Logging of Forest Products
Logging has mainly to do with the production of logs for sawmilling veneer and pulpwood production, either locally or overseas and will be considered in these aspects. In the world-wide sense it also includes the production of railway sleepers, poles, pilling, mine timbers, firewood and many other products.
Logging is the most important step in the utilization of a forest, as the quality of the logs produced, costs and wastage due to careless felling and crosscutting all have their effect on the success or failure of the full utilization of a forest area. Good quality logs immediately step up output from a sawmill or ply wood factory and increase prices if the logs are intended for export. Costs are all important as excessively high logging costs naturally have a depressing effect on mill or export profits.
Wastage in the bush particularly in felling and crosscutting is generally an indication of poor management and at the same time a waste of money as a considerable expenditure is involved in preparatory work, before the first tree is felled. In many cases, a look around the felling areas and loading depots can give a very good idea as to the standing and seriousness of the operator.
Planning, maps and methods of enumeration, length of tractor haul, sitting and condition of truck roads, loading methods and major transport systems are also important factors in the overall logging operation.
In America, Europe and Africa, the utilization of the forests plays a very important part in the social economic welfare of these countries. The lumber and associated industries employ large numbers of men, vast amounts of capital are invested, and large sums of money flow to and fro from the workers and operators and corporations concerned with equipment for logging and sawmill operations.
Logging can be divided into the following main groups:
- The felling and preparation of logs for transport.
- Minor transport or collecting the logs.
- Major transport, or main log haul.
In the case of naturally regenerated forests, careful logging can assist silviculture. Continuity of production, or sustained yield is the main principle of forestry practice. The method by which the forests are logged is an important factor without which sustained yield may not be assured.
In America, progress in improved logging methods as a silvicultural as well as a utilization measure, has been directed to selective felling. In the past the object of selection, was to get the most profit possible and not to see that the forests continued for ever. Silviculturists were not generally interested in methods and costs and loggers in the past cared little for the future of the stands. This has happened in many other part of the world as well, but nowadays, in India, Europe and Africa we find the forester and lumber man working in much closer cooperation, to make sure that the forest will last for ever and provide work and revenue for the country.
The forester’s part is to assist in the reduction of general extraction cost, create more demand for forest products, find profitable ways of disposing of wood and mill waste for by doing this he will be helping in the better business management of the forest on a sustained yield basis. Economical logging is important to successful forest practice. Great steps in this direction have been made in America and Europe where advice is given to private owners by the forestry services and trained foresters are often employed by private firms to properly manage their forest.
For every operation, there must be a carefully considered plan which is drawn up on the following guide lines:
The special features of the area must be considered. This includes information as to the exact location and extent, with respect to known points such as rivers, towns, roads and possibly railroads. If a mill is to be constructed for the manufacture of the timber to be moved, it should be located so that the forest products can be delivered at the most economical cost, with due consideration being given to facilities for shipping and moving finished products to market.
- The distribution of timber must be decided and the amount estimated, sometimes this is provided by the government. forest services, but in many parts of Africa the actual mapping, counting of trees and general preparation must be done by the concessionaire himself. Usually in the forest reserves the trees are marked for felling by the forest department and control is strict with heavy fines for felling unmarked trees and damaging young standing trees of valuable species.
- Methods of extraction must be studied.
- Financial policies settled.
- A careful study of he probable cost must be made.
These costs can be split as follows:
Cost of construction for major transport.(forest to mill or waterside)
Cost of operation and maintenance of major transport.
Cost of camp construction.
Cost of construction for minor transport. (Stump to main road, rail or river).
Cost of operation and maintenance of minor transport.
Loading and unloading cost for major and minor transport.
Cost of operating loading dumps etc. under these method of transport.
Cost of felling, log making and clearing.
All these cost must be considered together with equipment, labour available and never treated as separate items.
Some inducement must be offered to men, to leave their villages and come to work in the remote parts of the bush. These are usually offered in the following forms:
Good wages, with or without a contract.
Cheap or free rations. A most important item.
Good houses. These can be made from local materials to suit the individual needs of the workers. Simple wooden pre-fab houses can be built for senior staff.
A shop supplying cheap necessities.
Medical and sanitary services.
Saving scheme from wages.
Bonus for good work.
Leave to visit their villages.
Land for farms on the concession, if this is possible.
Amusement such as football.
A happy contended labour force will give better work and make the project successful while one which is discontented will work badly and may result in serious losses due to strikes, go-slow and careless work.
