Thinning Ready Reckoner
Is my conifer forest ready for thinning?
The following steps describe a useful guide to assess if your Sitka spruce forest is ready for thinning. However, it should not be read as a Black or White indicator for suitability to thin! Teagasc advises that in all cases forest owners should seek professional forestry advice to assist with a thinning decision.
Count the number of all live trees over 7cm DBH in a 10 metre by 10 metre plot. Multiply this figure by 100. This gives you an estimate of the number of trees per hectare (i.e. stocking density).
Measure the Diameter at Breast Height (DBH) of all live trees over 7cm DBH in the plot and write the results down.
Once all these trees have been measured, take the sum of all these figures and divide by the number of trees measured. This will give you the average Diameter at Breast Height.
Please note: DBH (cm) is measured at 1.3 metres above the ground using a specialised tape. This tape can be purchased from outlets specialising in forestry equipment.
Now that you know both the stocking density per hectare (see step 1) and the average DBH (see step 2), you can use the Ready Reckoner below to see if your Sitka spruce forest may be ready for thinning.
But remember, this is only a useful guide and you should seek professional forestry advice prior to thinning.
The Ready Reckoner was developed by Teagasc Forestry researchers and is a very simple and handy tool to assess if your conifer forest is ready for thinning.