| By definition, reforestation refers to the establishment of a tree crop or stand on land on which a forest was present within the last fifty years (Evans 1992). This definition would include the cases where natural forests have been logged and then replaced with a plantation, often of a single species. When, in contrast, tree crops are established on land where no forest has existed for over fifty years, such as grasslands, the process is deemed afforestation. Forests are also commonly reestablished by natural regeneration through a host of reproductive strategies, depending on the sites and species involved. In this article, however, reforestation refers to the establishment and management of tree plantations, deemed plantations from here forward.
Extent and Importance of Plantations
Although tree planting for diverse purposes has a long history, only during the last century has plantation forestry taken on global importance as a source of wood and other products for industrial and non-industrial purposes. Indeed, worldwide, in the last century the area under plantations has increased from a negligible amount to an estimated 143 million hectares, half of which have been established for industrial purposes (FAO 2005; Kanowski 2005; Varmola et al. 2005). This is a remarkable figure when one considers that in 1980 there was an estimated 17.8 million hectares of plantations worldwide. But the importance of plantations can not be discerned by area alone. In 1995, for example, only 3.5% of global forest area corresponded to that under plantations (Brown 2000). Nonetheless, the proportion of global, industrial roundwood supplied from this resources in 1999 was estimated to be 35% and is expected to exceed 40% in the near future. In Latin America, plantations account for only 2.0% of the forested area, but supply more than 27% of industrial roundwood. In Chile, with its highly advanced plantation industry, this percentage increases to 85% (Brown 2000) and in Costa Rica, a country which has traditionally harvested its wood from natural forests, an estimated 62% of roundwood consumed now comes from plantations (Arce and Barrantes 2004). Clearly, plantations are capable of producing considerable volumes of wood over comparatively small areas when compared to natural forests.
In the Americas, the country with the largest industrial plantation areas is the United States with over 18 million hectares. In Latin America over 11 million hectares have been planted, 70% of which are found in Brazil (5.4 million hectares), Chile (2.7 million hectares), Argentina (1.2 million hectares) and Uruguay and Venezuela (0.8 million hectares each) (Food and Agriculture Organization of the United Nations – FAO 2001, 2005). Although plantations are often considered important for offsetting forest loss due to deforestation, in most countries total plantation area is only a fraction of the area deforested on average each year. In other words, the land under trees continues to decline. Notable exceptions include the United States and Canada, where forest area has tended to stabilize or even increase in some regions. The reduction of forest cover in many regions has been accompanied by a steady increase in demand for forest products (FAO 1995). These trends have been a strong argument for promoting reforestation with plantations.
Industrial versus Non-industrial Plantations
An estimated 26% of the world’s plantations have been established for non-industrial purposes (fuelwood, soil and water conservation, wind protection and other products). In terms of area, however, the great majority of the plantations in the Americas have been established for industrial purposes. Forest industry has made remarkable advances in nursery and plantation technology, including genetic improvement, clonal propagation, site preparation and precision silviculture. In many countries, the initial impetus for establishing plantations has been publicly financed incentive programs providing attractive conditions for investment into plantations. Incentives have ranged from direct cash disbursements and fiscal incentives to the use of food aid to encourage local participation of rural communities in plantation establishment. When incentive programs are discontinued before a viable plantation-based forest industry is consolidated, reforestation rates tend to fall off rapidly, creating disruptive gaps in wood supply for fledgling industries (Arce and Barrantes 2004).
Even in countries where deforestation is problematic and people are forced to invest considerable time and resources to obtain fuel wood and wood for other uses, incentive programs have not always been successful. For reforestation to be successful, whether it be for industrial or non-industrial purposes, a number of conditions must be met, some of which are discussed below.
Important Conditions for Successful Plantations
Conditions important for the success of plantations, and hence, for reforestation programs in general, include a wide host of planning considerations, technical and financial aspects and local capability to access attractive markets and manage business concerns. Oftentimes, the establishment of plantations is viewed as a cure-all, a nearly infallible strategy for offsetting deforestation, providing environmental benefits and stimulating local development. In practice, the reality is a great deal more complex. In this section, a small number of examples of these conditions will be provided that illustrate their importance to the success of reforestation programs.
