Deforestation activities and its public health implications

Introduction

The word deforestation is the process of clearing forest for a variety of purpose such as lumbering, fuel wood, farming, mining, industrialisation and settlement without immediate planting of trees. The forest is a good source of income, ecological resources, social and cultural feature 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 wild life to conserving biological and cultural diversity. It is now widely recognised that many protected area also have important social and economic functions. These include protecting watershed, soil and coastline, providing natural product, tourism and recreation (Lee, 2003).

Deforestation can lead to global warming which is as a result of the exposure of the troposphere to excessive heat (sun) or rain, washing the top layer of the soil resulting to flood and  erosion.. The effects of global warming can lead to several diseases such as cancer, eye damage, immune system, etc. (United Nations Environmental Programme, 2002).

There are many causes of deforestation. The World Wild Life Fund (WWF) reports that half of the trees illegally removed from forest are used as fuel, to make land available for housing and urbanization, to harvest timbers, to create commercial items such as paper, furniture and homes, to create ingredients that are highly prized consumer items such as the oil from palm trees (World Bank, 2006). Studies in China have also confirmed that medical herb production is big business and that the suppliers have chosen to invest in forest protection and reforestation in order to guarantee future supply and to prevent problems of flooding, erosion, loss of natural wild life, etc.. In spite of the multi-various usefulness of the forest resource, rapid population growth and changes in land uses have put the forest resource under pressure. Poverty has also made many people to be carrying out logging activities. The use of forest timber or wood, excessive cultivation of land and policy failure are also factors contributing to deforestation (Olorunda, David, Samuel, Mercy & Adams, 2007).

Conceptual framework

Problems of an ecological degrading world have focussed new attention upon naturally forest ecosystem. This is necessitated by the fact that there has to be a check and balance in man’s activities in order to maintain and sustain his natural environment for its well-being. In the tropics, forest ecosystem are the life zone with a constitute a controlling factor in the planning and execution of large scale projects. This brings about the need for conservation which is a major threat to the existing few natural forests.

Deforestation is not phenomenon and has been continued since centuries bit its repercussions were not known in the medieval or later periods. Its repercussions has shown great diversity of threat not only to mankind but also to organisations has been keenly working on its limitations.

According to Emielu (2005), deforestation is the process of clearing forest for a variety of purpose such as lumbering, fuel wood, farming, mining, industrialization and settlement without immediate replanting of trees. Related, Phileze (2005) asserted that literally deforestation implies cutting down of trees for 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, every human being has basic needs such as food, clothing, shelter, therefore because of large number of people, more materials particularly those sourced from the forest are needed to satisfy these basic needs for instance wood in building construction, to provide shelter for the populace. It is highly demanded as source of fuel and raw material for furniture hence multiplicative cause of deforestation.

The major determinants of deforestation are the available natural resources in the area, how the resources are used and population pressure. According to Meyer and Turner (2009), societies have profoundly altered their environment in the pursuit of wealth and power has been punished by environmental catastrophes (natural and man-made). They opined further that world forest area has original vegetation cover but housing and infrastructural activities, vegetation, crop and timber export, agricultural practice, cutting of fuel wood for sale, forest fire, logging, agriculture and over-harvesting has put the forest resources under pressure. A large empirical literature exist on the effect of deforestation.

Causes of deforestation

Research has confirmed that both natural and anthropogenic forces are responsible for deforestation (Food and Agricultural Organisation [FAO], 2006).

1. Human induce deforestation

Man contribute to deforestation in many ways such as expansion of farmland, property and fire wood use, overgrazing, bush burning, urbanization, industrialization and provision of infrastructure, road construction and mining, etc.

2. Expansion of farm/shift cultivation

Property, joblessness and inequitable land distribution has enforces many landless peasants to invade the forest and for lack of economic means continue to drive forest clearance for subsistence farming. Shifting agriculture also called slash and burn agriculture is the clearing of forested land for growing of crops until soil is exhausted of nutrients and/or overtaken by weeds and then moving on to another more forest. It is been often reported as the main agent of deforestation. Increase numbers of shifting cultivators were the main cause of deforestation (Meyer & Turner, 2009). Mostly all reports have indicated shifting agriculture as responsible for about one-half of tropical deforestation and some put it up to two-thirds.

3. Poverty and fuel wood use

Poverty in South Africa varies in intensity from province to province and from rural to urban areas (Blockfield, 2004).  According to Phileze (2005), forest has been cleared for logging, timber export and notably the collection of food for fuel which remains problematic in Nigeria and other West African countries.

4. Overgrazing

Research has confirmed that overgrazing is one of the factors responsible for deforestation. This occurs when plants are exposed to intensive grazing for extended period of time without sufficient recovery period. It can be as a result of poor agricultural application or overpopulation of animals. It is also accepted that heavy grazing can change the composition of plant communities (Rign & Haffman, 2003).

5.Bush burning

According to Olorunda et al. (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 allowed to run free, it poses a significant threat.  FAO (2000) analysed that fire related deforestation also rose sharply in Indonesia as severe drought condition helped in spreading fire set by plantation workers and farmers into forest areas destruction run from 150,000 to 300,000 hectares which destroyed a habitat of varieties of wildfire 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 allowed to run free, it poses a significant threat.

