Vegetation
comprises of plants growing over the surface of the earth. The plant
geographers have divided the vegetation of the world into four great biochores
:
The Forest Biochore : Defined
as plant formation consisting of trees growing close together nd forming
a layer of foliage that shades the ground.
The Savanna Biochore : It
is a combination of trees and grasslands.
The Grassland Biochore : An
upland vegetation of herbs which include grasses or grasslike plants and herbs.
The Desert Biochore : It
is associated with arid climate and thinly dispersed plants.
According to
varied climate and density of vegetation cover, the vegetation of world is
divided into three types.
1. Forests Forests
are classified on the basis of coverage, density and greenery.
(a) Tropical Rainforests : These
are known as equatorial forests and found in Amazon Basin, Zaire Basin and
other wetter areas in the monsoon regions. These are broad-leaved
hardwoods composed of trees like Mahogany, Rubber, Cinchona, etc.
(b) Monsoon Forests : These
are found in areas having 100 to 200 cm of rainfall. They are hardwood forests
and generally deciduous.
(c) Coniferous Forests : These
are evergreen, needlelike softwood forests found in North America and South
America.
2. Grasslands
Grasslands are characterized by less rainfall.
Grasslands are characterized by less rainfall.
(a) Savannas : These
are tropical grasslands, occuring as a transitional belt between hot
desert and monsoon regions and are areas of thick high grasses. These are known
by different names like Parkland in Africa, Illonos in Venezuela, Campos in
Brazil and Downs in Australia.
(b) Steppes : These
are short, shallow rooted grasses growing in bunches. These are found in low
latitudes and middle latitudes. These are reduced to weedy plants due to
overgrazing.
(c) Prairies : These
are temperate grasslands. The grasses are tall and deep rooted. These are found
in Southern Russia, Central Europe and Argentina. The original vegetation in
these regions is destroyed and the land turned into agricultural land.
(d) Meadows : These
are grasslands maintained artificially and known as pastures; common in England
and North Kalahari desert.
3. Desert Shrubs Desert
shrubs consist of bushy plants in hot sandy deserts and mosses in cold tundras.
These occur in parts of Atacama desert in South America.