Planning Considerations
The formulation of clear objectives is one of the first steps in planning a reforestation program. Clear objectives will influence the species to be planted, the planning of appropriate stand management regimes and will indicate the types of market opportunities that must exist for the products generated to be sold. Surprisingly, reforestation programs have often been launched and implemented without meeting this basic condition. When this has occurred, plantations have often been left to develop without any intermediate management interventions leading to the production of low-value products with poor market opportunities, if any .
To understand why this is the case, it is important to how plantations grow. Trees in plantations are generally grown at narrow uniform spacings, for example, 3 x 3 meters or even narrower (a 3 x 3 meter plantation would have 1,110 trees per hectare). A plantation owner with a young stand has the option of producing a large number of small trees or a fewer number of larger trees. Thinning is an intermediate operation carried out in plantations in which the production of larger diameter is desired. Thinning not only leads to the production of larger diameter trees, it also serves to remove inferior quality trees possessing quality defects or phytosanitary problems. Plantations have a fairly narrow window of opportunity when tree density can be reduced to enhance diameter growth to an optimal degree. In fast-growing tropical plantations this window can be exceptionally narrow and unless thinning is planned right from the start, this opportunity can be and often is missed. The common result is a dense plantation composed of spindly, small diameter trees of deficient quality with poor market perspectives (Galloway et al. 2001).
Another common problem arising from deficient planning relates to timing. For outplanted seedlings to flourish during the establishment phase, they must be of good quality and they must be planted during a favorable period of the year, preferably early in the rainy season. The availability of high quality seedlings at the appropriate time of year is a product of good planning, made possible by knowledge of nursery time requirements for individual species and timely availability of seeds and other inputs. When planning fails due to insufficient knowledge or the late provision of essential inputs, acceptable seedlings may not be available until late in the rainy season. If the decision is made to proceed with planting, poorly established seedlings will be forced to endure the dry season, increasing the chances of seedling mortality and poor growth of the trees that do survive. Thousands of hectares of plantations have failed in Latin America due to these types of problems. The development of comprehensive timelines detailing important steps in the nursery and during plantation establishment and optimal dates for their realization are instrumental to good planning.
Technical and Financial Aspects
A large number of technical and financial aspects must be taken into account in the implementation of successful reforestation programs. Examples of technical aspects include: species selection, site selection, site preparation, seedling production and transport, organization of planting crews, weeding, fertilization, road construction, insect and disease problems, plantation protection, thinning, pruning, inventories, harvesting, among others. Since plantation forestry is not a traditional land-use in many regions where it is promoted, a considerable amount of knowledge must be generated and/or brought together and disseminated to favor plantation quality and success. Whether the entity establishing the plantation is a private company or a rural community, those carrying out the operations in the field must possess the required knowledge for success. Therefore, practical research and training are essential components of any successful reforestation program. The decision to move forward with deficient knowledge and/or insufficient training of operational personnel is a common precursor to plantation failure.
Apart from the importance of opportune cash flow for the purchase of key inputs such as seeds, tools and other materials during plantation establishment, it is equally important to ensure their availability for the execution of intermediate operations such as thinning. Incentive programs often channel support to landowners and communities during the initial period of plantation establishment and fail to project the costs and labor requirements for operations later in the rotation. When this occurs, lack of adequate financial resources can often lead to plantation abandonment, with the implications alluded to earlier in this article.
Commercialization and Business Concerns
In many countries, plantation programs have tended to emphasize the technical aspects of plantation establishment and devote insufficient attention to intermediate operations. This skewed approach to plantation forestry is logical when considers that incentive programs and reforestation projects normally have limited time horizons and sometimes terminate before intermediate operations are underway. Other problems commonly arise when plantations do attain commercial size, especially if the producer has no prior experience in marketing timber and administering the resources generated. Well-established forestry enterprises usually have clearly identified market options and possess adequate administrative and accounting procedures. This is often not the case in rural communities and among unconsolidated small and medium forestry enterprises growing plantations as a commercial crop for the first time. Gradually, more attention is being given to these concerns in an effort to enhance the commercial success of plantation initiatives.
The Controversy over the Desirability of Plantations
In recent years much debate has raged in Latin America on the impacts, both positive and negative, of plantations. On the positive side, trees are perceived to produce wood and other products, sequester carbon, generate employment, reduce erosion and contribute to the regulation of the hydrologic cycle. On the negative side, plantation critics cite the replacement of natural forests with monocultures of exotic species, the reduction of water yields from fast-growing plantations in water catchments, laminar erosion under species like teak and social problems when plantations are established over large areas. In this section some of these contentious issues will be briefly addressed.
