Tree Felling and Preservation
Harvesting of forest trees that is felling of trees depends on the objectives of afforestation. When afforestation is made with the objectives of producing firewood, pulp wood and poles, then rapidly growing forest tree species are planted. This type of plants may be harvested after 10 -12 years of planting. But if the trees are planted for the purpose of producing timbers for construction and furnitures, harvesting should be done after 30-40 years of planting depending on the characteristics of the species.
However, some general rules are required to be followed when harvesting forest plantation. The harvesting rate should be determined considering the usual growth rate of the forest species. The harvesting rate from a certain plantation area should not exceed the growth rate of the forest trees. It is known as forest conservation. Conservation is very important for maintaining forest resources. Because, a forest resource or plantation can not be raised overnight.
Bamboo is harvested usually after 3 years of planting. As a result of growth and multiplication bamboos attain a form of bush. New bamboo tillers are found to grow at the outer side of the bush. That's why the older bamboos rennin in the centre of the bush, the younger shoots being at the exterior. During harvesting it is required to cut one or more outer bamboos. In this way space is created in the bush so that one can enter the inner side of the bush for cutting the matured bamboos.
The timber and material loss from trees and bamboos may be greatly reduced by cutting if appropriate scientific methods are followed. These forests harvest may be scientifically treated for ensuring its prolong use. Some of the methods of tree felling and preservation of wood and bamboo are described here.
Felling of trees in unplanned and unskilled way results in great loss of wood. One should be very careful while cutting a tree specially for the purpose to timber and poles. A tree is required to be grown for 30-40 years to get a good quality of timber from it. To get strong pole a tree is require to be grown for 18 to 20 years. Cutting of a tree in unplanned and unskilled way may result in irregular fracture or breakage of the timber at the main base of stem. Just for a wrong decision a long grown tree may be spoiled in a moment.Cutting trees by saw always reduces wood loss. So in order to reduce valuable woodloss, it is important to know the techniques and use of modern tools for cutting a tree.
It is very much usual that there may be houses and other trees nearby matured tree, which has been selected for cutting in a homestead. In such a situation the tree after cutting may fell on those nearby houses or other trees causing serious damage. The tree may fell in a ditch where from it may be very hard to pull or carry it. On the other hand unplanned felling of trees grown on road side or embankment, etc. may block the transports. But if the technique of tree felling is known then a tree may be cut and felled in any desired side or position. The tree may be cut at the base of the tree near the soil level as close as possible. Because the base of the tree is always more thick and have more quality wood. Cutting of tree at an elevated higher place above the soil spoils more quantities of quality wood.
At first the surrounding of the tree selected for felling should be cleared. Then the direction towards which the tree will be felled is to be decided. The selected tree should be felled on a nearly level and open space. If the land have some slope then the tree should be felled across the slope. The first cut by saw and axe should be given at that side at which the tree is planned to be felled. At first a cut measuring two third of the diametre of the plant should be given parallel to the ground. Then a tangent cut should be given from the 15-20 cm upper surface side. Then second cut should be given from the opposite side of first cut 12-15 cm above the first cut. The second cut should be extended up to the end of the first parallel cut. Then a flat point peg is to be entered to the second cut. When this peg will be pressed by the axe or hammer, the tree will be felled at the side where first cut was given.
This first cut-second cut method of felling tree ensures fell of tree at a expected direction or side.
The major enemies or pests of wood and bamboo are termites, fungus and ghoon. Treating them appropriately may prevent destruction, rotting or damages of wood and bamboo. Treating process may increase the longevity and durability of wood and bamboo.
Seasoning of Wood The actual meaning of wood seasoning is reducing moisture content of wood by drying the wood to a certain range. When wood is dried to a certain range; its moisture content is reduced. As a result, attacked by insects and fungus is reduced giving the wood a longer life.
The two popular methods used in wood seasoning are given below:
A. Air drying
B. Kiln drying
Kiln is a special type of room or a chamber. The temperature, relative humidity and aeration through the arranged woods in the kiln can easily be controlled. The range of temperature in the chamber are maintained within 30˚ C- 125˚ C. The expected temperature is maintained by burning fire wood or oil. The internal relative humidity is maintained by artificially entering air or steam inside the chamber. Wood seasoning by this process requires 30-45 days.
1. Moisture content of woods may be reduced as needed.
2. Time requirement is low.
3. Seasoning defects are minimum.
Chromic oxide 47.5%
Copper oxide 18.5%
Arsenic penta oxide 34.0%
The preservatives may be prepared by purchasing these chemicals separately and mixing in rightly measured quantities. Then 2.5% solution of the preservative is mad by mixing with water. The solution is pushed into wood and bamboo by a special mechanical arrangement of giving high pressure. The preservative solution must be pushed deep into wood. It is recommended to push 0.4 pound of preservative into one cubic foot of wood.
