WEEK 3

VEGETATION OF NIGERIA

Vegetation is defined as an association two or group of plants growing together in a particular habit or environment.

The vegetation in Nigeria can be grouped into three major zones.

These are

(1) Forest zone or Vegetation

(2) Savanna zone or vegetation

(3) Montane vegetation

(1) The Forest Zone

This forest zone or vegetation contain mainly trees and has the following forest belt.

(a) Mangrove Swamp forest (salt and forest water swamp)

(b) Rainforest

Mangrove swamp forest

This vegetation is found mainly in Delta and Coastal areas like Portharcout, wam, Uyo and Calabar.

Characteristics

(i) It has tall woody trees.

(ii) It has aerial roots.

(iii) It has evergreen trees with bound leaves.

(iv) Trees found include white mangrove, red mangrove and some raffia palms.

Importance

(i) Rafia palm is used for making basket bags, brooms, cane, chairs and the production of palm wine.

(ii) Mangrove trees are used for boat building and firewood.

(iii) Farming activities such as swamp rice cultivation are embarked upon

Rainforest

It is found in Southern part of Nigeria in Benin Sapele, Akure, Ibadan, Abeokuta, Aba e.t.c

Characteristics

(1) It has tall trees with buttress roots evergreen and broad leaves.

(2) Trees exist in different heights storeys or layers i.e. bottom, middle and upper layer.

(3) Presence of little under growth due to canopy of the forest.

(4) Presence of climbers, creepers, epiphytes and parasitic plants.

(5) It has numerous heterogeneous species of tree like Iroko, obeche, mahogany, African walnut.

(6) Plants species are not in pure stand i.e. trees are scattered.

Importance

(i) It provides tropical hardwood like iroko, obeche, mahogany etc. timber, for construction purposes.

(ii) Lumbering of the trees provides employment.

(iii) Farming activities especially the cultivation of tree crops in plantation e.g.

rubber, cocoa, oil palm etc.

(iv) Forest provides wood as sources of fuel.

Savanna Zone or Vegetation

The Savanna zone is made up of mainly grasses and is further sub-divided into three savanna belts which are:

(i) Guinea Savanna

(ii) Sudan Savanna

(ii) Sahel Savanna

Guinea Savanna

This savanna is found in Enugu, Lokoja, Ilorin, Makurdi, Osogbo etc.

Characteristics

(1) It is the largest of all the vegetation belts in Nigeria.

(2) Presence of tall grasses.

(3) Presence of tall trees with broad leaves.

(4) The trees are scattered and deciduous i.e. they shed their leaves during dry season.

(5) Important trees include locust bean trees, shea-butter and isobelina.

Sudan Savanna

This vegetation belt is found in Sokoto, Katsina, Kaduna, Kano, Dutse, Bauchi etc.

Characteristics

(1) It has short numerous grasses

(2) Presence of scattered and short deciduous trees.

(3) Plant species include acacia, date palm, silk cotton plants, baobab.

(4) Some trees have thorns while others have thick barks

(5) Some trees wither in dry season and spout at the beginning of raining season.

Sahel Savanna

This savanna is found in Maiduguri and Damatru

Characteristics

(1) It has short scanty grasses.

(2) Presence of short and tough shrubs or trees.

(3) Grasses are fewer, poorers and in patches

(4) It has many drought resistant and scattered plants.

(5) Popular plants include acacia, gum Arabic, date palm, baobab etc.

Montane Vegetation

This vegetation is found in Jos and Adamawa area.

Characteristics

(1) It is associated with highland areas.

(2) It has varied trees at its round ward side.

(3) It has grasses at its leeward side

(4) Presence of short, scattered and deciduous trees.

Importance of Montane Vegetation

(1) Livestock production especially transhumance is common.

(2) Cultivation of crops also takes place.

Importance of forest vegetation to the economic growth of Nigeria

(1) Provision of food

(2) Provision of timber

(3) Foreign exchange

(4) Employment

(5) Raw materials for industries

(6) Provision of fuel wood

(7) Tourism and wild animals.

Problems Associated with forest

Explain

(i) Soil erosion

(ii) Depletion of natural vegetation

(iii) Leaching of the soil.

(iv) Exploitation that causes flooding.

(v) The problem of transportation of logs.

(vi) The disappearance of wildlife.

