Introduction
The forest is a source of food, income, ecological resources, social and cultural features as well as physical facilities like wind power and building materials. Other functions of the forest are prevention of erosion as well as the provision of essential habitat for wildlife to survive. Hence the necessity to conserve the forest and biodiversity is important.
According to Emielu (2005) deforestation is the process of clearing forest for a variety of purposes such as lumbering, fuel wood, farming, mining, industrialization and settlement without immediate replanting of trees.
According to Phileze (2005) deforestation implies cutting down of trees for non-forest use like agricultural or building of industries and other urban uses. Thus deforestation is the removal of forest resources by man to enable him put the land into other uses without immediate replacement.
According to the Food and Agricultural Organization [FAO] (2006) estimated that 18million acre (7.3million hectares) of forest are lost each year.
Causes of deforestation
Researcher has confirmed that both human activities and natural are responsible for deforestation (FAO, 2006).
Human activities
Man contribute to deforestation in many ways such as expansion of farm land, overgrazing, bush burning, urbanization/industrialization, logging, mining etc
Expansion of farm land
About 60 percent of the clearing of tropical forest is for agricultural settlement. Expansion of agricultural land for more farming activities lead to deforestation (FAO, 2006). According to Meyer and Turner (2009) increase number of shifting cultivation were the main causes of deforestation.
Over grazing
Over grazing is one of the factors responsible for deforestation. This occurs when plant are expose to intensive grazing by animal for extended period of time with out sufficient recovery period. It can be as a result of poor agricultural application or over population of animals, it is also accepted that heavy grazing can change the composition of plants communities (Rigns & Haffman, 2004).
Bush burning
Hundred of trees are lost each year due to forest fire in various portions of the world. This happens due to extreme warm summer (dry season) and mild winter. Fire whether cause by man or nature result in huge loss of forest cover.
According to Olorunda, Onojeharho, Keme, Ogene and Sule (2007) fire is an integral part of the environment of many plant and animal communities. Fire if controlled and use intelligently is an effective management tool but if allow to run free it poses a significant threat.
FAO (2006) analyzed that fire related deforestation also rose sharply in Indonesia as severe drought condition help in spreading fire set by plantation workers and farmers into forest area.
Logging
Logging activities can seriously degrade forest. Wood based industries like paper; match-sticks, furniture etc. need a substantial amount of wood supply. Wood is used as fuel both directly and indirectly therefore trees are chopped for supplies. Fire wood and charcoal are example of wood being used as fuel. Some of these industries thrive on illegal wood cutting and felling of trees. Thus logging catalyzes deforestation (Chomitz, 2007). According to Phileze, (2005) forest has been cleared for logging and timber export.
Mining
According to Olorunda et al (2007) mining is the process of deriving or exploiting minerals from the earth crust. This may be through manual or mechanical means. Oil and coal mining require considerable amount of forest land, mining is very intensive and destructive. Mining is a lucrative activity promoting development which may attract population growth with consequent deforestation.
Urbanization/industrialization
Expanding cities and town require land to establish the infrastructures necessary to support the growing population which is done by clearing the forest (Meyer & Turner, 2009). Tropical forests are major target of infrastructure development for soil exploration, logging, concession or hydro-power, dam construction which inevitably conveys the expansion of the road network. The construction of roads, railways, bridges and airport open up the land to development and bring increasing numbers of people to the forest by using logging trails or new roads to access the forest for subsistence land.
Natural causes of deforestation
There are natural hazard which result in deforestation. They include;
Storms
Storms can cause extensive damage in the rainforest through tree fall. When a canopy or emergent tree falls dozens of other neighboring tress attached by lianas are bought down with it. Larger storm such as hurricanes (cyclone or typhoons) can cause substantial damage to forest and may to take decade to centuries (Rhett, 2012).
