I have a woodlot roughly 10 acres (4 hectares) from which I harvest firewood. From a permaculture perspective, this is my Zone 4; Zone 5 lies along the back edge of the woodlot. I'm in the northeast USA, USDA Zone 5 -- it was recently -10°F (-20°C) during a cold snap. Acidic, loamy, gravelly soil.
The species makeup is mainly beech and Eastern hemlock; with significant amounts of sugar maple and white pine; and smaller amounts of black cherry, ash, paper birch, and spruce. I harvest using a selective cutting strategy -- removing diseased or damaged trees first, then less-desirable species (hemlock has lower energy density than beech or maple), and paying attention to the amount of light and wind that I'm letting in via cuts as well as which mature species are left in place to scatter seed.
The woodlot is just for firewood and wildlife; it is not used for other crops or pasture.
I do not plant anything back there. Actually, in areas where I have thinned and lots of sunlight is reaching the floor I think I am "overstocked". Many seedlings are growing up very densely -- which leads me to the question: What guidelines should I follow for thinning?
- How do I know how densely various species should be growing for optimum yield? It seems obvious that beech shouldn't be grown 4-6" apart, but how many should I remove?
- Which seedlings should I (de-)select? (I.e. which to cut and which to keep.)
- Is it sensible to deselect the (less energy dense) softwoods and encourage the hardwoods? I don't want to destroy biodiversity, but I don't want to maintain the current ~30-50% hemlock makeup -- or, in one area, ~80% white pine saplings. Also, encouraging sugar maple makes the land more valuable -- sugaring businesses are active in the area, and these trees provide ongoing yields without having to cut them down.
- Should I thin in phases? E.g. aim for a certain density when the seedlings are under 6' (2m) and then a certain lower density when they get to say 15' (5m).
- Is there an ideal time of year to thin? I don't think seedlings are strong enough to regrow when cut, but perhaps some slightly larger trees would -- timing thinning to minimize regrowth (and rework) would be nice.
- Is there any consideration I should give to yields that I can get from thinning? It's quite a bit of work, and I'd love to be able to get something out of it now, instead of waiting to get everything 40 years from now. (Note that I'm obviously in this for the long haul, but I'm more than willing to get a yield from what would otherwise be waste.)