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Plantation forestry is a well established form of intensive forest management. It is estimated that plantations provide 7 to 10 percent of the world's present commercial wood production. There are roughly 100 million hectares of forest plantations in the world (Gauthier, 1991).
Statistics on plantations must be treated with caution. Sometimes the figures are based on the accumulated area planted without any deductions for the areas felled. When estimates are made of the areas planted by local communities or farmers, the margin of error is even larger. Often the figures are based simply on the numbers of seedlings distributed and not on the numbers planted or surviving. On the other hand, the figures may omit the numbers of trees planted by farmers from their own seedlings.
The net area of forest plantations (taking into account the estimated survival rates) in the tropical countries in 1990 was estimated to be about 30 million hectares, counting industrial and community plantations but not including trees planted by farmers themselves on their own lands (Pandey, 1992). It has been calculated that plantations were established at an average rate of around 2.6 million hectares per year during the 1980s, and the present rate may be as high as 3 million hectares per year.
The world's rubber, coconut and oil palm plantations are not included in the area of forest plantations. These are mainly in Asia and the wood obtained from them is increasingly important. Their total planted area is about 14 million hectares, of which about 7.2 million are planted to rubber, 4.2 million to coconut and 2.7 million to oil-palm.
One of the oldest methods of plantation management is the taungya system. This was introduced in Myanmar (then Burma) in the 1850s for teak plantations and has since been used in many other areas. After logging, the forest is replanted. Farmers are allowed to grow crops in the planted areas in exchange for protecting the saplings and weeding the plot. In a few years, when the new trees are so large that food crops can no longer be grown in the shade they cast, the process is repeated m another area. Although the system offers a low-cost means of plantation establishment, it is not necessarily sustainable, since it relies on a shortage of permanent agricultural land and a supply of people willing to take part.
Plantations can be highly productive. The increment of timber from a tropical plantation may be 30 m³ per hectare per year (or more) compared with 2 to 8 m³ from a managed natural forests. But such figures need to be treated with caution Experience shows that the yields assumed at the planning stage of many plantations are overestimated, often by a factor of two or more. This was the case, for example, in the dendrothermal programme in the Philippines, which intended to use wood from rapidly growing plantations as fuel for electric power stations. The fact that yields turned out to be half those planned or less was one of the reasons for the failure of the programme.
Other aspects of plantation forestry, especially in the tropics, also leave much room for improvement. There are numerous examples of plantations that have failed or sites that have been degraded by ill-chosen exotic species. A review of tropical plantations (Pandey, 1992) observed that planning is generally poor, particularly in relation to vital issues such as the matching of species to the site. It also noted that plantation projects are often designed in haste, with scant attention paid to important issues because of time or financial constraints.
In the developing world, the main physical constraint to the future contribution of plantation forestry is the availability of land. With expanding farming populations using all the available unforested land for food production, the areas available for plantations are becoming ever more restricted. The experience of the past two decades has shown that degraded or "waste" land may be the only resource available to poor people.
There are, however, large areas where the natural forest has been badly degraded or where the soil fertility has been lost through overcultivation, which could be used for plantations. Such schemes could provide a source of employment and long-term income, provided the existence and needs of local people are recognized from the beginning. There are also large areas of salt-affected land; the total in the developing world is estimated to be about 150 million hectares. Much of this land could be brought into productive use by planting it with salt-tolerant trees. But even here there could be competition from agriculture; major efforts are being made in some areas to rehabilitate these lands or to use them for salt-tolerant crops.
As investments, the main feature of plantations is their long production cycle. Tropical timber plantations have rotations ranging from 15 to 20 years up to 60 to 80 years. In the temperate zones, the rotation periods are even longer. Because broadleaf species such as oak are now being used in response to the popular reaction against uniform conifer plantations in some European countries, some of the plantations now being established will have a rotation period of up to 150 years.
A highly ambitious global forestry programme was included in the Noordwijk Declaration (Noordwijk Ministerial Conference, 1989), the resolution of a ministerial-level, global meeting convened to discuss the problems of atmospheric pollution and climate change. Among the aims set out in the declaration were a world net forest growth of 12 million hectares per year by the turn of the century. It was not anticipated that all of the net forest growth would come from forestation of currently treeless land, but nevertheless a high proportion of the increase would be new plantations.
At present, there appears to be little prospect that the required planting rate will be achieved.
Plantation forestry nevertheless can continue to make a significant and expanding contribution to the needs of the world for wood. Without plantations, supplies can only be drawn from the natural forests. It is therefore important that governments continue to invest in plantations. It is also highly desirable that private-sector investments be encouraged. Because the returns from plantations are subject to a variety of long-term risks ranging from price collapses to natural calamities, as well as having long payback periods, it is essential that governments provide the necessary incentives to communal and private investors - with proper controls.
Plantations generally have one major objective for their establishment; often it is the production of wood, but some plantations are created for shelter and protection. Sometimes, however, plantations can supply both wood and non-wood products. Examples are the growing of cardamom under the shade of eucalypts India, or the raising of mushrooms in Pinus radiata plantations in Chile (FAO, 1993a).
There can be no pretence that plantations can provide the full range of goods and services supplied by a natural forest. They comprise tree crops, analogous to agricultural crops, with a simplified ecology of one or at most a few species usually chosen for their yield and ease of management. The primary purpose of most plantations is to produce wood or other products quickly and cheaply. Their role, which is a highly valuable one, is as a complementary element in national or global forestry management strategies.