Willow, alder and hazel are the quick coppice species: willow can be cut every 3-5 years, alder every 5-8 and hazel every 7-10, so a new coppice gives fuel years before oak does. Their wood is lighter per volume than oak or ash, so each cubic metre of log gives less heat, which is the price of speed.
Part of Coppicing & Fuel Management
The fast-growing coppice species: what each offers, where it grows, and the trade-off between speed and density.
The Species
The parent article lists these, with poplar and aspen:
- Willow (Salix): the fastest grower and coppices eagerly. Low heat value but abundant, and also used for baskets and living fences. Rotation 3-5 years.
- Hazel (Corylus): an excellent coppice species with straight poles, good for rocket stove fuel. Rotation 7-10 years. Nuts come from uncoppiced standards.
- Alder (Alnus): fixes nitrogen in the soil, improving fertility; burns hot when dry; good for wet ground. Rotation 5-8 years.
- Poplar and aspen: very fast, very light wood that burns quickly with low heat per volume. Rotation 3-5 years.
The parent groups these as a “3-7 year rotation”, but hazel’s own figure is 7-10 years, so read the group heading as loose and use each species’ own rotation.
Why Light Wood Gives Less Heat Per Volume
Dry wood of different species has similar heat per kilogram, so what separates them is how many kilograms fit in a given volume. Using the net heat of air-dried wood, 14.3 GJ/t (at 20% moisture, wet basis, derived in BTU Content Compared to Wood), and the parent’s hardwood density range of 500-800 kg/m³:
- Low end: 14.3 × 500 = 7,150 MJ/m³ = 7.2 GJ/m³.
- High end: 14.3 × 800 = 11,440 MJ/m³ = 11.4 GJ/m³.
- Ratio = 800 ÷ 500 = 1.6.
So the densest hardwood in that range holds 1.6 times as much heat per cubic metre as the lightest, and willow and poplar are lighter still.
Method: Using The Quick Species
Step 1: Plant them on wet or poor ground where oak would struggle.
Step 2: Cut on the short rotation, in the dormant season.
Step 3: Use the straight hazel poles for stove sticks, and the willow for baskets, fences and kindling.
Step 4: Dry it. Light wood dries quickly, so the first year’s cut is burnable the next (Seasoning & Drying).
Common Mistakes
- Relying on willow alone. A cubic metre of stack goes quickly in a stove.
- Planting hazel in the wet. Alder and willow are the wet-ground choice.
- Forgetting the fence. Fresh shoots of all three are browse.
Safety
Whippy stems and sharp stools
Long springy willow and hazel poles whip when cut under tension, and a billhook swung through dense shoots hits the leg below. Cut one stem at a time from the side, keep legs out of the arc, and wear boots (Cutting Technique).
What’s Next
- Learn next: High-BTU Species — the dense, slow alternative
- Combine with: Multi-Purpose Species — getting more than fuel from them