Chapter 11

How Big a Woodlot for Fuel Independence?

This question is probably impossible to answer with any great accuracy because there are so many variables involved. But that’s why it’s so much fun to discuss. The general rule of thumb says an acre of woodland can produce one-half to one cord of wood a year without diminishing itself. That would depend of course on annual rainfall, length of growing season, and richness of soil. It would also depend on how many trees are growing on that acre presently, and of what age, and especially of what kind of wood. A cord of oak can produce twice the BTUs as a cord of pine, so again, simply measuring by the cord doesn’t tell you much about relative heating value.

But cords per acre or BTUs per acre are not as important in determining adequate woodlot size for fuel independence as the amount of heat required to keep the house comfortable. This presents a whole computer full of other variables. What indoor temperatures do the humans involved desire for comfort? How big is the house? How efficient is the stove or furnace or fireplace? How well insulated is the house? Is the house designed to take advantage of passive solar heat? What is the average winter temperature where the house is located? Do the occupants want to rely on wood exclusively for heat or only for backup? How much backup? Do they just want a good pile of sticks around to throw at loose running dogs?

Four cords of good seasoned oak per year might be a safe average for all situations, but averages aren’t very helpful. Old Tom Smith, who years ago lived in the house next door to us, said he nearly drowned during a rainy spell in our creek, which has an average depth of about four inches. I asked our market-garden friends Andy Reinhart and Jan Dawson how much money they calculate they have saved by burning wood almost exclusively for the past fifteen years or so. They don’t know and point out that the amount of wood burned is not the best way to calculate money savings. “What we save comes mostly because our house is modest in size and we built it into an embankment on three sides so it would be easy to keep warm,” Jan points out. “The side open to the south is mostly glass to take advantage of solar heat. We burn much less wood than a typical suburban house with the same amount of space in it.”

Before an inquiry into the amount of woodland a homestead needs for fuel independence can even begin, there is an overarching fact of life that must be addressed. The first time I saw this “fact of life” was in a Clemson University Cooperative Extension bulletin in 1974 when it was first being suggested that using renewable wood for electric power generation might not be as impractical as most environmentalists believed. A tree in its lifetime “produces oxygen and consumes as much carbon dioxide as it will release when it is burned. Fossil fuel such as coal or oil releases carbon dioxide and thermal energy withdrawn from circulation million of years ago.” In other words, burning renewable wood maintains the balance of oxygen/carbon dioxide necessary for life as we know it. Burning fossil fuel upsets that balance because the oxygen released by the ancient trees that made coal and oil has long since dissipated. No matter how handy or cheap fossil fuel is, or even if the supply is infinite, which it isn’t, what is the use of burning it if the result is a steadily diminishing oxygen level? Nor does burning wood create the potential hazards and troublesome by-products that come from nuclear energy facilities. It may well be that for those of us living in less congested areas, there will be no choice but to use wood once we resign ourselves to living in modest homes rather than castles.

I suppose the first step toward ascertaining how much woodland one needs to keep the house warm in winter would be to rank the species of trees by the amount of heat each produces per cord, since we seem bound for all eternity to measure firewood in cords. But if you already have an established woodlot, the trees in it are what you will be using, whatever they are. Even if they are not of the highest BTU value, they will generally do the job. Pine has by volume only half the value of oak in BTUs but will burn just as hot—actually hotter. You just need more of it. By weight, a pound of pine will provide as much heat as a pound of oak; the pound of pine will just take up more space.

But BTU value on paper is not a good way to assess the fuel value of wood. More important is how dry and well seasoned the wood is. I can’t emphasize this factor enough. A really dry piece of, say wild black cherry, which has only average BTU value, will burn more satisfactorily than a piece of high BTU oak that has not been dried completely. Moreover, starting a fire is much easier if you have well-seasoned wood. Ease of starting a wood fire is very important when you are doing it every winter day or maybe more than once a day (see chapter 18). Often homeowners get discouraged and decide to go to some more automatic heat source simply because, without truly dry wood, getting a fire to start quickly and keep on burning hot is too much of a chore.

