0122-A2
Joseph Adeola Fuwape 1
The impacts of forest industries and wood utilization on the environment were considered. The operational activities of sawmills, plywood veneer, particleboard and pulp/paper mills in Nigeria were reviewed. The effects of tree harvesting and logging operations on forest biodiversity, soil erosion, soil compaction and hydrological cycle are reported. Environmental pollution due to wood processing, wood utilization and waste management in forest industries was discussed. Methods of mitigating the detrimental effect of the operations of forest industries in Nigeria on the environment are suggested.
Forests have been the major source of livelihood for most Nigerian. The forestry sector is one of the main pivots on which the nation's welfare was built. The forest is not only important for material goods but also as a valuable ecological and cultural resource. The forestry subsector has over the years contributed immensely to the socio-economic development in the country. It ranks among one of the highest revenue and employment generating sectors. It also serves as resource base for many forest industries. The raw materials for the production of timber, pulp and paper are derived from the forest.
The demand for wood raw material by these industries in recent times has outstripped the production capacity of the forest. Thus, exploitation of forest resources for industrial purposes if not well planned may be deleterious to the environment. It is therefore necessary to examine the impact of the activities of forest industries on the environment in order not to jeopardize the other goods, services and benefits of the forests. These benefits include: amelioration of weather pattern, provision of clean air, protection of biological diversity, protection of watershed, soil and food crops and provision of recreational facilities.
The objective of this paper is to review the impact of forest industries on the environment. For a comprehensive understanding of the subject matter the write-up has been sub - divided into five complimentary subtopics.
Wood is the most versatile raw material the world has ever known. Throughout history, people relied on wood for needs varying from farming tools to building materials, from fuel to weapons of hunting and warfare.
Wood remains virtually the most predominant material used for construction and energy generation until the last half of the 19th century (Douglas, 1995). People used timber in the construction of houses, barns, fences, bridges, furniture items and musical instruments. In contemporary times, wood is still widely used for constructional purposes. It is also a valuable industrial raw material for the production of pulp, paper, paperboard, rayon, cellophane, photographic film, tannin, methanol, ethanol, wood adhesives and chemical derivatives as shown in Figure 1.
The ubiquitous nature of wood has made it a valuable material in every stage of human development. At early age, the baby rests in wooden court, plays with wooden toys, and learns to write on wooden slate and paper when he is of school age. On graduating from school he receives a paper certificate. If he is lucky to secure employment his salary is paid in paper currency. When he is old he uses a wooden walking stick, sleeps on wooden bed and when dies the body is laid in wooden coffin.
Thus, man depends on wood right from the cradle to the grave.
The versatile nature of wood has endeared it to multiple forms of domestic and industrial uses. In this write up, attention would be on forest industries that use forest resources as the major raw materials.
The forest enterprises in Nigeria can be classified into either formal or informal sector enterprises (GWVC, 1994). The formal sector enterprises include the organized wood based industries such as sawmills, plywood mills, particleboard mills and furniture factories. The informal enterprises are small forest based enterprises operating without formal corporate entity, this include enterprises that engage in the production of firewood, charcoal, chewing stick and sculptured wood items. The formal enterprises constitute the forest industries in the country. The number of the wood based mills is presented in Table 1.
There have been some changes in wood based industries in Nigeria between 1974 and 1997. The total number of wood based industries increased from 358 in 1974 to 1483 in 1990 but decreased to 1373 in 1997. The reduction in the number of wood mills between 1990 and 1997 was attributed to deficit in supply of required wood raw material due to over exploitation of the forest for export market. The projected wood requirement for major wood products in Nigeria is presented on Table 2. Although the highest quantity of wood is expected to be consumed as firewood in 2010, the highest volume of industrial wood raw material would be required for production of sawnwood.
