2. The rubber tree

2.1 The rubber plantation resource
2.2 Present status of the rubber plantation resource
2.3 Economic and social importance of rubberwood
2.4 Outlook for rubberwood

2.1 The rubber plantation resource

The rubber tree, Hevea brasiliensis Muell. Arg is indigenous to the Amazon basin. During the nineteenth century, Brazil was the main supplier of hevea latex, which was collected through tapping of trees in the natural forest.

Rubber seedlings smuggled out of Brazil became the parent planting stock for all rubber plantations developed in present-day Malaysia and other Southeast Asian countries at the turn of the twentieth century. Rubber has since been planted in a number of tropical countries as a plantation crop. The most important rubber producers today are in Southeast Asia. Today Brazil plays an insignificant role in international markets (Table 1).

Tapping of rubber trees starts in the fifth to seventh year after planting and then continues for 25 to 30 years. A special knife is used to incise the bark so as to wound the resin canals without damaging the cambium.

After 30 years a decline in latex production makes further tapping of the trees uneconomic. The trees are then removed and replaced with new seedlings. In the past, felled rubber trees were either burnt on the spot or used as fuel for locomotive engines, brick burning or latex curing.

A 30-year old cultivated rubber tree is about 30 m tall with an average branch-free bole of 3 m. The diameter at breast height (dbh) may reach about 30 cm. The stem tends to taper. Young rubber trees have a smooth brown-green bark. The constantly tapped portions of the stem may develop, with age, a latex-smeared cortex.

Available log volume for diameters above 15 cm ranges from 52 m³ ha^-1 to 162 m³ ha^-1 (assessed for nine cultivars by Gan et al. 1985); in assessments a figure of 100 m³ ha^-1 is normally used. The utilizable wood volume per hectare depends upon numerous factors such as clone, site and management. Sawn timber recovery lies between 25 and 45 percent.

Rubberwood’s favourable woodworking and timber properties make this medium-dense timber (air-dry density 560-650 kg m^-3 - Lee 1982) suitable for a wide scope of applications. It can be easily steam-bent, or stained to resemble any other timber, depending on consumer demand. Its favourable qualities and light colour make it a good substitute for ramin (Gonystylus bancanus Baill.), a timber known for its quality in furniture making and other applications. The natural colour of rubberwood is one of the principal reasons for its popularity in Japan, where it is increasingly used to replace more traditional timbers, e.g. Fagus spp. and Quercus spp., in a wide variety of applications.

Table 1. Plantation area of Hevea brasiliensis and available wood volume

Country	1975 (1000 ha)	1990 (1000 ha)	1997 (1000 ha)	%	1990* mature	Rubberwood volume (million m 3)
Indonesia	2 296	3 040/3 1551	3 5161	36	1 863	186.0
Thailand	1 496	1 860/1 8441	1 9661	20	1 500	150.0
Malaysia	1 694	1 8371	1 6351	17	1 614	161.4
China	120	6031	5921
India	224	4511	5331		306	3.0
Vietnam	n.a.	200	2751
Sri Lanka	228	1991	1631		146	1.5
Philippines	n.a.	86	881
Myanmar	n.a.	76	901
Cambodia	n.a.	52	521
Asia total	6 058	8 503	8 910	92	5 429	543.0
Nigeria		2471	2472
Liberia		1101	1102
Côte d’Ivoire		67	672
Cameroon		41	411
D.R. Congo		401	402
Ghana		12	171
Others		111	112
Africa total		528	533	5.5
Brazil		197	1801
Guatemala		26	381
Mexico		8	141
L. Amer. total		231	232	2.4
World		9 262	9 675	1 00		968.0

Source: IRSG, 1997
¹ Source: IRSG, 1999
² No data available for 1997.

2.2 Present status of the rubber plantation resource

About 80 percent of the 9.7 million ha of rubber plantations established worldwide for latex production in 1999, are in Southeast Asia; 72 percent of the total (or 5.2 million ha) are in Indonesia, Malaysia and Thailand (IRSG 1999). With an overall area of more than 3.5 million ha, Indonesia is now the world’s largest producer of natural rubber.

In 1990, 64 percent of the total area planted with rubber in Southeast Asia was overmature (Table 1). In Malaysia alone the figure was over 85 percent of the plantations, with a total available timber volume of 543 million m³, thus indicating a decrease in replanting over time (Table 2). The total annual available volume of rubberwood in the area of the Association of Southeast Asian Nations (ASEAN) was estimated at about 17 million m³ (Ser 1990). However, only a small portion of this calculated volume was actually converted. From 1982 to 1992 rubberwood production figures for Malaysia increased from 30 000 m³ to 1 872 000 m³ (Malaysian Ministry of Primary Industries 1993).

Table 2. Area replanted with rubber trees in Malaysia (ha)

Year	Rubber	Other crops	Total	% rubber
1991	31 500	7 700	39 200	80
1992	33 000	8 400	41 400	80
1993	31 100	10 400	41 500	75
1994	26 100	12 800	38 900	67
1995	22.900	14 000	36 900	62
1996	21 600	13 000	34 600	61
1997	11 300	13 000	24 300	47
1998	9 100	11 000	20 100	46

Source: FDM Asia, 1999.

