CLEAR FELLING SYSTEM
· The complete felling and removal of all the trees in one installment, growing in a specific area of the forest (considered a mature forest) and is followed by obtaining natural or artificial regeneration in that area.
· Old crop is felled to ensure regeneration over the demarcated area in a block, strip or alternate strip method in a single operation.
· It is also adopted for regenerating the Riverain Shisham forests by root suckers supplement by stump planting under Bela techniques.
· It is also adopted for regeneration Riverain Acacia nilotica (Babul) forest through Natural seed fall and artificial sowing.
o Methods of Clear Felling in Pakistan: Two Methods:
1. CLEAR CUTTING WITH NATURAL REGENERATION BY ROOT-SUCKER
§ This method is applied for regeneration to Shisham (Dalbergia sissoo) forests growing along with river banks.
§ Usually the Annual coupe is clear felled and trenches are made at a spacing of 10 feet (3 meter).
§ If the area is infested with grasses these are burnt in winter.
§ Concentrated Trenches are dung out around Shisham stump at different radio to get root-suckers.
§ The regeneration is obtained mainly from root-suckers by making trenches, coppice obtained from stump and seedling coppice which sprout from the cut back saplings.
§ The areas which are not regenerated by the above method are Artificially Regenerated through BELA techniques.
§ The number of shoots on each stump is reduced to one after one year.
2. CLEAR CUTTING WITH ARTIFICIAL REGENERATION FROM SEED
§ This technique is adopted for Riverain Forests of Acacia nilotica (Babul) growing along Indus River in Sindh.
§ The area is divided into equi-productive annual coupes which may vary accommodating erosion felling in the area which is endangered of being eroded by River action.
§ When fellings are carried out advance growth up to about 4″ DBH (10 cm) is retained which forms a part of the future corp.
§ Regeneration is ensured through Artificial sowing supplemented by seed from natural seed fall.
§ Where heavy silt deposition is not expected in a particular year, sowing is done before the flood otherwise sowing is done after the flood water resources.
· The execution of this system is made in a specific area of a forest which is known as felling and regeneration block .this block may be one-fourth , one-third are even one –hundredth part of a forest.
· All the felling and regeneration activities are confined to this region successive area are considered as a felling and regeneration blocks according to the directions available in the working plan of the forest. All the trees present in this block are cut, felled and removed in one installment, which is followed by natural or artificial regeneration of new species in this block. All this work is done in a particular sequence.
· If a forest is divided in to ten (10) parts then block will be treated in the first year and the new plants will be placed in this block.
· The next, felling and regeneration block will be formed in the area adjacent to the previously treated block. At this time the species, which were planted in the first block, would be aged one year.
· In the third year , the block number 3 will be treated at this moment the species planted in block 1 , and 2 will having the ages of two or one year respectively.
· The same practice will be treated for the next ten years and after ten years, when we will come back towards the block no 1, the species present here will be having the age of ten years and it will be ready again to provide us timber.
· For the execution of clear felling silvicultural system, it is very important to make the demarcation of blocks periodically. For this purpose a particular formula is utilized.
· According to which whole of the forest area (in acres) is divided by the rotational age of the trees present in the forest .this provides us with the number of blocks , which we have to make in order to perform the clear felling silvicultural operations.
· If some forest is scattered over an area of 240 acres and the rotational age of the trees is 120 years, then the annual blocks will be formed in the following way.
· Annual blocks =total forest area/Rotation age
o ADVANTAGES OF CLEAR FELLING SYSTEM:-
1. It is the simplest of all high forest systems. This system is very easy to operate /perform.
2. It requires little technical skills during markings.
3. Little time on the part of the forest staff and lesser money.
4. By and large, regeneration is obtained more easily in this system, thus saving time, money and energy.
5. There is a provision of complete overhead light. This greatly helps in the regenerations of species which are strongly light demanders.
6. Little or no damage is caused to the young crop during felling operations as most of these operations are completed before the new crop regenerates.
7. This system gives a very high outturn per unit area. Hence it gives a greater economy in working.
8. The process of regeneration by artificial means is very much convenient.
9. It is very beneficial as it provides an opportunity to the management to make a complete change in the species of the forests.
If in a forest of “Dalbergia sissoo” is found in abundance and the management wants to replace it with some other species like “Morus alba” or “Acacia nilotica” then it is very convenient to apply clear felling silvicultural system in that region, there will be no competition from already existing species and a vast area will be available for planting the desired species.