The sawmills account for 93.32% of the total number of wood based industries in Nigeria in 1997 (Fuwape, 1998). These mills are concentrated in the southwestern part of the country, with Ondo, Ogun and Lagos states having the largest numbers. The main type of log conversion machine used in these mills is the CD horizontal band saw. The Lumber recovery factor in most sawmills varies between 45 and 50% (Aliviar 1983, Fuwape, 1989). This implies that about 50 to 55% of log input into the sawmills are left as wood residues. The poor log conversion efficiency of the mills is partly responsible for the high pressure on the forest and the destruction of forest cover
There were ten plywood and veneer mills in Nigeria in 1997 (Fuwape, 1998). The production capacities of the mills are presented in Table 3. The annual wood requirements in plywood and veneer mils are approximately 170,000m3. The peeling lathe machine in the plywood mills in Nigeria requires large diameter logs for effective operation. The harvesting and logging operation of these mills have adversely affected the forest ecosystem.
The particleboard mills in Nigeria are integrated with some plywood mills and sawmills. Particleboards are mainly produced from wood residues and plantation tree. The wood requirements of the particleboard mills are not considered to be significantly detrimental to the environment (GWV, 1994).
In the bid to meet the growing demand for paper in Nigeria, three pulp and paper mills, namely: Nigerian Paper Mill (NPM) Jebba, Nigerian Newsprint Manufacturing Company (NNMC) Oku-Iboku and Nigerian National Manufacturing Company (NNPMC) Iwopin were established. The NPM Jebba was established in 1969 but was expanded in 1983 to produce 65,000MT of Kraft paper, linerboards and corrugated paper per year. The NNMC Oku-Ikobu was commissioned in 1982 to produce 100,000MT of printing and writing paper. However, the mills were functional for only very few years before they stopped production in 1993. Thus the impact of the mills on the environment in terms of tree harvesting is no longer very significant but the clearing of natural forest for the establishment of Gmelina arborea plantation must have disrupted the hydrological cycle of the plantation sites.
The indiscriminate logging in the rainforest and uncontrolled felling of trees for fuelwood are reported to have had adverse effect on the environment (Fuwape and Onyekwelu 1995, Oke and Fuwape, 1995). The adverse effect caused by the operations of forest industries include loss of biodiversity, migration of wildlife, ecological imbalance, soil erosion, flooding, desert encroachment and disruption in hydrological cycle of water catchment area.
The tropical forest provide habitat for two-thirds of all identified terrestial species (Myers 1992).
These plant and animal species serve as source of food, medicine and fuel in most rural communities in developing countries.
Tree harvesting adversely affects the population and variety of plant and animal species in the forest. The removal of forest cover during logging has in some instances resulted in the scarcity or out-right extinction of many important plant and animal species. Some wild animals have also been observed to migrate from areas where tree cover was removed to undisturbed vegetations.
Some plant and animal genetic resources that could be used in producing new pharmaceuticals or traditional medicine are lost as a result of the destruction of forest cover.
Destruction of forest cover during tree harvesting results in the loss of the protection, which the plant cover gives to the soil (Hamilton and Pearse, 1985). Timber harvesting also interrupts the normal nutrient cycle of the forest, promotes nitrification and increases nutrient leaching thereby leaving the topsoil impoverished and susceptible to erosion. Myers (1988) reported that soil under primary forest erodes at an average rate of 12 tonnes per hectare while open vegetation in deforested areas of upland topography erode at the rate of about 84 tonnes per hectare per year. There have been reports of accelerated erosion that resulted in extensive gullies in various deforested parts of Nigeria (NEST, 1991). Eroded soil are often deposited in rivers and fish ponds thereby causing siltation and contamination of such water body. These adversely affect the aquatic ecosystem and disrupt biodivesity by killing fish and other organisms.
Unplanned logging operations have resulted in soil compaction (Greacen and Sand 1980, Froehlich and McNabb 1984). Soil compaction adversely affects tree growth, plant productivity and soil aeration (Gupta and Allmaras, 1987). The movement of wheeled and tracked vehicles on forest soil has been reported to cause increase in bulk density and reduction in air-filled porosity of the soil (Startsev et al 1995).
