bear their fruits e.g. the spruce trees. This conical shape and the downward sloping branches prevent the snow from accumulating on the tree so that the branches do not break during heavy snowfall.
5- The softwood bark of a conifer is resinous and helps to conserve food and moisture, especially through the long cold winter.
6- The leaves besides being needle-shaped to reduce transpiration are thick, waxy, and leathery to prevent frostbite. Despite the tree's shallow roots, the trunks are highly flexible and bend easily with the wind.
The largest forested area in the world is the vast coniferous forest of northern Russia Siberia lying between latitude 55°N and the Arctic Circle 661/2°N. It has an estimated wooden area of 1100 million hectares making up about 25% of the world's total forest.
Types of Vegetation
The coniferous forests have a limited number of species. They occur in pure stands. This makes lumbering operations simpler and compares favorably with tropical lumbering where the various species are closely mixed. They yield excellent softwood for commercial and industrial timber, especially for pulp and paper making. The most important commercial coniferous trees include the various kinds of pine, first and sources.
4- Tropical Grassland (Savanna)
Distribution:
Tropical grasslands are also known as Savanna. They are found within the tropical latitudes in extensive areas like the west, central, and East Africa, the Campos of Brazil, the Llanos of the Orinoco Basin, northern Australia, and parts of India and Indo China.
Characteristics:
1- Savanna lands are often described as extensive grasslands dotted with trees, grass being the most predominant ground cover. The Savanna landscape varies a great deal from the wet savanna nearer to the equator with heavier rain to the dry savanna nearer to the hot deserts where there is more scrub and coarse grass.
2- In savanna lands grasses grow in clumps or tufts with much barren ground in between. The grass, which may grow to a height of 2 meters or even 5 meters in the wetter areas are known as elephant grass.
3- The savanna is green in the wet, rainy summer season turning brown and withering away in the long drought and lying dormant during winter. The trees in the savanna adapt themselves in various ways to conditions that result from the scant rainfall and the long drought. These trees include:
a- The Baobab that stores water in their succulent or swollen stems.
b- The Acacias have long taproots with which to search the groundwater.
c- The Spinifex has thorns instead of leaves to reduce the loss of water.
4- The savanna with its grass and tree environment attracts many herbivorous grass-eating and carnivorous meat-eating animals and also numerous birds, reptiles, insects, and flies.
Types of Vegetation
The savanna has a great variety of tall and short grass, tussock, bushes, and thorny scrubs. There are no commercially valuable trees. The baobab trees yield seeds and fruit which can be eaten, acacias are just as useful.
5- Temperate Grassland (Steppes)
Distribution:
The temperate grasslands are the most extensive in the northern hemisphere and consist mainly of the Steppes of Eurasia and Prairies of the USA and Canada. In the southern hemisphere, the temperate grasslands are less extensive. An example is the Pampas of Argentina.
Characteristics:
1- The temperate grasslands are almost treeless and are vastly different from tropical grassland or Savanna. Low annual rainfall about 500 kilometers of strong winds and high summer evaporation make the tree growth difficult except in areas such as along streams and around ponds.
2- In the wetter areas such as in many parts of the prairies, the grass is tall and is therefore excellent for pastoral activities. In these areas both cattle and sheep graze. In the drier areas such as the Eurasian Steppes, the grasses are shorter, stiff, and course, e.g. the tussock grass, which are more suited to sheep and goats.
3- The temperate grass has shallow roots and withers in the cold winter. But it has resistant seeds that sprout to life again when spring comes.
The African savanna, the North American prairies, the Eurasian steppes, the South American pampas. These and the other grasslands make up a quarter of the land surface of the earth. More than three-quarters of the world's food comes from crops and herds they support.
Types of Vegetation
The original areas of most temperate grasslands are the tough tussock grass. The prairies have long prairie grass while the steppes have short steppe grass. In some areas of the temperate grasslands, man has replaced the original tussock grass with alfalfa or Lucerne grass which is far more nutritious for sheep and cattle. There are very few trees in the temperate grasslands only the toughest elders, willow, and pillars.
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