10. Foresters are of the view that growing timber in Even-aged stands, produces timber which is more cylindrical, clean and has fewer knots.
o DISADVANTAGES OF CLEAR FELLING SYSTEM:-
The main disadvantages of the clear felling system are as follows
1. Complete clear felling of the forest may give rise to the adverse condition mentioned below
(a) Desiccation and general degradation of the soil is a result of exposure to sun, air, and water.
(b) Increases in general swampiness of moist and wet areas.
(c) A luxuriant growth of a grass and weeds which may prove a hazard to regeneration operations.
(d) Multiplication of insects, fungi, bacteria etc which are harmful to the young crop.
2. On steep slopes and hillsides, clearfelling exposes the area to serve soil erosion .as a result, there is an ever-present danger of landslides.
3. A serious disadvantage of the clearfelling silvicultural system is that it presents the phenomena of “Global Warming “ has increased up to an alarming extent and the trees are the only source of making counter the horrible effects of the global warming as trees sink/sequestration carbon dioxide.
Almost 18 billion tons of carbon dioxide is emitted in the atmosphere early.
4. This system is not friendly for the wildlife, because wildlife loses habitat and as a result migrate to some other place.
5. The soil is completely exposed to the erosional agent i.e. sun, water, air, snow, frost, rain.
6. Trees are supposed to be the lungs of a nature. They produce oxygen and absorb carbon dioxide. They make the environment fresh. They reduce the element of pollution up to the great extent. This system can not be considered good from environmental aspects.
7. This system is also not good whereas the strategical viewpoint is considered because when trees are removed from a specific block, it becomes impossible for the army man to hide in the trees and also becomes impossible to have an eye on the movement of the enemy.
8. Aesthetically this system is not considered friendly.
9. An even-aged forest is produced which are more prone to attack by insects, pests, fungi, and damage by snow, wind and even frost as compare to an uneven-aged forest.
· This system should be applied in the plain where the change in the species is required. This system cannot be applied in the areas where the erosional hazards are present up to great extent.
i. Where the original species is not valuable e.g In tropical thorn forest Prosopis cineraria, beri , capparis species its annual yield is 10 cft/acre .we clear these forests and introduce Shisham and get 1500 cft/acre firewood and 150cft/acre timber by raising plantations.
ii. Where Exotic is to be introduced to eucalyptus species, hybrid popular are introduced .hybrid popular is a combination of P.nigra and P.deltities.
iii. Where trees have become too old to be retained.
iv. It is suitable for the species capable to establish under full exposure (full temp, full frost, wind, a tender crop cannot survive).
· When a mature crop is removed in a single felling, resulting even-aged crop.
It is further subdivision into:-
i. Clear felling in blocks.
ii. Clear felling in strips.
iii. Clear felling in alternate strips
The clear felling system is applied in:
i. The tropical thorn forest of Pakistan.
ii. The riverain forest of Pakistan.
iii. The coastal forest of Pakistan.
o SUITABILITY FOR APPLICATION:-
II. Locality conditions.
III. Soil and soil cover.
IV. Regeneration conditions.
V. Nature and type of forest produced.
VI. Change of forest composition.
VII. Economic considerations.
i. The clear felling system is best suited for
a) Strong light demanders intolerant of shelterwood.
b) Species which are resistant to frost and drought.
c) Species which are able to withstand exposure in youth.
This system is unsuitable for sensitive shed bearers.
ii. This system is not suited for
a) Unsuitable hillsides prone to soil erosion
b) In water supply catchment areas
c) Areas which are mentioned as protected areas.
iii. This system is not fit for areas where there are erratic rains during the monsoon season. This should not be adapted for areas where regeneration each year or period cannot be established fully.
iv. When there is a demand for the production of large quantities of timber for special purposes i.e pulp wood etc.
v. It is the most economical of all high forest systems. The quickest return on the investments.
vi. It is best suited for mechanized forestry operation of modern times.
i. CLEAR FELLING IN BLOCKS:-
· Clear felling system is also been termed as the clear-cutting system or the coupe Blanche or coup rare.
· Under this system successive clear felling and regeneration (artificial or natural) is carried out in a particular area.
· As a general rule the coupe or the felling areas should be fully completely cleared although pre-existing pole and sampling crop which occurs in groups may be retained as a part of the future crop .however isolated poles and saplings should be removed as they are likely to develop into branchy trees, there be interfering with new crop.
· Yet, on the other hand, it may become essentials to introduce nurses in order to assist in the establishment of a new crop.
· Before a particular forest is treated under this system it is divided into a number of annual or periodic coupes.
