Whitewood (Endospermum medullosum) in Vanuatu: development of the silviculture of a native rainforest species

Transcription

1 Session B2: Markets Tropical Plantations Whitewood (Endospermum medullosum) in Vanuatu: development of the silviculture of a native rainforest species J. Doland Nichols 1, Kevin Glencross 1, John Grant 1, Kate Convery 1, Rexon Vira 2, Ioan Viji 2 Neil Croucher 3 Rodney Aru 4 1. Sustainable Forestry Program, School of Environmental Science and Management, Southern Cross University, Lismore NSW. doland.nichols@scu.edu.au 2. Department of Forestry, Port Vila and Luganville, Vanuatu 3. Melcoffee Sawmills, Luganville, Vanuatu 4. Vanuatu Agriculture College, Luganville, Santo, Vanuatu Biography J. Doland Nichols is an associate professor and course coordinator in the forestry program at Southern Cross University. He began working with the US Forest Service in the Douglas-fir region of western Oregon, in fire and fuels and silviculture. For six years he worked as teacher, extension agent and researcher in Costa Rica and has also worked in Ghana and American Samoa. For more than twenty years he and two forestry colleagues have managed their own small farm forestry operation in Costa Rica. Abstract Whitewood (Endospermum medullosum), Euphorbiaceae, is a fast-growing native rainforest species found naturally from Irian Jaya, PNG, the Solomon Islands through to Vanuatu. The current ACIAR project is developing recommendations for best silvicultural practices to support expansion of both large and small-scale plantations. There are many impediments to the development of the treegrowing potential of Vanuatu, including insecurity about land ownership, limits of the domestic market, and uncertainty about markets for processed wood. Vanuatu Vanuatu consists of a group of about 80 islands. This is a relatively new island group, having mostly emerged from the Pacific around 1.8 million years ago. The volcanic soils are highly productive and can yield up to 40 tonnes per ha of traditional island agroforestry crops like taro, yams, and sweet potatoes. Culturally Vanuatu is a part of Melanesia, and because of highly productive soils and well-developed agriculture, had a population estimated at one million at the time of European contact, whereas its current population is approximately 200,000. In 1980 Vanuatu received its independence from the condominium government of shared rule by France and the U.K. Whitewood in Vanuatu In native forest Whitewood is a dominant longlived pioneering, shade-intolerant species, attaining large size, up to 40m in height. It has been the major timber species taken from natural forests, being popular for many uses, including canoes and firewood locally and for light construction and furniture. Moldings made from this soft, low-density, light-colored timber have a well-established overseas market, mainly in Japan. For the most part native forest Whitewood on flat ground and reasonably accessible has been logged and therefore an interest has developed into how to grow it as a plantation tree. An AusAID project called SPRIG (South Pacific Regional Initiative on Genetics) operated in two phases from the mid-1990s in five island countries. One of its many accomplishments The ACIAR Whitewood silviculture project The Australian Centre for International Agricultural Research (ACIAR) sponsors research on agriculture and forestry throughout southeast Asia and the south Pacific. The four-year Whitewood silviculture project began in late One of its first objectives was to define the amount of land on Santo island, the largest island in Vanuatu, where Whitewood could be planted. Soil sampling of 35 sites with moderate topography indicated little variation in soils, all sites having volcanic soils over limestone and all being highly productive. Our estimate is that there are some 101

2 69,000 ha on Santo capable of supporting Whitewood plantations. The project also aims to investigate what are the best practices for both large and small-scale plantations of Whitewood, testing various establishment and management techniques. After two and a half years there are some 15 hectares of trials and demonstration plots across Espiritu Santo. These include 27 small permanent sample plots, multiple spacing-thinning test plots, a five hectare experiment on site preparation, fertilization, weed control, and spacing and thinning, and other trials involving agroforestry combinations and tree species mixtures. An AusAID project called SPRIG (South Pacific Regional Initiative on Genetics) operated in two phases from the mid-1990s in five island countries. One of its many accomplishments was to collect seed and establish a provenance trial of Whitewood on Santo. These trials resulted in one paper (Viji et al. 2005) and the original trial has now become a seed orchard. Our current Whitewood silviculture project is collaborating with a new ACIAR project on genetic resources in Sandalwood and Whitewood in Vanuatu, led by Tony Page of James Cook University and with John Doran in charge of the Whitewood component. Site preparation and weed control Mostly landholders in Vanuatu do not have access to heavy equipment or even basic tractors, mainly using bush knifes for most purposes. This is in contrast to the large industrial operators who own logging equipment and can utilize bulldozers for site preparation. A notorious weed throughout the south Pacific is Merremia peltata, an aggressive vine in the morning glory family. Another difficult weed is known in Vanuatu as piko (Solanum torvum), a short spiny member of the Solanaceae. There is an abundance of labour available in Vanuatu and rural people tend to be highly skilled at manual brush control. Further, proper equipment for use of herbicides is expensive, not likely to be used in the high heat and humidity, and the herbicides themselves are expensive and not something at least this group of researchers wanted to promote. Thus the main site preparation and weed control techniques tested by this project were manual control with hand tools or heavy equipment and the limited use of glyphosate. It appears that site preparation that disturbs the soil surface may stimulate the germination and growth of piko, creating a weed problem that is worse than what results from merely crushing the weeds from above. Thus where a bulldozer is available simply having it drive over the top of the weeds is preferable to having it disturb the soil surface with its blade. Then the planters cut lines through the vegetation, lines which need to be maintained as often as every six weeks for the first two to three years. Plate 1: The vine Merremia peltata (Convolvulaceae) is a strong competitor with any planted seedlings and must be dealt with. 102

