Published on International Journal of Forestry & Plantation
Publication Date: August, 2019
Isese, M. O. O.
Forestry Research Institute of Nigeria
Journal Full Text PDF: Impacts of Deforestation on the Loss of Biodiversity.
Deforestation has been in the center of most world discussions as the major cause of climate change and environmental as well as atmospheric challenges which has adverse consequence on human settlement as well as plant and animal natural habitat. The impact of deforestation on biodiversity in Nigeria is seen in terms of loss of valuable plant species, reduced plant biomass, extinction of animal species. Deforestation is an ongoing phenomenon in Nigeria and is becoming more visible with increasing population and urbanization in almost of parts of the country. The effects of deforestation have led to a decline in forest cover, forest degradation and loss of biodiversity. This review paper provides concise insight into the functional strategies for reversing deforestation trend and the effective conservation of the wide varieties of Nigeria’s natural vegetation.
Keywords: Deforestation, Biodiversity & Population growth.
1. Introduction: Deforestation a major Biodiversity set back
Deforestation has been described as one of the threatening global development challenges and a serious environmental problem facing the world and Nigeria. Deforestation is basically the change of forest. It results from the removal of trees without sufficient replacement, which leads to a reduction in habitat, biodiversity as well as wood and quality of life. (FAO, 2011) defines deforestation as the long-term reduction of the tree canopy cover below the minimum 10 percent threshold. (UNFCCC,2006 ) description has a different threshold, in which deforestation is defined as a measurable sustained decreased in crown cover from greater than 10-30 percent to less than 10- 30 percent. In their definitions emphasis is put on the direct human-induced conversion of forested land to non-forested land. Land-use changing from forest to non-forest uses is counted as deforestation while temporary tree cutting where the forest is expected to regenerate is not considered as deforestation (Indarto and Mutaqin, 2016).
One very serious impact of deforestation is loss of biodiversity. Heywood and Baste (1995), posited that biodiversity is defined in its broadest sense, as the “variety of life on earth,” otherwise described in terms of gene, species and ecosystem. However, exotic organisms that have been introduced and communities such as agricultural fields that are maintained by regular intervention were excluded (Sala, 2000) from this definition. In cases where any species, either exotic or indigenous, is an integral part of the bio-ecological landscape, such definition becomes inappropriate. Biodiversity or biological diversity has been studied at different levels (genetic, species, ecosystem and community level. Global Biodiversity Assessment of the Global Environmental Change (1995) has reported that species are now becoming extinct at 10,000 times the natural rate. The rate at which different plant species are used for medicinal purposes without replacement has also contributed to the loss of this species. According to Sofowora (1993) he reported an increasing trend in the use of medicinal plants amongst both urban and rural dwellers in Nigeria. He opined that this trend will have serious implications on the survival of some plants species because of the unsustainable manner in which many species are harvested. Malaria control is suffering a setback in many rural southern Nigeria societies because of loss of curative plant species due to deforestation (Uneke and Ibeh, 2009).
Population growth has been reported as the major cause of environmental change and degradation (Philip, 1990; McNamara, 1992a). Deforestation, soil deterioration, and loss in genetic and species diversity are factors commonly associated with this phenomenon (Charkeseliani, 1990; Agarwal, 1992). This review work aimed to examine the impact of deforestation on biodiversity in Nigeria.
2. Decreased Biodiversity a function of Habitat Loss
According to (Myers and Mittermeier,2000), forests especially those in the tropics serve as storehouses of biodiversity and consequently deforestation, fragmentation and degradation destroy the biodiversity as a whole and habitat for migratory species including the endangered ones, some of which are still to be catalogued.
Tropical forests support about two-thirds of all known species and contain 65 per cent of the world’s 10, 000 endangered species. Retaining the biodiversity of the forested areas is like retaining a form of capital until more research can establish the relative importance of various plants and animal species. According to the World Health Organization, about 80 percent of the world’s population relies for primary health care at least partially on traditional medicine. The biodiversity loss and associated large changes in forest cover could trigger abrupt, irreversible and harmful changes. These include regional climate change including feedback effects that could theoretically shift rainforests to savannas and the emergence of new pathogens as the growing trade in bush meat increases contact between humans and animals. The heavy fragmentation of this habitat has resulted in an intense human-elephant conflict causing not only in the loss of agricultural crops but also human and elephant lives. Mortality of about 50 persons and 20 elephants was reported due to these severe human-elephant conflicts from this hotspot area annually (Sukumar et.al, 2003, Mangave H.R, 2004). A very important consequence of deforestation is the elimination of the gene pool, the permanent loss of valuable plant and animal genetic resources. Many plant species of importance such as valuable commercial species and source of pharmaceutical products are near extinction as a result of deforestation. Also, the destruction of wildlife habitat has drastically reduced animal populations and productivity such that many rare species are now threatened with extinction as reported by Roper (Roper.J &Robert.R, 2006). In Nigeria, many trees, shrubs, herbs and assorted animals have been depleted while some are endangered. Several plant species have been overexploited especially those with edible seeds, nuts and kernels are now endangered (Mfon et.al, 2014). Most primates such as guenons, mangabeys, drills, chimpanzees and gorillas are now endangered (Akachuku, 2006). Adetola O.O & Adebisi M.A, 2019 sited that biodiversity loss poses a significant threat to humanity. The global encroachment by humans into natural habitats drives habitat loss and fragmentation, leading to declines in species richness (Hadad et al. 2015).
