Long Term Planning

Forestry involves waiting many years before the timber can be harvested. The rotation period for the softwood pine trees in Thetford Forest is about 50-55 years.

"We are still dealing with a significant amount of clear felling from the first rotation of crops," explains manager Simon Malone. These trees were all planted over a short period, and Forest Enterprise is developing a more even age structure for the forest of the future, so that trees come to maturity at a steady rate. This will ensure that timber supply in years ahead is sustainable, meets the needs of the customers and allows them to plan ahead. It also ensures a steady income stream for Forest Enterprise.

The current programme is to harvest 190,000m3 - about the same in tonnes -a year. The timber fetches between £36/m3 and £47/m3, depending on its grade and the market. A typical Corsican Pine for example would contain about 1.5m3 when mature

Trees are measured in yield classes - the widely grown Corsican Pine has a yield class of 16, meaning that over its rotation it can produce 16m3 of new timber a year from a hectare. The once more commonly grown Scots Pine has a yield class of 12.

There is an optimum time for felling a block of mature trees and putting new ones in their place. This is because the rate of growth slows as the trees get older, making it more efficient to fell them and to replant a successor crop than to leave them growing.

Timber comes from thinnings as well as clear felling, explains Mr Malone. A hectare would generally contain 2,200 young saplings. Eventually they start to fight for space. The right time to start thinning them is at about 25 years - they are big enough to have a commercial value by then, which means that the operation can be carried out with a small profit. By the time the trees are ready for clear felling, aged 50-55, there will be 500 giants left per hectare, says Mr Malone.

Hardwoods make up about 15% of the forest's area, and one of their uses is as firebreaks - though of course they also have landscape and wildlife value too. The wait for harvesting them is even longer than for the pines - typically 120-140 years.

About 70% of harvesting is carried out by Forest Enterprise's own staff - the rest is "sold standing", meaning that someone buys the timber standing and makes their own arrangements to harvest and market it. Forest Enterprise harvests about 110,000m3 a year itself using machines called harvesters. Another 30,000m3 is cut down by chainsaw, for example where it is in a particularly environmentally sensitive area. Commercial sales of timber are carried out by two tenders and one auction every year.

Trees are only felled to suit the rate the customers need the timber. It is safest left growing until required, particularly in summer. Otherwise it can soon become stained blue through a fungal attack. Structurally it is fine even with this, but is off putting to purchasers of the finished product.

©2000 Lisa Russell