6. Ubanisation/industrialisation and infrastructure provision

Expanding cities and towns required land to establish the infrastructure 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 oil exploration, logging concession or hydropower dam, construction of roads, railways, bridges and airports open up land for development and bring increasing numbers of people to the forest by using logging trials or new roads to access the forest for substance land. According to Destto (2000), land conversion and land tilling offers significant opportunities for building and storing wealth.

7. Mining

According to Olorunda et al. (2007) mining is the process of deriving or exploring minerals from the earth crust. This may be through manual or mechanical means. Mining is very intensive and destructive. The area of land involved is quite small and it is not seen as the major cause of primary deforestation. Mining is a lucrative activity promoting development which may attract population growth with consequent deforestation.

8. Logging

Logging activities can seriously degrade forest logging in South East Asia is more intensive and can be settlers and large scale can help finance the cost of clearing remaining trees and preparing land for planting of crops or pasture. Logging thus catalyses deforestation (Chomitze, 2007). According to Phileze (2005) forest has been cleared for logging and timber export.

9. Overpopulation and poverty

The role of population in deforestation is a global issue. The impact of population density on deforestation has been a subject of controversy, poverty and over population are believed to be the main cause of deforestation. According to the international agencies such as FAO and inter-government bodies. However there is a good evidence that rapid population growth is a major indirect and over-arching cause of deforestation. More food and space which requires more land for agricultural habitation. This in turn results in more clearing of forest (FAO, 2006).

Natural causes of deforestation

There are natural hazard which result in deforestation, they include:

• Disease: It is quite common to some diseases which include trees stand in the forest. Some tropical tree diseases include mistletoes, blister, rust blightic all cause by fungi and capable of destroying mature tree and subsequently large stands to cause deforestation. In sell within a forest ecosystem also play roles in causing plant disease as their day to day feeding habits makes forest trees susceptible to disease infection.
• Damage of trees by other plants: Forest trees are damaged in various ways by plants of the community whilst the superficial epiphytes flora causes little direct damage. It may reduce tree photosynthesis by cutting off the supply of light to the leaves of trees, climbing plants such as honey, suckle, lontcera perrly menum part-strangle young trees leading to the destruction of their steam and sometimes the sheer weight of climbers thereby destroying it completely.
• Damage climate factor: Climate factor such as wind, temperature are also agent of deforestation. Strong winds are capable of breaking down trees on the path of large number or in some cases uproot them completely. High or very low temperature is known to cause disease to trees. In low temperature is known to cause death. In very high temperature plants tissue are burnt and this could lead to death of trees.
• Damage to trees by mammals: Heavy browsing modifies the form of seedling and may prevent a shrub layer form development and in an old forest creates a browse line beneath which young living tree sheet survive. Selective browsing can radically alter the proportion of different plant species present and eradicate some trees. Tree bark is eaten by many group of mammals notably rabbits, squirrels, porcupines, mouse, elephant and relatively small beavers is just as capable as the elephant of trees falling.
• 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 nutrient. These deficiencies predisposed the plant to attack by insects or fungi which result into death and subsequently elimination of trees.

Effects of deforestation

Effects of deforestation include the following:

• Global warming

According to Olorunda (2007), global warming occurs as a result of increasing concentration of greenhouse in the atmosphere. Green house is an experimental polythene house having temperature more than the temperature of the surrounding environment. Green house effect is a term used in describing the situation in which the global temperature of the world rises beyond its normal level resulting to global warming.

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) oxide CO₂ each year from industrial activities, agriculture (bush burning) and deforestation for agricultural purposes and grazing leads to increase in  greenhouse gases including carbon (iv) oxide CO₂ methane gas CH₄,nitrogen (iv) oxide and chloroflorocarbons (CFCs).

According to Olorunda et al (2007), due to  human activities, there has an increase in the greenhouse gases in the atmosphere lead to global warming, ocean acidification, smog pollution, ozone depletion and altered plant health. The temperature has been on the increase from 1^oC to 3^oC during the last century. The Intergovernmental Panel on Climate Change (2007) forth assessment report estimated that forest sector contribute about 14 – 17.4 percent of all greenhouse gases from anthropogenic sources most of which is due to deforestation activities.

Tropical deforestation is responsible for the emission of roughly two billion tons of carbon dioxide (CO₂) into the atmosphere per year. The release of carbon dioxide due to global deforestation is equivalent to an estimated 25 percent of omission from combustion of fossil. Decomposition and burning of trees pump even more carbon dioxide along with methane gas into the atmosphere subsequently causing global warming.

• Soil erosion

When trees are cut down, it will result in soil erosion due to the fact that forest serves as a cover against erosion by holding the 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 lead to pollution of water body through run off (Brugnzee, 2004)

• Flooding

Flooding can be regarded as an unusual high rate of water discharge which often leads to the inundation of land adjacent to the river which the river overflows both its natural and artificial banks. Deforestation can also result into watersheds that no longer capable flow from river and streams. Trees are highly effective in absorbing water quantities keeping the amount of watershed at manageable level. But once these trees are cut down, it result into downstream flooding many of which have caused disaster in many parts of the world destroying lives and properties (Desto, 2000)

• Loss of biodiversity

Loss of biodiversity simply put is the destruction and extinction of many of our plants and animal species (Odjugo, 2010). Apart from domesticated animals use the forest as a source of protection for predators through camouflage but when forest is destroyed, the numbers of species declines.