SIZE, FORM AND ARRANGEMENT OF COUPES:-
· The clear felling system involves the felling and regeneration of equal areas (COUPES) each year. The forest stand in such areas has reached a pre-determined maturity. If this procedure is repeated year after year the entire rotation period, a normal series of age gradations of 1, 2,3. . . . . . .n years is established.
· However, under conditions where the quality and the productivity of the soil varies within a particular forest, equi-productive coupes (in place of equal area coupes) are worked.
· As a matter of fact the ideal form of clear felling system involving the felling
· And regeneration of equal Annual coupes and the establishment of a sequential series of age gradations have been found to be more or less impracticable in the high forest except under extremely favorable conditions.
· There is a considerable variation in the size, form, and arrangements of coupes according to local conditions and needs in the case where there is little or no danger of damage from insects, winds, soil erosion etc .equal area coupes may be worked.
· Every main unit of a forest is divided into a number of cutting sections, so as to facilitate the formation of small, manageable coupes. Coupes are formed within these cutting sections, so as to meet the requirements of the case. For the constitution of small and narrow coupes, it may become necessary to divide the forest to be worked out into two or more small parts.
· Wind shelterbelts may also be created in wind areas, in the form of severance cuttings such severance cuttings run more or less at right angles to the prevailing winds may be used as a road or suitability plants up.
· The length of the cutting sections may be from an average length of about five hundred to thousand meters but may be kept as low as possible.
PATTERN OF COUPES ON HILLY TERRAIN:-
· The clear felling system is generally not adapted on very steep slopes because of the danger of soil erosion. On the hilly terrain, coupes are arranged into two ways as discussed below.
i. The long axis of the coupe, running more or less along the contour.
ii. The long axis of the coupe is oriented across the slopes, with the felling against the wind direction.
CLEAR FELLING WITH ARTIFICIAL REGENERATION:-
· Planting is more common than sowing in C.F system. They are carried out as soon as possible after felling.
CLEAR FELLING WITH NATURAL REGENERATION:-
· In the clear felling system the mature crop is removed in one harvesting operations. The clear felled area then can be regenerated by natural or artificial means.
· For natural regeneration of the area the seeds or seedlings are obtained from the following sources.
i. Seeds that are already lying dormant in the soil of the clear felling area.
ii. From the adjacent standing mature crop.
iii. Ripe seeds of mature trees. The felling should be carried out only after the seeds ripening or seed fall.
iv. Seeds obtained from the advanced growth already present in the clear-felled area.
· This is one of oldest method of clear felling with natural regeneration felling proceeds successively in a definite direction in a pattern usually prescribed under clear felling with artificial regeneration. It is advisable to carry out felling against the direction of the wind, if it is constant at the time of the fellings and seed dispersal. This arrangement helps the seed to be blown on the adjoining strip which has been clear felled. The breadth of these strips should be so planned that a good quantity of seed reaches all its parts.
· The interval between successive adjacent felling depends upon the following factors.
i. The frequency of occurrence of good seed year
ii. The readiness with which regeneration comes up and is able to establish itself.
e.g entire area is divided into four cutting sections of three coupes each .
· Alphabet denote cutting section while number shows the coupes i.e 1,2,3.
· F is the direction of felling and
· W is the direction of prevailing winds.
· When one strip is cleared then the one adjoining it should not be felled till the previous one has fully regenerated itself.
ii. CLEAR STRIP SYSTEM:-
· The large clear felled coupes are dangerous and undesirable with smaller coupes, large blocks of Even-aged wood are avoided, the factors of the locality are better preserved and work is better distributed.
· The area to be worked under a clear felling system is therefore usually divided in a so-called cutting section of forest management. The clear felled strip is only a further modification essential when the strip is to be regenerated by seed from the adjoining forest and even employed with artificial regeneration, especially in the mountainous country.
· In reality, each strip is an Even-aged crop which can be differentiated from the next strip and shown separately on the management map, to all intents and purposes and each strip becomes sub-compartment.
iii. THE ALTERNATIVE STRIP SYSTEM:-
· This is a method in which felling a parallel strips of the forest is carried out, leaving the intervening strips of similar width unfelled.
· The initially felled trees are regenerated by seeds from the adjoining unfilled areas. However natural regeneration in the unfilled may have to be supplemented by artificial means under certain conditions.
· In case the crop of the initially felled strips have attained an age during which it is able to produce fertile seeds , the subsequent may be strips may be successfully regenerated by natural means , or else artificial measure may be adopted . It is more practical if both the initially felled strips as well as the alternate strips are regenerated naturally by seeds obtained from the adjoining areas or strips.
· In this method, an Even-aged crop is produced in the alternate strips.
