In 1990, forests and other wooded lands (a category that includes natural open woodlands, natural closed forests, and tree plantations) covered 40 percent, or 5.1 billion hectares, of the Earth’s surface. Forests alone accounted for 3.4 billion hectares. Such lands have always been important to people, providing food, building materials, and other resources for our use. They also play a key role in the Earth’s biosphere, affecting the atmosphere, the water cycle, the carbon cycle and other biogeochemical cycles, and erosion.
Today’s forests have survived centuries of human transformation. To meet the needs of an ever increasing population, human beings have consistently converted large swaths of forest and grassland into cropland and permanent pasture. This trend continues. Between 1960 and 1990 alone, developing countries lost one-fifth of their natural tropical forest cover. The continuing harvest of the remaining stands of old-growth forest and the degradation of second-growth forests are taking their toll worldwide. Recognition of these problems, in combination with growing awareness of forests’ value as biologically rich habitats and carbon sinks, have worked in recent years to stimulate the development of new approaches to forest management.
This article focuses on the approximately 50 percent of worldwide harvests of raw wood used to produce construction materials, paper, and fiber products1 and explores three alternative models that have been developed to meet future demands sustainably. The first model, the traditional extensive approach, involves obtaining wood primarily from old-growth and other natural forests as well as from some managed forests and plantations. Under the second model, wood would be harvested from intensively managed plantations that produce high yields on relatively small areas of land. The third model relies primarily on using annual or herbaceous crops such as kenaf, hemp, and begasse as a substitute for wood fiber.
Each model has environmental implications but, as it turns out, the intensively managed plantation model has some major environmental advantages over the other two. If tree planting and intensive management of a small area of forest can produce enough wood to meet the world’s requirements, this could free large areas of natural forest from the pressures of timber harvests. The vast majority of remaining natural forests could consequently be devoted to nontimber uses, such as wildlife protection and habitat conservation.
Of course, not all of the wood fiber required for global consumption in the future can come from intensively managed forests. However, more than 90 percent of the world’s demand for wood to be used as pulp or construction material could be satisfied with what is known as commodity-grade wood, which can be produced in managed, high-yield, intensive forest plantations. There are several alternative ways to produce the remaining less than 10 percent of specialty-grade wood. Specialized tree plantations, such as those for teak, could supply some of it; another portion could be harvested from specially managed natural forests. On the whole, the amount of land and natural forest involved in producing these specialized woods would be relatively small due to the modest quantities required. Thus, the overall area devoted to timber production under the intensive plantation model could be a small fraction of the total forested area of the globe — conceivably as little as 5 percent.
Factors Driving Change
Three factors are driving the transition toward the intensive management model: rising costs associated with the increasing scarcity of accessible old-growth forests; technological improvements that have increased productivity and yields on intensively managed plantations; and increased social pressure to protect old-growth forests either directly through set-asides or indirectly through the imposition of more stringent standards, which increase the costs of harvesting. The primary factor retarding this shift has been social resistance to the intensive management model.
This resistance has historical roots. People today still rely heavily on centuries-old patterns, harvesting large volumes of timber from old-growth and regenerated second-growth forests, albeit with sophisticated harvesting techniques. Those resistant to the intensive management model fear, in part, that the development of tree plantations will be used to justify the additional cutting of oldgrowth, riparian, and other forests that provide habitat for endangered species and as such have substantial conservation and ecosystem management value. This fear reveals a failure to realize that plantations, when carried out carefully on appropriate lands, can actually reduce the pressure placed on old-growth and other forests, thereby benefiting conservation and global forest sustainability.
For their part, those who argue in favor of an agricultural model that employs kenaf, hemp, begasse, or other fiber crops do not appreciate the fact that this approach would surely have been adopted by now if financial returns had proved to be adequate. Forest products companies have already looked into the possibilities of using annual fiber crops. In fact, 8 percent of the world’s paper and paperboard is currently made from crops such as kenaf and begasse (although almost exclusively in China and India). Close inspection has shown, however, that there are serious limitations, both environmental and economic, to the use of an annual crop for pulp production2.
Where The World Gets Its Wood
As Figure 1 on this page suggests, wood is drawn today from a wide variety of raw sources. The three primary sources, however, are oldgrowth, second-growth, and plantation forests.