(vii) High cost of lumbering and difficulty in cutting trees because they are not in pure stand.

Importance of Savanna Vegetation to the economic growth of Nigeria

(i) For livestock farming.

(ii) Arable crop farming

(iii) Employment

(iv) Development of game reserves.

(v) Provision of fire wood.

(v) Tourism

Differences between forest vegetation and savanna vegetation

(1) High rainfall gives rise to mangrove swamp forest in the South while low rainfall gives rise to savanna vegetation.

(2) High rainfall and high temperature give rise to evergreen forest in the South low or seasonal rainfall gives rise to the growth of short deciduous trees which shed their leaves during the dry season.

(3) Heavy rainfall gives rise to the growth of tall trees like iroko, obeche while low rainfall supports the growth of short drought resistant trees with tiny leaves.

(4) Heavy rainfall in the forest belt does not support the growth of grasses while scanty rainfall in the extreme north gives rise to short scattered grasses.

(5) High rainfall support the growth of climbers, creepers, epiphytes etc. while scanty or no rainfall gives rise to desert in the extreme north.

(6) Arrival of rainfall does not mark the beginning of growth of trees in the South while arrival of rainfall marks the beginning of the growth of grasses in the Savanna.

WEEK 4

RAINFALL

Rainfall is a form of precipitation in liquid state which is derived from large droplets of water. It is produced by clouds.

Rainfall is defined as the releases of excess condensed water vapour in the atmosphere into the earth. Rainfall is the most important form of precipitation.

On maps lines used to join places having the same average annual rainfall are called Isohyets. It is measure by an instrument called Rainguage.

Other forms of precipitation include:

(i) Snow: Snow is formed when water vapour condenses in the atmosphere at temperature below freezing point resulting in the forming of ice crystals.

(ii) Hail: This is formed from condensed water droplets at great vertical height and usually associated with thunderstorm ice crystals are also formed.

(iii) Dew: Dew is formed when condensation takes place on the ground, buildings or on top of leaves. The temperature at which condensation occurs is known as dew point.

(iv) Fog: This is also formed when condensation takes place near the ground or over the sea, resulting in tiny particles of dirt and dust in the air. Fog usually causes poor visibility especially in the morning.

(v) Frost: This form results from the direct condensation of water droplets into ice crystals when the temperature is below freezing point.

(vi) Mist: Mist, just like fog is formed when condensation takes place near the ground where it occurs and tiny water droplets. The difference between the mist and fog is that mist is not as thick as fog.

Types of Rainfall

(1) Convectional rainfall: Convectional rainfall occurs in area intensively heated. Hot or warm air accompanied by a rise in relative humidity rises. The rising air becomes saturated and water vapour condenses with cloud being formed quickly. This results in heavy rains accompanied by thunder and lightening.

Characteristics of Convectional rainfall

(i) It is short-lived.

(ii) It is characterized by heavy winds, lightening and thunder.

(iii) Rainfalls within limited areas usually in the afternoons.

(iv) The sky becomes clear immediately after the rain.

(v) Hail stone may also occur.

(vi) The rain is always torrential or heavy accompanied by lightening and thunder.

(vii) The cloud associated with thundest and conventional rainfall is called cumulo- nimbus.

(2). Orographic or relief rainfall: In orographic rainfall, moist air is forced to rise above a mountain or relief barrier, usually in the windward slopes of mountain. Rising air expands and become cooler and relative humidity rises and air becomes saturated water vapour condenses, clouds is formed with rainfall on the wind ward side and descending air on the leeward side.

Characteristics of orographic or relief rainfall

- Orographic rainfall is associated with mountains regions with even distribution of rainfall over a highland.

- Windward area has rainfall while leeward side has little or no rainfall.

- It is also characterized by ascending and descending wind.

- This rain only forms or takes place on the windward side of a mountain while the other side i.e leeward side experiences little or no rainfall at all.

(3). Cyclonic or frontal rainfall: Cyclonic rainfall is caused by the meeting of two air masses which are different in terms of origin and characteristics. Warm light, moisture laden air rises above cold and dense air. Ascent of the warm air over cold air lowers the temperature of the warm air. Cooling takes place and condensation occurs – cloud formation and precipitation follow.

Characteristics

- Cyclonic rainfall is characterized by weather system in mid latitude.

