Yield Regulation in the Clear-Felling System

A term generally applied to the determination of the yield and the prescribed means of releasing it. Yield regulation determines the what, where, and when of the forest harvesting on the managed forest.

The main purpose is to provide an estimate of present yield and future increment and yield.

Functions of Yield Regulation

  • Calculation/ Determination of yield and prescribing means of achieving it.
  • Construction of a cutting plan

Concept & Importance of Yield Regulation

Yield regulation determines the what, where, and when of the forest harvesting on the managed forest. The regulation decision indicates what species and how much of them should be cut and also indicates where on the ground, the cutting should take place.

Objectives of Yield Regulation

  • To cut each crop/tree at maturity
  • To obtain max yield of desired products
  • To limit the area to be felled to that which can be regenerated

Yield Regulation in Clear-felling system

Clear felling is a silviculture system in which equi-productive areas of mature crops are successfully clear felled and regenerated.

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The crop obtained is even aged in which age gradation is determined by area.
Under a clear felling system, yield regulation can be obtained by two methods.
1. Annual Coupe by Gross area
2. Annual Coupe by Reduced area

Annual Coupe by Gross Area

It is the oldest and simplest form of regulating yield. It was first applied in France in the 14th century. The area of forest or the felling series is divided into a number of annual coupes equal to the number of years in the rotation (R).

Annual coupes so formed are equal in the area on the ground and are known as equi-extensive coupes.

When the crops are usually irregular both in composition and density, this method ensures equal sustained yield from the 2nd rotation onwards.

This method is widely used in areas where there is abundant regeneration.

Annual coupes by Reduced Area

The density and site quality may vary from coupe to coupe. So, the felling of equal annual coupes may not guarantee equal sustained yield over years.

In order to make yield regulation by area more perfect, suitable reduction factors should be applied for equalizing annual yield.

And based on the reduced (or modified) area of the felling series area are allotted to annual coupes, so that annual coupes, though not equi-extensive become equi-productive.

This method gives better results than the above method and also a modification to implement in different site qualities.

• Easy to apply
• Leads to absolute age graduations
• Change in the rotation will require a change in coupe area.

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