DEFORESTATION CAUSES, EFFECTS AND CONTROL STRATEGIES
Background of the studies
Nigeria is naturally endowed with vast expanse of forest land, the swamp forests in the extreme Southern part of the country, the tropical rainforest in the South- western axis and the wooded savannah in the middle belt. Nigeria ranks among the countries of the world with abundant forest resources. Mfon, et al (2014) said forests in Nigeria occupied about 110, 890km2 of the country total land mass of about 910,770km2 in other words, forests is about 012.18% of vegetation cover of the country. Park (1992), has stated that at least 60 percent of all known species of plant, about 90 percent of all the world’s non-human primates such as monkeys, about 40 percent of all the birds of prey and about 80 percent of all the insects live in the tropical rainforests of the world. In other words forest provides us a wide variety of ecosystem services, including provisioning regulating, cultural, and supportive services. These ecosystem services not only deliver the basic material needs for survival, but also underlie other aspects of well being, including health, security good social relations and freedom of choice. In the past, timber production was regarded as the dominant function of forests. However, in recent years this perception has shifted to a more multifunctional and balanced view. Today, it is understood that forest biodiversity underpins a wide ranges of goods and services for human well being. Ecologically intact forests stores and purify drinking water, they can mitigate natural disasters such as drought and floods, they help store carbon and regulate the climate, they provide food and produce rainfall, and they provide a vast array of goods for medicinal cultural and spiritual purposes (CBD, 2009). Similarly, most Nigerians have always depended on the forest for their survival, economic development, as well as environmental amelioration. The level of community nutrition is sometimes linked to fuel wood availability and cost, others depended directly on forest for their livelihood; among them are a high number of forest and wood worker ( Aliyu et al, 2014) This is a part from contributing substantially to the National Gross Domestic Product (GDP). In spite of its importance, the natural forest has continued to diminish rapidly in the world especially in Africa continent and particularly in Nigeria. According to EFC, (2010), the world continues to lose some 15 million hectares of forests every year. Deforestation over the period 1980 to 1990 reached 8.2% of total forest area in Asia, 6.1% in Latin America and 4.8% in African. Most modern deforestation takes place in developing countries, particularly in tropical areas. Deforestation and forest degradation directly threaten as many as 400million people including 50million forest indigenous people who depend on forest for subsistence in sub-Sahara Africa (EFC, 2010). Deforestation estimates for some. African countries have been given by Lanly (1983). For example, the of forest depletion in Cote divoire and Nigeria is estimated as high as 5 to 6% per year while Ochanda and Epp (1982) stated that in Kenya the indigenous forest now covers only 1.9% of the land area and remote sensing have shown that about 16% of the forest is being lost in each ten year period. In Nigeria, the scenarios is not different, regional breakdown of deforestation from 1979 to 1995 shows that total forest declined by 48% in the North-central 7% in the North East, 60% in the North West, 53% in the south East, 13% in the South-South and 12% in the South West (FORMECU 1996). In 2000 the forest cover was estimated at 13.5 million hectares compared to 17.5 million hectares in 1990 (FAO, 2001), indicating a forest cover loss of close to 400 thousand ha per annum, or a decline of about 2.6%. Forest/woodlands now stand at only 13% of the total land area (FAO, 2001). With global outcry on the consequences of continuous unsustainable forest destruction topping major intellectual discourses the needs to examine the current deforestation situation in Nigeria requires a work of this nature.
The year 2011 is ‘The International Year of Forests’. This designation has generated momentum bringing greater attention to the forests worldwide. Forests cover almost a third of the earth’s land surface providing many environmental benefits including a major role in the hydrologic cycle, soil conservation, prevention of climate change and preservation of biodiversity (Sheram, 1993). Forest resources can provide long-term national economic benefits. For example, at least 145 countries of the world are currently involved in wood production (Anon., 1994a). Sufficient evidence is available that the whole world is facing an environmental crisis on account of heavy deforestation. For years remorseless destruction of forests has been going on and we have not been able to comprehend the dimension until recently. Nobody knows exactly how much of the world’s rainforests have already been destroyed and continue to be razed each year. Data is often imprecise and subject to differing interpretations. However, it is obvious that the area of tropical rainforest is diminishing and the rate of tropical rain forest destruction is escalating worldwide, despite increased environmental activism and awareness. Deforestation is the conversion of forest to an alternative permanent non-forested land use such as agriculture, grazing or urban development (van Kooten and Bulte, 2000). Deforestation is primarily a concern for the developing countries of the tropics (Myers, 1994) as it is shrinking areas of the tropical forests (Barraclough and Ghimire, 2000) causing loss of biodiversity and enhancing the greenhouse effect (Angelsen et al., 1999). FAO considers a plantation of trees established primarily for timber production to be forest and therefore does not classify natural forest conversion to plantation as deforestation (but still records it as a loss of natural forests). However, FAO does not consider tree plantations that provide non-timber products to be forest although they do classify rubber plantations as forest. Forest degradation occurs when the ecosystem functions of the forest are degraded but where the area remains forested rather cleared (Anon., 2010). Thirty per cent of the earth’s land area or about 3.9 billion hectares is covered by forests. It was estimated that the original forest cover was approximately six billion hectares (Bryant et www.intechopen.com 4 Global Perspectives on Sustainable Forest Management al., 1997). The Russian Federation, Brazil, Canada, the United States of America and China were the most forest rich countries accounting to 53 per cent of the total forest area of the globe. Another 64 countries having a combined population of two billions was reported to have forest on less than ten per cent of their total land area and unfortunately ten of these countries have no forest at all. Among these countries 16 are such which had relatively substantial forest areas of more than one million hectares each and three of these countries namely Chad, the Islamic Republic of Iran and Mongolia each had more than ten million hectares of forest. The forest area remained fairly stable in North and Central America while it expanded in Europe during the past decade. Asian continent especially in India and China due to their large scale afforestation programme in the last decade registered a net gain in forest area. Conversely the South America, Africa and Oceania had registered the net annual loss of forest area (Anon., 2010; 2011).
