SELECTION SYSTEM
Selection system is defined as a silvicultural system in which felling and regeneration are distributes over the whole of the area and the resultant crop is so uneven aged that trees of all ages are found nixed together over every part of the area.
Basic feature
• Felling distributed over the whole area.
• Resultant crops are completely uneven aged.
• The regeneration operations are carried out the life of the crop and thinning are done simultaneously for improving the growth and form of the trees.
Pattern of felling
• Selection system follows nature in respect of its pattern of felling.
• Scattered single mature trees are selected all over the area and felled to enable regeneration to replace them.
• Regeneration appears in small groups because of periodicity in seed years and age classes are found in small groups.
• Felling of scattered trees all over the area of a forest is possible when the area is small.
• In large area forest is divided into coupes which create certain interval in felling of specific area know as felling cycle.
• Felling cycle is defined as the time that elapses between successive main felling on the same area.
• The length of the felling cycle affects the silviculture of species, exploitation of forests and the nature of crop produced.
• Example –felling of 2% of growing stock in 10 years rotation would result removal of 20% of the growing stock in the coupe.
• Base on felling system it can be divided into two categories:
1. Ideal selection system- selection from whole area each year.
2. Periodic selection system –selection carried out over only a part of the forest each year.
Conduct of felling
1. Dead, dying, diseased, decay and deformed.
2. Undesirable species.
3. Immature tree to balance different age class.
4. Mature tree(above exploitable diameter)
Mode of regeneration:
Natural regeneration, artificial regeneration has to be accepted in some cases.
Tending
Weeding and clearing
Character of the crop produced:
Absolutely uneven aged
Advantages of selection system
1. Full use of site factors
2. Conserves soil and moisture to the fullest extent possible
3. Most resistant to injuries by insect pests and adverse climatic factors
4. Prevent invasion of grass and weeds.
5. Sufficient seed bearers for natural regeneration.
6. Produce more growing stock and large size tree per unit area.
7. Best system of producing large size tree.
8. Forest is superior biologically as well as in its aesthetic and scenic values.
Disadvantages of selection system
1. Considerable skill is required for regeneration felling
2. Cost of logging and extraction is higher
3. Felling, logging and extraction results in damage to the young crop
4. Quality of young crop might be low
5. Difficult to control grazing and fire in regeneration area
6. Success or failure of regeneration is difficult to assess.
7. Growing stock progressively degenerates with every felling
Condition of application
1. Topography
2. Catchments area
3. Low accessible area
4. Market requirement
5. Silvicultural consideration
Application
This is very common and traditional practice of forest management.
Basic feature
• Felling distributed over the whole area.
• Resultant crops are completely uneven aged.
• The regeneration operations are carried out the life of the crop and thinning are done simultaneously for improving the growth and form of the trees.
Pattern of felling
• Selection system follows nature in respect of its pattern of felling.
• Scattered single mature trees are selected all over the area and felled to enable regeneration to replace them.
• Regeneration appears in small groups because of periodicity in seed years and age classes are found in small groups.
• Felling of scattered trees all over the area of a forest is possible when the area is small.
• In large area forest is divided into coupes which create certain interval in felling of specific area know as felling cycle.
• Felling cycle is defined as the time that elapses between successive main felling on the same area.
• The length of the felling cycle affects the silviculture of species, exploitation of forests and the nature of crop produced.
• Example –felling of 2% of growing stock in 10 years rotation would result removal of 20% of the growing stock in the coupe.
• Base on felling system it can be divided into two categories:
1. Ideal selection system- selection from whole area each year.
2. Periodic selection system –selection carried out over only a part of the forest each year.
Conduct of felling
1. Dead, dying, diseased, decay and deformed.
2. Undesirable species.
3. Immature tree to balance different age class.
4. Mature tree(above exploitable diameter)
Mode of regeneration:
Natural regeneration, artificial regeneration has to be accepted in some cases.
Tending
Weeding and clearing
Character of the crop produced:
Absolutely uneven aged
Advantages of selection system
1. Full use of site factors
2. Conserves soil and moisture to the fullest extent possible
3. Most resistant to injuries by insect pests and adverse climatic factors
4. Prevent invasion of grass and weeds.
5. Sufficient seed bearers for natural regeneration.
6. Produce more growing stock and large size tree per unit area.
7. Best system of producing large size tree.
8. Forest is superior biologically as well as in its aesthetic and scenic values.
Disadvantages of selection system
1. Considerable skill is required for regeneration felling
2. Cost of logging and extraction is higher
3. Felling, logging and extraction results in damage to the young crop
4. Quality of young crop might be low
5. Difficult to control grazing and fire in regeneration area
6. Success or failure of regeneration is difficult to assess.
7. Growing stock progressively degenerates with every felling
Condition of application
1. Topography
2. Catchments area
3. Low accessible area
4. Market requirement
5. Silvicultural consideration
Application
This is very common and traditional practice of forest management.
thanks for updating , it was fruitfull