John A. Stanturf and Daowei Zhang 1
This paper reviews the development and current conditions of forest plantations in the United States of America. Market demand, public policy and new technology drive plantation development. Only 11% of timberland is planted (22 million ha), mostly in the South. Plantation area is projected to increase. Management intensity is greatest in the South and lowest in the Northeast. The near-term opportunities for intensification of plantation management in the South are greatest for improving nutrition and further deployment of other intensive practices. New plantations established on former agricultural land might help meet future fibre demands. Biotechnology offers great potential for forestry but many scientific, social, ethical and regulatory concerns must first be addressed. The economic viability of plantation forestry is tied to the health of the forest industry, which some observers question. Nevertheless, forest plantations will play a larger role in future timber supply and forest resource conservation.
The United States has 302 million ha of forestland, or 33% of the total land area. About two-thirds of forestland is classed as timberland (204 million ha), capable of producing more than 1.4 cubic meters per hectare per year and not legally withdrawn from timber harvest (Smith et al. 2002). Public forests dominate in the West, while eastern forests are mostly privately owned. Only 11% of timberland is planted (22 million ha) and most of that is in the South (67%--14.5 million ha). Planted forests must contain at least 40% planted trees and may be further divided into plantations and augmented forests. In plantations, there is on-going management to maintain a composition of almost exclusively planted trees. To a great degree, actively managed plantations are privately owned.
Intensively managed plantations could reduce the pressure on natural forests to meet fiber demand (Sedjo 2001). One extreme estimate is that world demand for wood could be met by intensively managed plantations on 10% of the area now open to harvesting (Oliver 1999, Sedjo 2001). Although there are many unintended consequences of not managing natural forests (e.g., forest health, wildfire risk, economic dislocations; Oliver In Press), a greater dependence on plantations to supply industrial fiber is occurring in an ad hoc fashion as public land is removed from timber management. Discussions of the Botkin-Sedjo approach usually assume that intensively managed plantations will be located in the tropics and sub-tropics on former agricultural land or converted from degraded natural forests (Nilsson et al. 1999, Victor and Ausubel 2000, Sedjo 2001). Yet there are already intensively managed plantations in the United States and they are projected to increase in area (Haynes 2002, Prestemon and Abt 2002). Our objectives in this paper are to present an overview of the current status of plantation forests in the U.S. and to discuss some of the factors that will shape their development in the near-term.
Forest plantations went through three phases of development: initiation, acceleration, and steady growth (Zhang 2002). The initiation phase, beginning in the colonial period and extending through the end of the Second World War (1945), was characterized by limited tree planting. It was not economical and was rarely supported by government policies until the Great Depression (1930s). Tree planting accelerated during the postwar period until 1976, fueled by strong market demand and accompanied by high prices for fiber. Favorable tax policies and various government cost-share programs made tree planting economical on private land. The area of private land planted during this phase increased 90 fold, from 15,834 acres in 1946 to 1.43 million acres in 1976 (Zhang 2002).
Plantation area grew steadily from 1977 to 1999. Private tree planting expanded but at a lower rate. By 1999, private tree planting had increased to 2.42 million acres. Public environmental policy had a major, although somewhat indirect impact on private plantation development. For example, agency implementation and judicial action under the 1976 National Forest Management Act and the 1973 Endangered Species Act gradually decreased timber supply from public land, mostly in the Pacific Northwest and increased demand from private land, mostly in the South. The share of timber production from private forests in the U.S. has increased dramatically (Zhang 2002). During the period from 1970 to the present, domestic timber production has been at all-time high levels, peaking in 1990 at 530 million cubic meters (Howard 2001). Timber production on public forests decreased over this period, from 25% of total U.S. production in 1970 to 11% in 1997. Over the same period, non-industrial private forests provided an increasing share of production, jumping from 48% to 60%.
Comprehensive information for the area of plantations is lacking. Official estimates of 16,238,000 ha (FAO 2001) exclude the 5.5 million ha of planted forests in the Western U.S. because it is impossible in field sampling to distinguish between plantations and augmented forests due to rapid in-growth of unplanted species. Underestimation may be a problem in other regions, especially of older plantations. On the other hand, areas counted as plantations may cease to be managed and never harvested due to changed ownership and urbanization.