Changes in forest cover alter catchment water balances and stream flows. The effect of destruction of forest cover on catchment water balance and runoff dynamics depends on the climate, topography, soils and the type of forest (Vertessy and Dye 200). Water quality and yield are also affected by tree harvesting. Flooding seems to increase as result of broad - scale deforestation in catchment zones. Indiscriminate tree felling in hilly areas reduces the ability of soil to absorb water thereby inducing high volume of run off. Oguntala and Oguntoyinbo (1982) attributed Ogunpa flood disaster that occurred in Ibadan in 1981, to the destruction of forest along banks of river Ogunpa.
The removal of forest cover during tree harvesting predisposes the environment to destructive actions of wind and rainstorm. Devastating destruction of farmland and houses have been reported in areas where indiscriminate tree felling had taken place (Oke and Fuwape 1995)
Clear felling of trees for firewood has been recognised as one of the factors responsible for environmental degradation in arid and semi-arid parts of Africa. When trees in an area are removed the rate of evapotranspiration is disrupted this affects precipitation and makes the area become increasingly and thereby inducing desertification. Couzin (1999) reported that on the average precipitation is 30% lower and temperatures are 1 degree Celsius higher in deforested areas of the Amazon than in forested areas. It was also reported that the indiscriminate felling of trees aggravated the effect of wind erosion and deposition of sand dunes in northern part of Nigeria thereby enhancing desertification (Ezenwa 1986, Gwandu 1990).
The environmental pollution problems in forest industries include solid waste disposal, air emission of toxic and non-toxic particulates, veneer dryer emission and glue waste disposal. Noise generated during the operation of machines also constitute serious source of health hazard to workers in the forest industry (Harden, 1958).
In converting round log to lumber, sawmills generated vast quantity of bark; sawdust, shavings and trimmings. The solid wood waste may be used in particleboard production while the bark may be used as fuel or in land filling.
The problem of glue waste disposal can be resolved by retaining used water in settling tanks where solid sediments are removed. Waste water from pulp and paper industries are also retained in treatment ponds for a period of time to ensure the decomposition of chemical residues before it is linked into the main river (Haskell 1971). The dust and particulate emission during industrial wood processing can be collected in bag filter, cyclone collectors and wet scrubbers.
Providing personal protective equipment to workers can solve the problem of noise pollution. Noise abatement could also be carried out by installing noise damping enclosure around the machine (Lamb, 1971)
The most critical environmental impact of the activities of forest industries that require urgent attention is the destruction of forest cover. Over the years, much exploitation of the forest has been done in order to meet the increasing demand of the teeming population. This has resulted in serious depletion of the resource base to the extent that some favoured timber species have become scarce while others have become scarce in certain ecological zones. Geomatics (1998) reported that the land area occupied by high forest in Nigeria decreased by 11, 254km2 between 1976 and 1995 while the land area occupied by savannah decreased by 90, 593km2 during the same period. This reduction in forest cover has negatively affected the environment and is partly responsible for soil erosion, loss of biodiversity and disruption of hydrological cycle.
Adopting aggressive reforestation strategy could solve the problem of reduced forest cover. Technology that aids forest productivity and efficient utilization of forest resources on sustainable basis should also be employed during forest operations. The use of appropriate tree harvesting and logging techniques will reduce destruction of forest ecosystem. A well planned skidding and haulage of logs will reduce instances of soil compaction (Greacen, 1980). Indiscriminate felling of trees in water catchment areas should be prevented in order to guide against disruption of the hydrological cycle.
