The clear felling system is a silvicultural system in which equal or equiprodcutive areas of mature crop are successively clear-felled in one operation to be regenerated most frequently, artificially but sometimes naturally also. The new crop produced is absolutely even-aged. It requires large sums of money and large number of laborers to regenerate the forest artificially.
The area to be clear-felled each year in uniformly productive sites is l/n of the total area allotted to this system, where n = number of years in the rotation and is usually referred to annual coupe. The coupes to be felled every year are made equi-productive.
Removal or felling of mature crop
According to definition, the entire crop of the coupe should be felled and removed in one operation but in practices following variations are observed.
- Retention of some mature trees as frost protection measures or as an insurance against failure or as nurse crop to facilitate establishment of frost tender species.
- Retention of promising groups of saplings and poles to prevent unnecessary sacrifice of immature crop of the desired species.
- Isolated saplings and poles are ordinarily not retained as they may develop in to wolf trees.
Methods of obtaining regeneration
The area can be regenerated sometimes naturally but mostly artificially. Artificial regeneration is preferred due to following reasons:
- It is the surest and quickest method of improving crop composition.
- It facilities introduction of fast growing and high yielding exotics.
- It provides better financial returns.
- The regeneration is established sooner, so the area can be opened for grazing sooner.
Method of artificial regeneration
- Departmental plantation
- Departmental Taungia
- Leased Taungia
- Village Taungia
Method of natural regeneration
- Natural regeneration from seed
- Seeds stored in the area
- Seeds received from outside
- Natural regeneration from advanced growth
- It is simplest of all high forest system. It does not require a high degree of skill.
- As felling is concentrated, the yield per unit area is more and consequently the cost of felling and extraction is low.
- Introducing fast growing exotics and regulating composition of new crop through artificial regeneration is advantageous.
- It makes the supervision of all operations easy.
- There is no damage to new crop by felling
- It is the most artificial system.
- Soil remain open there is more danger of soil deterioration and erosion
- The danger of weeds and grass invasion increases.
- It produces even aged crop, which is less resistant to damage by wind.
- When the crop is pure it becomes more susceptible to damage by Insects, plant parasites and pathogens.
Variations in clear felling system
- Alternate strip clear cut system: A silvicultural system in which clear felling is done in the form of strips and the clear strip alternate with unfelled strips of similar width. Clear cut strips are oriented at right angle to the direction of wind.
- Progressive strip clear cut system: A silvicultural system in which, clear felling is done in the form of strips which progress successively in one direction across the regeneration area. The crop produced is even-aged considering each strip as a compartment.
- Block or patch clear cut system: It is applied on rugged and irregular terrain or in even-aged stands that lack uniformity.
Pattern of felling in alternate strip Pattern of felling in progressive strip Patch clear cut system