Using CCA preservative may prevent the rotting of stored woods. Besides, this chemical can also prevent attacks of termites. The following 3 points must be considered while using treated wood. These are_
1. Treated wood will be ready for use after 7 days of treatment
2. Before use, the treated wood should be dried as described earlier.
3. Extensive carpentry should not be done with treated woods.
Bamboo, which is to be used in association with soil and water, do not last usually more than two years. The causal agents for rottening and damage of bamboo are fungus and insect pests. Protection of bamboos by using preservatives can greatly increase its durability. If the preservatives are rightly used, then the user need not to replace the bamboo frequently and extra costs in this regard may be avoided. Thus loss of bamboo is reduced.
Previously bamboos were sufficiently soaked in water for a certain period as a preservation process of treatment. This method is known as "Pinat". This process protects the bamboo from ghoon insects but can not protect the bamboo from fungus, termites and other insects, presently improved methods have been developed for bamboo preservation in Bangladesh. In this method chemical preventive for fungus and insect pests is pushed into the bamboo in the form of solution: A chemical namely CCB is widely used in Bangladesh for the purpose. The ingredients of CCB are as follows. CCB is pushed into Bamboo in two ways, such as-
A. Sap Displacement System
B. Soaking System.
The sap of bamboo is displaced by a 20% CCB solution by this process. The 20% solution may be prepared by diluting 2 kg of CCB in 10 litres of water. The solution is pushed into a newly cut bamboo by pressure and sap is replaced.
In soaking method the materials to be preserved are kept submerged in a 10% solution of CCB in a tank of required size.
However, some general rules are required to be followed when harvesting forest plantation. The harvesting rate should be determined considering the usual growth rate of the forest species. The harvesting rate from a certain plantation area should not exceed the growth rate of the forest trees. It is known as forest conservation. Conservation is very important for maintaining forest resources. Because, a forest resource or plantation can not be raised overnight.
Bamboo is harvested usually after 3 years of planting. As a result of growth and multiplication bamboos attain a form of bush. New bamboo tillers are found to grow at the outer side of the bush. That's why the older bamboos rennin in the centre of the bush, the younger shoots being at the exterior. During harvesting it is required to cut one or more outer bamboos. In this way space is created in the bush so that one can enter the inner side of the bush for cutting the matured bamboos.
The timber and material loss from trees and bamboos may be greatly reduced by cutting if appropriate scientific methods are followed. These forests harvest may be scientifically treated for ensuring its prolong use. Some of the methods of tree felling and preservation of wood and bamboo are described here.
1. Methods of Felling Trees
Felling of trees in unplanned and unskilled way results in great loss of wood. One should be very careful while cutting a tree specially for the purpose to timber and poles. A tree is required to be grown for 30-40 years to get a good quality of timber from it. To get strong pole a tree is require to be grown for 18 to 20 years. Cutting of a tree in unplanned and unskilled way may result in irregular fracture or breakage of the timber at the main base of stem. Just for a wrong decision a long grown tree may be spoiled in a moment.Cutting trees by saw always reduces wood loss. So in order to reduce valuable woodloss, it is important to know the techniques and use of modern tools for cutting a tree.It is very much usual that there may be houses and other trees nearby matured tree, which has been selected for cutting in a homestead. In such a situation the tree after cutting may fell on those nearby houses or other trees causing serious damage. The tree may fell in a ditch where from it may be very hard to pull or carry it. On the other hand unplanned felling of trees grown on road side or embankment, etc. may block the transports. But if the technique of tree felling is known then a tree may be cut and felled in any desired side or position. The tree may be cut at the base of the tree near the soil level as close as possible. Because the base of the tree is always more thick and have more quality wood. Cutting of tree at an elevated higher place above the soil spoils more quantities of quality wood.
At first the surrounding of the tree selected for felling should be cleared. Then the direction towards which the tree will be felled is to be decided. The selected tree should be felled on a nearly level and open space. If the land have some slope then the tree should be felled across the slope. The first cut by saw and axe should be given at that side at which the tree is planned to be felled. At first a cut measuring two third of the diametre of the plant should be given parallel to the ground. Then a tangent cut should be given from the 15-20 cm upper surface side. Then second cut should be given from the opposite side of first cut 12-15 cm above the first cut. The second cut should be extended up to the end of the first parallel cut. Then a flat point peg is to be entered to the second cut. When this peg will be pressed by the axe or hammer, the tree will be felled at the side where first cut was given.