- Rainfall is convectional type in cold front and it lasts for duration than convectional rainfall.

- It covers extensive area and moves from the West to the East in the Northern hemisphere and vice-versa.

- It moves from West to East in the Northern hemisphere and east to West in the Southern hemisphere.

- Cyclonic rainfall is common between latitude 500N – 700N and 500S – 700S.

Importance of rainfall

- It supplies soil with fresh water.

- It supplies oceans and rivers with fresh water

- It modifies the temperature of the environment.

- It supplies plant with water.

- It supplies water from domestic and industrial uses.

Lateralization is the corresponding soil forming process in the hot, humid tropics where rainfall and temperatures are high throughout the year.

WEEK FIVE

SOIL IN NIGERIA

The soil in Nigeria can be grouped into four major zones: These soil zones include:

(1) Zone of laterite soils

(2) Zone of forest soils

(3) Zone of sandy soils

(4) Zone of alluvial soils

(1) Zone of laterite soils

Characteristics

1. They are found in the interior zone of Nigeria like Jos, Makurdi, Minna, Enugu, Abuja etc.

2. The soils are associated with Guinea Savanna.

3. The soils are heavily leached due to rainfall.

4. The soils are usually reddish in colour due to the presence of iron.

5. They are sticky when wet and hard when dry.

6. The soils support the growth of tuber crops like yam, cocoyam, cassava etc. due to the accumulation of nutrients at the B-horizon.

7. It contains iron and aluminium compounds.

(2). Zone of sandy soil

Characteristics

1. These soils are found in the extreme Northern part of Nigeria like Sokoto, Katsina, Kano, Dutse, Damatru, Maduguri.

2. The soils are associated with Sudan and Sahel type of Savanna.

3. The soils are formed due to dryness and depositing of sand by wind.

4. The soils are sandy loam, friable, easy to cultivate with little leaching.

5. It supports the growth of crops like groundnut, cotton, maize, millet, guinea corn etc.

6. It contains little humus and little leached.

7. The grains are coarse in texture.

(3). Zone of Forest Soils

Characteristics

1. The soils are found in the Southern belt of Nigeria like Ibadan, Akure, Abeokuta, Benin city, Anambra and Imo States.

2. It is associated with the forest vegetation.

3. The soils are rich in humus due to fallen and decayed leaves.

4. Owing to heavy rainfall, the nutrients are leached to the sub-soil i.e (B-horizon).

5. The soils support growth of the crops like cocoa, rubber, oil palm, kolanut.

(4). Zone of Alluvial soils

Characteristics

1. The soils are found in Ilorin, Lokoja and Niger Delta area of Warri, Calabar and

Port-Harcourt etc.

2. They are associated with water deposits along river courses of Niger and Benue, coastal plains and the Delta.

3. Colour of the soil varies some are dark grey while some are white.

4. The soils are usually sticky and support water logging.

5. The soil supports the growth of crops like swamp rise and raffia palm.

6. They are sandy, very pervious and porous.

Soils

Meaning: Soil covers the earth surface that is the topmost layer of the earth crust on which plants grow. Soil as a natural body is form as a result of complex interaction of parent materials, climate, relief biological organisms and time.

The composition of soil

Soil is made up of five distinct components namely organic, inorganic soil organism, soil water and soil air.

(1). Organic matter: This soil is made up of the remains of decayed plants and animals that form humus soil and provide essential nutrient to plants.

(2). Inorganic matter 45%: This type of soil forms the greatest proportion of the solid materials which provide support and gives nutrient to plant.

(3). Soil water: Soil water contains about 25% of the total volume of soil which can be found between the pore spaces of the soil. The significant role of soil water is that it helps to dissolve plant nutrients and aids plant growth.

(4). Soil air is about 25% of the total volume of soil: It contains almost the same proportional volume as that of soil water and it can also be located between the soil water and it can also be located between the soil particles. Soil air is important because it aids the respiration of soil organisms.

(5). Soil organisms: Soil organisms include earthworm, rodents and bacterial which are useful to plants and animals. Atimes it may cause diseases to these plant and animals.

Factors of Soil Formation

(1). Parent Materials: The chemical composition and minerals materials affect the type of soil which is formed. Parent materials are made up of quartz which gives rise to poor sandy soil.

