Thinning woodlands is best management practice as it maximises timber growth and income. While in the past it was often an expense to the woodland owner, it can now be a lucrative exercise. James Pyrah discusses the benefits.
We have seen an increase in timber prices over recent years, partly driven by a continued strong demand for sawn timber to produce construction products, but with the addition of relatively new markets including wood fuels for heating systems and shavings for large scale poultry units.
Thinning operations can be undertaken in both hardwood and softwood woodlands, and the end product can be used for a variety of purposes depending on the size and quality of the extracted timber.
Why thinning is a productive activity
Thinning is important as it allows trees to grow to their maximum potential size. Trees are initially planted close together, with softwood plantations typically stocked at a rate of 2,500 stems/ha and hardwood at 1,100 stems/ha.
This creates early-stage competition among saplings to increase growth rates, but over time the trees begin to encroach into each other’s space and if left the trees would be short of room to grow and a number would naturally diminish. To prevent this, thinning should take place to extract valuable timber that may otherwise deteriorate and in turn, allow the remaining stems to grow to their full potential.
Timescales vary according to commercial and environmental needs
The timing of thinning depends on the tree species and growth rate, for example Sitka spruce is the main commercial timber crop in the UK and is usually thinned at approximately 15 to 20 years of age.
There will generally be two or three thinnings prior to the clear fell of a Sitka spruce plantation at approximately 35 to 40 years old. However, this timescale will vary from site to site and will be dependent on the characteristics of each wood, the management system and owners’ objectives. It is also important to monitor market conditions to ensure timber is sold at a time when prices are high as the market fluctuates with supply and demand.
How thinning operations are conducted
Before any works can commence, the site should be assessed to determine if it would be appropriate for thinning to take place, and if so, a felling licence must be obtained from the Forestry Commission.
Robson & Liddle can handle the process from start to finish including oversight of all works and management of payments. This includes forecasting timber volumes and financial returns, obtaining a felling licence, and then putting the timber out to tender by standing sale, a process whereby contractors bid to buy the product in situ on a tonnage basis.
Prior to the commencement of works it is vitally important that a contract is in place with the winning bidder to clarify matters such as payments, timescales and responsibilities.
What you need to know about thinning methods
Edge-trees are usually left with greater density, partly for aesthetic reasons, but also to create protection against the risk of wind damage to the inner crop.
An increasingly popular approach to thinning is Continuous Cover Forestry (CCF), which involves gradual thinning of the canopy to let sunlight reach the forest floor. This allows natural regeneration to occur, creating an understorey and as the name suggests provides a continuous cover of trees on the site with a diverse range of ages.
We are always happy to discuss any part of the process.