All work in the forest should be done on a task basis if possible, felling, cross-cutting, skidding, loading and even rafting or transport. This leads to easier control and everyone knows what has to be done and the task can be fixed so that each man does a full days work. When he has finished his task the rest of is his own for his farm or family. In America and Europe, daily or weekly wages are paid to labour and in Africa the pay is usually every fifteen days or per month of thirty days loss Sundays and rest days.
2 CAMPS (Location)
- Convenience to the present working area is of the greatest importance together with the possibilities of working other areas from the camp. The camp should be sited as near the centre of the working areas as possible, to avoid moving too often.
- Dry ground is essential for health and sanitation purposes. Nothing can be worse than a badly sited camp and it is better to go up a hill than build in a poorly drained hollow. For sanitary reasons, heavy bush should be cleared away from the camp site and the site kept free from small bush, which will grow very quickly.
- A good clean water supply must be near, as many troubles can arise if the water is bad. Rivers can be used for washing but it is better to make sure that the drinking water comes from springs or wells.
- Always consider the possibility of constructing a small air-strip for light planes to use in cases of emergency, sickness or supply of urgent materials etc. accidents can easily happen in the bush, especially when felling trees and skidding logs and nothing is so disastrous as to be without transport with an injured man in the camp, or lacking some urgent items of supply.
The camp or village should be constructed in an orderly manner with houses arranged in lines, with roads or tracks, as a camp is much easier to keep clean if it is properly laid out. Labourers houses can usually be constructed from local materials by the men themselves. If there is more than one tribe working in the area there will usually prefer to have their own sections of the camp and elect their own headmen.
There are usually Government. rules regarding the size of the houses, but if not, plenty of room should be given to married men with families and two bachelors can share the same house. It is a good idea to keep married men with families and bachelors separate as far as possible as there will be less trouble. A chapel or church should be constructed and the camp made as much like a small town, as possible.
Senior staff can be housed in wooden pre-fabricated houses, which are easy to build and can be taken down and moved to a new camp without much difficulty. Latrines arrangement must be made and this must be checked and re-made when necessary.
It is quite possible that there will be a main camp near a sawmill or main logging with smaller camp in the forest for felling or crosscutting, road clearing and skidding. Those smaller camps should be within reasonable distance of the main camp, for control of the work and supplies and always linked by a road.
The Marking for Felling
This operation can be conveniently combined with the inventory taken during the preparation of the logging plan. It does not follow that all species will be extracted at one time; this depends on market condition available. The normal method is to plan or scribe the numbers on the trees to be felled and at the same time form an estimate of the height and measure the girth or diameter at breast height, the result are recorded for each species and provide essential information as to the species available in a given area and also provide a reasonably accurate estimate of the timber volume. If more detailed records are required the felled trees must also be numbered and a check kept on the actual measured output from each tree. This system of numbering, carried forward throughout the logging operations also provides a method of ensuring that all trees in the area have been felled, crosscut and skidded to the loading depots.
This usually governed by the following factors:
Minimum Diameters: these are usually laid down for each species.
Type of Operations: depends upon the ultimate use of the producer.
Harvesting Cost: those naturally hinge around the marginal tree and
Management Policy: Forests under proper management are cut according to plan. This may call for the retention of seed trees of any particular species, the retention of lower girth trees to provide a future crop or clear cutting for replanting or some other purpose.
The choice of trees to be cut in managed forest is largely based upon the management plan and the silvicultural system in pratice. Forest not under any fixed system of management and working to girth limits the cutting specification should preferably be written and clearly specify for each species, the minimum diameter or girth, either over or under bark, which can be removed.
In reserved forests were seed trees are to be left, the marking must be carried out by a responsible forest officer who is fully conversant with the management and silvicultural plans. The marked trees should be entered on the forest map and some indications given as to the extraction routes, all which will assist in the final harvesting of the area.
In some countries and with some species, trees are girdled at the same time as selected to allow for preliminary seasoning, with the object of reducing the moisture content and possibly making the trees floatable.
Any extra cost involved in this work is fully justified in the easier control of the extraction operations and the provision of data for future operations in the particular forest area.
- Methods of Obtaining Logging Rights.
In carrying out exploitation, a strict management approach is followed, so that forest areas are not unduly depleted. Logging can be carried out based on
Ownership of a Private Forest- This is where a farmer plants and manages his own tree farm. Harvesting is usually done to ensure protection of the environment.
Right to exploit in private or public land- In this case a forest permit (concession) is often considered necessary and is obtainable from the resident forest officer before any form of exploitation or harvesting. The permit or concession is a license which empowers one to cut down tree crops.
