FIRST TERM E-LEARNING NOTE
SUBJECT: BASIC SCIENCE
CLASS: JSS 3
DESERTIFICATION AND DEFORESTATION
- Definition of Deforestation
- Causes of Deforestation
- Effects of Deforestation
- Control of Deforestation
Deforestation is the continuous removal of trees without replacing or replanting them. Deforestation is also the permanent destruction of forest in order to make land available for other uses.
CAUSES OF DEFORESTATION
- Removal of trees to make land available for the construction of roads, building of houses and industries, recreational centres and so on.
- Indiscriminate logging by poachers for industrial purposes like the production of paper, furnitures, sculptures etc.
- Felling of trees to make wood available for domestic purposes like cooking.
- Burning of forest for hunting and farming.
- Natural causes like forest fire during thunderstorm or landslides can also lead to loss of forest trees.
- What is deforestation?
- State five causes of deforestation.
EFFECTS OF DEFORESTATION
- Deforestation leads to the loss of of wildlife and biodiversity. This means that wild animals in the forest like monkeys, gorillas etc, will gradual die off.
- Deforestation contributes to climatic change and increase in global warming.
- Deforestation lead to the lost of habitat of so many species of animals especially birds.
- Deforestation lead to decrease in atmospheric oxygen and increase in CO2. This means that plants and animals are in danger because there will less oxygen to breathe in.
- Deforestation leads to flooding and erosion.
- Deforestation may lead to starvation and homeless. This is because there will be no food or wood to build shelter.
- Deforestation may lead to economic loss if forest raw materials are no longer available for industry to use or export.
WAYS TO CONTROL DEFORESTATION
- Afforestation: This is the planting of trees in places where they are not planted before. Afforestation helps to bring forest condition to places where they do not exist before. An example of afforestation is the “Plant A Tree” initiative.
- Reforestation: This is the replanting of trees to replace those trees that have been removed from the forest.
- Government should make laws against indiscriminate poaching and logging.
- Government should make laws against bush burning.
- The use of forest guards to keep trespassers away from the forest.
- State four effect of deforestation.
- State four ways to control deforestation.
IMPORTANCE OF FOREST
- The forest provides raw materials like timber, latex, and medicinal extracts etc, to industries.
- Trees of the forest help in purifying the atmosphere by removing excess CO2 from the atmosphere for photosynthesis.
- The forest is the home of many animals which provides hides and skin for us to make clothes, bags, shoes and so on.
- The availability of forest provides employment for a lot of people.
- The presence of trees slows down erosion and desert encroachment.
What are the importance of forest to man.
- Definition of Desertification
- Causes of Desertification
- Control of Desertification
A desert is a large area of land with little or no rainfall where very few plants grow. Desertification is the process of making a non desert area a desert. It is the spread of desert to places where they previously do not exist. In Nigeria, about 50% to 75% of the northeast and northwestern states are deserts. State like Bauchi, Bornu, Gombe, Taraba, Jigawa, Kano, Katsina, Kebbi, Sokoto, Yobe and Zamfara all have deserts. Like most environmental hazards, desertification is majorly influenced by climatic change and human activities.
LIST OF SOME DESERTS IN AFRICA
- Sahara desert is the largest hot desert found in North Africa.
- Namid desert found in Southern Africa.
- Kalahari desert also found in Southern Africa.
CAUSES OF DESERTIFICATION
- Frequent bush burning.
- Water impoundment.
- Increased salinity.
- Climatic change.
- What is a desert?
- What is desertification?
- Mention four causes of desertification.
CONTROL OF DESERTIFICATION
- Planting of leguminous crops to restore soil fertility.
- Digging of artificial grooves to retain rainfall and trap wind blown seed.
- Planting of trees and cover crops.
- Public awareness on the need to prevent desertification.
- Use of proper farming method can help prevent desertification.
Mention four ways to control desertification.
- What is deforestation?
- List three major deserts in the world and their location.
- List five ways to control erosion.
- What is a skeleton?
