Trees are thinned to increase the growth rate of the remaining trees by reducing competition.
Wide-spaced trees grow quicker because there is less competition for nutrients, water and light. To grow trees to sawlog size in the shortest possible time, densities can be as low as 100 to 150 trees per hectare. (Trees are typically planted at 800-1200 per hectare). Higher final densities of 200 to 400 trees per hectare) will maximise the volume of timber produced per hectare, although the trees will take longer to reach sawlog size.
After thinning, other activities such as grazing and cropping can be combined with tree growing, especially while the trees are young. Any crooked, forked, unhealthy, competing, or slow growing trees are removed which also reduces the number of trees that require labour-intensive pruning.
Trees with straight trunks, small branches, and narrow, healthy crowns are potential crop trees. In order of importance, selection criteria for crop trees are:
Thinning regimes typically start when the trees are about 4 to 6 metres tall.
For faster growing species, thinning will take place at about four years of age when any undesirable characteristics should be obvious. By the time trees are about 10 metres tall a final thinning can be carried out, leaving only crop trees.
Factors affecting the timing of thinning include availability of labour and markets for thinnings. For example, a sawlog grower who plans to sell thinnings for pulpwood may have to delay thinning until the culled trees are marketable at eight to ten years old. A different grower may concentrate on rapid sawlog production and thin after four or five years, if labour is available.
Tree density affects branch (and knot) size. At lower stocking rates trees develop long thick branches. However, at densities greater than 1000 trees/ha, lower branches are soon shaded and have little room to grow outwards. This results in small branches, small knots, and high quality wood. The control of branch size is one factor to consider when deciding how heavily to thin a stand of trees. In a heavily thinned stand the remaining trees respond to the extra light by growing larger branches. These branches must be pruned to produce high quality wood
Thinnings can be used (or sold) for firewood, chipwood, pulpwood or posts and rails.
Simple, low cost techniques are available for preserving posts and seasoning timber on the farm. If thinnings have no commercial value, they can be left on the ground to rot, pushed into heaps for burning or chipped for use as mulch.
Extract from TreeNote No. 3 (Revised July 1998) Department of Agriculture, Western Australia
Thinning for sawlogs
Wide-spaced trees grow quicker because there is less competition for nutrients, water and light. To grow trees to sawlog size in the shortest possible time, densities can be as low as 100 to 150 trees per hectare. (Trees are typically planted at 800-1200 per hectare). Higher final densities of 200 to 400 trees per hectare) will maximise the volume of timber produced per hectare, although the trees will take longer to reach sawlog size.
After thinning, other activities such as grazing and cropping can be combined with tree growing, especially while the trees are young. Any crooked, forked, unhealthy, competing, or slow growing trees are removed which also reduces the number of trees that require labour-intensive pruning.
Trees with straight trunks, small branches, and narrow, healthy crowns are potential crop trees. In order of importance, selection criteria for crop trees are:
- form-- choose trees which are straight, and free from large branches
- vigour-- select the biggest and healthiest trees; and
- spacing-- where possible, choose crop trees which are fairly evenly spaced.
Thinning regimes typically start when the trees are about 4 to 6 metres tall.
For faster growing species, thinning will take place at about four years of age when any undesirable characteristics should be obvious. By the time trees are about 10 metres tall a final thinning can be carried out, leaving only crop trees.
Factors affecting the timing of thinning include availability of labour and markets for thinnings. For example, a sawlog grower who plans to sell thinnings for pulpwood may have to delay thinning until the culled trees are marketable at eight to ten years old. A different grower may concentrate on rapid sawlog production and thin after four or five years, if labour is available.
Tree density affects branch (and knot) size. At lower stocking rates trees develop long thick branches. However, at densities greater than 1000 trees/ha, lower branches are soon shaded and have little room to grow outwards. This results in small branches, small knots, and high quality wood. The control of branch size is one factor to consider when deciding how heavily to thin a stand of trees. In a heavily thinned stand the remaining trees respond to the extra light by growing larger branches. These branches must be pruned to produce high quality wood
Thinnings can be used (or sold) for firewood, chipwood, pulpwood or posts and rails.
Simple, low cost techniques are available for preserving posts and seasoning timber on the farm. If thinnings have no commercial value, they can be left on the ground to rot, pushed into heaps for burning or chipped for use as mulch.
Extract from TreeNote No. 3 (Revised July 1998) Department of Agriculture, Western Australia
Thinning for sawlogs