By truly dry wood, I mean wood that has been split into three- to five-inch thicknesses (round wood rarely does dry enough in some species), then seasoned for at least two years. The manuals almost always say that four to six months or over a summer are adequate. Don’t believe it. Rack the split wood up at least for two summers out where it gets sunlight and air and then get it into a woodshed or garage or some such sheltered arrangement in the fall before you burn it so that you don’t have to sweep snow off it when you bring it in the house. A University of Maine Cooperative Extension information sheet on forest conservation (December 1973) says it well: “Even though wood has been cut and stored under cover for six to ten months, moisture content will still be 15 to 25 percent. This moisture must be driven off in the burning process before the wood can be consumed. . . . Green wood will not burn until the water has been driven out and evaporated.” John McPhee in The Pine Barrens (cited earlier) has one of his piney woods characters saying the hottest fire comes from green pine laid on a bed of hot oak coals. That contradicts basic physics and chemistry. The fire may feel hotter if the pine being burned is full of volatile oils, but the real secret here is the bed of hot oak coals. On the other hand, a little rain or snow on wood that has been seasoned for two years doesn’t hurt its heat output. It is just too much botheration to get it burning in the stove unless you have hot coals already present.

So the very first consideration in determining the size of the woodlot you need for fuel independence has little to do with the number of trees, or the denseness of the wood, but the quality of its seasoning. The first line of business is to get two or three years ahead on your wood supply. Many people are too busy or too procrastinating to do that and so never enjoy wood heat to the fullest. And that’s what having your own woodlot is really about: joy and peace of mind.

Ranking wood by BTU value should also not take precedence over some other considerations. Unless there are other reasons that you want to grow Osage orange, like for making bows or other specialized woodworking projects, you might not want to plant it or encourage it if already present. Although it is very high in heat value, perhaps highest of all, it is a hard and thorny tree and once established is not easy to get rid of. Cutting it dulls your chainsaw blade fast, and a stump will sprout right back up. This is also true of black locust, but I will later on contradict myself about this tree a little because of its other advantages in specialized situations. Mulberry wood is a high heat producer too, but as I have said elsewhere, it spreads fast and its seedlings can become a nuisance around gardens.

Also, ease of splitting is more important than BTU value if you split by hand with a maul. Red oak splits much easier than white oak or hickory in most situations, so even if it has less BTU value, you may find it more convenient to split two cords of it than one cord of white oak or hickory. Any wood from a log more or less free of knots is much easier to split than knotty wood, so a woodlot with a dense stand of straight, knot-free logs is much more desirable for splitting, hang the BTU value. This is especially true of evergreens. If grown out in the open, they have lots of side branches and the log is almost impossible to split without a mechanical splitter, which means more expense. Some woods are hard to split even when the log is free of knots. White elm is the worst.

If you are selecting trees to grow in your woodlot beyond the ones already there, or are thinning out unwanted trees, you might value multiple use of your grove more than simply the highest possible yield of BTUs. You want your trees to provide you with intangible products like fall color and the mellifluous song of the wood thrush in the evening as well as tangible goods like forest food, shade, and windbreak. That means you will want a variety of trees, some of which may not have high BTU value. Those plans and schemes that endeavor to produce the very highest yield of firewood per acre turn the woodlot into a commercial operation not all that different from growing corn commercially. I don’t mean to be critical of such endeavors at all, but most lovers of tree groves are looking for more than just fuel.

Another consideration about forest productivity that needs to be put into the equation is a point of geometry. A tree that is six inches in diameter puts on an annual growth ring that may be about the same as the annual growth ring on a tree with a diameter of 30 inches. But the amount of wood actually being added to the bigger tree is quite a bit more. But this is tricky addition. You must then try to figure out if the one bigger tree is actually taking up the space that several smaller ones would be occupying, and if those several smaller ones together are adding on as much wood to their growth rings as the one large tree. Good luck.

Having said all that, I am loath to place importance on listing trees according to their heat output per cord, but some well-meaning editor will surely insist that I do it anyway. Okay. Rankings are readily available in many books and manuals and from search engines, comparing the BTUs in a cord of wood to its equivalent in No. 2 fuel oil or gas or electric heat. Don’t take the numbers too precisely. A billet of wood split out of the center of a three-hundred-year-old white oak log is going to produce more BTUs than one from a sixty-year-old log because the wood in virgin timber is significantly denser. Also, I find among the various texts on this subject that the numbers can vary considerably. White oak may be given a BTU output per cord anywhere from 24.6 million to 28.2 million BTUs, with equivalency ratings of 135 to 200 gallons of heating oil. Some of these numbers are probably outright mistakes: Some authors (like me) are famous for carelessness with numbers, and of course the price of fossil fuels varies from year to year. The only number that doesn’t change, and I’m not sure of that either, is the BTU value of heating oil or gas.