Large areas of oldgrowth and other natural forest can be found in a number of regions around the globe, including Russia, Canada, the Amazon basin, and certain other areas with tropical rain forests. Substantial tracts of second-growth forest (forests that have regrown without planting by people following cutting of the original old growth) with trees of merchantable size also exist. In fact, second-growth forests have replaced the old-growth forests that once covered much of eastern North America, Europe, and large parts of South America and Asia. These reserves are actively harvested. Many of the plantation forests that provide an increasing portion of the world’s industrial wood are located in traditional forest areas, including parts of Europe, China, and the United States where growth is often, although not always, relatively slow. Others, however, are situated in nontraditional wood-producing regions such as Brazil, Chile, Venezuela, Uruguay, and Argentina; Southern Hemisphere nations such as New Zealand, Australia, and South Africa; Asian nations such as Indonesia and Thailand; and the Iberian countries of Europe. Growth is faster on these often exotic (i.e., nonindigenous) forest plantations and for this reason they are beginning to supply an increasing share of the world’s wood. Entrepreneurs are also developing a new type of intensively managed forest called a fiber farm. A fiber farm takes plantation forestry to its logical conclusion. On them, farmers grow fiber as an agricultural crop, using intensively managed, short rotations of trees located on sites that were in many cases used until recently for agricultural crops.
Table 1 on page 16 provides a crude disaggregation of the types of forests that supply current timber harvests. The table indicates that approximately 30 percent of these harvests come from old-growth forests, 10 percent from exotic plantations, 24 percent from other plantations, and 36 percent from second-growth forests, most of which are managed in some way. (These figures are for illustrative purposes only; the thesis of this article does not depend on the specific distribution of current timber harvests.).
Table 2 on this page provides data on the industrial wood production of major regions and countries around the world. Clearly, North America ranks as the dominant supplier3. Global production and consumption, which amounts to about 1.5 billion cubic meters annually, are balanced by adjustments in market prices4. Although some forest industry observers anticipate significant increases in fiber consumption as average incomes in developing countries rise, recent annual consumption has increased only modestly5.
As explained earlier, financial considerations and concerns about future supplies are in large part driving the trend toward managed and intensively managed plantation forests. As natural forests become increasingly inaccessible, plantation forests generate more and more positive financial returns. Moreover, as society’s view of forests and their role continues to change, industry’s access to natural forests will be further restricted and harvesting costs will surely increase. Environmental legislation already limits access to natural forests and restricts harvests in many old-growth forests by either directly prohibiting taking trees or by imposing constraints on practices that result in higher costs.
Current Land Requirements
The growth rate of usable timber in natural forests ranges from about 1 to 3 cubic meters per hectare per year6. To produce the 1.5 billion cubic meters currently being consumed annually worldwide thus requires between 0.5 and 1.5 billion hectares. Forests cover approximately 3.4 billion hectares of the Earth. Thus, to meet demand, between 20 and 40 percent of the growth from these forests must be captured. Suppose, however, that planted forests could produce 10 cubic meters per hectare annually — a growth rate readily achieved in most of the high-yield forests7. Then only 0.15 billion hectares of plantation, or roughly 4 percent of the global forest, would be required to produce this growth. Yields of 20 cubic meters per hectare per year (which, as Table 3 on this page shows, are not uncommon for high-yield plantations in some regions) imply a requisite area of only 2 percent of the global forest. Even an average production of 5 cubic meters per hectare would require only 8 percent of the world’s forests.
Intensively managed plantations offer more than just an opportunity to reduce the amount of land required to meet global needs, however, as the following more detailed discussion of the environmental and economic aspects of using natural forests and nontimber fiber crops illustrates.
Until very recently, new areas of natural forest existed for people to exploit as those mined earlier became devoid of harvestable timber. In the United States, loggers first harvested the resources of New England, the mid-Atlantic states, and parts of the southeastern coastal plain. They then moved on, making their way into the Ohio Valley, the Great Lakes states, the south central region, and eventually the Pacific Northwest. Gradually, the industry extended the U.S. forest frontier into Canada. Today, Canadian wood has become a large component of U.S. consumption.