ined by densely-tall woody and non-woody vegetations as well as other communities of flora and fauna in symbiotic relationships. Forest is an intricate system made up of plants and trees that protect biodiversity, providing home to terrestrial biodiversity and improving the quality of life forms on earth (Popoola, 2014). Onyeanusi and Otegbeye (2012) defined forests as large areas of land covered with trees and brush that grow thick but forest according to the Food and Agriculture Organization (FAO) Forest Resources Assessment (2002) is an area where trees cover ten percent or more of the land. Forest was originally used to mean a vast expanse of land covered by trees usually associated with game hunting. Forest has been variously used to define any tall densely packed area of vegetation, even underwater vegetation such as kelp forests, or non-vegetation such as fungi and bacteria but a typical forest is composed of the overstory (canopy or upper tree layer) and the understory which includes shrub layer, herb layer, and moss layer, and also soil microbes. Forests are found in all regions capable of sustaining tree growth at altitudes up to the tree line, except where natural fire frequency or other disturbances is too high or where the environment has been impaired by anthropogenic activities. Forests are naturally endowed with numerous resources that are valuable to mankind (FAO, 2003). Forest functions depend on the daily needs of livelihood of people living close to it. For instance, rural populations depend most fundamentally on forests in terms of subsistence, health, income and culture (Van et al., 1997; Adebisi, 2008). The forest is a source of resources that are of environmental, economic, socio-cultural and aesthetic benefit.
Types of Forest Forests vary considerably in composition, structure and geographic distribution. It can be classified into different types based on the following criteria:
- Based on spontaneity: natural and artificial forest
- Based on indications of human activity: primary/frontier and secondary forest
- Based on leaf longevity: evergreen and deciduous forest
- Based on leaf broadness: broadleaf tree, coniferous trees or mixed forest
- Based on geographic zone: temperate forest, sub-tropical and tropical moist forest, sub-tropical and tropical dry forest
- Based on physiognomy: old growth and second growth
- Based on dominant species
Functions of the forest: Forest are important to sustainability of the earth and hence the existence of man. Broadly, functions of the forest can be categorized as follows:
- Environmental function Biodiversity protection and conservation
- Moderation of weather elements e.g. rainfall,
- temperature etc. Carbon sequestration
- Soil management
- b. Socio-cultural function and economic function Food security
- Provision of medicinal products
- Source of fuel wood
- Source of employment and income
- Source of raw materials for industries
- Source of national revenue and exchange
- income earnings Provision of religious and cultural sites
- Aesthetic and sporting
Concept Of Deforestation, Forest Degradation And Fragmentation Deforestation: Deforestation is basically the conversion of forested areas to non-forested land for several purposes basically agricultural, industrial and urbanization. Deforestation is a process whereby trees are felled for several purposes but without replanting to replace the ones felled (Aina and Salau, 1992). It is the large scale removal of forests resulting to nonforest areas for urbanization, agriculture and for some other reasons without corresponding re-afforestation of the area (Fiset, 2011). According to FAO (2005), deforestation is the conversion of forest to another land use or the long term-term reduction of tree canopy cover below the 10% threshold. On a broad sense, deforestation can apart from conversion of forest areas to non-forest ones, include reduction of forest quality in terms of its density, structure of the trees, the ecological and other essential services supplied, biota biomass and species diversity as well as the genetic diversity of the composing biota. Deforestation is a major problem in many parts of the world, and the idea underlying the phenomenon can be a diminution of vegetal covers from thick forest to light forest, from heavy or light forest to open area under development. It can also be from heavy or light forest to savannah or grassland and or from savannah to open or isolated land (Okorie, 2012). In spite of the multi-various usefulness of the forest resources, rapid population growth and changes in land uses have put the forest resources under pressure. For instance, majority of logging operations in tropical countries are considered unsuitable and damaging. The widespread failure of forest governance – characterized by illegal logging, associated illegal trade, and corruption-directly undermines sustainable economic growth, equitable development, and environmental conservation. It puts at risk poor and forest-dependent populations, which rely on timber and non-timber forest products; undermines responsible forest enterprises by distorting timber and reducing profitability; and results in a loss of government revenue that could be invested in sustainable forest management or general economic development (World Bank, 2006).
Forest degradation Forest: degradation is a process leading to a temporary or permanent deterioration in the density or structure of vegetation cover or its species composition (FAO, 2007). It results from disturbances that cause changes in the forest attributes that leads to a reduced productive capacity of the forest. For the purpose of having a harmonized set of forest and forest change definitions, that also is measurable with conventional techniques, forest degradation is assumed to be indicated by the reduction of canopy cover and/or stocking of the forest through logging.