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Exotic Forest Plantations

Jesús A. Espinoza  and Ronalds W. Gonzalez
North Carolina State University

Introduction

Exotic species have several definitions; some researchers define exotic species as trees growing in an area different to their natural habitat or species growing in area where they do not naturally occur (Zobel and Talbert, 1984; (Webster and Mcetchnie (1980); Wright (1976); Morandini (1964) cited by Zobel  and Talbert, 1984); others use the “exotic” term as a reference to species that are not only able to survive but also able to reproduce outside their habitats where they evolved or spread naturally (United States Environmental Protection Agency, 2003).

The term “Exotic” is also used as synonymous of introduced, foreign, invasive, non-native, naturalized, immigrant, non-indigenous species; however, differences among those terms could be found. In fact, one of the difference between the terms exotic species and invasive species is that exotic species is associated with a benefit (i.e. conservation or profits) while invasive is relate to species that have been introduced and become a pest in its new location.

Benefits of Using Exotic Species

a.         Exotic species are used as an alternative in many places where local indigenous forests cannot produce the type, quantity and quality of forest products required.

b.         In general, exotic species have growing rates much greater than native species; therefore, they produce more wood per unit of area and time. In the tropics, exotic species could grow 5 to 10 times more wood than native species.

 c.      Many of the exotic species used in forestry plantations can grow in sites with limited edaphological conditions (as pH, nutrient availability, moist content, texture, etc) with better yield than indigenous species.

 d.         Exotic species usually can adapt to different environmental conditions; nevertheless, is important to test the exotics in the zone where it is needed prior deciding a large scale plantation establishment.

 e.         With features as fast growing and wider adaptation, exotic species could be used as source of different type of products and so reduce the pressure over native species (which in general growth less and slower).

Risks of Using Exotic Species

 
a.         If the provenances and seed sources of the exotic species are not the most appropriate, the plantation could result in a disaster. Therefore, it is important to test the species in the area where it is to be grown before it is planted at commercial scale.

b.         The use of exotic species could be associated with new pests and diseases and affect native species; therefore, it implies new or stricter disease and pest controls.

c.         The use of exotic species has many opponents, not only ecologists but also politicians, who are against the use or modification of natural forests and their biodiversity. Some ecologists point out that  “once established, some exotic species have the ability to displace or replace native plant and animal species, disrupt nutrient and fire cycles, and cause changes in the pattern of plant succession” (Jeff Lovich, 2003).

The Role of the Exotic Trees in the Americas

The use of exotic species has played an important role in the production of roundwood, fiber, firewood and other forest products. There are many examples in the literature about how exotic species have met the requirements of the forest product industry.

Among the most outstanding examples, we could point out the use of Eucalyptus as exotic species in Brazil, Chile, Colombia, Venezuela, Uruguay, and South Africa. Indeed, Brazil has reported growth of Eucalyptus that has reached up to 40 – 55 m³/ha/yr at seven years of rotation (FAO, 2001).  Other important species used as exotic is Pinus radiata (Montery or radiata pine) when it is grown in New Zealand, Australia, and Chile.

It is well known that one of the main reasons to establish exotic species plantations is the fast growth which allows obtaining satisfactory and profitable results. For this reason, tropical and subtropical regions offering excellent conditions in soil quality and climatic factors are the best places for the establishment of new forest plantation.

Yield and Feasibility of Exotics in the Americas

Over a selected group of native and exotic species plantations in the Americas, exotic plantations in South America were the most profitable with return rate values raging from 12.9 to 16.9 % in softwood and 13.8 to 22.9% in hardwood (Cubbage et al. 2007). Table 1 (see attached link at the bottom of the page for the table) displays the rotation, growth, timberland cost and rate return for selected native and exotics plantation in the Americas. The highest return rates are from plantation of E. dunii in Brazil and E. grandis in Uruguay (22.9 and 21.9 % respectively). Plantations of Pinus taeda in Brazil (exotic) yields 1.5 times more than the average productivity of the same specie (native) in U.S. in 0.6 of the time. The higher annual medium increments (MAI) in hardwood are from Eucalyptus sp plantations in Brazil and Argentina (43 and 40 m³/ha/year), while the higher MAI in softwood are from Pinus taeda plantations from Argentina (35 m³/ha/year).

In 1994, FAO estimated that there were about 100 million hectares of forest plantations worldwide and 2.6 million hectares/year of new forest plantation being established in the tropics. According to experts in this area, it is estimated that a number of  50 to 100 million hectares of new forest plantations are needed to meet the projected industrial wood requirements of the developing countries by the year 2010 (FAO 1994 cited by (Boyle 1999).

The growing demand of wood products, the shift of forestlands to agriculture, the destruction of indigenous forests, and the difficulty of managing tropical hardwoods prompts the establishment of forestry plantations using exotic species.

