Wood of Gmelina arborea in Costa Rica

Transcripción

1 New Forest 28: , # 2004 Kluwer Academic Publishers. Printed in the Netherlands. Wood of Gmelina arborea in Costa Rica RÓGER MOYA ROQUE Technological Institute of Costa Rica (ITCR), Research Center the Forestry Industry Integration (CIIBI), Apartado , Costa Rica ( rmoya@itcr.ac.cr) Received 5 April 2003; accepted in revised form 10 December 2003 Key words: Plantations, Silviculture, Solid wood products Abstract. Gmelina arborea Roxb. (gmelina) was introduced in Costa Rica in the late 1960s. At the present time, gmelina is the most widely planted tree species in Costa Rica. According to estimations by the Food and Agriculture Organization (FAO), there are about 65,000 ha reforested with gmelina in the country. This forested land has the potential of producing over 400,000 cubic meters of timber per year. Most of the gmelina plantations in Costa Rica were planted at 3 m 3 m spacing and were established with cuttings from seedlings. Trees are thinned and pruned three times during a rotation on sites that are good and only two times on sites of medium or low quality. In both cases the average rotation age is approximately 14 years. At the end of the rotation, the average diameter increment at breast height is approximately 3.5 cm with total yields of m 3 =ha=year. The introduction of this species into Costa Rica has produced a radical change in the primary wood industry, since the kind of equipment needed to process the small diameter logs from young plantations was not previously available in the country. Today, the wood from gmelina plays an integral part in the forest industry of the country. The logs coming from the lower part of the tree are being used for furniture and plywood production. The logs from the middle of the stem are used for construction timbers and the smallest logs are processed for boxes, pallets and log cabins. Palabras clave: Productos de madera sólido, Plantaciones forestales, Silvicultura Resumen. La especie de Gmelina arborea fué introducida en Costa Rica a finales de la década de los 60 y en la actualidad, es la especie forestal más utilizada para la reforestación comercial. De acuerdo con los estimaciones por la FAO (Food and Agriculture Organization), se estima que en Costa Rica existen cerca de 65,000 hectáreas reforestadas con esta especie, cifra muy alta para la extensión territorial del país, y que estas tienen la capacidad de producir alrededor de 400,000 metros cúbicos al año. En general, las plantaciones de esta especie se han plantado con espaciamientos de 3 3 m por medio de seudoestacas. En sitios de buena calidad, los árboles son podados y raleados 3 veces durante una rotación y solo 2 veces en sitios de calidad media ó baja. En ambos casos, la edad de rotación promedio es de aproximadamente 14 años. Al final de la rotación, el incremento promedio en el diámetro a la altura del pecho es de aproximadamente 3.5 cm y su rendimiento de m 3 =ha=año. La introducción de esta especie en Costa Rica dió lugar a un cambio radical en la industria forestal primaria, debido a que no se contaba con los equipos necesarios para procesar trozas de pequeño diámetro procedentes de plantaciones forestales. En la actualidad, la madera de la gmelina forma una parte integral de la industria forestal en Costa Rica. Las trozas procedentes de la parte inferior del árbol están siendo utilizadas en la industria del mueble y en la fabricación de madera aglomerada, las trozas procedentes de la parte intermedia del tallo en la industria de la construcción, y las trozas más delgadas se están utilizando para la fabricación de embalajes y para madera en rollo para la construcción de cabaña rústicas.

2 300 Table 1. Gmelina arborea planted area by country (from FAO 2002) Country Territorial extension (1000 km 2 ) Reforested area G. arborea (ha) % World total % National territory India 297, , Indonesia 181, , Nigeria 91, , Philippines 29, , Costa Rica , Venezuela 88,206 25, Guatemala 10,843 22, Mali 122, Solomon Islam Other countries 411,002 35, Total 1,239,402 1,040, Introduction Gmelina arborea Roxb. (gmelina) was introduced in Costa Rica in the late 1960s for pilot plantings and provenance trials. The results were to be used by Jari Florestal, which had land holdings in Pará in northern Brazil (Lega 1988). The main objective of the Jari project was to produce gmelina for pulp. Therefore, initial silviculture practices for gmelina were aimed to promote plantation forestry. In the mid 1970s, the Costa Rican government initiated a reforestation program based on incentives to restore degraded lands, and gmelina was chosen as one of the primary commercial species. From 1975 to 2000, 65,000 ha have been planted (FAO 2002). This represents 6.24% of about 1.06 million ha of gmelina established in plantation throughout the world (FAO 2002). Costa Rica has the fifth largest plantation area of gmelina, surpassed only by countries with larger territorial regions like India, Indonesia, Nigeria and the Philippines (Table 1). However, Costa Rica has the largest percentage of its area planted with this species. Available volume of G. arborea for industrial use In Costa Rica, wood availability from industrial plantations increased significantly in Today, it is estimated that availability of gmelina wood is approximately 400,000 m 3 per year (Meza 1999; Sage and Quirós 2001). This is enough wood to supply 50% of the local market for logs. However, this amount represents an overproduction for the local sawmilling industry processing capacity, which is about 200,000 m 3 per year or 25% of the total local consumption of wood from logs (Carrillo 2001). Variation in the availability of gmelina is expected in the future (Figure 1) since the industry is not able to absorb the entire production. The