2.3 Economic and social importance of rubberwood

Rubberwood has traditionally been used as a cheap source of woodfuel in most of the countries where rubber plantations are abundant, such as for industrial brick burning, tobacco curing, or for fuelling of locomotive engines. Due to lack of durability, rubberwood was rarely used as utility timber except in timber-scarce countries. After a number of problems had been overcome with the help of applied research, particularly in connection with wood seasoning and preservation but also related to the small size of logs, rubberwood developed as one of the most successful export timbers of Southeast Asia.

Salleh (1984) reported 61 different products made from rubberwood. The most important uses are: furniture and furniture parts, parquet, panelling, wood-based panels (particleboard, cement and gypsum-bonded panels, medium-density fibreboard (MDF), kitchen and novelty items, sawn timber for general utility and fuel.

Rubberwood has certain advantages over conventional timbers from the natural forest. Because it is a plantation by-product, it is available at a relatively low cost. Thus in spite of its comparatively low recovery rate, the production cost per cubic meter of rubberwood is only about 30 percent of the production cost of meranti (Shorea spp) (Kollert and Zana 1994).

The most developed rubberwood sawing and downstream processing industries are located in Peninsular Malaysia. In 1993, 116 stationary and 26 mobile sawmills - i.e. 20 percent of total Malaysian sawmills - cut only rubberwood (MPI 1993). The production of rubberwood sawn timber in Malaysia increased from 88 000 m³ in 1990 to 137 000 m³ in 1997. In addition, rubberwood has been supplying a growing panel industry. At present, four particleboard mills, four moulded particleboard mills and one wood cement board mill are in operation (Forestry Department, Peninsular Malaysia 1998). Branches and sawmill offcuts have become an important raw material particularly in the manufacture of MDF. In 1999, Malaysia had nine MDF mills with 13 production lines using primarily rubberwood, with an overall production capacity of 1.16 million m³ per annum (MTC 1999).

Rubberwood is also still used for charcoal manufacturing and woodfuel.

The demand for, and popularity of, this timber and its products in traditional timber-importing countries such as Japan and the United States stimulated the growth of the downstream processing industry in Malaysia (Hong 1995). This growth in turn encouraged the development of similar rubberwood processing industries in neighbouring countries, particularly in Indonesia and Thailand. In Malaysia, rubberwood has outperformed some of the traditional furniture timbers in export earnings. In 1994, exports of rubberwood furniture brought in US$297 million, accounting for 70 percent of Malaysia’s furniture exports. In 1998, the country exported rubberwood furniture for a value of about US$683 million (Table 3).

Table 3. Exports of rubberwood furniture from Malaysia (million US$)

YEAR	VALUE
1991	74.2
1992	106.0
1993	197.1
1994	297.4
1995	352.4
1996	439.8
1997	532.7
1998	683.3

Source: Malaysian Timber Industry Board statistics cited in FDM Asia, 1999.

Smallholders provide logs of lower quality than large estates as they devote less attention to management and proper tapping practices. For example, in Johore, Malaysia, only 18 percent of the rubberwood logs harvested in smallholder areas were found suitable for sawn timber. As a result, only 5 percent of the rubber tree wood volume available was converted into wood products, the remainder being left behind in the plantations or burnt.

Transport costs of the logs are usually borne by the supplier. Because the prices of rubberwood logs, particularly those of poor quality, are low, financial gains for smallholders from log sales are negligible (Kollert and Zana 1994). Therefore smallholders often prefer to burn the logs or let them rot in the plantation after felling. Hence a major portion of industrially used rubberwood comes from large-scale plantations, where logs are of much better quality, and, due to higher volume, better infrastructure and better organization, felling and transport are less costly.

2.4 Outlook for rubberwood

Timber availability, extensive research and aggressive marketing have contributed towards making rubberwood one of the most important export timbers in Southeast Asia, a substitute for light tropical hardwoods and one of the major timbers for the production of furniture and indoor building components.

The main reasons for success are its favourable timber and woodworking properties and the relatively low cost of the raw material since rubberwood is an agricultural by-product. This factor makes the timber highly competitive in comparison with timber from forest species that have comparatively high raw material costs. An additional asset is its “green” aspect: rubber trees have to be removed and the areas replanted once the latex yield has declined to uneconomic levels. The acceptance of rubberwood as a sustainable, plantation-grown, “environmentally friendly” timber has contributed to its universal appeal.

It can be safely assumed that market prospects for rubberwood will continue to be favourable. This is also reflected by the increased overseas investments in the Southeast Asian rubberwood industry. Rubberwood now has a position no other single tropical hardwood species can match in terms of available volume. If we assumed that all plantations would be available for wood production and that there was a ‘normal’ distribution of age classes, then the potential annual production could be up to 30 million m³ of rubberwood logs.

With the increase in plantation area and research in improved hevea clones, which may yield both high-quality latex and timber, prospects for a continuous supply of rubberwood seem to be good.

However, it remains to be seen if the increased plantation area in Southeast Asia will be sufficient to meet the industrial processing capacities built up regionally and nationally, and to meet the market’s growing demand for rubberwood products.