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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 plantation
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.
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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.
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 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 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.
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.
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).
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