BIOMES
The plant cover of the
earth is usually referred to as its vegetation. This includes trees
and grasses of various kinds. Vegetation differs from place to
place and the kind of vegetation found in a place is usually
influenced by various factors. There are four major factors
influencing the Nigerian biome and these are; climate which can be
further broken down to humidity and rain fall pattern,and are the
most important climatic factors affecting vegetation in Nigeria.
Other factors include soil, relief and mankind.
The Nigerian biome can be divided into two broad vegetative belts.
They are the forest belt which consist of salt water swamp, fresh
water swamp, and rain (high) forest. The other is the savanna belt
which is further divided into Guinea Savanna, Sudan Savanna and
Sahel savanna.
There is also another vegetative type referred to as Montane
vegetation which can be found in areas with high elevation such as
the Jos Plateau and Adamawa Plateau.
Salt water swamp
They are restricted to the estuarine environment on the coastal
fringes of the country an area estimated to be 30 to 50 kilometers
wide.
The area which is swampy and waterlogged consist of mangrove
vegetation of various species, hence the salt water swamp is
sometimes referred to as mangrove swamp. The vegetation usually
appears like a tangled mass of stems with aerial roots. Mangrove
trees are of two broad.
The red mangrove is seaward while the white mangrove is land ward.
This area is usually characterised by high volume of rainfall of
over 300 cm on the average per annual. Wood from red mangrove are
strong and are used for boat/canoe making, also this area is
blessed with coconut trees.
Fresh water swamp
Fresh water swamp is further inland where tide cannot reach the
land, thus the water is free of salt and is usually referred to as
fresh water. Although the area is free of saline water it is still
water logged with the absence of mangrove trees.
One of the predominant plant species in this area is the raffia
palm from which local wine can be gotten. This area is rich in
fish, crabs e.t.c.
Rain (high) forest
The rain (high) forest which is found in the southern part of
Nigeria stretches from the west across the river Niger to the
eastern part of Nigeria, with an average width of 130 kilometers,
although it is considerably narrower around the river Niger, due to
the north ward protrusion of the fresh water swamp in that
vicinity.
The rainforest belt has a high annual rainfall of between 130 to
150 centimeter in the west and over 200 centimeter in the east,
with a long wet season of between 8 to 10 months and a high
relative humidity of over 80%. This ensures an adequate supply of
water, giving rise to large perennial plants such as the Iroko,
Mahogany etc. the rainforest is stratified into 3 basic layers
namely the top layer which is further divided into 3, the upper –
middle and lower layers, the shrub layer and finally the
underground vegetation.
The forest is rich in epiphytes, climbers, parasitic plants and
saprophytes such as the mushroom. Small animals such as rodents,
millipede, etc. abound in the forests as well as birds an aboreal
organisms such as monkeys. Cities such as Benin, Akure, Owerri, etc
are all located in the rainforest belt of Nigeria.
Guinea Savanna
Guinea savanna is by far the largest vegetative zone in the country
covering nearly half the nation’s total land mass. It is located at
the middle of the country extending south to areas such as Enugu,
Nsukkaetc and reaching far into the north, to Zaria, Kaduna etc.
Guinea savanna covers the area which has an average rainfall of
between 100 to 150 centimeters, with its wet season lasting for between
6 and 8 months. Guinea savanna may be divided further into parkland
savanna, gallery forest and derived savanna.
Parts of guinea savanna with tall grasses and trees which gives it
the appearance of a park are usually referred to as parkland
savanna. It is also sometimes referred to as savanna wood land or
wooded savanna. Trees which predominate in this area are the shea
butter tree, isobellna etc. places such as Bauchi are found in
savanna woodland.
The extension of forest into the savanna along river banks, due to
the presence of moist is usually referred to as gallery forest.
These areas are easily identified in the air because they are
darker and grow dense enough to cover the river. An example can be
found in Markurdi, along the Benue river.
The southern most part of the guinea savanna has few trees, as a
result of desire station.
These were former parts
of the rain forest which have become part of the savanna country
due to excessive logging. These areas are therefore termed derived
savanna because they were not originally parts of the savanna
country. Examples of places in derived savanna are Enugu Nsukka
etc.
The Guinea Savanna is rich in herbivores such as antelopes, zebra,
etc and their predators such as lions, leopards, tigers etc. smaller
creatures such rodents, miccipede are also found in guinea savanna
.
Sudan savanna
This belt is found in the far north, stretching from the Sokoto
plain through the high plains of Hausa land to the Chad Basin. It
covers about a quarter of the entire nation. This belt lies in the
geographical area of the country with an annual rainfall of between
65 to 100 centimeter and has a relative humidity less than 400%,
except during the dry season in which it may rise to about 60%,
it’s wet season span between 6 to 8 months. Places in the Sudan
Savanna include Sokoto, Kano etc.
The landscape is less generously covered with plants than the
guinea savannah. The actual vegetation is made up of short grasses
1.5 to 2 meters high and stunted trees. The isobelina and shea
butter trees at the guinea savanna are replaced by acacia and
baobab trees which are much more hardy.
Sahel savanna
The sahel savanna can be found on the northern fringes of Nigeria
in Borno State. It is the closest of the nation’s vegetative zones
to what a desert is. It has an annual rainfall below 65 centimeter
and a long dry season which exceeds 8 months. The grasses in this
area are short and Tussocky, having a height of between 0.5 and 1
meter. They are interspaced with sand dunes.
The Acacia is the tree which predominates in this area, although
the date palm starts appearing gradually. Except for the swampy
shores of lake Chad which support tall reeds growing on seasonally
flooded land, vegetation in the area is scanty, as such the chief
occupation of the people in this area is nomadic farming of live
stocks such as cattle.
Montane vegetation
The Jos Plateau, Adamawa Plateau, Bauchi highland all lie in the
guinea savanna belt of the country, but because of the relief of
these areas their vegetation cover is quite different showing signs
of montane vegetation, although it must be clearly stated that
typical montane vegetation is not found in Nigeria.
The grasses found on these highlands are shorter and the trees are
fewer than at lower levels. the fields are used as pasture land by
the Fulanis who live there. |
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