3 Spacing/thinning Whitewood is a wide-spreading species, not unlike the Australian rainforest tree Elaeocarpus grandis, and consequently it is usually recommended that it be planted at wide spacings, 6 to 8 m between rows and 2.5 to 4 m within rows. Further, designs are often intended to accommodate ongoing agroforestry gardens or cropping of peanuts or coconuts or to leave room for operating heavy equipment. Growth and yield and expansion of Whitewood plantations Whitewood grows extremely well on the well-watered and highly fertile soils of Vanuatu, when the tree is free from major weed competition. Yields are in the range of m 3 /ha/yr for perhaps the first 15 or 20 years. The twentyseven permanent sample plots installed by the project in late 2007 should provide a more thoroughly quantitative basis for these claims. Certainly the 270 ha plantation established at a site called Loro by Melcoffee Sawmills in 1993 has grown well, with six logs up to 47.7cm in dbh yielding a gross volume of 6.3m 3 in Since the mid 1980s numerous consultancies by international agencies as well as Vanuatu government agencies, including by one of the present authors (Nichols 2003) have emphasized the great potential for plantation forestry, particularly on sites like the Industrial Forestry Plantation near Shark Bay. Here there are approximately 5,000 ha, mainly dominated by Merremia and brushy weeds, where extensive planting could take place. Most of these reports have suggested that with growth rates of m 3 /ha/yr with 250 ha being planted per year on 20 year rotations, a profitable plantation industry could develop here. But to date not donors, not investors, not government agencies whether national or local, not local landholders, have embarked on large-scale planting. Plate 2: Whitewood (on far left and right) can be planted at wide spacings and the interrows utilised to grow typical Pacific island crops, like the taro and paypaya here Other species and mixed-species plantations Given that Vanuatu has large extensions of soil that Australians can only envy, as well as consistent year-round rainfall, the possibilities for tree planting are ample. Furthermore, the wisdom of planting large extensions of one species, though few serious pests on Whitewood have yet emerged, could be questioned. One of species tested in the 1980s at the Industrial Forest Plantation site near Shark Bay was Cordia alliodora. This Central American species has grown reasonable volumes (10m 3 /ha/yr) of high-quality timber in agroforestry systems in Costa Rica, notably when combined with nitrogen-fixing shade trees and coffee. It has not succeeded in Vanuatu, producing trees with poor form and slow growth. But the idea remains valid: on excellent sites with active gardening or farming there is potential to produce high-value wood in combination with agricultural crops, with the associated tending benefiting the trees. 103

4 One popular native species is Flueggea flexuosa, which can be used in roundwood form and be harvested for income at around 6-8 years of age. Also the pantropical Terminalia catappa has shown potential as a timber species. These two have been combined in our trials with Whitewood to try to work out spacing standards and the timing of harvests: possibly 6-8 years for Flueggea, years for Whitewood, and perhaps 30 years for Terminalia. Wood properties of plantation-grown Whitewood There is a specialized market in Japan for the uniform, low-density, white, characterless wood for internal uses, especially moldings. Early indications are that the wood properties from plantation-grown trees will compare favourably with those from trees taken from native forest. In fact, verifying this is one of the major objectives of the ACIAR project, which is harvesting plantation trees, milling them, and testing for density and shrinkage and planning to devise a local device for modulus of rupture testing. Much of this work is now done not only in collaboration with the partners on the project, Melcoffee Sawmills and Dept of Forestry Vanuatu but also with the students in a new forestry technical officer program at Vanuatu Agriculture College. Future prospects Because of the newness of Vanuatu as a country and traditional Melanesian land ownership patterns it has seemed unlikely that anyone would invest in large-scale plantations in Vanuatu. In addition to the usual risks associated with plantations (cyclones especially) there is a perception that generally one cannot be assured of ownership of trees that might be planted. This has been a major impediment to large-scale development for the last 25 years and may well continue to be so, in spite of the fact that there is a well-established market for processed Whitewood in East Asia. Attempts to develop a large area of land to meet the Japanese demand have so far not been successful but there are nevertheless indications that major industrial-scale plantations of Whitewood may eventuate. Small farmers are increasingly aware that Whitewood plantations can produce large volumes within 15 to 20 years but again are reluctant to devote large areas of land to it, given questions about future markets. The domestic markets are fairly small (only about 10,000 people on Santo, many of whom live on subsistence agriculture) and transport to other islands is expensive. Further, these markets are subject to dumping of unwanted low-grade timber, including belowstandard radiata pine from New Zealand. Nevertheless, this ACIAR project, like many others throughout Asia-Pacific, is developing the technical basis for a thriving plantation-forestry based sector. Plate 3: A thirteen-year old stand of planted Whitewood at Loro site on Espiritu Santo Island, Vanuatu. 104

5 Plate 4: Sixteen-year old Whitewood tree harvested from plantation at Loro site. Acknowledgements This work is funded by the Australian Centre for International Agricultural Research (ACIAR) project FST/2005/089. Southern Cross University is the commissioned organization and the Vanuatu partners are Melcoffee Sawmills and Department of Forestry, Vanuatu. References Nichols, J. D Consultant report on options for industrial forest plantation (Shark Bay Agroforestry Project), Espiritu Santo, Vanuatu. For: Food and Agricultural Organization of the United Nations, Apia, Samoa and Bangkok, Thailand. Thomson, L. A.J Endospermum medullosum (whitewood). Species Profiles for Pacific Island Agroforestry, Volume 2.1, April, Access: Viji, I. N. V., Tyagi, A.P., Thomson, L.A. J., and Heads, M Comparison of performance of whitewood (Endospermum medullosum L.S. Smith) provenances and families in Vanuatu. The South Pacific Journal of Natural Science 23: