“I want to cut some firewood but don’t want to jeopardize my valuable timber trees. How do I choose which trees to cut?”
You can make firewood from most any hardwood, but you can only make sawtimber from those with the best form. Even in a down market and with expanded options for selling fuelwood, it still pays to know the difference.
Start by finding trees with the greatest timber value – nearly perfect, cylindrical stems with minimal taper. They should be sound, mostly free of irregularities, and with full, green crowns beginning two-thirds of the way up the trunk. These are your keepers; they have good prospects for growing well and making you happy.
Don’t put them in the woodstove. Once you’ve identified these high-value, timber-quality trees, promote their growth by cutting the trees that directly steal light from them. This is called “crop-tree release.” The keepers flourish in additional sunlight and their competitors go to the woodshed.
Another way to identify standing firewood is to look for trees with structural defects. Keep in mind the image of the perfect tree. Departures from that form are easy to spot: gnarled trunks, multiple stems, retained lower branches, poor or sparse foliage. Since trees with any of these problems will never produce valuable sawlogs, it makes sense to cut them for the firewood pile. Value here is in the wallet of the beholder.
Concentrate on cutting first the living trees that don’t have a good chance of becoming keeper trees. Ask this question about each candidate: will this tree be here looking at least this good or better in 15-20 years? If not, it’s in the running to be cut for firewood.
Some tree risk factors are easier to spot than others. Those multiple-stemmed red maples, for example, seem to beg to become firewood. They take up lots of growing space but don’t have much high-value promise. And, due to their poor structure, they are at increased risk of splitting apart every time the wind blows. The junction where two or more trunks seem to fuse together in any tree – this is called included bark – is notoriously weak. The trunks are anything but fused, and these weak unions of bark-on-bark tend to rot and split more than single stems. It happens in V-shaped forks in branches, too, so look up into the crowns of single-stemmed trees to spot weak unions.
If none of your firewood prospects are V-shaped, look for external clues that can betray internal problems. Whereas keeper trees have sound stems, firewood trees often show symptoms of decay or weakness that can compromise the structural or physiological integrity of the tree. Learn to spot these stem and branch oddities that make it a firewood tree: cankers, wounds, cracks, and fungal fruiting bodies.
Let’s start with fruiting bodies – the mushroom kind. They are easy to spot, and when you see a conch or bracket fungus, or those fleshy white or yellow blobs on a living tree’s trunk, they indicate that some portion of the wood inside is rotten. If the tree is alive, structurally sound, and doesn’t have dead branches that could make felling it dangerous, it may make excellent firewood, even if you leave the rotten parts on the forest floor. Cankers are swollen, deformed areas on a tree that are initiated by a fungus and that increase in size as the tree attempts to wall off the fungus. They often increase the chance of breakage, and they usually render long segments of the trunk unacceptable as sawtimber.
The same is true for wounds from non-infectious sources. Basal scars from past logging, or other major bole or branch openings, increase risk. Vertical cracks and seams up the trunk certainly degrade the value as timber, but some of them – those that have closed cleanly – may not increase risk. Make firewood only from the worst of these.
But don’t cut all the trees with defects like these. In some woodlots, if you were to take out all the defective trees, there would not be much left. Many firewood-quality trees provide shelter and food for wild animals, and the truth is, who knows what else they may provide? Also, resist the temptation to take for firewood all of one kind of tree. If you retain a diversity of tree species, sizes, and conditions, you’ll be keeping your options open, and it will likely make for better wildlife habitats. In the meantime, unless your woodlot is a whole heck of a lot better than average, you’ll still find plenty of candidates to fill your woodshed.