Farmers and landowners must get the timing it right when harvesting trees damaged by recent storms.

Up and down the east coast of Scotland thousands of acres of trees have been blown over and snapped in the storms this winter. During Storm Arwen, wind speeds were measured at 60mph with gusts of 120mph providing the perfect rocking motion to topple trees. Many of the forests which were damaged were commercial mature plantations of fir and pine which are susceptible to rot if left untouched.

Foresters have warned that leaving trees too long to harvest and sell could see them rot and lose value – but equally, selling them too fast will push timber onto a market depressed by over-supply. Oli Hands, from LTS Forestry, spoke to The Scottish Farmer offering advice to farmers affected by wind blown woods.

He noted that the tidy up and harvesting of woods has resulted in a boom in supply of trees and depressed prices – but believes that by the end of summer the price should start to rise again as the backlog reduces.

“One of the important distinctions to make when assessing a damaged wood is, are the trees snapped on the trunk or are they blown over still attached to the root bowl,” explained Mr Hands. “The clock is ticking for snapped trees as they quickly get damaged by blue stain fungus.”

Read more: Working group to help woodland owners clear up windblown trees

The blue fungus spreads through the tree and means it will not be accepted by saw mills for construction, leaving only the less valuable biomass and firewood market open. The fungus is a particular problem for pine trees which are most susceptible.

Meanwhile if the trees are still attached to their roots then the urgency is reduced and they stay intact for up to 12 months before damage.

Mr Hands estimated that selling to the biomass market was likely to see a return of around £6/t compared to £20/t returned for logs destined for milling. Typical woods would yield between 300 to 350t/hectare, but could range up to 500t/hectare for well managed forests.

He was also keen to point out that landowners with a more significant amount of trees, such as a 20 hectare block of spruce, should consider being certified through an assurance scheme. The two main ones are the Programme for the Endorsement of Forest Certification (PEFC) or the Forest Management Certification (FCS) schemes.

This can cost the land owner around £5000 for a five year membership with audits, but has the ability to add £5/t onto saw logs and £2/t onto wood for chipping. Importantly, many mills will only handle up to 30% non-assured timber, resulting in long waits for those selling uncertified trees.