A harvesting system can be described as the way in which a tree is processed and extracted from point of felling to the forest road. In the UK, five harvesting systems are operated, classified by the form in which the produce is extracted:
- Terrain chipping:
Utilises the whole tree, resulting in little or no crown and branchwood residues being left on site.
Utilises stem wood, crown and branch wood, normally down to a specific diameter size.
Utilises only the stem wood and results in crown and branch wood residues.
- Part pole-length:
Utilises parts of the stem wood and results in crown and branch wood residues.
- Whole-tree harvesting:
Utilises the whole tree and results in little or no crown and branch wood residues left at stump.
Extraction machine options
- Portable winch
- Log chute
- Cable crane/highlead
- Wire loader
- Specialised terrain chipper
- Fell to waste /chemical thin.
There is a relationship between harvesting systems and suitable extraction machine options. For example, extraction by wire loader is suitable for shortwood harvesting, but not for whole-tree harvesting.
Potential sources of woodfuel
There is potential to produce woodfuel from a wide range of sources, including:
- Early thinnings from commercial plantations
- An alternative product stream from a commercial harvesting operation
- Timber harvesting residues
- Arboricultural residues
- Previously undermanaged woodlands and farm woodlands
- Short rotation coppice
- Short rotation forestry
- Traditional coppice
- Traditionally low value broadleaf crown wood, late thinnings and poor form clearfell timber
- Sawmill co-products
- Wood waste.