Lumber by the Numbers
Growing away from historical precedence, can we build smarter to conserve our wood resources with innovation and efficiency?
Use the following learning objectives to focus your study while reading this month’s Continuing Education article.
Learning Objectives - After reading this article, you will be able to:
- Discuss historic wood use patterns in U.S. homebuilding.
- Broadly identify primary domestic lumber sources.
- Consider forest effects of timber harvesting for lumber production.
- Describe deforestation and reforestation in America.
Credits: 1.00 HSW
In 2005, lumber production in the U.S. exceeded 54 billion board feet, according to the U.S. Department of Agriculture (USDA) —the biggest year in modern history. About half of that wood was used in over two million housing starts, and lumber used for repair and remodeling exceeded 20 billion board feet for the first time. Wood imports peaked as well—an additional 21.5 billion board feet from Canada; another two billion from Europe; and about a billion and a half more from places like Chile, New Zealand, and Finland.
But now, with the economy crippled, housing starts have plummeted. The total at the end of 2009 was expected to be just one-fifth that of 2005. This means that U.S. lumber demand has decreased more than 55 percent in just four years—the sharpest decline in the industry’s history. In the first half of 2009, American and Canadian lumber production—together—was down to just over ten billion board feet. A board foot is the equivalent of a one-inch-thick, twelve-inch square piece of wood. If ten billion board feet was made into two-by-fours and laid end to end, they’d stretch from ocean to ocean across America almost a thousand times, or nearly three million miles—a 280-foot-wide, 20-lane wooden freeway across the country. That’s just six months’ harvest during the biggest slump in modern history.
The construction crash offers us the opportunity to examine how we’ve done things in the past, and to think about how we want to go forward from here. This article looks at some broad historical trends in housing, lumber production, and forestry in the United States.
Illustration: Bryan Christie Design with data from the USDA Forest Service
Why wood, and why so much?
Why do we build with wood? Simple answer: We’ve got a lot of it. Five percent of the earth’s remaining forest cover is in the U.S., and Canada has another 10 percent. In addition to its availability, wood is fast and easy to work with; we’ve been using it for a long time, and have things pretty well nailed down (so to speak). According to the Western Wood Products Association, over 90 percent of American homes are built with wood. Less quickly answered, but almost as simply, is how we manage to keep using so much more wood for building all the time. Mostly, it boils down to plain old math.
First, since 1940, the number of housing units in the United States has more than tripled—from less than 37.5 million to more than 128 million. (“Housing units” includes things like apartments.) The percentage of single-family detached houses has been relatively consistent over that time, at around 60 percent. So, the number of single-family detached houses over the last 70 years has gone up from about 23 million to around 77 million.
Second, over the last 40 years, the average size of new houses has gone up from 1,500 to 2,500 square feet. (The 1950 housing census didn’t measure square feet, but counted rooms; 75 percent of dwelling units had between three and six rooms. Four and five rooms were the most common.)
Over the last 70 years we’ve tripled the number of houses on the ground, and the size of new houses has trended up until they’re now more than one-and-a-half times bigger. A common estimate is that a contemporary, 2,000-square-foot, wood-framed, single-family house uses upwards of 16,000 board feet of framing, and about 11,000 square feet of other wood materials, such as sheathing.
TREES AT THE TOP
Illustration: Bryan Christie Design with data from the USDA Forest Service
|PROTECTION AND PROFIT
While 94 percent of Canada’s forests are publicly owned, in the U.S. the majority are privately held, giving the government limited power to protect the land.
|LAND OF MANY USES
Over 650 million U.S. acres consist of harvestable, working forest. Urban land is a comparatively small 60 million acres.
|MY HOUSE, YOU'VE GROWN
Wood use per square foot has dropped over time but the average house size has increased by almost 1,000 square feet, resulting in more net wood use per house.
|Illustrations: Bryan Christie Design with data from the USDA Forest Service|
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“Laying low the mighty redwood forest” in Humboldt County, California, around 1915.
Photo: Library of Congress, Prints and Photographs Division
The land area of the United States is nearly 2.3 billion acres; it’s estimated that well over a billion of those were forests before 1620. Today we’re down to around 750 million acres of forests. Most of the loss in America happened between 1850 and 1910, but the big driver of the deforestation wasn’t logging. It was land-use conversion from forests to farms, and coincided with booming immigration. During the last 50 years of the 19th century, our adolescent agricultural nation wiped out 13 square miles of forest in the U.S. every day.
This was recognized as a problem even at the time. A 1920 publication of the U.S. Forest Service warned, “Three-fifths of the original timber of the United States is gone … we are using timber four times as fast as we are growing it. The area is being increased from three to four million acres annually as the cutting and burning of forests continues.” Since the early 1900s, however, the amount of forest land has been relatively stable and actually increasing slightly.
