|Abstracts on Sustainable Agriculture (GTZ, 1992, 423 p.)|
|Abstracts on agroforestry|
In: Proc. of the Humid Trop. Lowlands Conference, Panama City, Panama, 1991, pp. 55-68
This paper lays down the principles governing successful plantation forestry in the lowland, humid tropics and seeks to address the issues which underpin sustainability: land capability, species choice, and management. Relevant examples are drawn from across the tropics.
While plantation forestry is often associated with industrial plantations the enormous expansion in social forestry is not neglected.
Accurate data for areas of tropical plantations are notoriously difficult to obtain. Gathering information from just over 100, mainly developing countries inevitably leads to a variety of definitions, confusion over units, optimism by some of equating seedlings supplied or planted with plantation established, lack of proper inventory, and so on. Nevertheless, from the available data, it seems clear that some 20 million ha of forest plantations of various forms have been established throughout the tropics and hotter subtropics in the last 10 years to give a global figure in excess of 40 million ha.
The virtual doubling of plantation forest area in the last 10 years arises from a massive social forestry program in India, though the quality and stocking of much new 'plantation' is questionable; a clearer picture of afforestation in tropical China; and programs of steady expansion in many countries. The bulk of the increase in the neotropics has occurred in Brazil, owing to the fiscal incentives program which ran from 1967 to 1986 and averaged some 300,000 ha per year from the early 1970s, but has since diminished to about one-tenth of this level.
An examination of tree planting schemes in the last 10 years shows a shift from one of replacement of natural forest formations, e.g. Jari, Brazil, to afforestation of already badly degraded land or natural savanna, cerrado, or grassland. This change is both laudable from a conservation point of view and reflects the fact that huge areas of land, since long deforested, are suitable for tree planting but not a lot else. The 40 million ha of Imperata grassland in Indonesia are a striking example.
Correct choice of species for a given site is fundamental to sustainable plantation forestry. Poor species choice will not only give poor yields about may increase risk of pest and disease damage. The ingredients of successful matching of species to site include first climate matching followed by attention to soil factors.
Industrial plantation forestry has been dominated by planting of a very few species in the lowland tropics. Indeed Pinus caribaea, Gmelina arborea, teak, and Eucalyptus grandis, E. camaldulensis and E. urophylla probably account for 90%.
The last 10 years has seen a significant broadening. Increased use of little tested species, promotion of nitrogen fixing trees, and advances in vegetation propagation technology have contributed to this.
In addition to variation due to provenance, and to all sources of variability, there is evidence of an interaction between the selected genotype and the site. The highest ranked provenances, varieties, families or clones will not necessarily be the same on all sites. This is known as genotype x environment interaction (GEI) and breeding strategies must recognize this feature.
Plantation forestry is a feasible silviculture in the lowland tropics provided attention is paid to sound practice to ensure properly matched species and sites and regular management inputs. It is not a cheap form of forestry, but with commitment over time to a project, including tree breeding programs, the large investment can repay in highly productive forest which appears to be sustainable on most sites.
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Latin America, Peru, study, project, forest management, Indians, land tenure, forestry cooperative