Management varies by ownership, region, and species (Escalante et al. 2002). Forest industry manages the most intensively, other corporate owners (essentially financial institutions and investment entities) and large non-industrial private owners somewhat less intensively, with lowest intensity by small non-industrial private owners. Management intensity of publicly owned plantations is least on federal land and most some on state and local government land, especially in the Lake States. In general, management intensity is greatest in the South and lowest in the Northeast. Broadleaves are both the most and least intensively managed plantations; fertigated hybrid poplar in the Pacific Northwest are the most intensively managed, while the widely spaced and direct-seeded restoration plantings in the South are the least.
Large areas of the South have been planted to species of pine, primarily loblolly (P. taeda) in the coastal plain; slash pine (P. elliottii) in Florida and adjacent states; and increasingly longleaf pine (P. palustris) for restoration. All are native species although timber management has drastically changed their relative dominance. One out of six ha of timberland in the South is a plantation; of every 100 ha of plantations in the South, 94 are privately owned (54 ha by industry, 40 ha by other private owners); of the 6 ha out of 100 ha that are publicly owned, 4 are in National Forests and the rest owned by other public entities such as state forestry or wildlife agencies (Guldin and Wigley 1998). Loblolly pine achieves 25% or greater growth than slash under intensive management and is more resistant to fusiform rust. Wood quality of slash pine is superior to loblolly, especially for lumber, and it is more resistant to Southern pine beetle. Longleaf pine has been more difficult to regenerate in the past and is less favored for plantations for timber production but interest in restoring native longleaf ecosystems is driving conversions from plantations of other pine species and on former longleaf sites now occupied by low-quality hardwoods.
Widespread planting of red pine (P. resinosa), white pine (P. strobus) and jack pine (P. banksiana) took place during the 1930s in the Lake States and Northeast on abandoned farmland, cutover forestland, and following catastrophic wildfires. Planting was primarily of red pine. White pine, while valuable for timber, was plagued with problems of white pine blister rust and white pine weevil. Red pine planting on new sites continued in the Lake States into the 1980s, and it is the species most often planted after harvesting. Today red pine is the most important conifer in the Lake States, and markets have developed to use the material. Although widely planted on public land in New York and other northeastern states during the Depression, demand did not develop to the same extent and it is doubtful that these plantations will be maintained into another rotation. In Maine, older pine plantations are allowed to naturally regenerate following harvest.
Industrial plantations of Douglas-fir (Pseudotsuga menziesii) occur west of the Cascade mountain range in Washington and Oregon in the western U.S. Management intensity is less than in the South, with little site preparation following harvest. Banded herbicide may be used to control competing vegetation in the first year, with little fertilization. Rotation age is around 40 to 45 years, with 2 or 3 thinnings.
The native Eastern cottonwood (Populus deltoides) is the fastest growing tree in North America. Interest in growing cottonwood has fluctuated and objectives have shifted between sawlogs, pulpwood, and biofuels. Most plantations today are established for pulpwood or chip production on rotations of ten years or less (Stanturf et al. 2001a). Plantations are established using clones and the native P. deltoides clones have out-produced hybrid poplar in the South. There are approximately 15,000 ha of cottonwood plantations, primarily in the Mississippi River Valley.
Oaks and other Hardwoods
Forest industry has dabbled in hardwood plantation culture in the South, focusing primarily on sweetgum (Liquidambar styraciflua), sycamore (Platanus occidentalis), green ash (Fraxinus pennsylvanica), and various oaks (Quercus spp.). Industry interest has waned in recent years but public agencies are active in restoring floodplain hardwood forests in the primarily the states of Mississippi, Arkansas, and Louisiana. Current plans for restoration on public and private land suggest that as many as 200,000 ha could be restored over the next decade (Stanturf et al. 2001b, Stanturf and Madsen 2002). The dominant goal of these restoration programs has been to create wildlife habitat and improve or protect surface water quality.
Approximately 1,000 ha per year of hybrid larch (Larix spp.) were planted in Maine by one company for several years. When another company acquired the land, larch planting ceased. Nevertheless, there is a demand for high quality long fibers in the Lake States and Maine that could be furnished by hybrid larch.