3 301 Figure 1. Trends in Gmelina wood availability in Costa Rica (Meza 1999; Sage and Quirós 2001). oversupply of wood will reach a maximum between the years 2006 and 2009 (Sage and Quirós 2001). Gmelina arborea silviculture in Costa Rica Gmelina is produced in forest nurseries and has been planted using cuttings and bare-root systems (Murillo and Valerio 1991). The seeds are germinated at the end of the rainy season (September October) in seedbeds and then transplanted to obtain the bare-root seedlings, cuttings or striplings that must be planted during the beginning of the rainy season the following July (Murillo and Valerio 1991). Gmelina has been planted in Costa Rica on sites with temperatures that range between 18 and 38 8C and at altitudes up to 600 m above sea level in areas with as much as 4500 mm of annual precipitation and two dry months per year (Alfaro 2000). The sites where it has performed the best are well-drained, deep and moist soils, with good nutrient status. It can grow well in acid or basic soils and even on lateritic soils. It performs poorly on heavy clays with drainage problems (Murillo and Valerio 1991). Plantation management is easiest on level sites with little gradient in moisture (Alfaro 2000). There is a government program in Costa Rica with established planting regions to help users match gmelina to good planting sites (FONAFIFO 2001).

4 302 Table 2. Normal management protocol for G. arborea in Costa Rica (from Sage and Quirós 2001) Site quality Type of harvest Thinning age (years) Trees to cut (n=ha) Mean diameter (cm) Mean height (m) Good Thinning SI ¼ 28 Thinning Thinning Final harvest Medium Thinning SI ¼ 21 Thinning Final harvest Poor Thinning SI ¼ 14 Thinning Final harvest SI: Site Index at 12 years. The type of plantation management used for gmelina in the past was a function of governmental policies and federal incentive programs. Several management schemes for gmelina have been implemented, depending on the time and circumstances. One of the consequences of these varied approaches is overall poor management of gmelina because the government did not have the resources to control silvicultural activities on the land. Therefore, many early plantings of gmelina were not managed or were poorly maintained (Meza 1999). However, this situation has changed in Costa Rica in the last few years. There are now planting and management protocols in the country. Initial densities are 1100 trees=ha (3 m 3 m spacing), which allows for two to three thinnings per rotation depending on the plantation site index (Sage and Quirós 2001). Typically, three thinnings are made on good sites and two on the medium and poor quality sites (Table 2). Final harvest is usually done at 14 years of age, but with two exceptions. On good sites final harvest is at 12 years of age because average diameter of the trees is well above 35 cm, the size that most organizations require for processing industrial products (Alfaro 2000). On sites where the final goal is pallet production, harvest age is 8 9 years because the tree diameter requirements are cm (Sánchez 1997). Pruning is done at the same frequency as thinnings in most plantations. A 50% pruning is performed when trees are 5 m tall. The second and third pruning occurs when trees reach 10 and 16 m height, respectively. The second and third pruning removes 50 and 40% of stem branches, respectively (Alfaro 2000). When reforestation programs started in the country, trees were planted on all soil types and productivity was good in some cases and very poor in others. Today, plantations are established to produce m 3 =ha at 12 years of age (Vallejos 1998) with a mean annual increment (MAI) of m 3 =ha=year at the same age. The MAI for the average tree diameter is 3.38 cm=year (Barquero 2001).

5 303 Figure 2. Band saw used to process large-diameter logs from natural forests in Costa Rica. Forest industry sector At the beginning of the twentieth century, intensive agriculture expanded in Costa Rica with the development of monocultures like bananas and coffee, which led to widespread deforestation in the country. Likewise, the forest products industry had a history of being oriented towards utilization of natural grown forest. During at the beginning of the twentieth century, there were about 220 sawmills, a very high number for the size of the country. Sawmills for natural grown wood are mainly band saws equipped to work large logs with diameters well above 33 cm (Figure 2) and without automation (Carrillo 2001). As a result of the plantation program begun in 1975, large wood volume from gmelina became available in However, the logs produced in these plantations had diameters less than 25 cm and were not suitable for the sawmill industry already established. The need to utilize small diameters gave rise to a transformation within the forest products industry in Costa Rica. Initially, gmelina logs were processed using portable sawmills that are common on small farms in North America. The approach was based on taking the sawmill to the plantation and not the logs to the sawmill. This practice was not continued mainly because the volume produced in the plantations far exceeded the capacity of the sawmills. A type of high-capacity machinery was then developed, taking into account the resources and the conditions of our country. This allowed the use of a twin circular saw (Figure 3(a)) and semiautomated production lines (Figure 3(b)), but still without full automation (Moya and Monge 1997). In developing new alternatives for utilizing plantation grown timber, the industry soon determined that the minimum diameter that could be used in existing