Shagbark hickory, black locust, ironwood, and Osage orange are all about equal in BTU value, between 25 and 30 million BTUs per cord. Dogwood is very dense wood and probably belongs in this top category too, although I have not seen it listed because not much of it ever ends up as firewood.

In the next category down are the oaks, especially the white oak and red oak families; apple, and probably most other fruit trees, especially mulberry; hickory species other than shagbark; honey locust; beech; sugar maple (rock maple); white ash; red elm; and yellow birch. These are all in the 20 to 25 million BTU range. Red elm is not always in this category, probably because it gets confused with white elm. Red elm burns nice and hot; white elm does not. The old refrain says elm “burns cold.” The same old saying says that, “Ash wood wet or ash wood dry, a king shall warm his slippers by.” That is sort of true, but ash wood dry is a whole lot better than ash wood wet. What I like about ash is that it not only burns well and lights quickly if it’s dry, but it doesn’t seem to leave as many ashes, despite its name. When I am burning white ash, I have to carry out only about half as many ashes as when burning hickory or oak.

In the next lower category are black cherry, black walnut, tamarack, white birch, red maple, and green ash, with BTU ratings per cord of around 19 million. Solid, dry black cherry is one of my favorite fuel woods, again because, like ash, it seems to burn more completely with fewer ashes to carry out. Since cherry is a highly prized furniture wood, it seems wasteful to burn it, but the market is down right now, and if a log isn’t nearly perfect, it is worth more as firewood than as furniture wood.

Most of the other common trees, like sycamore, silver maple, willows of all kinds, aspen, and basswood, plus all the evergreens, are lighter, and softer and average about 17 million BTUs per cord.

So can you save money cutting and burning your own wood? Again the floodgates of speculation open as various experts get very precious about adding in every real or imagined cost they can think of, like wear and tear on your chainsaw per cord, cost of a pickup truck for hauling per cord, how long a pair of boots lasts, or cost of a mechanical splitter per cord (I never have used one). I suppose one must figure in the cost of keeping the horses if you use a team to drag out logs. Or if you use a four-wheeler to haul your wood, it costs only about a fourth of what a pickup sells for. And don’t forget the wear on your splitting wedges, which must amount to at least a penny per century.

But to play the game to the hilt, one must wax eloquent on the plus side too, not just about the amount of fossil fuel your wood replaces but considerations like the value of the ashes for fertilizer and the value of the exercise you get splitting the wood. Wood ashes contain considerable potash. If you buy muriate of potash in small amounts at garden supply stores, it can cost over a dollar a pound. Over every winter I collect about four hundred pounds of ashes that I spread on garden or pasture. Pound for pound, wood ashes don’t contain as much potash as chemical muriate of potash, but the ashes are considered organic and the nutrients in them are more quickly available to plants. Also, ashes contain lots of calcium and serve as a substitute for agricultural lime to sweeten the soil. The way I figure it, they are worth just as much as the muriate of potash.

It so amuses me to listen to proponents of fossil fuel of one kind or another question in minute and negative detail the cost and efficiency of a wood-burning stove, applying a scrutiny that they never use in examining their gas, oil, or electric heaters. I would like to see the efficiency numbers involved in fracking gas out of shale, or pumping oil up from two miles below the sea, or removing mountaintops to get coal, or mining uranium and making nuclear power plants “safe.” The proponents of these “high-efficiency” heating units should also prorate the cost of the oil spill or the cost of ruined groundwater supplies while fracking for shale gas as preciously as they like to prorate the wear and tear on my maul as I split wood. Then calculate, if possible, how much cost is involved in getting all that fossil fuel refined and transported to every home and business that uses it and paying an army of workers to refine and deliver the fuel and account for every speck of it until consumers pay their bills. Defenders of fossil fuel primly remind us woodcutters that what we consider profit from our trees we must spread over the hundred years or so that it takes for the tree to grow. Do they spread the cost of their coal, oil, gas, and uranium over a span of the millions or billions of years it took for these fuels to collect in the earth?