The Replacement of Natural Forests by Plantations of Exotic Species
In some parts of the world, large swaths of native forest have been cleared to free up land for fast-wood plantations -- plantations that produce at least 15 m3 of wood per hectare per year (Cossalter and Pye-Smith 2003). Although this practice has certainly occurred in some countries, the predominant tendency in Central and South America is to establish plantations where forests have been previously cleared for cattle grazing or agricultural production, by far the greatest causes of deforestation in these regions. Indeed many companies involved in reforestation now make a concerted effort to conserve remnant natural forests on marginal sites and along streams and rivers to enhance biological connectivity across the landscape. In general, the idea of destroying native tropical forests -- with their wealth of biodiversity and other values -- to establish monocultures of exotic tree species is no longer viewed as an attractive or even acceptable option.
The Impact of Plantations on Water Yields from Water Catchments
Misunderstandings abound with regards to the impacts of plantations on water yields from water catchments. “Myth-makers” as Cossalter and Pye-Smith (2003) term them, have credited plantations with the remarkable ability to attract rainfall and increase water yields from watersheds. Although plantations certainly do not attract rainfall, they do impact the hydrological site on sites where they are planted. The type and degree of impact depends on many factors such as plantation density, the species planted, slope, rainfall patterns, annual precipitation, soil characteristics, among others. Dense plantations with closed canopies intercept rainfall which through evaporation can be returned to the atmosphere. Dense stands will also transpire appreciable quantities of water through their leaves: the combination of these two processes is termed evapotranspiration. In regions with light intermittent rainfall, these losses can reduce water yields to a significant degree. In contrast, in regions with higher precipitation and torrential rains, these losses will be insignificant to water yields. Water runoff on reforested sites will depend on slope, soil type and its degree of saturation. Again, plantations will do little to control runoff during extreme rainfall events. Prudence would suggest avoiding the establishment of dense, fast growing plantations in water catchments important to communities, especially where annual precipitation is moderate to low. Negative impacts can be reduced by lowering stand density which will allow more through fall and reduce evapotranspiration.
Exotic Versus Native Species
Fast growing species pines and eucalypts are the most common species planted in Latin America in both industrial and non-industrial plantations. Teak is gaining in importance as the world market for quality timber increases. One attribute these species have in common is that they are exotic to the Americas. Although the areas under these species is still comparatively quite small, there use has generated considerable concern among some groups of environmentalists, who fear a replacement of natural vegetation with exotic species. These fears would appear to be misplaced, since the great majority of plantations established today, are planted on sites previously deforested for cattle grazing and agricultural production. Indeed studies in Costa Rica, Colombia and elsewhere have discovered that natural regeneration is often favored under exotic plantations, since grazing and fire are controlled within their confines.
On the other hand, there are many reasons to increase attention in the use of native species in reforestation programs. In most countries, there are a large number of species highly valued by local populations and known to provide important habitat for species of fauna. A recent consultation with farmers throughout Central America, for example, yielded a list of over 1000 species mentioned as important, including both native and exotic species, but of the 150 species deemed “most important”, only 12 species were exotic (Cordero and Boshier 2003).
In most cases, native species are incorporated into agricultural landscapes – sometimes into agroforestry systems – but much less so in pure block plantations. As in the case of exotic species, the potential of a specific native species for use in plantations must be determined through research, certainly before embarking on a massive promotional campaign encouraging its use. Valuable, native tropical hardwoods have been found to be equally sensitive to site conditions that limit the success of exotic species: poor soil fertility, soil compaction (common in previously grazed sites), grass competition, etc. Thus, native species must be given the same technical considerations as exotic species when planted in plantations (Galloway et al. 2005).
The Role of Plantations on the Reduction of Pressure on Natural Forests
Many people have argued that reforestation with fast-growing plantations will reduce the pressure on natural forests. The idea is that by establishing extensive plantations, forest industry will shift from a dependency on wood produced in natural forests to the more concentrated and uniform resource generated by plantations (Cossalter and Pye-Smith 2003). As was indicated, there are examples in Central and Latin America where countries are meeting a greater proportion of their wood needs, through the harvesting of plantations: Chile and Costa Rica, for example. Plantations have also been the driving force behind forest industry development in Brazil. More local examples can also be sited. In southern Guatemala, small-scale eucalypt plantations now supply tobacco growers in Mexico with poles for drying tobacco, thereby reducing pressure on diminishing mangrove forests. Carton de Colombia, based in Cali, Colombia, was successful in making the shift from tropical hardwoods harvested from natural forests to plantation grown wood in a relatively short period of time.