This first cut-second cut method of felling tree ensures fell of tree at a expected direction or side.
2. Timber log and Sawn Wood
Forest trees after harvest are cut into pieces for easiness of transportation and sawing. This type of round pieces is known as Long wood. The log pieces are made by cross cut saw. The logs are then cut for sawing to give them their usable forms. Wood logs after sawing have specific length, width and thickness of less than 4 cm is known as wood sheets or Takta.Measurement of Usable Wood
A portion of the Log wood is always lost in the process of sawing. All the woods can be utilized to giving a regular shape. How much usable wood will be available from a log may be calculated by a formula, according to the Hompus Law
Seasoning and Treatment of Wood and Bamboo
The major enemies or pests of wood and bamboo are termites, fungus and ghoon. Treating them appropriately may prevent destruction, rotting or damages of wood and bamboo. Treating process may increase the longevity and durability of wood and bamboo.Seasoning of Wood The actual meaning of wood seasoning is reducing moisture content of wood by drying the wood to a certain range. When wood is dried to a certain range; its moisture content is reduced. As a result, attacked by insects and fungus is reduced giving the wood a longer life.
The two popular methods used in wood seasoning are given below:
A. Air drying
B. Kiln drying
A. Air Drying
Drying of wood in open air is known as air drying. But very thinly sliced woods may show fracture or may be curved when left under strong sun in open air. That's why these types of woods are kept in shade 30-40 cm above the ground in layers. The wood layers are arranged such a way that aeration is ensured surrounding every wood piece. The wood pieces cannot be left in a disarranged manner, which may result in curving of the wood. Air drying process of wood treatment requires much time, at least one dry season in Bangladesh.
B. Kiln Drying
Kiln is a special type of room or a chamber. The temperature, relative humidity and aeration through the arranged woods in the kiln can easily be controlled. The range of temperature in the chamber are maintained within 30˚ C- 125˚ C. The expected temperature is maintained by burning fire wood or oil. The internal relative humidity is maintained by artificially entering air or steam inside the chamber. Wood seasoning by this process requires 30-45 days.
Advantages of Kiln Drying
1. Moisture content of woods may be reduced as needed.2. Time requirement is low.
3. Seasoning defects are minimum.
Wood Treatment or Preservation
The seasoned woods may rightly be used in furniture and in other construction works. However, if comes in direct contact with soil or water the seasoned wood can also lose its durability. Because when comes in contact with water, it absorbs water and its moisture content is increased. Fungus and insects easily infest moistened woods. For this reason woods to be used in moist places or soils should be well treated. The main theme of wood and bamboo treatment is the entering of chemical or preservative into the wood or bamboo. A preservative mixture namely CCA is widely used in Bangladesh for preserving wood and bamboo. The CCA preservative is composed of 3 ingredients, such as:Chromic oxide 47.5%
Copper oxide 18.5%
Arsenic penta oxide 34.0%
The preservatives may be prepared by purchasing these chemicals separately and mixing in rightly measured quantities. Then 2.5% solution of the preservative is mad by mixing with water. The solution is pushed into wood and bamboo by a special mechanical arrangement of giving high pressure. The preservative solution must be pushed deep into wood. It is recommended to push 0.4 pound of preservative into one cubic foot of wood.
Using CCA preservative may prevent the rotting of stored woods. Besides, this chemical can also prevent attacks of termites. The following 3 points must be considered while using treated wood. These are_
1. Treated wood will be ready for use after 7 days of treatment
2. Before use, the treated wood should be dried as described earlier.
3. Extensive carpentry should not be done with treated woods.
Preservation of Bamboo
Bamboo, which is to be used in association with soil and water, do not last usually more than two years. The causal agents for rottening and damage of bamboo are fungus and insect pests. Protection of bamboos by using preservatives can greatly increase its durability. If the preservatives are rightly used, then the user need not to replace the bamboo frequently and extra costs in this regard may be avoided. Thus loss of bamboo is reduced.
Methods of Bamboo Treatment
Previously bamboos were sufficiently soaked in water for a certain period as a preservation process of treatment. This method is known as "Pinat". This process protects the bamboo from ghoon insects but can not protect the bamboo from fungus, termites and other insects, presently improved methods have been developed for bamboo preservation in Bangladesh. In this method chemical preventive for fungus and insect pests is pushed into the bamboo in the form of solution: A chemical namely CCB is widely used in Bangladesh for the purpose. The ingredients of CCB are as follows. CCB is pushed into Bamboo in two ways, such as-A. Sap Displacement System
B. Soaking System.
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