Compare all that fossil fuel effort to the family at home in the woods, whose source of heat is growing nearby at no expense to mankind—actually providing atmospheric and environmental benefits as nature produces it. When the tree is cut down, the woodcutter hauls it maybe one thousand feet at the most to his house, often less; maybe even carries it by hand or wheelbarrow or uses horses to move it. He or she makes sure there is another tree already growing to take the harvested one’s place. If you add in all the costs and benefits of home heating, I daresay, your own wood from your own grove is far and away the cheapest and most beneficial fuel available.

Using a price of $3.50 a gallon, which is about what heating oil costs as I write, and a BTU value of 139,000 BTUs per gallon, a cord of hickory rated at 28 million BTUs has a value roughly of $700 a cord—about five times what it sells for. I don’t care how imaginative or poetic the experts want to wax in calculating every single imaginative cost involved in getting that wood from your grove to your stove, I am sure you can’t squeeze more than $300 per cord of cost out of that gross profit, leaving you $400 a cord net profit over burning fuel oil. In my own way of accounting, where cutting wood is as much recreation as labor, and where I put an intangible but priceless value on the security I feel when the electricity goes off in the middle of the winter (the electric generator and hookup stuff I’d need instead would cost a couple of thousand dollars anyway), I reckon my firewood to be a very profitable spare-time activity using only dead wood not marketable for other purposes. Those trees when growing meanwhile are preventing erosion, protecting and recharging groundwater, producing oxygen, contributing to clean air and carbon sequestration, and providing food and shelter for humans and wildlife. My experience is that I could get all the wood I actually use for heating from five acres, even after selling the bottom, high-grade eight-foot log for lumber or using it for purposes other than heat.

Just for fun, I roped off a 50-foot-square area in my woods behind the house here—about an eighth of an acre. Within that square there are 3 very large trees, 1 white oak and 2 black oaks, each with a diameter of about 32 inches. The rest of the space is taken up by 44 trees with trunk diameters from 10 inches down to sapling size. Multiplying by eight, that means roughly 24 large trees and 352 smaller trees per acre. Whenever I have tried counting trees in other old-growth sections of my woodlots, I get between 300 and 350 trees of all sizes, so my roped-off area is fairly representative. Because of the many trees I have cut down, I know that these trees represent two ages: the big old trees are over one hundred years old, the young ones from forty years old down to year-old saplings. What are missing are trees between about forty and one hundred years old. That sixty years was roughly the time this woodlot was pastured. The sheep kept about half a generation of trees from growing. However, it is my experience from studying non-pastured groves that if sheep had not been present, there would be, along with the 3 old trees, about 10 that would be forty to one hundred years old but fewer of the younger trees because those intermediate ones would have taken up space and sunlight for some of the younger ones now growing there. The sheep did not lessen the overall production of wood, only delayed it. Without a calculator and an expert to help figure out the total number of board feet present, five acres of this kind of tree stand can keep me supplied with wood, even with the lack of trees from that intermediate sixty-year interval.

I’m not sure my way of reaching this conclusion is legitimate. You be the judge. Let us say I am going to live forever, or that someone is going to replace me who lives like I do. Using the 50-square-foot model, I have 24 big trees per acre or 120 per five acres. Two of these giants can provide me with my annual supply of firewood (three to four cords). So it would take me 60 years to use them up, probably a little longer than that because the ones not harvested would mostly be growing larger during those 60 years. In 60 years the oldest of the younger trees, let’s say 80 of the 352, will be nearing 100 years of age. I would need 3 of them to produce my annual supply of firewood for the next 10 years. The remaining 50 would then be 110 years old and I would need only 2 of them per year for firewood. In 10 more years there would still be 40 trees left that were 120 years old. They would easily last until the next aged trees were nearly that old, so there would be a continuing supply of wood forever, barring tornado or bulldozer.

With 17 acres, I have much more than I need for fuel, but the surplus allows me to let trees grow longer before harvest if I am so inclined. That means a few big old dead and hollow trees for wild animals and birds. Another reason I think it is important to have older trees growing in the woods, other than the sheer delight of it, is the point of geometry mentioned above. A tree of 30-inch diameter and a tree of 12-inch diameter might add the same width in annual growth rings, but obviously the larger tree’s circumference means considerably more increase in wood than is the case with the smaller one. This can be very important when trying to grow veneer-quality logs, since the larger logs are increasing in value much more than the smaller ones. The downside of that is the risk that lightning might ruin the log for veneer.