There are two approaches to timber exploitation; it is either selective or total. In selective exploitation, it is the act of felling only trees that have been marked for a particular purpose while total exploitation involves clear- felling of all the trees in plantation or forest, thereafter selection is made for different end uses.
- Method of Sales of Standing Tree
On obtaining the concession or permit, there are three approach adopted by forestry department for the sales of standing tree. These are:
- Out-Turn Volume (OTV): this method is mostly used in concession area granted to big timber companies and is based on the actual out turn volume of trees of different species. Prices are set at fixed rates per cubic meter of merchantable volume of each tree and trees are classified according to their economic importance.
- Stumpage Rate/Single Tree Permit: this system is based on the market popularity of tree species and assumes a certain average of each tree. Different species usually have different tariff rate.
- Area Bases Assessment: under this method, forest is demarcated into coupes. The inventory of the merchantable timber standing in each coupe is taken and mapped. Based on the stock map, a bill of quantity which approximates the value of standing timber is prepared.
Timber inventory is embarked upon to obtain data with regards to species available in an area, their size and level of maturity. Such information help in planning and execution of logging programmes.
Timber inventory procedure involves the following:
Map out the area of operation in square km from which felling of expected species is to be done annually.
Mark out boundary demarcation for these annual areas into blocks.
Divide the blocks into 8 compartments.
Enumerate economic trees with the aid of an enumeration gang.
After the inventory procedures, trees are marked for felling. Such trees could be thinning, diseased or injured trees and choice species.
Whatever the method of felling employed, care must be taken to:
Protect water and watershed.
Protect other trees not ear-marked for felling.
Protect grazing land, shelter belts etc.
Ensure minimal damage to the eco system allowing water percolation and soil aeration which in turn prevents soil erosion.
LOGGING FLOW CHART
Equipments used in felling are:
- Wedges (prevents pinching & directs tree fall).
- Gunstick (precision in directing tree fall).
- Springboard (platform when felling large buttress trees).
Make a back cut on the side the tree is to fall (less than 45 degrees).
Make under cut at height slightly higher than the back.
Push in wages as you cut.
This is the same as land use management plan and involves a land management map and a written plan. There are 2 aspects of harvesting plan:
- Strategic plan- This gives a long term description of what should be done to ensure a technically and environmentally sound logging operation. It involves drawing of map to scale such as 1:10,000, and to 1: 50,000. Such maps could be fairly detailed in terms of the topography of the area, vegetation type, annual areas of operation (coupes), location of communities, reserves, religious and cultural grounds.
- Tactical plan- This is a short term plan and is usually more It gives information on the various trees that should be felled in each coupe, the number of loggers or crew required to do the job, and other equipments that may be required to ensure a hitch free operation.
- Cutting- Involves all operations in preparing the tree for extraction such as felling, delimbing and bucking. In felling of selected stands, there is need to ensure minimal damage to the eco system for long term productivity and profitability. Delimbing involves cutting off of branches from the log using an axe, handsaw or the chainsaw. Bucking involves cutting of the logs to desired length, which may apply to branches of large diameter. Bucking is influenced by the shape of the log as well as the requirement. It is a critical operation which can easily lead to wastage.
Factors to consider in determining the length of buck log are:
- Log taper.
- Straightness of log.
- Crookness of log.
d. whether branches are incorporated
Extraction– Refers to the series of procedures from the removal of logs (felling) to the point of transportation. It involves delimbing, cutting to a desired length and minor transportation (skidding and yarding). Tractors and hinches are used for transportation, so also special equipment is used for gripping of logs to facilitate sliding along the ground. Timber arches (in form of inverted “U”) earned on wheels are set on caterpillars or trucks to lift large diameter end of logs between the fork of frames by means of a hinch but allow the small end to drag on the ground. Transport can also be by head cable ways and skyliners depending on the terrain.
Landing- Refers to the collection point in the forest where logs are stored pending their transportation to mills. At this point, logs are stored out and given some identification mark. Landing site should be accessible and centrally located in the forest to ensure collection of plenty logs from the various sites of felling.
- Loading- Various equipments are used for loading onto vehicles, they include, guyline loading, gunpole, heel booms, and cranes.
- Transportation- Various methods exist from landing area to mills such as:
This involves the movement of felled trees from their collection points to various primary procession points where there are processed or conditioned for further uses. This is often critical because careless handling may lead to deterioration in quality of logs thus affecting both technical and economic value. Logs are usually loaded onto transport equipment by cranes mounted on heavy trunk or overhead cranes.