Additionally, despite our continually increasing use of wood, our forests’ tree density—the average growing stock volume per acre—has increased in the past 50 years. Net forest growth in the U.S. is at about three percent, while harvesting is reported to be at two percent of inventory. In the North and South, per-acre volumes are more than 35 percent higher than they were in the early 1950s. This increased volume doesn’t necessarily reflect natural forest patterns, however.
Forests in the contiguous states are distinct and widespread, split by the swath of prairie running through the middle of the country. Broadly speaking, the Northeast has a mix of hard and soft woods—that is, deciduous and coniferous trees, respectively—while the Southeast and West have a preponderance of pine (coniferous softwood) varieties.
Nearly all of our domestic building wood is softwood (it’s estimated to comprise about 97 percent of that used in new houses), which comes primarily from the South and West—60 percent of the Southern harvest is softwood, and 98 percent out West. Northern hardwood building products generally include hardwood panels, flooring, and cabinetry.
Forty-four percent of U.S. forests are owned by federal, state, and local governments, but over 11 million private owners have the rest—ranging from people with an acre or two behind the house, to industrial owners with millions of acres. Most of those big parcels are corporate-owned for commercial use. In fact, corporations own a third of the private forest land in the U.S., or about 18.5 percent of the country’s total forest area. These industrial forests are mostly clustered throughout the lower South and in the Pacific Northwest, and in Maine and the Great Lakes area.
There’s been a growing corporate trend of holdings divestiture, mostly to banking institutions. The forestry industry is hanging on to the prime woodlands, but Timber Investment Management Organizations (TIMOs)—forest-asset managing brokerages for institutional investors—now control more acreage than International Paper. It can be argued that this is a perpetuation of the same cut-and-run technique of the old lumber barons (get what you can, then get out); or that it’s just smart business; or that the industry increasingly sees its future offshore. How the TIMOs manage their profit-generating land holdings over the long term remains to be seen.
In contrast to the U.S., all but six percent of Canada’s billion-plus acres of forests are publicly owned. Provincial governments manage 71 percent; the federal government, 23. This puts a lot more legislative power behind Canada’s wood assets than the U.S. has.
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About 10 million acres of U.S. forest are harvested annually. Over 90 percent of those are private holdings—mostly corporate-owned. Almost 60 percent of family owners have their forest land commercially harvested at some point as well. Selective cutting makes up over half of forest harvesting activity (about 60 percent). Even though selective cutting is less harmful to natural forests than clear-cutting, it still impacts a wide harvest area, requires additional energy and infrastructure (such as roads), and has other environmental consequences.
Millions of acres are clear-cut every year—an average of 20 acres per day. According to the industry, clear-cutting mostly happens on timber plantations in the South (it can be argued that these aren’t even really forests), but also in the North on managed natural stands of species that need open sun to repopulate. Clear- cuts in the West are increasingly followed by replanting, a process (no matter where it takes place) that can be both well-meaning and self-serving.
The West was historically our lumber production leader, but has been overtaken by the South as a result of a couple things: Cutting in the National Forests—most of which are in the West—was drastically reduced, and the South had established over 30 million acres of plantation forests since the 1950s.
A sawmill in Winona, Minnesota, a big lumber town in the late 1800s that borders the Mississippi River.
Photo: Library of Congress, Prints and Photographs Division
Harvesting from public forests
There are controversial timber manage-ment plans for public forests, especially at the state level, but harvests on federal land have decreased significantly. It might come as a surprise that harvests from National Forests took a nosedive during the first Bush administration. In the record-breaking days of 2005, less than two percent of that year’s take came out of the National Forests—a 75 percent reduction from the 1991 peak.
Still, the West, with its high proportion of public forest, accounts for most of the public-lands forest harvest. (In the East, most forest is in private ownership.) Until the mid-1970s, and briefly during the 1980s, when the West was the biggest lumber-producing region, a lot of that timber was old-growth harvested from federal land in Washington, Oregon, and California.
When a forest isn’t a forest
Most North American forests are natural stands of native species. A lot of our forest land has regenerated by itself in the wake of overzealous harvesting and abandoned use changes (such as derelict farms and pastures on former forestland); most northern hardwood forests are such regrowth. But it’s not all like that: A couple million acres of forest are now replanted in the wake of logging each year. In the West, planting is typically an augmentation to natural regeneration. More common in the East and South are “man-made” planted forests.