Could wood supply a significant and self-sustaining source of home heat and energy for society at large? Could Ohio, the state I live in and am most knowledgeable about, get, let us say, half of its energy requirements from trees? Not if humankind cannot manage to bring population in line with fuel supply. But if people ever evolve enough to understand the absolute necessity of population control, then the question is not an idle one at all. Even electric power companies have been among those asking the question. To put it another way, just how many BTUs could the forestland of Ohio produce without depleting itself, if we really put our minds to it? Putting our minds to it would mean that we managed the trees of our cities and suburbs and farmland at least as assiduously as the way we manage our commercial forestland and applied the best forest management practices to many more acres that now grow volunteer trees and brush haphazardly.

There are about 500 million acres of commercial forest land in the United States, varying all over the place in the amount of wood actually growing there. That figure is not very helpful for purposes here since it ignores all the acres and half acres and quarter acres outside the commercial forests that could potentially be used for forest food and fiber production. Ohio, which is a fairly average state in its proportion of woodland to farmland, has about 7.8 million acres in commercial forests and who knows how many in noncommercial groves. My county, Wyandot, is so intensively farmed that it is often not credited in the statistical tables as having any noncommercial forestland at all—a shockingly false notion, since I live on such land. The surprising fact about the number of acres in forest statewide is that the number has been going up, not down, as we are often led to think. That is true of almost every state where there’s enough rainfall to support trees. (Pennsylvania is down slightly at the moment.) The forested hill country of southern and eastern Ohio has increased significantly. Even in the northern and western regions where society seems to prefer corn to trees, the decline in forests has leveled off, and woodlands have even increased a bit, mostly because, in intensively farmed areas, the hillier areas along rivers and creeks that were in permanent pasture in the middle of the twentieth century are reverting to forest again, as I have pointed out earlier. If you examine these vagrant areas of unmanaged woodland along creeks, rivers, and steep hills, you will be struck by the awesome amount of dead wood that is rotting away unused. You can say that the rotting wood is adding to the organic matter in that soil, which is true, but most of this kind of land is already chock-full of organic matter because of years of wood wasting away.

These tree groves in areas of more intensive farming, as well as the trees in urban and suburban areas, are the most interesting to contemplate in terms of new sources of fuel and energy because their extent and capabilities are largely unknown. These little, and sometimes not so little, out-of-the-way groves generally have fertile, even virgin soil because they have always been in pasture (or backyards), and they could support a good, dense stand of trees. If all of them were managed at least as intensively as the best commercial forests, how much additional energy could they supply? And this could happen under totally delightful circumstances if families would occupy such groves and love them.

As early as the 1970s, scientists and foresters, seeing a future in which nuclear energy might become the new norm as coal, oil, and gas became more and more expensive to get out of the ground, began wondering whether part of our energy consumption might come more practically from trees. That was the inspiration for the Clemson report referred to above, which went on to say that it takes about 350 square miles of forestland—let’s say an area 10 miles by 35 miles—to fuel a 400-megawatt electric generating plant. Nuclear reactors seemed to offer much better efficiency in the 1970s than burning wood, so the idea did not gain much support in science, nor among environmentalists.

But now we know a whole lot more about the costs and risks of nuclear power and realize that the amount of available uranium or other elements needed for nuclear reaction is limited too. When the environmental advantages of forestland are figured into the equation, wood energy begins to look very exciting if we do not burn more wood than the forest can naturally replenish. Could that be done?

Scientists and foresters pursuing this idea have done lots of experimenting on growing trees more like a farm row crop than as a forest. In the 1970s they tended to concentrate on fast-growing trees, especially hybrid poplars, which were pioneered by my friends, the Miles Fry family (see chapter 6). Since hybrid poplars react well to coppicing—that is, they grow back quickly when the tree trunk is cut off close to the ground—foresters at Penn State experimented by planting trees one foot apart with two feet between rows and harvesting the wood every five years thereafter. Hybrid poplars were especially suitable for this purpose because they would readily grow from cuttings, not seed or transplants, and so on proper terrain could be planted mechanically. In five years, a plantation like this would produce about thirty thousand pounds of main stem-wood fiber per acre, or over forty thousand pounds if the whole tree were fed into the chipper. That amounted to some seventy-eight cords of pulpwood per acre in thirty years (thirteen cords every five years)—quite a bit more than the forty-five cords from red pine, twenty-seven from aspen, or twenty from oaks that was being obtained from more traditional forest harvests.