A similar pattern has been occurring globally. In many respects, the exploitation of the last of the major “frontier” forests and their huge inventories of mature trees is currently under way. Worldwide, few new native forests remain that could be developed or exploited. The largest remaining areas that have not been intensively developed for large-scale commercial logging are found in the Amazon, which shelters a high diversity of noncommercial tree species, and parts of Russia, where the remaining stands are still largely inaccessible.
Because of these reductions in availability, native forests are declining in their ability to provide wood. This reflects both the effects of earlier harvests and environmental legislation that has created forest set-asides or restricted harvests. One way to limit declining harvests in natural forests involves managing the forest for nontimber outputs, such as endangered species, while continuing limited harvests. The idea, in effect, is to have the same tract of land serve multiple uses8.
This strategy can generate both timber and other outputs, but it often entails a high-cost operation where much management effort is directed toward mitigating the environmental damage to habitat and riparian zones even as the harvest levels are reduced. Such operations also tend to be environmentally controversial in that tensions frequently exist between timber production and environmental values. Because environmental considerations result in reduced harvests and longer rotations, harvest levels per unit area will be modest. These modest harvests mean that the impact on individual forests is likely to be small. However, they also entail the need for larger areas of forest to satisfy global consumption needs. Continuing to rely on natural forests to supply most of the world’s industrial wood ensures this fact. There are better ways to have the land serve multiple uses. The land can be divided geographically, with small areas devoted to intensive timber production and large areas to other uses, including biological conservation.
Nontimber Fiber Crops
Among some environmentalists, the idea of using nontimber fiber sources enjoys great popularity as a way of reducing environmental damage. This belief stems from the implicit assumption that agricultural methods are less damaging environmentally than periodic tree harvesting and replanting. The reality is that the nontimber fiber approach has some serious economic and environmental drawbacks.
For example, most modern, large-scale pulp mills must operate year around for economic reasons. Annual fiber crops are harvested over a relatively short period of time, usually about a month, during which time the “ripe” crop absolutely has to be picked. These short harvest periods imply two things: First, a “peak period” of demand for harvesting labor and equipment, as well as transportation of the product to the mill, and second, a need for mills to have facilities to store most of the harvested crop as inventory. However, most nontimber fiber crops are subject to a substantial degree of perishability over a year. Thus, mills would either need to build additional facilities to reduce perishability or resign themselves to absorbing substantial losses as part of the cost of doing business.
In contrast, tree harvests can occur throughout the year,9 thereby avoiding the difficulties associated with peak-period harvests, the need to create massive inventories, and the problem of perishability. The possibility of year-round harvests allows mills to maintain modest inventories and to rely on materials arriving “just in time.” Equipment can also be used year round, thereby reducing a mill’s total equipment needs and down time. Further, a tree harvest can always be delayed for several years if necessary without risking an adverse effect on the crop. In essence, timber can be stored on the stump where additional growth may occur. Once cut, logs also have relatively low levels of perishability.
Market cycles can exacerbate the problem of peak-period harvests. The paper industry is particularly prone to business cycles, which force mills to vary their rates of production and to draw on their inventory in unpredictable ways. For this reason, wood that can be left on the stump until needed or that can be stored for relatively long periods of time offers many economic advantages over other fibers10.
Because of the advantages wood offers, forest products firms that have investigated using nontimber fiber crops have largely rejected those crops as economically unviable or noncompetitive with trees under most circumstances.
From an environmental perspective, plantation forests have even greater advantages. Annual cropping of nontimber fiber involves a regime of planting, including heavy fertilizer and herbicide use, followed in a few months by a harvest. Heavy equipment is used at both planting and harvest. Additionally, the ground is typically left bare after the harvest until the next planting, which would presumably occur sometime the following spring. Over a 20-year period, heavy equipment would roll over the land some 40 times. The land, altered by consistent applications of pesticides and herbicides, would be left unprotected by vegetation during each fall and winter.
By contrast, a plantation with a 20-year rotation, which is relatively common in the southern United States, would receive one planting, one harvest, and perhaps two applications of pesticides and herbicides. The ground would be fully covered with vegetation for the entire period except immediately after the 20-year harvest. Clearly, the annual planting regime associated with nontimber fiber crops is much more environmentally invasive than a multiyear regime of tree planting.