Climate factor
Climate factor such as temperature is agent of deforestation. High or low temperature is known to cause death to trees. In low temperature, tree roots are frozen to deprive the shoot system of water thereby causing death. In very high temperature plants tissues are burnt and this could lead to death of the trees (Teja, Edzo, Heiko & Edi, 2010).
Death and decay of trees
Trees are living things and often die naturally. Death may be premature due to root competition or lack of sufficient light or nutrients. These deficiencies predispose the plant to attack by insect or fungi which result into death and subsequently elimination of trees (Phileze, 2005).
Effects of deforestation on the ecosystem and human health
Deforestation is a worrisome environmental problem ravaging the Niger Delta leading to climate change, global warming, soil erosion, flooding, loss of biodiversity, decrease in the amount of rain fall, desertification, destruction of medical plants, economic lost, etc.
- Climate change
Forest are vital for life, home to million of species. They protect soil from erosion, produce oxygen, store carbon dioxide and help control climate. Forest play huge impact on the carbon cycle by absorbing the carbon dioxide in the atmosphere and giving out oxygen but when these forests are cut down the carbon dioxide released radiate in the atmosphere and mix with atmospheric gas such as Nitrogen (N2) to cause change in weather condition.
According to Unuraye (2010) the resultant evil of natural and environmental hazard gave birth to climate change. He also opined that this evil had divastatedely affect both living and non-living element in our fragile environment which need support and rescue. According to intergovernmental panel on climate change [IPCC] (2007, as cited in Olojoba, 2009) that human activities is responsible and that the climate change have severe effects on human societies, agriculture and natural ecosystems in the form of green house effect, ozone layer depletion and acid rain.
2.Global warming
Trees play a major role in the carbon cycle, they convert the carbon (IV) oxide in the air to oxygen through the process of photosynthesis and in this way they can be looked at as a natural regulator of the carbon dioxide. The more the trees (forest), the less carbon dioxide in the atmosphere and the more oxygen. Since we live in the age where carbon dioxide is very abundant in the atmosphere, release though man made invention such as cars, factories and power plant.
According to Olorunda (2007) global warming occurs as a result of increase in concentration of green house gases in the atmosphere. Green house effect is a term use in describing the situation in which the global temperature of the world rises beyond it normal level. She opined further that tremendous increase in the consumption of fossil fuel by human activities resulting in a corresponding continuous increase in atmospheric carbon (IV) oxides CO2 each year from industries, agricultural activities (bush burning) and grazing which lead to increase in green house gases. The green house gases include; Carbon (IV) oxide (CO2), Methane gas (CH4), Nitrogen (IV) oxide (NO2) and Chlorofluorocarbon (CFCS) etc.
3.Soil erosion
When trees are cut down, it will result in soil erosion due to the fact that forest serve as a cover against erosion by holding particles of the soil together thus preventing the fertile top soil from being carried away. Once the trees are destroyed, erosion can easily occur washing away the soil nutrient and may also led to pollution of water body through run off (Brujnzeed, 2004).
4.Flooding
When it rains, tree absorbs and store large amount of water with the help of their roots. When they are cut down, the flow of water is disrupted and lead to flooding. According to Olorunda et al (2007) flooding can be regarded as an unusual high rate of water discharge into natural and artificial banks.
5.Loss of biodiversity
Loss of biodiversity is the destruction and extinction of our plants and animal species (Odjugo, 2010). Fresh water animal and other animal use the forest as a habitat. The forests do not only provide a place for the animal to leave but also provide them with food and act as a source of protection from predators. When forest is destroyed, the number of species decline.
6.Decrease in the amount of rainfall
The forest helps in transpiration, the process by which plants release water through their leaves and thus add to local rainfall. In water cycle, moisture is transpired and evaporated into the atmosphere forming cloud before being precipitated as rain. According to Odjugo (2010) when forest trees are cut down, less moisture is transpired into the atmosphere resulting in the formation of fewer clouds, subsequently there is a decline in rainfall subjecting the area to drought. If rain stops falling within few years the area can become arid.