Today pulpwood production for fuel energy is coming mostly from plantations of pine in the South. The pulp is pelleted and sold to homeowners as a home heating fuel or used in chipboard or flakeboard by the construction industry, but also much of it is being used to fuel bio-energy power plants, especially in Europe. All this is, of course, controversial from an environmental point of view. No one is sure just what would happen in the long run if we relied on such plantations managed like an agricultural monocropping system. If it worked well, would humans harvest more of the wood than the forests could replace sustainably? And shipping wood to power plants in Europe doesn’t sound very energy efficient to me.

Information on pulpwood production and use is easily available and hardly the focus of this book. It has its dark side and its bright side. I confess to being extremely leery of any large-scale operation extracting wood from forests since history has shown it invariably leads to excess. But the idea of using trees for energy is intriguing and needs to be investigated more. One application of the idea I found in quite an unlikely and very old place, The Economist Library, published quarterly in Springfield, Ohio, in a volume entitled Success in Farming written by Waldo Brown in 1886. In chapter 20 (pp. 223–28), he describes his experiences in growing small acreages of trees for firewood, fence posts, and other uses. Considering that, at his time, timber was still something most farmers were trying to get rid of as quickly as possible, Brown shows extraordinary vision, insisting that more money could be made from timber than from cultivated crops and urging his readers to put out tree plantations immediately. I will quote just one part of what he says where he surely seems, 125 years ago, to be writing specifically for this book.

If firewood or a quick-growing windbreak is the object sought, I would advise Soft Maple. I cut a half-cord of wood last spring from eighteen trees of Soft Maple occupying a single row fifty feet long, which had been growing nine years. This would be at the rate of over twenty cords to the acre with the rows one rod [16.5 feet] apart. I have trees of this timber eighteen years old which measure from three and a half feet to four feet in circumference and I estimated they will make over a half cord each. Near my farm is a plantation of two acres of Black Locust which was started in 1850 [from seed]. . . . In 1879, eleven years after it was cut off clean, the owner began cutting the second crop of posts and I visited it and made a careful examination of it. When planted in 1850, the trees were four feet apart each way; but they were thinned out and sold for bean poles and stakes, so that at the time it was cut off the trees stood eight feet apart. When I visited it eleven years later, I found that each stump had thrown out from three to seven sprouts and the largest of these were now large enough for posts and cutting them out was a positive advantage to the remainder, and as the stumps averaged over four of these sprouts I found that over two thousand posts could be cut and still leave the original number of trees—680. . . . In twenty years from the first cutting, if the straightest and best trees were allowed to stand, one to each stump, there would be 680 trees that would make several posts each. . . .

There is much more know-how and sheer genius being displayed here than the words tell us. First of all, black locust is one of the densest woods with very high BTU value, and so excellent for firewood as well as fence posts. Unlike most dense woods, black locust grows comparatively fast. Most opportune of all, it splits easily. Black locust was the wood favored for splitting out fence rails in pioneer time. It responds very well to coppicing, obviously, but what Mr. Brown doesn’t seem to appreciate since he gives detailed instructions on how to soften the seed so it sprouts readily, black locust will grow well from cuttings. Just stick a twig in the ground and stand back, says a friend of mine who considers the tree something of a pest on his farm. Last but not least, black locust does not rot in contact with the soil. It used to be used not only for fence posts but ship hulls and other places where wood comes into contact with water. The wood’s only drawback is that its hardness will dull saw blades quicker than most woods, but it takes a beautiful finish that woodworkers rave about.

Nor does the genius end there. In a later sentence, Brown notes that on his own farm, in his locust grove “there was growing there a heavy crop of blue grass. . . .” But of course. Black locust is a legume. It puts nitrogen in the soil to make the grass grow better. Because the leaves of the tree are fine, not heavy, enough sunlight gets through to encourage the nitrogen-fed grass to grow better in summer when bluegrass often stops growing because of dry weather; the light shade of the trees is still enough to keep the ground slightly moist. The only dark side to black locust is that it is slightly toxic, and horses have been known to sicken from chewing on black locust fence posts. If I had a horse eating fence posts, I’d deduce that they were probably not getting fed properly. I’ve checked with several farmers who pasture animals where black locust trees are growing and they have not had any problems in this regard.