Silviculture with Exotics

Exotic species respond to intensive silviculture management much better than indigenous species, which enhance better growing yield per unit of area and thus reducing per unit production costs.  Figure 1 (see attached link at the bottom of the page for the figure) shows the difference in growing between native species and exotic species.  In addition to cost reduction, intensive silviculture allows the production of the same or greater amount of wood on fewer acres. Intensively managed plantations can play an important role in supplying our wood needs in a sustainable and environmentally sound manner (Sedjo and Botkin 1997, Moore and Allen 1999, Fox 2000 cited by Allen et al. 2007). Based on the fact that intensive silviculture includes integrated systems where species and genotypes are selected to match the site and subsequent silvicultural treatments that are targeted at ameliorating resource limitations (Allen et al. 2005).

Most of the leading international forestry companies in the tropics are using exotic forestry plantations as source of raw material. In fact, Brazil having the world's second-largest area of native forest, after Russia, is also being benefited from 5 million hectares of planted forest, 60% eucalyptus and most of the rest pine, (Associacao Brasileira de Celulose e Papel, 2007)

Industrial plantations in Latin America almost always are related to “exotic” species.  In South America almost 100% of the plantations are established with exotic species as eucalyptus and pine. This is much different than North America, where exotic timber species have not grown well due to cold climates.  Industrial forestry in North America still relies mostly on natural stands and native tree species plantations.Most of the requirements of virgin fiber from the pulp and paper industry in South America are supplied from exotic species plantations.

Since the 1970s, the area under commercial plantations in South America, using exotic species, has increased significantly. In 1999, Sedjo reported that in a period of 15 years (1977 – 1992), South America (Brazil, Chile, Uruguay, and Argentina) all have approximately doubled their industrial wood production, whereas Chile and Uruguay have tripled their production in the same period. This trend has continued through 2007; however, the increase in the area of plantations per year has decreased, largely due to the increased rate of growth due to intensive silviculture.  Brazil and Uruguay are two countries with tremendous potential for new industries that use the wood as raw material for their end product. Similar situation are occurring in countries as Spain, Portugal, South Africa, and New Zealand.

Most of the fiber used in papermaking in Brazil comes from exotic plantations, in fact the pulp and industry in this country is mostly supplied from Eucalyptus sp (hardwood, short fiber) and Pinus taeda (softwood, long fiber). Brazil is the larger producer and exporter of forest products in South America, especially pulp and paper, which is a direct result from the benefits of using exotic species plantations.

Uruguay, the larger exporter of roundwood in South America at present has one of the highest rate return in Eucalyptus plantations.  These plantations have allowed the current establishment planning of three world class pulp mill, which would take Uruguay to the third place of market pulp  producer in the region.  However, opposition from various interest groups in Argentina may prevent at least one of these mills to be constructed.

Final Thoughts

The establishment of fast growing exotic plantations is one of the best alternatives to produce the raw material needed to supply the increasing demand of the emergent economies. Features as fast growth, wider adaptability, higher response to intensive silviculture management and for instance higher profitability, makes of exotic species the ideal material to be used in the establishment of new forest plantations.

References

Allen, H.L., T.R. Fox and R.G. Campbell 2005. What is Ahead for Intensive Pine Plantation Silviculture in the South? Southern Journal of Applied Forestry. 29:62-69.

Associacao Brasileira de Celulose e Papel, 2007. Desempenho do Setor em 2006 e projecao para 2007. Saw in http://www.bracelpa.org.br. In 06/05/2007.

 Boyle, J.R. 1999. Planted forests: views and viewpoints. New Forests. 17:5-9.

Cubbage, F., P.M. Donagh, J.S. Júnior, R. Rubilar, P. Donoso, A. Ferreira, V. Hoeflich, V.M. Olmos, G. Ferreira, G. Balmelli, J. Siry, M.N. Báez and J. Alvarez 2007. Timber investment returns for selected plantations and native forests in South America and the Southern United States. New Forests. 33:237-255.

Lovich Jeff, 2003. THE ECOLOGICAL IMPACTS OF INVASIVE EXOTIC SPECIES. Western Ecological Research Center. U.S. Geological Survey. http://www.werc.usgs.gov/hq/weed.htm.

Oxford Analytica. 2003. FY03 Brazil: Forestry fortunes, growth prospects for forest products exports. Forest Management. The world Bank group. http://wbln0018.worldbank.org/ECA/ForestryAR/DocLib.nsf/(By+Category+Web)/93BFE4EF0A3D28CB85256D170075FC37?OpenDocument. Accessed on 08/01/2007.

Sedjo, R.A. 1999. The potential of high-yield plantation forestry for meeting timber needs. New Forests. 17:339-359.

 United States Environmental Protection Agency (2003). Exotic. http://en.wikipedia.org/wiki/Exotic_species.  Accessed 08/01/2007.

Zobel, B. and  Talbert, J. 1984. Applied forest tree improvement. Published: New York. Wiley.

Jesús A. Espinoza and Ronalds W. Gonzalez are Graduate Students with the Department of Forestry and Environmental Resources and the Department of Wood and Paper Science, respectively, North Carolina State University, Raleigh, NC 27695

Posted 8 September 2007

Updated 24 September 2007