7.Desertification
Deforestation is one of the reasons behind the conversion of many tracts of land into deserts. Deforestation disrupt normal weather pattern creating hotter and drier weather thus increasing drought and desertification (Odjugo, 2010).
8.Destruction of medical plant
Some trees are use as herb. Trees such as cinchoma have been used for treating against malaria since time immemorial. Studies in china have confirmed that medical herb production is a big business (FAO, 2006). Destruction of forest leads to destruction of medical plants that could be used as treatment for various ailments.
9.Economic lost
The tropical forest destroyed each year amount to a loss in forest capital. Destroying the forest will lead to lost of economic tree that will lead to loss of revenue and future employment that could be derived from their sustainable management (FAO, 2006).
Health problems associated with deforestation
Global warming which is caused by human activities such as deforestation lead to the destruction of the ozone layer that shield the surface of the earth from excessive ultra-violent rays. Diseases such as skin cancer, eye damage, immune system damage etc. are cause by these activities (United Nation Environmental programme [UNEP], 2004).
- Skin cancer: Exposure to ultra-violet rays poses an increase risk of developing several types of skin cancer including malignant, melanoma, Basel and squamous cell carcinoma.
- Eye damage: Direct exposure to ultra-violet radiation can result in photo keratitis (snow blindness) and cataracts.
- Immune system damage: Effects of the ultra-violet rays lead to impairment of the immune system. Increase exposure to ultra-violet rays weakens the response of the immune system.
- Accelerated aging of the skin: Constant exposure to ultra-violet radiation can cause photo allergy which result in the outbreak of rash especially in fair skinned people.
Conclusion
Based on the seminar research topic, it was concluded that deforestation is cause by many factors and have many effects on human health and the environment.
Recommendations
Based on the findings made during the course of this research work, it is recommended a suitable means for solving the problem associated with deforestation (Strenstrup, 2010).
- Proper health education should be given to the community members especially those that engage in deforestation.
- The government should enact laws on environmental protection which includes monitoring and licensing of forest worker e.g. ministry of agriculture and natural resources which help to establish regulation, guideline and standard that will compel forest users in or worker to carry out their activities in the forest in a controlled pattern.
- Government should start practicing reforestation and forestry and this will drastically help to reverse the incidence of deforestation.
- Government should develop policies and agencies responsible for monitoring and regulating the activities of forest users or workers.
- Bush burning should be discouraged by community member.
References
Emielu, S.A (2005). Senior Secondary Geography: Ilorin: Geographical Bureau Nigeria.
Food and Agricultural Organization [FAO] (2006). Global forest resources: assessment 2005-progress towards sustainable forest management. Rome: FAO forestry paper, No 147.
Meyer, W.B and Turner, B.L (2009) the earth transformed: trends trajectories and patterns. London: Black Well.
Odjugo, P.A (2010) A General Overview of Climate Change Impact in Nigeria: Journal of Human Ecology, 29(1): 20-25
Olojoba, A.O (2009) Millennium Technology in Waste Management and Environmental Pollution Mitigation. Ughelli: Ama-Ohoror Press
Olorunda, J.O, Onojeharho, D., Keme, S, Ogene, N and Sule, A. (2007) Monitoring and Modeling Techniques of Environmental Pollution. Akure: His Mercy.
Phileze, P. (2005). Tropical Vegetation Resource Analysis. Onitsha: EMBA Printing Press.
Rhett, B. (2012, July, 27). Natural Threats to Rainforest. Retrieved on October 24th from http//: rainforests. Mongabay.com/0802..htm
Stenstrup, A. (2010) Forests Greensboro. North Carolina: Morgan Reynolds. P. 89
Teja, T., Christoph, L., Edzo, V., Heiko, F. and Edi, G. [Ed] (2010) Tropical Rainforest and Agroforest Under Global Change. P 270-271.
Unuraye, L.O (2011) Fundamental of Industrial and Environmental Health Management [2nd ed]: Ughelli: Kabaka Press.