Fast-Growing Forest Plantations
The advantages of industrial forest plantations are similar to those of agricultural cropping over simple foraging. Tree planting and intensive management allow for the control of inputs to achieve higher growth rates without introducing different species or genetic improvements11. The land for a forest plantation can also be chosen to ensure that the terrain is favorable to planting and harvesting activities, the soil and climate are conducive to higher biological productivity, and the area is accessible to mills and markets. Furthermore, on such plantations, even the species of tree can be selected.
The choice of tree species allows fast-growing species, some of which may not occur naturally on a site, to be introduced. For example, various types of pine have been introduced into South America, New Zealand, and Australia, where they do not grow naturally. In many cases, the growth rates of these species in their new environments have exceeded those in their original environment12. As a result, pine plantations are now common in many of these regions. Similarly, eucalyptus, an Australian genus, now flourishes in many regions (though it is causing some environmental concern). Table 3 on page 18 surveys the variety of fast-growing species being used in different regions. A recent study reveals that the share of industrial wood produced by intensively managed plantations in the tropics and subtropics roughly doubled in the 15-year period from 1977 to 1992, from about 5 to 10 percent of the world’s total production13. As in agriculture, the evidence suggests that high-intensity management generates the most favorable financial returns on high-productivity sites and lower returns on less favorable sites14.
Ultimately, if intensive plantation forests are to remove the pressure to cut existing old-growth and second-growth forests that are important for biological conservation, they must be managed in a way that is sound for the local environment. Thus, the sites chosen for intensive plantations must not be habitats crucial to biological conservation and they should be physically managed in such a way as to ensure that riparian zones are adequately protected by buffer zones. Erosion rates need to be managed so that they remain as close to natural rates as possible, ecologically sound methods of pest management should be implemented, and fertilizer use minimized. At present, intensive plantations often use exotic species (see Table 3). Because of the well-known environmental problems associated with the introduction of exotic species, plantation managers must select species carefully. Although there are some advantages to exotic species, other things being equal, it is always preferable to use native species.
The need to create areas within plantations that are not harvested (such as riparian buffer zones) means that the area allocated to intensive plantations will be greater than the 2 to 4 percent of the total forest area estimated to be the minimum needed to meet global timber and pulp demand. However, the total area allocated for intensive plantations, including internal set-asides and the areas required for the production of some specialized woods, will not likely be double that minimum. Therefore, even allowing for local environmental considerations, it seems that through intensively managed plantations, less than 10 percent of the world’s forest area could provide a supply adequate to meet major timber and fiber needs.
Some people argue that using nontimber fiber crops could eliminate the need to log forests altogether, but this result is not certain. To be sure, in much of the United States, the land can support either forests or crops15. But we must remember that industrial tree plantations are planted explicitly to produce commodity-grade wood. If this were replaced by nontimber fiber, one likely effect would be less investment in tree planting and more in annual fiber crops16. Ironically, this would probably result in less forest area in the United States and elsewhere.
The geographically dispersed, intensive-management model allows comparatively small areas to be used for intensive tree plantations and large areas to be designated for biological conservation. It also seems to offer a win-win situation, providing economic benefits to timber producers and environmental benefits for conservationists. This model, however, does demand that close attention be paid to the selection of land areas appropriate for intensive tree planting. For example, wherever possible, plantations should be developed on marginal farmlands. In many cases, such lands were originally forested tracts that have been subject to repeated cuts; as a result, they are unlikely to include unique habitats for rare or endangered species. Such lands are also likely to have high timber production value with poor suitability for agriculture.
In the long run, intensive tree planting schemes must be managed in a way that minimizes erosion damage, ensures that riparian zones and other sensitive areas within the plantation are protected, and is not used to justify clearing the remaining old-growth areas. If these guidelines are followed, the intensive model can be successful. If they are not, plantations will reinforce conservationists’ worst fears and stimulate political action against an approach that holds a great deal of promise.