(2). Climatic Weathering: Rocks exposed to weather are broken down to form soils. Mechanical and chemical weathering processes are involved. Leaching affects soil formation.

(3). Relief: Relief affects soils formation soils on hill tops are usually thin because of active soil erosion. The soil in the valley is thicker and heavier since the valley is more fertile for plant growth. The soils in the valley also receive eroded soil from the upland.

(4). Biological Organisms: Roots open up the soils for more aeration. Plants die and add minerals to the soil. The plants bodies are changed or decomposed into soils.

(5). Time: If a piece of rock is broken down and exposes to the factors above, over a long period of time, change will be observed.

Type of soil water

There are four major types of soil water.

These are:

(1). Hygroscopic water: This water is tightly held by the soil particles such that it is never available to the plant.

(2). Field Capacity: This is the type of water left in the soil after excess water has been drained off, following heavy rainfall. This water is available to the plants.

(3). Capillary water: This is the water rises above the water table in the soil and it is held in the fine and medium pores of soil particles by surface tension. Capillary water is easily available to plants.

(4). Gravitational water: This is the water which the influence of gravity. It is available to plants bit is after pulled down beyond the reach of the roots.

Characteristics of soil

Certain characteristics are used to identify or describe soil sample.

(1). Soil colour: The first observation made when a soil profile is dig is soil colour. Colour varies from one soil to another. There are brown black, red, and yellow. Black and dark brown soils are known to contain more nutrients while red or yellow soils are poor in plant food.

(2). Soil texture: This refers to the relative proportion on sizes of the various particles of the soil. It is also the degree of fines or coarseness of the various particles. The particles that make up a soil sample include gravel, sand, clayed salt.

(3). Soil structure: Soil structure refers to the ways in which the different particles of the soil are packed or arranged. The various types of soil structure include single grain, crumb, platelike, sphervidal, promatic, blocklike and columnar structures.

(4). Permeability: This is the ability of water to pass through a simple of soil while sandy soil is permeable, clay is not.

(5). Capillarity: This is the upward movement of water in the soil while sandy soil has poor capillarity because of its large pore spaces, clay soil has good capillarity because of its tiny pore spaces.

(6). Soil pH: This refers to the degree of acidity or alkalinity of the soil.

Soil Profile

Soil profile is defined as the vertical sections through the soil to the underlying rocks,

showing series of horizontal layers. These horizontal layers are called horizons.

A typical soil profile has three main layers or horizons which are A, B, C and D which is the bedrock.

(1). A – Horizon: Is also called top soil. It represents the surface layer of the soil profile. It contains more humus or organic matter and it is the zone of eluviations i.e where minerals are leached down the profile. It has maximum biological activities of plants and soil micro-organism.

(2). B-Horizon is also called sub-soil. It is the zone of illuviation i.e. where soil minerals form A-horizon accumulates. It contains lots of mineral matter. There is the conversion of organic matter from A-horizon into inorganic matter.

(3). C-horizon is also called zone of parent materials. It contains weathered parent rocks. It represents materials from which top and sub-soils are formed.

(4). Horizon D: This is the zone of un weathered rock from which the rock fragments which eventually disintegrate into soil particles are formed. It is also known as bedrock.

Local soils and their characteristics

(1). Loamy soil: Loamy soil is formed from combination of sand and clay with a high proportion of organic matter. This type of soil is very fertile.

Characteristics

(1). It contains a lot of organic matter.

(2). It is loose and moist in nature.

(3). It is well aerated and can hold water.

(4). It does not support erosion and water logged.

(2). Sandy soil: Soil is said to be sandy when the proportion of the sand particles in the sample soil are made up of over 50% coarse grains. Such soil is usually not good for forming because it is poor in plant nutrients.

Characteristics

(1). Sandy soil is coarse and gritty

(2). Sandy soil is not sticky when wet.

(3). Sandy soil has high percolation while capillarity is very low.

(4). Sandy soil is well aerated and cannot hold water.

(5). Sandy soil has large pore spaces.

(3). Clay soil: A soil is said to be clayey if the proportion of clay in a sample of the soil is high. Clay soil is fine-grained and holds much water and has the capacity of attracting and retaining plant nutrients.

Characteristics

(1). Clay soil is lightly packed with little pore spaces.

