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Thinning to improve profitability and timber quality in spruce crops



Many farmers with spruce may be considering thinning as a management option and whether the benefits accruing from thinning are worthwhile. Thinning presents an opportunity for growers to influence the production of higher value products thereby increasing the value of the crop.

The removal of smaller, poorer quality trees and bigger rougher trees should be prioritised in thinning as these trees cannot accumulate significant value over the rotation period. The ultimate objective is to focus site resources on trees with superior form and allow them to develop into higher value products.

In certain situations, it may be preferable to adopt a no-thin regime. This is especially so where there are concerns about the stability of the crop or where there is poor access or where the operation is not commercially viable.

A number of thinning trials in Sitka and Norway spruce have been established in counties Roscommon, Cork and Offaly with the objective to assess the effect of thinning on volume production, product assortment and timber quality.

Many Sitka and Norway spruce crops planted on farms are showing exceptional growth rates with a yield class of 24 and above. As a result, crops are suitable for thinning at 15 years of age, owing to the good mix of good genetic stock and the planting of fertile sites.

This research aims to provide guidelines on how to manage spruce crops to achieve the maximum return from the crop and aims to guide best practice development to assist with the intensification of thinning practice in the private sector.

The Project

The research will focus on the long-term effect of thinning. Different thinning intensities on crop development in Sitka and Norway spruce will be studied, particularly the effect of thinning on timber quality, volume production, rotation length, timber quality and profitability of the operation.

The purpose of this research programme is to build upon our previous research to provide recommendations to farm forest owners regarding best forest practice.

Specifically this programme will examine

  • The effect of different thinning types (i.e. low, crown and selection thinning) and thinning intensities on the growth and development of Sitka and Norway spruce crops
  • The effect of thinning on timber quality, product assortments, profitability and rotation length
  • To provide scientifically validated data in which to inform best practice development in the management of spruce crops


Further information


  • This project is funded by Teagasc under grant number FDFY0173