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(English) : deglupta, mindanao gum
(Filipino) : amamanit, bagras, banikag, Dinglás
(Indonesian) : aren, galang, leda
(Pidgin English) : kamarere
(Vietnamese) : b[aj]ch d[af]n v[or] d[aaf]y
Eucalyptus deglupta is a huge evergreen tree of up to 60 (max. 75) m tall; bole generally of good form, 50-70% of the tree height, up to 240 cm in diameter, sometimes with buttresses 3-4 m high; bark smooth, yellow, brown, and purple, but green after flaking; twigs 4-sided, often with 4 longitudinal wings. Juvenile leaves opposite, ovate to lanceolate; adult leaves opposite to subopposite, rarely alternate, shortly petiolate, held almost horizontal on branches, ovate to ovate-lanceolate or acuminate, thicker than juvenile leaves, 7.5-15 (max. 20) x 5-7.5 (max. 10) cm. Flowers 3-7 umbels in terminal or axillary panicles 5-20 x 5-18 cm; pedicels terete or slightly angular, about 5 mm long; young buds small, green with double opercula; developed buds pale green or cream, globular, apiculate, 0.2-0.4 x 0.2-0.5 mm, operculum hemispherical, apiculate and wider than long; flowers with many white to pale yellow stamens 2-10 mm long, strongly reflexed in the unopened bud; anther dehiscing by separate slits. Fruit pedicallate, hemispherical, with 3-4 valves, thin, deltoid, exserted to 2 mm, making the capsule appear globular, 3-5 x 3-5 mm, and disc very narrow; mature fruits brown to dark brown, containing 3-12 well-formed seeds per valve; seeds minute, brown, flattened, with a small terminal wing. The genus Eucalyptus was described and named in 1788 by the French botanist l’Héritier. The flowers of the various Eucalyptus species are protected by an operculum, hence the generic name, which comes from the Greek words ‘eu’ (well), and ‘calyptos’ (covered).
Ecology and distributionHistory of cultivation
E. deglupta is a comparatively newcomer as a plantation species. The earliest introductions were from indigenous stands that occur in the Cotabato area of Mindanao to other islands in the Philippines, for example Baguio in northwest Luzon in 1918 and 1926. The 1st introduction into Cebu Island was in 1954. The 1st major plantings on the main island of Papua New Guinea were made in 1948 from seeds collected in Keravat on the neighbouring Island of New Britain. Outside Southeast Asia, the 1st small-scale introductions were made in the late 1950s or in the 1960s, in countries such as Cote d’Ivoire and Solomon Islands in 1958, the Congo in 1961, and Sri Lanka in 1967. It is now a pantropic species.
E. deglupta requires full overhead light for development, and dense stands are commonly found along rivers where it has colonized newly formed banks and non-stagnant river flats. It is also found on sites that have been cleared or disturbed in some way, for example, by landslides, volcanic eruptions, or shifting cultivation. E. deglupta generally reproduces in pure stands. Occasionally, however, it forms an association with Octomeles sumatrana, an aggressive secondary species. As stands pass maturity, they are invaded by primary forest species such as Pometia pinnata, Dracontomelum mangiferum, Celtis spp., and Pterocarpus indicus. E. deglupta is the only species of Eucalyptus that is adapted to lowland and lower montane rainforest habitats. It does not grow naturally in areas with a pronounced dry season but occurs in those where the annual rainfall is very high and the monthly rainfall usually exceeds 150 mm. Because of this, it is widely planted throughout the wet tropics. E. deglupta does not withstand prolonged flooding, is highly sensitive to fires and, although it may grow in cool environments, it does not tolerate frost.
Native : Indonesia, Papua New Guinea, Philippines
Exotic : Brazil, Congo, Costa Rica, Cote d'Ivoire, Cuba, Fiji, Honduras, Malaysia, Puerto Rico, Samoa, Solomon Islands, Sri Lanka, Taiwan, Province of China
Biophysical limitsAltitude: 0-1800 m, Mean annual temperature: 23-31 deg. C, Mean annual rainfall: 2500-5000 mm Soil type: It can grow successfully on coarse-textured sands and loamy soils, volcanic ash and limestone-derived soils (pH 6-7.5). Best growth occurs on deep, moderately fertile, well-drained, sandy alluvial loams with adequate soil moisture.
Flowering may occur within the 1st year but more often it takes place after 2 years and annually thereafter. Flowering can occur in all months of the year, depending on the locality. In Indonesia, E. deglupta flowers the whole year and bears fruit at the beginning of the rainy season. In New Britain, seeds of E. deglupta are often dispersed by rivers. The flooding rivers in the wet season deposit the seeds mixed with humus on uncolonized alluvium in full sunlight. This constitutes ideal conditions for germination.