Seasoning Degrade- Wood is a hydroscopic material and thus losses and gains moisture depending on the environmental condition, in doing thus it exhibits a marked anisotropy in movement below FSP. Green wood will quickly loose moisture to the environment at a faster rate than the interior. This will create an uneven stress distribution in the fibre, and the effect of such uneven movement is usually split and checks which are both disruption in fibre continuity and thus adversely influence mechanical property. To prevent seasoning degrades, end of logs (exposed surfaces) should be coated with impermeable substance and quick transport and processing.
Handling Damage- These are mechanical damage resulting from rough handling of logs, this causes fracture of wood fibre hence lowering mechanical and economic value. Careful handling is recommended in other to abate this, so also immobilizing the logs while in transport prevents excessive shaking of logs in transit.
Wet Wood or Woods with High Moisture (near but below FSP) – Such woods are susceptible to attack from various microbes (Basidiomycetes, Ascomycetes, & Bacteria) and attack by certain insects (Embrocia, beetle) and marine borers attack when transported by sea. At moisture above FSP prevents attack by organisms because of the low level of O2 in water soaked wood. So also at reduced moisture level, well below FSP biodeterioration will cease. Exposed end should be treated with wood chemical preservatives thereby impacting fungicidal & insecticidal properties.
Chemical Stain (Enzymatic Stain) – These are non microbial with certain species of wood. They result from the reaction between oxygen and 02 certain chemicals (extractives) present in the wood such as tannin. This can be prevented by quick reduction of moisture to a level of FSP and also a correct kiln schedule is essential in situations where reduction of moisture cannot control.
Log Transportation Methods
The choice of method to be used will depend on:
Level of infrastructural development.
Cost benefit of using the method of choice.
Level of technology.
Topography of the area.
The volume of timber available.
- River/Water Transport – involves the use of mass body of water through public or private canal. Logs are moved through rafting or the use of the ships and tugs attached to requirement for water transportation are:
Logs should be floaters
Water must be deep enough to support weight of logs and to keep them afloat.
Water should be flowing otherwise additional energy will be required in movement.
Water must be navigable (absence of rocky obstruction,)
Low cost due to little energy expended and sometimes very little is expended on infrastructural development.
Protects wood from seasoning degrade as wood is totally saturated with water.
Prevents microbial attack by fungi, sap stain or blue stain and insect.
Can convey large quantity of log at a time.
Usually slow there by requires large material out flow to ensure continuous operation.
There is possibility of loosing logs on transit if rafters break.
Transportation could be seasonal as the volume of water drops during dry season.
In maritime environment, logs may be attached by marine borers. Thereby reducing the quality. There is also the possibility of bacterial attack which leads to increased permeability with adverse effect on utilization such as loss of toughness, effects on absorption of adhesives, finishes and preservatives.
Road Haulage – refers to transport on road using trucks, trailer, wagons, etc.
- Effective where road network is developed.
- Enjoys minimum cost with optimum result when compared with other methods.
- Also enjoys a unique competitive cost effectiveness.
- Roads may be seasonal thus hindering regular supply to mills.
- Vehicles have limited carry capacity and the maximum permissible load is thus per axle ( truck = 4 axle=3 )
- There is possibility of mechanical damage such as drying stress leading to splits, checks, and out cup fracture where logs are not fastened together tightly to resist movement when in gallops and also microbial damage as a result of sap stain or blue stain and as wood loses moisture. Both of which can be controlled by bathing ends of log with chemicals.
Movement is slow as there is a maximum speed limit of heavy trucks which is 56km|hr.
Has high maintenance cost when compared to others.
Rail Haulage – Involves the use of rail wagons on railway
- Conveys large quantity of log at a time thus it is considerably cheaper.
- Gentle movement ensures minimal mechanical damage.
Limited distributions as areas covered by rail tracks are only a small fraction of possible destination of logs.
There is double loading and off loading – logs are loaded onto trucks to rail station and then off-loaded onto trucks again to mills. This causes an additional cost and increases the possibility of mechanical damage.
It is slow, thus resulting in drying stresses and microbial attack.
Require high capital output to lay rail tracks where it is not in existence.
- Animal Transport – Involves the use of domestic animals such as bulls, oxen, elephants, etc to move logs from site of extraction to mills usually for limited distance.
It is very cheap.
It is slow.
Tends to cause mechanical damage as logs are dragged along the ground.
It is restricted to short distances.
Skyline (Helicopters/Balloons) – Involves the use of helicopters and balloons to air lift logs from extraction sites to mills. It is commonly employed in difficult terrains (steeply or swampy areas). It involves high cost, thereby practiced where it is commonly justified.
Source National Open University of Nigeria