thinning control

Thinning control, timber measurement and marketing

Thinning Control

Whether grown as a commercial crop or not, trees in a woodland situation need regular management if they are to reach their full potential and achieve the owners objectives.

Trees in forestry plantations are normally planted 2 - 3 metres apart (2,500 – 1,111 trees per hectare).  This helps to ensure they produce straight stems and provides a good number of trees from which to eventually select the final crop trees.  For example, 2,500 Douglas fir trees would be planted to produce 200 final crop trees when they mature at 55 years of age.

When the trees close canopy and start to seriously compete with one another for available space and light (which is normally around 20 years of age), they need to be thinned out.  This process needs to be repeated every 3 – 10 years (depending on species and rate of growth) throughout the life of the crop to maximise the percentage of high quality sawlogs.

Thinning control will normally include:

  • Establishing the yield class (potential annual timber production) of the plantation
  • Measuring the basal area (density) of the crop to check that it is ready for thinning
  • Deciding how many trees and what volume needs to be removed.
  • Selecting and marking the trees to be removed

Timber measuring

Trees can either be sold before they are felled (standing) or as sawlogs at stump or roadside. Whichever method is chosen, the trees will need to be accurately measured to ensure that the volume of timber is correctly recorded for sale purposes. The exact method of measuring the trees will depend on numerous factors (such as whether the plantation is of a single or multiple species) and may involve a complete measure or some form of sampling, all in accordance with Forestry Commission guidelines.

Timber marketing

In the past, thinnings of young plantations were not very profitable, but nowadays, due largely to the introduction of the Governments Renewable Heat Incentive, firewood can often fetch as much as higher quality sawlogs. 

ADAS Forestry Consultants can advise on all aspects of timber measurement and will obtain the best prices for timber available in the market place through a competitive tendering process.

Chris Huxley
Chris.Huxley@adas.co.uk
01759 318357 

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