ADVANTAGES OF ALTERNATE STRIP SYSTEM:-
I. Seed becomes available to the felled strips from both the sides.
II. Complete over head light conditions are available for the light demanding species.
III. Adequate protection is available for the seedlings of species which are sensitive to frost and icy winds.
IV. Less damage is caused to the seeds bearers by strong winds.
NATURAL REGENERATION UNDER CLEAR STRIP SYSTEM:-
· In clear strip system the object is to obtain seed from adjacent unfelled area. The regeneration area should in the form of a strip.
· The width of strip is selected in such a way that the seed from the adjacent area may reach the whole width. The direction of the wind at the time of seed fall has to be kept in view.
· The strips are selected in an alternate fashion and they are so narrow that the lateral shed and protection afforded by the adjoining crops as a direct influence on seedling survival and growth. The width of each strip is nearly half height to the full height of the trees in the adjoining crops. After the regeneration has come up successfully, it is weeded and cleaned and is thinned when it reaches at the pole stage.
· Ultimately the new crop is obtained after which the unfilled strips are also cleared. Clear felling followed by natural regeneration is not common in India.
CLEAR FELLING IN STRIPS:-
i. Progressive strips.
ii. Alternate strips.
In progressive strips the number of a strip is equal to number years in rotation length of the strip will equal to the width of the forest. Width of the strip will be equal to seed dispersal. Felling will proceed against wind direction. If the area is large then the strips, then the strips are further divided.
In the alternate strips, the whole is divided into a number of strips which are equal to rotation divided by an interval of felling.
Regeneration is natural in alternate strip we do not have a sequence in crop ages. It depends upon seed dispersal .e.g
A. Dr. Hold in 1992, experienced this system in India. In that he introduced felled strip is equal to 40-50 feet wide and unfilled strip is 100-120 feet wide.
This system failed in India due to the following reasons
i. Side shed in India is not available but in Europe it is available.
iii. Management problems due to uneven aged crop
iv. Extractional problems.
B. In Germany, this is prevailing on an experimental basis. There the felled strips is 100-120 feet wide and unfilled strip is 40-50 feet.
In Germany side shed is available.
WHY WE MAKE STRIPS OBJECTIVES:-
i. Aesthetic and public opinion.
ii. Better distribution of works, regular work is done.
iii. Overhead light is present but side shed is also provided by unfilled strips.
iv. Regeneration through natural means.
v. Crop protection from winds, diseases, sun etc.
vi. Artificial regeneration is not required.
vii. Suitable for those species for which seed supply is abundant i.e every year seed is produced.
viii. Good for those species that can grow in pure form.
SIZE AND SHAPE OF STRIPS:-
· Strips will be made at a right angle of the length of the forest. The length of the strip will equal to the width of the forest.
· The width of strip depends upon the distance to which the seed is liable to disperse by nature. Strips are made according to the direction of the wind.
· Due to insect attack some time strips are made alternately because some insects effect the seedling only.
· Shape and size also depend upon funds, labour and extraction means.
· In mature crop, a seeding felling is carried out leaving a suitable number of seed bearer uniformly distributed over the area.
QUALITIES OF SEED BEARERS:-
· While selecting seed bearer the following characteristics should be kept in mind
i. Wind firm wide spreading crown and a wide horizontal opening between branches.
ii. Seed bearer must be mature enough to produce abundant and fertile seeds
iii. These should be selected among the dominant and co-dominant(better)
iv. They must possess clean straight, cylindrical bole with a normal taper.
v. It must be free from all diseases
v NUMBER OF SEED BEARERS:-
The number of seed bearers depends upon several factors
1. SEED PRODUCTION:-
More seed production and dispersal rate than less number of seed bearers and vice versa.
2. LIGHT REQUIREMENTS:-
If species are light demanders then seed bearers will be less and more shed bearers.
3. DESIRED SPECIE MIXTURE:-
According to desire crop specie mixture, we leave seed bearers.
4. SURVIVAL %GE OF SEEDBEARERS
5. GERMINATION %GE OE SEEDBEARERS
6. SURVIVAL %AGE OF SEEDLINGS.
More seed bearer on hot and dry slopes and vice versa.
8. DISPERSAL DISTANCE:-
Depending on above factors the tree per acre is given as
i. Chir =6-8 trees/acre
ii. Kail =20trees/acre
iii. Deodar =20 trees/acre
iv. Fir =35 trees/acre
· Once regeneration appears on the forest floor the over wood is removed in one or more felling to assist the development of the new crop.
· If specie is strong light demander than seed bearer must be removed in one operation and if seedling require protection against drought.
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