(2). It is poorly aerated and can hold water.

(3). It is fine grained and smooth.

(4). It is sticky when wet and hard when dry.

(5). Percolation is low but capillarity is high.

Silt: This consists of very small quartz particles. They are micro sand grains but have more surface area than sand.

Laterite: This is leached soil and it is not very suitable for agricultural purposes.

Soil Erosion

As indicated at the beginning of this topic, soil is a major element of land which

influences many human activities. Soil erosion is the removal of top layer of soil either by water or wind. Soil erosion is also the rapid removal or destruction of the soil when exposed to weather condition and Man’s activities such as deforestation, cultivation, overgrazing, bush burning and quarrying.

Types of soil erosion

Soil erosion of two types

(1). Wind erosion: This type is more common in arid and semi-arid regions of the world. It also occurs in the humid regions also in dry seasons and the beginning of farming season when most farmlands have been tilled and are still bare of crop cover.

(2). Water erosion: This result from the exposure of the soil to rainfall and the run off water generated by the rainfall,

Types of Water Erosion

(1). Splash Erosion

This is the break up of soil aggregates by the impact of rain drop such that the soil particles fly out in all directions. In general the greater the size of rain drops the greater the ability to break up soil aggregates.

(2). Sheet Erosion

This is the removal of soil in thin layers by run-off water over broad, gentle sloppy surfaces. It is the most wide spread form of soil erosion by water and HS effect is the most damaging to soil because it removes mostly the fine humus and clay particles together with the nutrients that they carry.

(3). Gully Erosion: This occurs in areas of strong relief or loose sandy soil. It creates deep gorges or gullies which dissects the land surface and hinder movement and the cultivation of land. Gully erosion is more devastating in its destruction of the land and its occurrence is not as wide spread as that of sheet erosion.

Types of Soil water

There are four major types of soil water.

(1). Hygroscopic water: This water is tightly held by the soil particles such that it is never available to the plant.

(2). Field capacity: This is the type of water left in the soil after excess water has been drained up after a heavy rainfall. This water is available to the plant.

(3). Capillarity water: This is the water which rises above the water table in the soil and it is held in the fine and medium pores of soil particles capillarity water is also available to plants.

(4). Gravitational water: This is the water which can drain from the soil under influence of gravity. It is available to plants but is often pulled down beyond the reach of the roots.

Soil Conservation

This is the method of maintaining and retaining the fertility of the soil. Soil erosion has rendered millions of hectares of land highly unproductive. If the world is to meet up with the adequate provision of food for the daily increase in population and avoid famine and disease then measures must be taken to check the excessive erosion.

Types of Soil Conservation

(1). By terracing the hills sides.

(2). Through contour ploughing.

(3). By afforesting hill slopes.

(4). Replacing fallow with suitable crop rotation.

(5). By dividing large field into smaller ones surrounded by edges and walls that act as wind breakers.

(6). Limiting the number of animals on a farm to the actual holding capacity of the pasture.

Importance of Soil

(1). Soil provides the only medium through which agriculture is practiced to provide

food for man.

(2). Soil serves as the sources of all minerals used by man.

(3). Soil provides the habitat for most organisms especially bacteria.

(4). Soil provides plant with all the needed nutrients for their continuous existence.

(5). Soil acts as reservoir for air and water needed by soil living organisms to survive.

(6). All vegetation type form basis on soil.

(7). All forms of construction works are carried out on soil.

WEEK 6

GEOGRAPHIC INFORMATION SYSTEM (GIS)

A geographic information system manipulates, analyse, manage and present all types of geographical referenced data. G is describes any information system that integrates, stores, edits, analyses, shares and displays, geographic information for information decision making.

A geographic information system is a computer based tool for mapping and analyzing features and events on earth. G is manages location based information and provides tools for display and analysis of various statistics including population characteristics economic development opportunities.

Uses of GIS or Application of GIS

Geographic information system can be used in the following ways.

- Earth surface based scientific investment.

- Resources management.

- Reference and projections of a geographical feature both artificial and natural.

- Assess management and location planning.

- Environmental impact assessment.

- Infrastructure assessment and development.

- Urban planning and regional planning.

- Geographic history.

- Marketing and logistics i.e to make something successful with a lot of people and equipment.

- Population and demographic studies.