Propagation and managementPropagation methodsEucalyptus spp. can be propagated easily from seed and or cuttings. Seeds germinate in 4-20 days. They have a germination rate of 50-60%, and 1 g of dry seeds produces 1000-2000 seedlings. Seedlings are best raised in trays filled with sterile, fine, loamy sand. The trays should be kept in the shade for the 1st few days after sowing, but light can be gradually increased to 50% full sunlight. Seedlings can be transferred from planting tubes when they have 2-3 leaf pairs. Further growth requires sunlight. The seedlings are ready for planting in the field when they are 25-30 cm in height, usually after 3-4 months. About 2 weeks before planting them out, they should be hardened off by reducing watering and removing shade. Shoot growth of young trees appears to be continuous, provided soil moisture is adequate. In Thailand in the early 1980s, the annual production of seedlings of Eucalyptus spp. was approximately 2 million. Vegetative propagation is possible from branch cuttings taken from trees less than 2 years old. Best results are obtained from cuttings containing a stem node and a segment of a leaf. Hormones such as indole-acetic acid, indole-butyric acid or nephthalene acid will improve the success rate.
Growth is usually rapid, and subsequent management depends on the purpose for which the trees are being grown. Pulpwood production is the common object of management, and therefore short rotations with no thinning are the rule. For example, in the Philippines the spacing most commonly used is 4 x 4 m and the rotation 12 years with no thinning, and in Papua New Guinea the spacing varies from 3 x 3 m to 4 x 4 m, for a rotation of 7-10 years. Plantations grown for saw logs will require thinning. A new regime for saw log production has been introduced in Papua New Guinea of a 25-year rotation, with thinning at the ages 5, 10 and 15 years, the last of which reduces the stocking rate to 99 stems/ha. The annual volume increment in plantations is 15 cubic m/ha, but occasionally it is as much as 50 cubic m/ha. At the age of 25 years, the trees reach an average height of 42 m and an average bole diameter of 40 cm. Good weed control (usually a 1 m strip along each planting line) is essential, and weeding 4-5 times each year for 2 years may be necessary before site occupancy is achieved. E. deglupta does not coppice vigorously.
Seed storage behaviour is orthodox. The seeds are short lived at room temperature, but longevity is maintained in hermetic storage at 3-5 deg. C and -20 deg. C. There are 2,000,000 seeds/kg.
Functional usesProductsFuel: E. deglupta is used to a limited extent for firewood and charcoal. However, it is normally considered too valuable for firewood. Trees more than 15 years old yield good charcoal. The energy value of the wood is 18 500-21 100 kJ/kg. Fibre: Around the world most E. deglupta plantations are meant for pulp production. The wood makes a strong sulphate pulp that can be bleached to a high brightness. Kraft pulping of E. deglupta wood gives a yield of 50%, and a pulp of good brightness and satisfactory handsheet strength properties. The wood is also used for particleboard, hardboard and wood-wool board. Timber: E. deglupta wood is light to dark brown with a slight lustre, more like coarse-grained rainforest wood than an eucalypt. It is of moderate strength but is not durable. Its density is 390-810 kg/cubic m at 15% mc. Wood of E. deguplta works well with hand and machine tools, although it has a slight tendency to tear out in machining and boring and to slight chipping of sharp edges in turning. The heartwood is usually resistant to preservative treatment, and the sapwood permeable. But in plantation-grown material the uptake of copper-chrome-arsenate salts may be fair. Plantation-grown wood of E. deglupta is significantly easier to impregnate than wood from natural forest. The wood is useful for furniture, moulding, flooring, construction lumber, boat building, veneer and plywood. In Papua New Guinea, E. deglupta is one of the major export timbers. Essential oil: The aromatic oils of E. deglupta have been characterized but they occur in such small quantities (0.2% in the leaves) that they are not of commercial importance.
Reclamation: E. deglupta is capable of colonizing land eroded by landslides and areas of recent volcanic activity. It has been used in reforestation and in enriching planting trials in logged-over forest, where it has shown considerable potential. Ornamental: Due to its very attractive bark and quick growth, the species is frequently planted as an ornamental tree.
Pests and diseasesTermites are the most serious pests in both natural stands and plantations. Young trees are sometimes damaged by the cossid moth and a ring bark borer. The coreid bug causes tip die-back of young trees. In Papua New Guinea and the Philippines, a stem borer and a bark borer (Agrilis spp.) have attacked trees of some provenances. The wood, particularly the sapwood, is liable to termite and lyctus attack and to marine borers. In the nursery, E. deglupta seedlings are susceptible to damping-off. Regular application of a fungicide can control this problem. Heart rot is sometimes found in older trees of E. deglupta but is unlikely to be a problem in trees grown on a short (e.g. 10-year) rotation. Field observations suggest that heart rot is more common in trees growing on less well-drained sites.
BibliographyFAO. 1979. Eucalypts for Planting FAO Forestry Series No. 11.
FAO. 1986. Databook on endangered tree and shrub species and provenances. FAO Forestry Paper 77. FAO, Rome.
Hong TD, Linington S, Ellis RH. 1996. Seed storage behaviour: a compendium. Handbooks for Genebanks: No. 4. IPGRI.
National Academy of Sciences. 1983. Firewood crops. Shrub and tree species for energy production. Vol. 2. National Academy Press. Washington DC.
Noad T, Birnie A. 1989. Trees of Kenya. General Printers, Nairobi.
Soerianegara I, Lemmens RHMJ (eds.). 1993. Plant Resources of South-East Asia. No. 5(1): Timber trees: major commercial timbers. Backhuys Publishers, Leiden.
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