There are nearly 50,000 ha of hybrid poplar plantations in the Pacific Northwest (Oregon and Washington). West of the Cascade Mountains, poplar plantations have been established on poorly-drained alluvial soils of the lower Columbia River floodplain. High yields are obtained in 8 years. East of the Cascades in the semi-arid, sandy soils of the mid-Columbia River Basin, fertigated (fertilizer applied in the irrigation stream) plantations are merchantable after 6-7 years (Stanton et al. 2002). Established originally in response to a projected regional shortage of pulpwood, growers today are shifting toward solid wood products. Nevertheless, rotations will remain short (under 15 years) to maintain their status as agricultural crops, which provides more favorable regulatory environment for intensive management as well as tax advantages.
Projected shortages of native aspen for fiber production have led to interest in hybrid poplar in the Lake States, particularly Minnesota. The first commercial plantings in early 1990s began an active planting program that continues. Today, there are over 7,000 ha of hybrid poplar planted in Minnesota.
Demonstration scale plantings of Salix hybrids in New York have reached 200 ha. Plantings are clonal material, primarily of shrub willow types, intended for energy and bioproducts. Plantations are harvested on a 3-4 year cycle, with 6 to 7 harvests possible before re-planting is needed.
There are approximately 5,000 ha of Eucalyptus plantations in northern California. Extensive trials in the South failed due to low temperatures. Although Eucalyptus could thrive in Peninsular Florida, land values are too high for development for this to be attractive.
Timber supply models predict expansion of plantation area in the South and further intensification of management (Haynes 2002, Mills 2002, Prestemon and Abt 2002). The potential for intensification in other regions is greatest in the Lake States and Pacific Northwest where processing capacity exists. The question is whether plantation management will intensify in a similar fashion or will fiber needs be met by imports. The near-term opportunities for intensification of plantation management in the South are greatest for improving nutrition and further deployment of intensive practices. Although great strides have been made in understanding nutrient limitations and developing site-specific prescriptions and fertilization technology, management of forest nutrition is at a developmental stage similar to agriculture in the 1960s. Realizing productivity gains requires further development of spatial planning tools, together with growth and yield models that incorporate intensive treatments and interactions with genetic makeup.
New plantations established on former agricultural land might help meet future fiber demands. Afforestation of conifers and broadleaves occurs under several federal incentives programs designed to garner environmental benefits. Market forces may further drive this trend. In the South, afforestation with pine and cottonwood in less populated areas may compensate for conversions to urban uses (Prestemon and Abt 2002). To the extent that public funding pays for establishing new plantations on private land, public sentiment can influence private decisions. Conversion of existing low-quality hardwood stands to pine plantations will be resisted just as converting natural pine forests to plantations pine has been challenged (Wear and Greis 2002). Hybrid larch plantations in the Lake States could provide fiber of needed quality and reach pulpwood size in 20 to 25 years. Hybrid larch would be an exotic, however, of unknown acceptability to the public. Afforestation with hybrid poplar likely will continue and help meet regional demand for fiber for pulp, oriented strand board, and biofuels.
Biotechnology offers great potential for forestry but many scientific, social, ethical, and regulatory concerns must be addressed before the potential can be realized. Biotechnology is being used to vegetatively propagate superior genomes in clonal forestry. The technology exists now to develop Genetically Modified Organisms (GMOs) such as conifers able to tolerate herbicides that act on broadleaved competition, but there are no commercial plantings of GMO trees. Eventually, biotechnology will be used to develop disease-resistant trees and trees with specific wood properties. Such designer trees could be developed for pharmaceutical and chemical feedstocks, as well as with fiber properties attractive to papermakers. While the U.S. population appears to have a greater tolerance for GMOs in food than Europeans, use of biotechnology in forestry may be a flashpoint. To date, there has been limited public opposition to hybrids. Nevertheless, extremist groups have destroyed or vandalized hybrid poplar breeding programs in the Pacific Northwest and the Lake States, under the mistaken belief that they were genetically modified organisms (GMOs).
The economic viability of plantation forestry is tied to the health of the forest industry. Forest industry has been criticized for its low return on equity; one response has been to sell off corporate timberlands. In the South, where plantation forestry is concentrated, pine pulpwood prices peaked in 1998 and are now at 50% of that price level. Even before the peak in pine stumpage, the U.S. South was not the lowest cost pulpwood producer (Hytonen and Pihlajamaki 2000). Plantations in tropical and subtropical countries are more productive with lower production costs. The economics of the industry has always been cyclic, but some observers speculate that the latest downturn is different; they question whether forest industry will be economically viable in the long-term.
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1 U.S. Department of Agriculture Forest Service, 320 Green St., Athens, GA 30602, USA. [email protected];