- List the planets in our solar system according to their distance from the sun.
Basic Science Made Easy for JSS Three by F.I. Kehinde et al. Chapter 4. Page 12
- One of the method of control of the deforestation include bush burning B. Logging C. Afforestation D. Clean weeding
- The largest desert in the world is found in Australia B. South Asia
- North Africa D. Western Europe
- One of the following is not a method of controlling desertification.
- Overgrazing B. Afforestation C. Planting of cover crops D. Public awareness
- One importance of forest trees is that they Purify the atmosphere
- cause soil erosion C. destroy the ozone layer D. lead to loss of biodiversity
- The planting of trees where they do not previous exist is called
- Deforestation B. Desertification C. Afforestation D. Reforestation
- What are the benefits of forest to man?
- Explain how increased salinity can cause desertification
Soil erosion is the wearing away and loss of soil from an area. Soil erosion is the washing away of soil by heavy rain or wind resulting in formation of gulley and landslides and leaving behind barren rocks and slits on which plants can no longer grow. Soil erosion poses serious to agriculture as it wash away the nutrient from the topsoil.
TYPES OF EROSION
Based on the cause of erosion, we have:
Water erosion: This is the erosion caused as a result of heavy rainfall or flood which wash away the soil on slopes. Constant flow of water create gullies over a long time. When rain falls on sloppy ground the water runs off thereby washing away a large portion soil and also breaking down rocks in a process called weathering.
Wind erosion: This the erosion caused by fast moving wind which exposes the top soil and carry them away. Wind erosion can be controlled by planting trees along the wind path. These trees serve as windbreaker
HUMAN ACTIVITIES THAT CAUSE EROSION
Burning of bush: The deliberate or accidental burning of bush destroys the soil structure and exposes it to erosion and high temperature.
Farming: The cutting of trees and clearing of farmlands exposes the soil to erosion
Building of house and industries: The clearing of land before the building of houses promote erosion.
Growth of town: Development of town leads to the exposure of the soil surfaces which can easily be washed away.
Construction of roads: The construction of new road leads to the breaking of soil structure which make it easy for soil to be washed away.
EFFECTS OF EROSION
- It reduces soil fertility.
- It damages road and soil surfaces.
- It destroys farmland and farm produce.
- It may lead to lose of buildings.
- It leads to loss of lives through accident and building collapse.
CONTROL OF EROSION
- Indiscriminate burning of bushes should be stopped.
- Plant of trees and cover crops.
- The practice of mulching in which cut grass residue are spread over the soil surface under a growing crop which retains moisture, reduces weeds and prevent exposure of the soil surface thereby reducing soil erosion.
- Construction of terraces on sloppy land.
METHODS OF PREVENTING SOIL EROSION
- Wind erosion can be prevented by planting cover crops, grasses and belt of trees which serves as wind breakers.
- Water erosion and flooding can be prevented through proper canals and drainage channels to lead water away in to rivers.
- Gully erosion can be stopped by small dams with stones and sticks along the gullies in order to capture soil that is being washed away.
- Terrace should be build to prevent erosion. Terraces are barriers constructed along contours of the land which hinders the rapid flow of water down the slopes.
- What is flood?
- What are the activities of man that contributes to flooding?
- What is power?
- What is puberty?
- Explain what you understand by “teetotalism”
- What is pregnancy?
- The overflowing of rivers as a result of continuous rainfall leads to
- erosion B. deforestation C. flooding D. drought
- Which of the following will help to control flooding? Overgrazing
- Deforestation C. Damming of rivers D. Dumping of refuse
- Which of the following does not contribute to flooding?
- Blocked drainage B. Overflowing rivers C. Adequate drainage system
- Loss of lives
- Which of the following is a consequence of flooding? Growth and development B. Increased fertility C. Destruction of livestock D. Provision of food
- Flood is a ___ occurrence. natural B. Man-made C. Phenomenal
- List five things you can do to prevent flooding in your immediate environment.
- What are the environmental and economic impacts of flooding?
- Mention five ways to prevent erosion?