Efficient log conversion techniques should be practiced in order to improve lumber recovery and reduce the demand for round logs. The establishment of integrated wood industries should be encouraged while small sawmill holdings should be effectively controlled to minimize wastage of wood resources. Value added products such as particleboards and wood briquettes may be produced from industrial wood residue (Fuwape, 2001). This will improve the efficiency of wood utilization, reduce the demand for round log and reduce the destruction of forest cover.
The problem of the clear felling and destruction of forest vegetation due to fuelwood scarcity can be solved by planting fast growing tree species and establishing rural community wood lot. The example of fast growing species, which have been recommended for fuelwood plantation includes Gmelina arborea. Leucaena Leucocephala, Terminilia spp. Albizia lebbeck Gliricidia sepium, Sesbania grandifolia, Cassia siamea and Acacia albida. These species coppice very well and have good combustion characteristics (Lucas and Fuwape, 1984).
The forests are essential for healthy environment. Trees stabilize the forest soil, improve soil fertility, reduce the velocity of wind, protect watershed and reduce the amount of carbon released into the atmosphere. When forests are exploited beyond their capacity to regenerate, vicious cycle of environmental degradation could be set in motion.
The activities of forest industry Vis - a - Vis tree harvesting, transportation, wood conversion and processing have some negative impacts on the environment. These negative impacts include: destruction of forest cover, loss of biodiversity, ecological imbalance, soil compaction, soil erosion, flooding, desert encroachment and disruption of hydrological cycle. Environmental pollution resulting from disposal of solid waste, effluent and particulate emissions have also been linked with log conversion operations.
There is the need to ensure that forest industries abide strictly with principles of sustained yield management. Reforestation should be intensified. Forest concession owners should be involved in forest regeneration. There should be equivalent replacement for every tree removed from the forest. Tree harvesting, hauling and skidding techniques should be improved and made environmentally friendly. Forest based industries should strictly conform to guidelines on environmental protection. Government and people should be genuinely involved in forest management to ensure sustainable development and prevent environmental degradation
Table 1: THE MAJOR WOOD - BASED MILLS IN NIGERIA (1974-1997)
Types of Mill |
Years | |||||
Sawmill |
1974 |
1981 |
1984 |
1990 |
1993 |
1997 |
| Source: Fuwape(1998) (NF - Not Functional) |
Table 2. Wood requirements in Nigeria. (000 m3)
Products |
1993 |
2000 |
2010 |
Fuelwood |
103474 |
128495 |
156634 |
Utility wood |
2514 |
2874 |
3441 |
Sawlogs |
6182 |
7558 |
3441 |
Veneer logs |
618 |
618 |
618 |
Particleboard |
69 |
111 |
460 |
Pulpwood |
35 |
35 |
35 |
| Source GWVC (1994) |
Table 3: Estimated Capacity and Production of Plywood Mills in Nigeria
S/No |
Name |
Capacity |
Production |
Utilization |
1 |
African Timber & Plywood |
|
12,240 |
81.6 |
2 |
Piedmont Plywood Co. Ltd., |
16,000 |
12,800 |
80.0 |
3 |
Premier Timber Industry |
13,000 |
12,350 |
95.0 |
4 |
Delta Plywood Co. Ltd., |
15,000 |
12,000 |
80.0 |
5 |
Calabar Wood Company Ltd., Calabar, Cross River State |
18,000 |
6,000 |
33.3 |
6 |
Calabar Veneer & Plywood Ltd., |
16,000 |
3,445 |
21.5 |
7 |
WEMPCO, Ikom Cross River State |
20,000 |
NA |
NA |
8 |
Nig. Romanian Wood Ind. Ltd., Ondo, Ondo State |
17,000 |
3,405 |
20.0 |
9 |
Epe Plywood Co. Ltd., |
16,000 |
10,000 |
62.5 |
10 |
Omowood Industry |
25,000 |
24,000 |
96 |
| Source: Fuwape (1998) (NA - Not Available) |
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1 Department of Forestry and Wood Technology,
Federal University of Technology, P. M.B. 704, Akure