Nonetheless, these and other examples require further scrutiny. In the cases of Chile and Costa Rica, deforestation has already greatly reduced the area under natural forests, and much of the remaining forests are under some type of protection. In Brazil, forest conversion in the Amazon is taking place at a rapid rate, primarily for cattle and agricultural production. Although Carton de Colombia is an interesting success case, overall the natural forests of Colombia continue to be subjected to conversion to other land uses. Throughout the region, plantation initiatives can often be considered a separate phenomenon to that of natural forest loss, which is primarily taking place for agricultural purposes.
There is a consensus that the demand for forest products will increase in the future do to a combination of population and economic growth. In this scenario, it is believed that the importance of plantation grown wood will continue to augment in many countries. Nonetheless, increasing production from plantations will, in many cases, only offset increasing demand and will not necessarily reduce the pressure on remaining natural forests (Brown 2000).
Final Comments
The area under plantations has increased dramatically during the past twenty to thirty years. In like manner, a growing proportion of industrial roundwood is being produced in plantations, especially fast-growing plantations in countries like Chile and Brazil. Beyond the interest in the area planted, experience has shown a number of conditions must be met for plantations to be successful indicating the need for balancing plantation quantity with quality concerns. Finally, the existence of large reforestation initiatives has sparked heated debate on the impacts of plantations and on their future role in meeting societal demands for forest products. Experience suggests the need for objectivity in these debates, since plantations, in and of themselves, are neither inherently good nor bad. They do offer an effective alternative for supplying a portion of growing demand for wood and paper products, and they will no doubt continue to play an important role in forestry in the Americas in the future.
References and Further Reading
Arce, Hector and Alfonso Barrantes. La Madera en Costa Rica: Situación Actual y Perspectivas. Costa Rica: Fondo Nacional de Financiamiento Forestal, Oficina Nacional Forestal, 2004.
Brown, Christopher. The Global Outlook for Future Wood Supply from Forest Plantations. Rome. FAO Working Paper No: GFPOS/WP/03, 2000.
Cordero, J. and D.H. Boshier, Editors. Árboles de Centroamérica. Oxford. Forest Research Programme, 2003.
Cossalter, C., Pye-Smith, C. 2003. Fast-wood forestry: Myths and realities. CIFOR Forest Perspectives Series. 50 p.
Evans, J. 1992. Plantation forestry in the tropics (Second edition). Oxford Science Publications, Oxford, UK. 403 p.
FAO. Forestry statistics: today for tomorrow. Rome. Forestry Planning and Statistics Branch, Forestry Policy and Planning Division, 1995.
FAO. Global Forest Resources Assessment 2000. Main Report. Rome. FAO Forestry Paper 140, 2001.
FAO. 2005. The State of the World’s Forests 2005. Available at: http://www.fao.org/forestry/index.jsp.
Galloway, G., Ugalde, L., and W. Vasquez. “Importance of Density Reductions in Tropical Plantations: Experiences in Central America.” Forest, Trees and Livelihoods. 11 (2001):217-232.
Galloway, G. S. Kengan, B. Louman, and D. Stoian. 2005. Changing paradigms in the forestry sector in Latin America. In Forests in the Global Balance – Changing Paradigms. Eds. Mery, G., Alfaro, R., Kanninen, M., and M. Lobovikov. Helsinki. IUFRO World Series Volume 17, 2005.
Kanowski, P. “Intensively Managed Planted Forests.” Yale University. The Forests Dialogue (2005): 8 p.
http://research.yale.edu/gisf/assets/pdf/tfd/impf/Kanowski%20TFD%20Background%20Paper.pdf
Varmola, M., Gautier, D., Lee, D.K., Montagnini, F. and J. Saramäki. “Diversifying Functions of Planted Forests.” In Forests in the Global Balance – Changing Paradigms. Eds. Mery, G., Alfaro, R., Kanninen, M., and M. Lobovikov. Helsinki. IUFRO World Series Volume 17, 2005.
Posted: August 2006
Updated 30 April 2007
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