Thinning is best described as the selective removal of inferior stems in order to favour the growth of the remainder better quality stems. It is a normal and essential part of most forest crop rotations, and is essential if crops are to produce the maximum number of high value logs and consequently increase profitability. Thinning is generally undertaken 2 to 5 times over a forest rotation depending on the productivity of the crop.
It is essential that forest thinning be carried out correctly and on time. When done, the benefits of thinning for an owner are;
Not thinning will result in a larger number of smaller sized trees per hectare with a significantly reduced value on clearfelling.
Clear felling is the harvesting of all marketable trees at the end of a forest rotation. This can vary from year 30 to 50 depending on species.
To find out when your crop is ready to be thinned contact us.
Planning for first thinning should start when the crop is 10 years old. Inspection paths need to be cut to permit access to the crop to determine its productivity and its projected first thin year. Cutting an inspection path or ‘brashing’ involves removing the branches to head height between two lines of trees.
Forest roads need to be planned and a General Felling Licence applied for.
There are many forest thinning techniques, with the most common one being what is normally referred to as 1 in 7 plus selection. This means 1 in every 7 lines of trees is completely removed to facilitate access with inferior quality trees selected for removal in the intermittent lines.
This is normally completed mechanically with motor manual (chainsaw operator) employed only on specific stands.
Mechanical thinning uses specialised harvesting heads, which are fitted to purpose built harvesters or standard excavators. The timber is then removed to the roadside by a forwarder, which is a specialised forest machine.
In the past chainsaw harvesting combined with horse extraction of timber was common. This is now only used in exceptional cases.