So what Mr. Brown has here is an almost perfect example of sustainable forest farming. Although he was more interested in fence posts (a topic I will turn to in the next chapter), it is obvious that the wood, coppiced the way he describes, would also produce a bountiful supply of fuel wood. Though he seems to prefer the faster-growing “soft maple” (I think he means red maple rather than silver maple, but I’m not sure) for fuel, I would argue that since black locust has twice the heat power, it would actually produce more fuel per acre even if it grew more slowly. But why quibble over such a detail? What we need today is more Waldo Browns.

But I think a more fruitful kind of endeavor is to look at acreages that are already growing trees and figure out how to use them, even when they are not managed in such an intensive way. For example, I was driving through Shaker Heights and Cleveland Heights in Cleveland, Ohio, recently and was struck by how much of these beautiful, old, well-heeled residential areas are really old-growth forest with houses in them. And I mean real old-growth forest—lots of huge trees towering over the castlelike residences so densely that the houses are almost hidden from view.

My first thought was how much people love trees, because there is considerable risk involved when these trees inevitably die or age enough so that storms drop them on their houses. My next thought was to try to calculate how much wood was growing here in this urban forest, which will probably end up in a landfill.

Let us take, just for discussion purposes, five square miles of this kind of urban forest. A square mile is 640 acres, so five miles square would be 3,200 acres. An acre of established woodland can produce a cord of wood a year without diminishing itself, so the experts more or less agree. With good forestry practices it can do better than that, but let’s assume that every acre in this old-growth urban forest would produce half a cord a year because the houses and lawns take up some of the room. So this tract in Cleveland could be producing 1,600 cords of wood a year. At, let’s say, $200 a cord, that’s $320,000 a year.

Now try to imagine how many wooded urban acres there are in this country. We’re talking millions and millions and millions of dollars in wood mostly going to waste due to a lack of planning and management. The main problem is that we don’t think in tree time. Humans are lucky to live 80 to 90 years. The life cycle of trees is twice that at least, but it is, nevertheless, a cycle. But because it extends beyond a human lifetime, we don’t really know how to plan for it. We tend to think of our beloved trees as monuments, but they are living things. We should be planting them and harvesting them on a schedule of about eighty to a hundred years to take advantage of their value as lumber or fuel while avoiding most of the possibility of storm damage. The issue is increasingly pertinent because as more and more suburbs age, so do their trees. Every storm now means a much greater threat of property damage and power outages.

The management plan should first involve the choice of trees. Maples and oaks, for example, are just as pretty as smaller ornamental trees but contain more BTUs for fuel and better wood for lumber. But even small trees can make good firewood, and some of them (dogwood, for example) are high in BTUs or useful for making specific wooden products. Persimmon wood used to be used for sidewalk and road pavers that were almost as durable as brick.

The supply of this kind of wood is only going to increase tremendously. Newer subdivisions and their trees are in the process of becoming the mature urban forests of tomorrow. Older village and town residential areas are already facing lots of problems because of storm damage and power outages as their trees grow bigger and older. Starting now for a planned, orderly cycle of harvesting old trees and growing new ones, of varieties known for good lumber or fuelwood products, will at the very least alleviate the cost of removal and could eventually become a profitable enterprise. It will also generate jobs. Already there is a big increase in the number of tree-removal businesses, increasing use of bucket hoists and tree-handling equipment. You may have noticed, if you live in an urban forest, the appearance of a new job skill. A new brand of tree trimmer has come along who swings from tree to tree on ropes, able to remove huge tree limbs over houses with a chainsaw, piece by piece, in places where no other removal method is feasible.

Since residential homeowners almost always prune their trees as they grow, they can start doing it to produce clean-limbed, valuable logs for lumber sales. This kind of urban forest farming is a totally win-win situation because, although the rewards of selling the wood may be years and years away, the reward of enjoying the trees as they grow is ongoing, and the environmental benefits of those trees taking in carbon dioxide and releasing oxygen are lifesaving. Used to be, timber buyers shunned yard trees because of nails and other hardware so often embedded in them. But enlightened homeowners can avoid this problem, and new magnet gadgets can detect metal in logs quite handily now. City planners have often proposed the idea of managing urban forests for wood, and there are entrepreneurial minds already doing it. What are we waiting for?