• Decrease in the rate of rainfalls

The forest helps in transpiration (the process by which plants release water through the 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. 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 rains stop falling within few years, the area can become arid (Desto, 2000)

• Desertification

Deforestation is one of the reasons behind the conversion of many tracts of land into deserts. The phenomenon is known as desertification. Deforestation disrupt normal weather pattern creating hotter and drier weather thus increasing drought and desertification.

• Destruction of medical plants

Some trees are used as herbs. Trees such as cinchona have been for treatment against malaria since time immemorial. Studies in China have confirmed that medical herb production is big business (FAO, 2006). Destruction of medical plants could be used as treatment for various ailments.

• Water pollution

Water resources affected by deforestation include drinking water, fisheries and aquatic habitat. Water is also good for recreational activities but effect of pollution on water makes it unsuitable for recreation.

Erosion which result from deforestation lead to water pollution thereby making surface water to be turbid and unsaved for human consumption. Urban water protection is potentially one of the most important service that forest provide. Filtering and treating water is expensive but the forest can reduce the cost of doing so either actively by filtering run off but either when deforestation occur. This services provided by the forest is no longer possible leading to water pollution and subsequently destruction of aquatic life (Brugnzee, 2004)

• Economic loss

The tropical forest destroyed each year amount to a loss in forest capital. By destroying the forest all potential future revenue and future employment that could be derived from their sustainable management disappear (Breaking, 2007)

• Water borne diseases

This is another category of infectious disease indirectly associated with deforestation. Their natural life cycle may or may not involve forest but their transmission both among the animal host and human is facilitated by upland deforestation take place, run off rapidity flow into the stream especially during rainy season leading to water borne pathogens include enteric viruses, retroviruses, bacteria and vibro cholera which collectively cause millions of deaths annually particularly among the animal host and human is facilitated by altered surface water quality which may be influenced by upland deforestation (Brugnzee, 2004)

Health problems associated with deforestation

Global warming which is mainly caused by deforestation leads to several disease such as skin cancer, eye damage, immune system damage, etc. (United Nations Environmental Programme, 2002).

1. Skin cancer: Exposure to ultra violet rays poses an increased risk of developing several types of skin cancer including malignant, melanoma, basel and squamous cell carcinoma (American Cancer Society, 2002).
2. Eye damage: Direst exposure to ultra violet radiation can result in photo keratinize (shoe blindness and cataracts).
3. Immune system damage: Effects of the ultra violet rays include impairment of immune system.
4. Accelerated aging of the skin by constant exposure to ultra violet radiation can cause photo allergy, which result in the outbreak of rash especially in fair skinned people. Other problems ozone chemical can cause difficulty in breathing, chest pain, throat irritation and hamper lung infection.

Measures to control deforestation

1. Reforestation: Many countries in the world have started reforestation and forestry and have successfully managed to reverse deforestation. East Asia countries are leading in this regard.
2. Legislature: By making suitable changes in the law so that cutting trees in a forest area becomes a major crime will not only lead to deforestation being controlled in a major way but its flow also be reversed.
3. Commercial forest plantation: There can be special forest plantation for all the wood that is needed for the industry. This way the wood can be cut in a controlled and regulated environment.
4. Wildlife sanctuaries: The development of sanctuaries will not only protect wildlife but also save trees as well.
5. Incentive to corporations: Loans, credits and insurance incentive as well as tax cuts should be granted to corporations to get them actively interested in reforestation.
6. Cities: All cities let alone new cities have to be curtailed or at least done in a systematic manner so that there is enough green cover and new trees are planted where ever possible.

References

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Brookfield, H. C. (2002). Environmental tropical deforestation and concern other than global warming. Journal on Global Environmental Change, 11(2),4-8.

Brujnzeel, L. A. (2004). Hydrological functions of tropical forest. Agriculture Ecosystem and Environmental Journal, 104(1),5-9.

Desto, H. (2000). The mystery of capital: Why capitalism triumphs in the West and fails everywhere else. New York: Basic Books Press.

Emielu, S. A. (2000). Senior Secondary Geography. Illorin: Geographical Bureau Nigeria Ltd.

Food and Agricultural Organisation [FAO](2006). Understanding forest. Tenure study in South and South East Asia. Rome: Forestry Policy and Institutions Working Paper No. 14

Intergovernmental Panel on Climate (IPCC) (2007). Climate change. Geneva, Switzerland: IPCC Fourth Assessment Report.

Johnston, R. J. (2000). Environmental planning of protected area guidelines No. 10. Cambridge: LUCN Printing Press.

Lovekar, V. (2011). Deforestation solutions. Berlin: Hormies Printers.

Meyer, U. B. & Turner, B. L. (2009). The earth transformed trend, trajectors and pattern. London: Blackwell.