Fig 1: Map of Nigeria showing Vegetation zones
3. Effect of Deforestation on the Flora and Fauna of forest areas: A case of Extinction
Deforestation activities in Nigeria have negatively impacted on the flora and fauna resources of the country. Several forest reserves in the country have been converted to agricultural purposes using the tungya system. A large number of farmers (from the then south-west of Cross River state, now the neighboring State of Akwa Ibom) were permitted to move into ’’Ekinta, an 11,000 hectares forest reserve in the South East to establish plantations of Gmelina arborea using the taungya system. However, due to a shortage of funds for seedlings and supervision, virtually no plantations were established. In less than a decade, 90% of the forest reserve had become cassava farms instead of forest plantations, with hardly a tree standing.” Valuable timber species such as Iroko (Milicia excels), Mahogany (Khaya spp), Black Afara (Terminalia ivorensis), Mimusups (Baillonella toxisperma), White Afara (Terminalia superba), Cedar (Lovoa trichilloides), Ebony, etc. that used to be very common in Cross River State, are now extremely scarce and difficult to find. If available, the prices are so astronomical that only those at the upper echelon of society can afford to buy them. In some local communities, people are beginning to roof their houses with Gmelina arborea, a thing that now surprise the local people themselves. On the fauna side, several wild animal species have become extinct, some critically endangered, and some that were hitherto common have also become endangered. Extinct species include among others Leopards, Bush cow, African giant pangolin, etc. Critically endangered include Chimpanzee (Pantroglodytes), Drill (Mandrillus leucophaeus), Gorilla (Gorilla gorilla diehli), Preuss’s monkey (Cercopithecus preussi), Red bellied monkey (Cercopithecus erythrogaster), Sclater’s guenon (Cercopithecus sclateri—endemic to Nigeria), Wild dog (Lycaon pictus). The endangered list include African elephant (Loxodonta Africana), Cheeta (Acinonyx jubatus), Red eared guenon (Cercopithecus erythrotis), Pygmy hippopotamus (Hexaprotodon liberiensis), African pygmy squirrel (Myosciurus pumilio), West African mantee (Trichechus senegalensis), Spotted- necked otter (Lutra maculicollis), etc (Enuoh, 2012)
Fig 2: Map of Africa Showing rate of Deforestation
4.0 Suggested strategies to reverse the effects of Deforestation in Nigeria
4.1. Creation of Forest Reserves
These are areas delineated and gazetted by government and activities, such as taking and selling
Of forest produce without license, destruction of forest estate, destruction of water ways as well as kindling of fire without consent are prohibited.
4.2. Commencement of conservation processes
For biodiversity through the creation of strict nature reserves, National Parks, Biosphere
Reserves, Investigation plots for natural regeneration, some sanctuaries, fish parks, wetland conservation areas etc.
4.3. Rainforest Management
Many techniques have been utilized to manage the rainforest. These methods include; enrichment planting, tropical shelter wood system, taungya system, plantation establishment, Malayan uniform system etc. it is unfortunate that these management techniques have not been able to save the rainforest in Nigeria
4.4. Afforestation Programmers’
From Table 1 below shows that Nigeria is one of the world’s most deforested countries hence, afforestation programs must be encourages to reduce the menace. Many afforestation programmers have been carried out in Nigeria over the years. However, there are very few mature forest plantations to provide fuel wood and sawn timber. Also, very few wood based companies have plantations of their own. Even the annual tree planting campaign, which was started by the Forestry Association of Nigeria in order to create awareness for tree planting has been hijacked by politicians. Of recent, politicians created fanfare out of the tree planting with the president and state governors planting ceremonial trees followed by other dignitaries. After the planting, funds are not released as and when due in order to tend to the planted seedlings; thereby many of these seedlings do not survive after the first year of planting.