Roger A. Sedjo is a senior fellow and director of the Forest Economics and Policy Program at Resources for the Future in Washington, D.C. Daniel Botkin is president of the Center for the Study of the Environment in Santa Barbara, California, and a professor of ecology at George Mason University in Fairfax, Virginia. The authors may be reached through Sedjo at Resources for the Future, 1616 P Street, NW, Washington, DC 20036 (telephone: (202) 328-5065; e-mail: firstname.lastname@example.org). The Sloan Foundation provided partial funding for some of the preliminary work for this study.
Table 1. Global industrial wood harvests by forest type.
(Table) Forest type Global industrial wood harvest (Percent of total)Old growtha 30Second growth, minimal managementb 14Indigenous second growth, managedc 22Industrial plantations, indigenousd 24Industrial plantations, exotice 10Total 100.
a Includes forests in Canada, Russia, the Amazon, Indonesia, and Malaysia.
b Includes forests in parts of the United States, Canada, and Russia.
c Includes forests in North America, Europe, and Russia.
d Includes plantations in the Nordic regions, much of the rest of Europe, a significant portion of the United States (particularly in the South), Japan, and parts of China and India.
e Includes plantations in Brazil, Chile, Venezuela, Uruguay, Argentina, New Zealand, Australia, South Africa, Indonesia, Thailand, and the Iberian countries of Europe.
Source: R. A. Sedjo and D. Botkin.
Note: Because statistically accurate estimates of the relative shares of wood harvested from the different forest types do not appear to be available, the values in this table are for illustrative purposes only.
Table 2. Industrial wood production, 1994.
(Table) Country Production Cubic meters Percent of totalUnited States 399,725 25.8Canada 181,054 11.7Europe, excluding 194,166 12.5Nordic nationsNordic nations 114,301 7.4Russian Federation 152,743 9.9Japan 32,362 2.1Indonesia/Malaysia 74,608 4.8China/India 126,694 8.2Other 273,242 17.6World 1,548,895 100.0.
Note: The world supply of fiber also includes recycled paper and non-timber fibers used in paper production.
Source: United Nations Food and Agriculture Organization, Forest Yearbook 1994 (Rome, 1994).
Table 3. Plantation growth rates in selected countries.
(Table) Country Growth ratea Species SourceSouthern 12 Southern pine Coile and Schumacker, 1964United StatesIberia 11-12 Eucalyptus Bazett, 1993South Africa 25 Eucalyptus and acacia Bazett, 1993Brazil 15-40 Eucalyptus and pine Asociacão Nacional dos Fabricantes de Papel e Celulose, 1977Argentina 15-30 Pine Crosson et al., 1994Chile 20 Pine Schlatter, 1976New Zealand 20 Pine Fenton and Tennent, 1976Indonesia 15-25 Acacia and eucalyptus Sedjo, 1983.
Footnote: a Cubic meters per hectare per year.
Sources: T.S. Coile and F. X. Schumacker, Soil-Site Relations, Stand Structure, and Yields of Slash and Loblolly Pine Plantations in the Southern United States (Durham, N.C.: Coile, Inc., 1964); M.D. Bazett, Industrial Wood, Study No. 3. Shell/World Wildlife Fund Tree Plantation Review (Panda House, Weyside Park, Godalming, Surrey, U.K.: World Wildlife Fund, United Kingdom, 1993); Asociacão Nacional dos Fabricantes de Papel e Celulose, 1977, as reported in R.A. Sedjo, The Comparative Economics of Plantation Forestry: A Global Assessment (Washington, D.C.: Resources for the Future, 1983), 111-13; P. Crosson, J. Adamoli, K. Frederick, and R. A. Sedjo, Potential Environmental and Other External Consequences of the Program to Increase the Area in Plantation Forests in Argentina (final report prepared for the Secretaria de Agricultura, Ganaderia y Pesca, Gobierno de Argentina) (Washington, D.C.: Resources for the Future, April 1994); J. E. Schlatter, “Principales interrogantes en relación al uso del suelo en la actividad forestal de Chile,” (Main question marks regarding the use of land for forestry in Chile) in Charlas y Conferencias, Facultad de Ingenieria Forestal, Universidad Austral de Chile (Valdiva, Chile, 1976), 1-16; R. Fenton and R. B. Tennent, “Export Log Afforestation Profitability,” New Zealand Journal of Forestry Science 5, no. 3 (1976): 323-46; and R. A. Sedjo, The Comparative Economics of Plantation Forestry: A Global Assessment (Washington, D.C.: Resources for the Future, 1983).
