In forestry, plantations of trees are typically grown as an even-aged monoculture for timber production, as opposed to a natural forest, where the trees are usually of diverse species and diverse ages. A plantation is not a natural ecosystem. Plantations are also sometimes known as “man-made forests” or “tree farms”, though this latter term more typically refers to specialist tree nurseries which produce the seedling trees used to create plantations. More generally a planta
tion is a forest land where trees are grown for commercial use, most often in a naturally regenerated forest but could also be a planted. In the United States, the term “Tree Farm” is a trade mark of the American Tree Farm system, a third party verification system for certifying sustainable forestry. The American Tree Farm system dates back to 1941 as a progam to improve forestry practices on farms. The term tree farm is also sometimes used to describe the sale of live trees for landscaping.
A plantation is usually made up of fast-growing trees planted either to replace already-logged forests or to substitute for their absence. Plantations differ from natural forests in several ways:
Plantations are usually monocultures. That is, the same species of tree is planted in rows across a given area, whereas a conventional forest would contain far more diverse tree species.
Plantations may include introduced trees not native to the area, including (in a few cases) unconventional types such as hybrid trees and genetically modified trees. Since the primary interest in plantations is to produce wood or pulp, the types of trees found in plantations are those that are best-suited to industrial applications. For example, pines, spruces and eucalyptus are widely used because of their fast growth rate, and are good for paper and timber production.
Plantations are always young forests. Typically, trees grown in plantations are harvested after 10 to 60 years, rarely up to 120 years. This means that the forests produced by plantations do not contain the type of growth, soil or wildlife typical of old-growth natural forest ecosystems. Most conspicuous is the absence of decaying dead wood, a very important part of natural forest ecosystems.
Plantations are grown by state forestry authorities (for example, the Forestry Commission in Britain) and/or the paper and wood industries and other private landowners (such as Weyerhaeuser and International Paper in the United States Christmas trees are often grown on plantations as well. In southeast Asia, rubber, oil palm , and more recently teak plantations have replaced the natural forest.
By convention, plantations of fruit-bearing trees are termed orchards, even if grown on scales that occupy a landscape to the horizon. Plantations of grapevines are termed vineyards.
Classification of Tree Plantations
Industrial Tree plantations
Industrial plantations are actively managed for the commercial production of forest products. Individual blocks are usually even-aged and often consist of just one or two species. These species can be exotic or indigenous. Industrial plantations are usually large-scale.
Wood production on a tree plantation is generally higher than that of natural forests. While forests managed for wood production commonly yield between 1 and 3 cubic meters per hectare per year, plantations of tropical species commonly yield between 5 and 20 cubic meters per hectare annually; A eucalyptus plantation can have growth rates of 25 cubic meter per hectare per year or higher. World wide, forest plantations now amount to less then 5 percent of total forested area, but account for 20 percent of current world wood production.
Criticism of large scale industrial plantations
In the 1970’s Brazil began to establish high-yield, intensively managed, short rotation plantations. These types of plantations are sometimes called fast-wood plantations and often managed on a short-rotation basis,as little as 5 to 15 years. They are becoming more widespread in South America, Asia and other areas. The environmental and social impacts of this type of plantation has caused them to become controversial, In Indonesia for example large multi-national pulp companies have harvested large areas of natural forest with out regard for regeneration. From 1980 to 2000 about 50% of the 1.4 million hectares of pulpwood plantations in Indonesia have been established on what was formely natural forest land.
The replacement of natural forest with tree plantations has also caused social problems. In some countries, again, notably Indonesia, conversions of natural forest are made by with little regard for rights of the local people. Plantations established purely for the production of fiber provide a much narrower range of services then the original natural forest for the local people. India has sought to limit this damage by limiting the amount of land owned by one entity and, as a result smaller plantations are owed by local farmers who then sell the wood to larger companies. Some large environmental organizations are critical of these high-yield plantations and are running an anti-plantation campaign, notable the Rainforest Action Network and Greenpeace.
Farm or home Tree Plantation
Farm or home plantations are typical established for the production of lumber and fire wood for home use and sometimes for sale. Management may be less intensive then Industrial plantations. In time this type of plantation can become difficult to distinguish from naturally-regenerated forest.
Environmental Tree Plantations
Environmental Plantations may be established for watershead or soil protection. There are established for erosion control, landslide stabilization and windbreaks. Such plantations are established to foster native species and promote forest regeneration on degraded lands as a tool of environmental restoration.
Ecological Impact of Tree Plantations
Probably the single most important factor a plantation has on the local environment is the site where the plantation is established. If natural forest is cleared for a planted forest then a reduction in biodiversity and loss of habitat will likely result. In some cases their establishment may involve draining wetlands to replace mixed hardwoods that formerly predominated, with pine species.
If a plantation is established on abandoned agriculture land, or highly degraded land, it could result in an increase in both habitat and biodiversity. A planted forest can be profitably established on lands that will not support agriculture or suffer from lack of natural regeneration. The tree species used in a plantation is also an important factor. Where non-native varieties or species are grown, few of the native fauna are adapted to exploit these and further biodiversity loss occurs. However even non-native tree species may serve as corridors for wildlife and act as a buffer for native forest, reducing edge effect.
Once a plantation is established, how it is managed becomes the important environmental factor. The single most important factor of management is the rotation period. Plantations harvested on longer rotation periods ( 30 years or more) can provide similar benefits of a naturally regenerated forest managed for wood production, on a similar rotation. This is especially true if native species are used. In the case of exotic species the habitat can be improved significantly if the impact is mitigated by measures such as leaving blocks of native species in the plantation or retaining corridors of natural forest. In Brazil, similar measures are required by government regulations.
Plantations and natural forest loss
According to the FAO about 7 per cent of the natural closed forest being lost in the tropics is land being converted to plantation The remaining 93 per cent of the loss is land being converted to agriculture and other uses. World wide an estimated 15 % of plantations in tropical countries are established on closed canopy natural forest.
In the Kyoto Protocol there are proposals encouraging the use of plantations to reduce carbon dioxide levels (though this idea is being challenged by some groups on the grounds that the sequestered CO2 is eventually released after harvest).