6 304 Figure 3. (a) Use of twin circular saw (left) and (b) semi-automated production lines (right) for G. arborea wood processing. Figure 4. Chainsaw blades for sawing cm diameter gmelina logs. machinery was about cm. This meant that smaller diameter logs were going to be wasted since there was no suitable machinery or a well-developed pulp and paper industry to use them. As an alternative, a method was developed to utilize logs down to 11 cm diameter (Carrillo 1999). The machine had two vertical chainsaw blades, driven by an electrical or internal combustion motor. It could be stationary or mobile (Figure 4). The twin circular saw mills were not suitable to process the diameters produced in the final harvest. This lead to the development of two technologies: (a) the less used top saw circular saw (Figure 5(a)), and (b) the gang saw (Figure 5(b)).

7 305 Figure 5. Rica. (a) Top saw circular saw (left) and (b) gang saw (right) for sawing G. arborea logs in Costa The wood industry has grown quickly during the last 10 years and can now utilize small diameter logs (6 12 cm) for construction of log homes and fence posts. The increase in the available volume of gmelina wood not only produced changes in the saw mill industry but also in wood drying and preservation, which has grown 3 4 times since 1993 when gmelina wood started to be processed in Costa Rica. Gmelina wood products and integration of the forest resource Banana export was for many years the main income for Costa Rica. Transport of this type of product was in cardboard packages or on wood pallets for better handling. Before 1990 pallets were made from wood of native species. The main requirement for these products was that the wood be white in color. As the volume of gmelina wood increased in the early 1990s, it became apparent that it was well suited for the container and pallet markets for bananas. This use of gmelina wood for these products was officially allowed by the Industry and Economy Ministry in 1990 (MEIC 1990). This led not only to rapid changes in the forest industry but also to increased competition in the pallet market due to the high availability of raw material. As more gmelina wood became available, it led to a fall in the pallet prices of almost 40% in 3 years. The industry started to look for other markets for gmelina wood such as construction, and later, furniture manufacturing (Alfaro 2000). One of the products that became available at that time were the boards made of short, thin, clear pieces of wood easy to work and easy to cover with different types of finishing (Gardino 2001). Gmelina did not do as well as first expected in the construction market since it had to compete against local species from the natural forest with high mechanical strength. Civil construction is the largest market for wood in Costa Rica with nearly

8 306 Table 3. Main uses of G. arborea in Costa Rica Construction Furniture Other Trusses Filers Wood craft Solid columns Benches Facial tissue Flooring, decks Beds Paper Moldings Drawers Pencils Counters Dinning room furniture Pallets Doors Living room furniture Crates Frames Tables Fence poles Solid beams Chairs Construction poles Gluelams Arm chairs Matches Laminated columns Desks Ice-cream holders Laminated boards Office furniture Toothpicks Door and windows frames 70% of the total wood production, and gmelina wood did not meet the expected requirements. During this time the universities started to get involved in research to determine the basic mechanical and non-mechanical properties of wood with the objective of introducing gmelina into the sawn wood market. This allowed the characterization of the species according to geographical zone, the type of stand management, and the section of the tree from which the wood would be produced. This information was necessary to determine the best product from a specific section of the log. For example, the innermost wood in the trunk is used for pallets where high structural strength is not a requirement. The outermost wood is for structural purposes and for furniture manufacturing. Wood for flooring needs a required a strength above 300 kg=cm 2, a value which is reached in gmelina at 6 cm from the pith of the log. Other uses for gmelina wood include laminated beams (GLUELAMS), which are very successful in the local market and have acceptable strength. More recently, the plywood industry is using gmelina wood from the base of the trees at final harvest as raw material. Also, some construction industries are using small diameter preserved with Cooper, Chromium and Arsenic (CCA) treated logs (8 12 cm), for log cabin construction. A summary of different uses for gmelina wood is provided in Table 3. References Alfaro M Melina: la madera del futuro. Revista Forestal Centroamericana 29: Barquero M Evaluación de la calidad de las plantaciones de Gmelina arborea Roxb., Zona Norte de Costa Rica. Ministerio del Ambiente y Energía. Fondo Nacional de financiamiento Forestal Costa Rica Proyecto: TCP=COS=006(A): Mercado e Industrialización de materia prima proveniente de plantaciones forestales. Noviembre 2000-Enero San José, Costa Rica, 78 p. Carrillo O Análisis económico de una línea de diámetros menores. Materia prima provenientes de plantaciones forestales. Curso práctico: Industrialización de la madera con énfasis en diámetros menores. COSEFORMA. Cartago, Costa Rica, 19 p.

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