Figure 1. Wood flows and uses.
- This article does not address deforestation driven by the use of wood as a fuel or the desire to convert forests to other uses, e.g., agriculture.
- Most of the successful nontimber fiber operations use the waste by-product of an agricultural operation, such as straw or begasse (from sugar cane). However, collecting these by-products and transporting them can entail substantial expense. The extraction of agricultural wastes from fields can also remove important nutrients from the soils.
- Individual countries or regions may export when local production exceeds local consumption or import if they have production deficits. Globally, however, total production must equal total consumption.
- Changes in the inventories of logged but unprocessed wood are treated as negligible. Globally, the forestry industry responds to the normal market forces of supply and demand. Rising prices, which reflect decreased availability, will “choke off” consumption, while rising costs will reduce production. Similarly, falling prices will promote consumption and falling costs will promote production.
- See United Nations Food and Agriculture Organization, Forestry Yearbook 1994 (Rome, 1994). Total global consumption of industrial wood was only slightly lower in 1984 (1.523 billion cubic meters) than a decade later. Production/consumption peaked in the late 1980s.
- Natural forest growth rates vary depending upon a number of factors, including the climate, soils, etc. M. Clawson, Forests for Whom and for What? (Baltimore, Md.: Johns Hopkins University Press, 1975), 58, estimates growth at 2 cubic meters per hectare per year. The growth rate of U.S. public forests, which are often better managed, is estimated at 39 cubic feet per acre per year or about 2.7 cubic meters per hectare. See D. Powell, J. L. Flackner, D. R. Darr, Z. Zhu, and D. McCleary, Forest Resources of the United States: 1992, GTR RM-234 (Washington, D.C.: United States Department of Agriculture Forest Service, September 1993). Growth rates in the more northerly areas, such as Canada and Russia, are generally lower, however.
- M. D. Bazett, Industrial Wood, Study No. 3. Shell/World Wildlife Fund Tree Plantation Review (Panda House, Weyside Park, Godalming, Surrey, U.K.: World Wildlife Fund, United Kingdom, 1993). Bazett defines high-yield forestry as that achieving at least 12 cubic meters per hectare per year.
- B. Lippke and C. Oliver, “Managing for Multiple Values,” Journal of Forestry 91, no. 12 (1993): 14-18.
- There are some exceptions to this rule due to regional weather conditions. For example, tree harvests in the southern United States typically decrease during very wet periods, such as the spring, and some mountain harvests are not possible in winter due to deep snow.
- A mill with access to both wood and nontimber fiber crops might conceivably overcome some of these problems. However, the need for uniform quality would probably necessitate a constant mix of wood and nontimber inputs over most of the year, thereby still requiring a steady flow of nontimber fiber throughout the year.
- P. Farnum, R. Timmis, and J. L. Kulp, “The Biotechnology of Forest Yield,” Science 219 (1983): 694-702. This article shows that the theoretical maximum biological timber yield is 5 to 10 times natural yields.
- For example, Pinus radiata, commonly known as Monterey pine, grows much more rapidly in Chile and New Zealand than in its native California. Also, pines indigenous to the southern United States often grow more rapidly in southern Brazil and Argentina than in their native region.
- This estimate does not include production from wood plantations found in temperate regions, such as the United States or Europe. For more information, see R. A. Sedjo, The Potential of High Yield Plantation Forestry for Meeting Timber Needs: Recent Performance and Future Potentials, RFF Discussion Paper ENR 95-08 (Washington, D.C.: Resources for the Future, December 1994).
- R. A. Sedjo and K. S. Lyon, The Long-Term Adequacy of World Timber Supply (Washington, D.C.: Resources for the Future, 1990).
- For example, many of the lands in the southern region that initially supported native forest were subsequently used to grow tobacco, cotton, and food crops and then, more recently, replanted with trees.
- Similarly, if there were no market for beef, a large number of cattle would not be found in the feedlots of the Midwest or grazing the western rangelands.
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