- Damage prevention e.g. soil erosion

- Engineering analysis

- GIS might be used to find wet lands that need protection and strategies regarding pollution.

- GIS can be used by a company to site advantage of GIS data intensified trends to respond to a previously underserved market.

- GIS can be used to track the spread of emerging disease e.g. Ebola

Components of A GIS

A GIS integrates fine key components. These are:

(1). Hardware

(2). Software

(3). Data

(4). People

(5). Method

GIS Data

GIS data represents real objects such as road, elevation, trees, water way with digital data.

Sources of Data

- Land surveying

- Remote sensing.

- Map digitizing.

- Map scanning

- Field investigation.

- Tabular data etc

Satellite

Satellites are objects purposely place around earth, other planet or the sun. Moon is a natural satellite of the earth. Artificial satellites are objects made by man placed in orbit around the earth. The first satellite was launched in 1957. Today artificial satellites play key roles in communication, industry, in military intelligence and scientific study of both earth and outer space.

Types of Satellites

(1). Navigation Satellites

(2). Weather Satellites

(3). Military Satellites

(4). Scientific Satellites

Remote Sensing

This can be defined as perception and recording of phenomenon by devices which are not in contact with them. It is also the art and science of making measurement of the earth using sensors on airplanes or satellites. Remote sensing can also be defined as the process of obtaining information about land, water or an object without physical contact between the sensor and the object of analysis. The sensors collect data in the form of images and provide specialized capabilities for manipulation analyzing and visualizing those images.

Relationship between GIS and remote sensing

GIS is the computer system that analyse geographical data while remote sensing is one of the tools use to get the information for the GIS.

GIS is the computer system that records, stores and analyse information about the feature that makes up the earth’s surface while remote sensing is the process of obtaining the information about the features that makes up the earth surface.

Land Reclamation

Land reclamation is a term applied to the utilization and improvement of water and land resources for agriculture and other purposed through irrigation, drainage of tidal marshes restoration of strip mine areas and other construction activities.

This idea of land reclamation was initiated in 1992 in US. Department of interior to stimulate the settlement and economic development of 16 sparsely populated Western states by reclaiming arid lands through irrigation.

Methods of Land Reclamation

Depending on the environment different methods have been employed to displace water logging in an environment. These methods include Aforestation, Construction of Barriers, sand filling, construction of drainages and control of erosion as well as the irrigation practices in arid land.

(1). Aforestation: It is a method by which vegetables are planted to protest soil. When this is done evapo transpiration reduces the volume of surface water.

(2) Sand filling: This is the simplest method of land reclamation. It is done mechanically. It is a process by which area covered with water is displaced with sand. Loads of sands are deposited in area covered with water to sub-merge the water.

(3). Construction of Barrier: This barrier can be informed of dam to check the flow of rivers. The idea behind this is o regulate the flow of water. It is also aimed at storing water for use.

(4). Construction of Drainage: This is a method that allows water logged area to be freed from water. This method allows water to flow freely.

(5). Control of Erosion: Erosion is the washing away of top soil. It makes the nutrients of soil to be lost. It also deforms areas of land rendering it to be economically unproductive. Different erosion control method will improve the use of land economically.

(6). Irrigation system: This is artificial application of water to land.

Importance of land Reclamation

(1). Land reclamation ensured construction water level. It controls the over flow of water and also protect the aquatic ecosystem.

(2). It increases the land to be used for economic activities especially and filling. It has also helped irrigation farming a lot.

(3). Dams constructed prevent nutrient laden silt from flowing down stream into valleys. Water in a fast moving river carries tiny particles of soil and organic materials that are deposited in the floor of a dam.

(4). Where dam is constructed it could aid the generation of hydro-electric power supply which is regarded as one of the cleanest source of energy.

Problems of land reclamation

(1). The application of fertilizers and other chemicals an land that is irrigated has increased the salt content of soil and water. This will surely affect the aquatic ecosystem.

(2). It involves a huge capital to practice land reclamation.

(3). Green house gases are emitted where hydro electronic power station is found. This green house gases contribute to global warning which will result into climate change.

(4). Dams constructed alter water temperature and microhabitats downstream.

(5). Big dams artificially slow water to a near standstill, causing organic matter to

settle down to the bottom of the reservoir. This deprive downstream regions from benefiting from nutrient laden silt.