In the 1950s, the South had vast expanses of clearcut forest and degraded, non-producing farm land that have since been replaced by tens of millions of acres of southern pine plantations. They’re not natural forests; they don’t provide diverse habitat; and they have all the usual problems of monocultures—but they help prevent the logging of natural stands. Everything from site preparation to fertili-zation and weed control, and the use of “improved” and non-native trees, contributes to the high productivities of these intensively managed plantations. If we don’t curb our appetite for wood, are plantation forests (and their attendant problems) an acceptable answer to preserving our natural forests?
There’s an emerging wrinkle. In a joint venture designed to supply low-cost wood (and a competitive edge), International Paper, MeadWestvaco, and New Zealand’s Rubicon Ltd. have recently requested permission from the USDA to sell eucalyptus trees designed to survive in southern U.S. conditions. These would be the first genetically engineered forest trees sold outside China. Opponents fear gene-hopping that could contaminate native forests, citing evidence against Monsanto’s genetically modified food crops.
In addition to making oxygen, trees store carbon. It’s been estimated that U.S. forests remove over 1.5 trillion pounds of CO2 equivalent from the atmosphere annually, offsetting more than 10 percent of U.S. emissions. That carbon is slowly released back into the atmosphere when a tree dies and rots—or quickly, when it’s burned. Using lumber as a building material locks carbon up indefinitely. But it’s not just the trees; it’s also the forest. Soil studies in undisturbed woods indicate that fallen leaves, twigs, and roots contain significant amounts of carbon that will remain bound for hundreds of years. This suggests that replacing natural forests with plantations is counterproductive for carbon sequestration—but on the other hand, fast-growing forests store more carbon than slow-growing ones. It’s a quandary.
It may not matter, though. Studies suggest that Canada’s billion-plus square miles of forest have begun releasing more CO2 than they’re taking in. Rising tempera-tures are drying everything out and creating ripe conditions for fire. Mild winters are allowing the mountain pine beetle to overwinter and spread; the infestation has claimed 50,000 square miles of Canadian forest so far.
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Less is actually more
In the 1950s, solid-lumber use per square foot of new house began to drop with the rising popularity of slab-on-grade foundations, wider stud spacing, the use of roof trusses, and the substitution of plywood and particleboard for sawn boards. This downward trend continued until the 1980s. However, actual lumber use per house has increased nearly every year. And during the same period, the use of wood structural panels increased nearly tenfold. While plywood, particleboard, and oriented strand board (OSB)—which first gained a market share in 1970, and by 1998 had overtaken plywood—are a more efficient use of wood resources than solid wood, the significant increase in their use still translated into ever-increasing total wood use.
Construction of a housing development in Newport Beach, California, 1974.
Photo: National Geographic/Getty Images
Though there isn’t always a strong correlation between lumber production and its cost on the ground, it was rising lumber prices—not the green-building movement—that pushed the use of “weed” and smaller-diameter trees, along with logging and processing residues, for OSB, I-beams, laminated beams, truss framing, and other composite panels and engineered-wood components. These new materials and methods have reduced the overall growth of demand for softwood building products, but haven’t stemmed the rising tide—let alone reversed it. Using wood-alternative products won’t be the answer, either, if their manufacture translates to increased carbon and other emissions, energy use, and other consequences.
The future is a moving target
The natural resources and environ- mental issues think tank Resources For the Future (RFF) noted in 2005 that worldwide industrial wood demand (over 40 percent of which goes to make paper) was about the same in 2002 as in 1982, despite the growing world economy and population. Why? The major reasons cited included better efficiency in the use of wood as a resource; the increased use of non-wood materials in place of wood-derived ones; better recycling numbers (including paper); and an aging global consumer population that just plain has lower resource demands than younger folks.
Looking to the future, RFF suggested a shift in the population curve due to rapidly declining fertility rates worldwide: The countries that currently account for half the world’s people (and a majority of its wood use) aren’t going to be able to main-tain their population. This depopulation doesn’t appear to be happening—but it would solve a lot of the problems facing our forests if it did (while probably creating just as many new ones in other areas of human activity).
Here in the U.S., where we have five percent of the world’s population and five percent of the world’s forest cover, we use 27 percent of the world’s industrial wood products. The good news is that over three-quarters of that use comes out of our own forests.
It’s possible that we’ll see a future of weakening, possibly even negative, wood demand, thanks to smarter and/or fewer users. It’s also possible that we’ll just keep upping our numbers and our appetites. What might happen down the road depends on who you listen to—but more particularly, what will happen down the road depends on what we choose to do.
Forests in the U.S. aren’t what they used to be, but there’s not much that is. In many ways, in the big picture, we’re starting to do right by our wood resources in the wake of much undeniably bad behavior. But there’s always a leading edge, and always room for improvement (especially when that big picture is zoomed in to local levels). As green builders—as good people—that should be our goal.