I spent some time in my woodlot a few weeks ago, marking the trees that I will harvest for firewood this year. As I worked my way through each stand, inspecting trunks and crowns in order to find the trees best suited to end up in the woodpile—and ultimately the woodstove—I was thinking about engaging in this same process a decade ago, when I first became a forest landowner in need of a steady supply of dry, hot burning wood. Never having been in the position to be the executioner, so to speak, of so many trees all at once, I was quite daunted, and more than a little unsure of myself. How to pick the right trees? What size should they be? Can I cut any big ones? What age? What species are best? How many can I cut each year without depleting my forest? With this in mind I thought I might offer a few ideas based upon what I have learned over the years—-at least as pertains to the hardwood forests in my neck of the woods.
A general rule of thumb for the forests of the northeast dictates that 1/2 cord of firewood can be taken per acre/per year on a sustainable basis. Stay within this parameter and you will be living off the ‘interest’ your forest generates in annual growth, rather than cutting into the ‘principal’. The actual sustainable cut will vary depending upon the history and past management of your woodlot, as many forests in this area are actually overstocked—were not adequately thinned over time—and thus can support (and even benefit from) initial firewood cuts at higher rates—provided that the proper trees are selected. As far as what to cut, this can either become a highly technical scientific inquiry (which has its own merit), or it can simply be approached with a little knowledge and some common sense. When in doubt, I generally prefer the latter, as what better way to learn about something than by actually doing it?
First off, you’ve got to know how to identify the choice firewood species in your woodlot by sight, and the relative Btu or heating values of each. My friend Akiva, who used to work for a tree service, tells me that he has as many as 30 different species of wood in his woodshed. Most of us will have a much smaller number of core species to work with. In my forest, Sugar Maple, Black and Yellow Birch, Red and White Oak, American Beech, White Ash, and Eastern Hop Hornbeam are the top tier firewood species. Of these, I probably cut and burn over 80% Beech, as it is uniformly infested with Beech bark disease (or scale-nectria), an insect fungal complex which causes the trees to decay rapidly once infected, and often to snap in strong winds —as shown in the photo below.
So the primary criteria in my situation is to search out trees—and in this case an entire species of trees—that are wounded, diseased, dying, or dead. Sometimes this is obvious, sometimes it takes some careful examination. Fungal growth is a sure sign of internal decline, as are dead/dying limbs in the upper tree crown, and loose or otherwise damaged bark is often indicative of a tree with compromised health (much like our skin actually). Another reliable sign of a tree under stress is the presence of ‘epicormic branching’ or branch suckering from dormant buds found on the trunk, as seen in the declining ash tree in the photo below:
Some folks harvest only deadwood, and with enough acreage (or minimal fuel needs) are able to meet all their fuelwood requirements without ever even considering healthy trees. If you find yourself in this scenario, I would encourage you to leave some standing dead timber dispersed throughout your woodlot as wildlife trees, as a great many species will benefit by finding food and shelter there.
So that’s the easiest step—working with trees that are standing dead, or that are in obvious decline. This one criteria for selecting your firewood trees may keep you going for years, or it may not get you anywhere. If you fall into the second camp, upcoming posts will address criteria for tree selection from among the healthy tree population.