Forest Management | Notes of Forestry for IFoS Mains

What is Forest management

It is the practical application of the scientific technical and economics principles of forestry.

Definition of Different types of yield

  1. Intermediate Yield: It is the material or cash returns obtained from time to time from a forest not organized for continuous production.
  2. Final Yield: All the material that counts against the prescribed yield and which is derived from the main felling in a regular forest
  3. Total yield: Sum of the standing volume of a crop plus the total volume removed in thinning.
  4. Normal yield: Yield obtained from normal forest.
  5. Sustained Yield: It is the regular, continuous supply of the produce to the fullest capacity of forest from a unit area.
  6. Progressive Yield: Productivity of soil and of the crop by silvicultural treatments, judicious tending and enrichment of forest by changing the crop composition and by replacement of original inferior forest by valuable forest Species.


What is Rotation?

It is the planned number of years between the formation or regeneration of a crop and its final felling. it is the age of the plant beyond which deterioration of quality occurs.

The length of Rotation is Depends upon the following

  1. Rate of growth of species: Generally fast growing species have shorter rotation period and vice versa.
  2. Silvicultural characteristics of the species: Some species are fast grower and some are slow grower.
  3. Soil types: Fertile soil will produce better crop in shorter period and vice versa.
  4. Economic considerations: Rotation period will vary according to the money value and changes in wood prices.
  5. Social Conditions: Market price, Personal needs and others factors.


Types of Rotation

  1. Physical rotation: It is the rotation which coincides with the natural lease of life of a species on a given site. It is applicable to protection and amenity forest, park lands and road side avenues.
  2. Silvicultural rotation: it is the rotation through which a species is retained until satisfactory vigour of growth and reproduction on a given site.
  3. Technical Rotation: It is rotation in which a species yield the maximum material of a desired size for economic conversion or for special use.
  4. Rotation of Maximum volume production: It is the rotation that yields the maximum annual or net revenue irrespective of the value of the forest.
  5. Rotation of highest income: It is the rotation which yields the highest average annual gross or net revenue irrespective of the value of the forest.
  6. Financial rotation: It is rotation which yield the highest net return on the capital invested.


What is Normal Forest?

A forest which have Normal series of age gradation, Normal growing stock and Normal increment.

Normal series of age gradation: it is the presence of tree of all ages from one year old to rotation age in forest.

Normal growing stock: It is the volume of stands in a forest with normal age gradations or age gradation and normal increment.

Normal Increment: It is best or maximum increment attainable by a given species and for a given rotation.

How we can obtain the Normal Forest under different Silvicultural system?

  1. Clear felling system: In it, the total area is divided into number of coupes which is equal to A/R. The number of the coupe is equal to number of years in rotation (R). Here A is Area and R is Rotation years.
  2. Shelter wood systems: In it Total area is divided into number of regeneration blocks. The number of periodic block is equal to rotation divided by regeneration period (R/P). Each block will have single age class because each regeneration block is harvested and regenerated within the regeneration period.
  3. Irregular forest: In it, age class distinction is difficult because each unit area have trees of all the age classes. In this exploitable diameter is used instead of rotation age. So it is essential that every year we have to harvest all trees which attained the exploitable diameter all over the area.

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