Selecting Timber Tree Species
Any timber component destined for selling should ideally be marketable, high quality (favouring deciduous), fast (and straight) and upright growing, deep rooting, wind firm and suited to the site. Durability of timber is also very important when trees are grown for estate use. These qualities are not always easy to obtain, especially from deciduous trees, most of which grow with a poor form without the pressure of forest competition to the sides. High pruning will be needed with most trees to ensure a straight and knot-free bole of 6 m (20 ft); this raises the tree canopy and allows more light to reach the ground.
The straightest growing deciduous trees without forest shade pressure are those which are most light-demanding. When planting these, stock should be used which has been grown from seed collected from high-quality trees or seed orchards. Suitable species for Britain include:
In addition, straight-growing clones (varieties) of several species have been bred and are becoming available for planting. These species include:
(Prunus avium) Much used in France and Italy
(Juglans nigra x regia) Named French varieties available
(Robinia pseudoacacia) Widely used in E.Europe
(Salix alba ‘Caerulea’)
Several species of coniferous tree can also be used, some producing timber of good quality. When using evergreen species, alley widths should generally be wider to compensate for the extra shading. Suitable conifers for Britain include:
(Larix decidua, L.eurolepis, L.kaempferi)
Trees destined for fuelwood or estate use need not have such good form or value, but should still be fast growing (especially for silvopasture, so trees rise above animals quickly) and may be chosen from a wider range of species including those below. Of these, black locust has very durable timber. Those species which coppice or pollard well can be used to provide sustainable fuelwood production.
Nitrogen-fixers, can be pollarded.
Can be coppiced or pollarded
(Robinia pseudoacacia) Nitrogen fixer. Can be coppiced or pollarded
Can be coppiced or pollarded
All the above species, and also less light-demanding species (eg. oaks, Quercus spp.), can benefit from the use of rows of nurse trees. With the choice of a nurse species which grows at the same rate as the crop species, a straight form can be greatly encouraged; once the crop tree has a straight bole of the required length (usually 3-6m, 10-20 ft), the nurse trees are thinned and removed (some may be economically usable, eg. as cut Christmas trees). Some possible combinations are:
|Nurse Species||Crop Species|
|Sycamore, Black alder, Red alder, Sweet chestnut, European larch, Norway spruce, Corsican pine, Scots pine||Ash, Oak|
|Italian alder, Lawson’s cypress, Larches, Norway spruce, Lodgepole pine, Radiata pine, Scots pine, Cherry, Coast redwood, Western red cedar||Sycamore, Beech, Sweet chestnut, Black walnut|
|Italian alder, Larches, Hybrid poplars, Douglas fir, Lodgepole pine, Radiata pine, Coast redwood, Western red cedar||Cherry, Black locust|