2994

11: Auxiliary plants

Casuarina junghuhniana Miquel

Plantae junghuhnianae 1: 7 (1851).

CASUARINACEAE

2n = 18

Casuarina montana Junghuhn ex Miquel (1855).

Red-tipped ru, mountain ru (En). Indonesia: cemara gunung (Indonesian), adjaob, kasuari (Timor). Thailand: son-pradiphat.

Casuarina junghuhniana is indigenous to Indonesia where it occurs in East Java and the Lesser Sunda Islands (Bali and Nusa Tenggara) from Bali to Timor and Wetar. It has been introduced to Kenya and Tanzania. A male, hybrid plant was introduced into Thailand in about 1900, and its progeny was taken from there to India in the early 1950s.

Casuarina junghuhniana is planted widely, especially in Indonesia, to improve soil fertility and rehabilitate degraded soils and as a wind-break. Branches and foliage are burnt and the ash is spread on village gardens in Timor. The wood is highly suitable for firewood and charcoal production. In Thailand, it is a popular source of construction piles and for fish traps. In Kenya and Tanzania farmers plant Casuarina junghuhniana around fields for poles and firewood and as a live fence. The wood is a suitable source of raw material for kraft pulp. It can be used to make hardboard in a mixture with Dipterocarpus spp.
Although it is not a fodder, young trees are browsed by animals.

No statistics are available on wood production, international trade and areas planted to Casuarina junghuhniana. Most plantings in Thailand and Kenya are scattered in small plots of a few hectares.

Branchlets decompose slowly and provide good mulch. The air-dry density of the wood is 900—1000 kg/m³, and that of charcoal is 650 kg/m³. The energy value of the charcoal is 34 500 kJ/kg, which is among the highest for firewood species. Average durability of untreated wood is 4.5 years in direct contact with the ground. This can be increased to 15 years by treatment with a creosote preservative.
The weight of 1000 seeds is 0.6—1.0 g.

A fast-growing, dioecious tree, 15—25(—35) m tall; trunk diameter 30—50(—65) cm; crown somewhat open. Branching dimorphic with normal woody branches and determinate, deciduous branchlets; deciduous branchlets (switch twigs) numerous, articulate, internodes 10—15 mm long, greyish-green. Leaves reduced to tiny teeth, in whorls of 9—11(—13). Male inflorescence a cylindrical or slightly clavate spike, 3—8 cm long, borne on the apex of a deciduous branchlet; sheathing bracts hairy outside; lobes 10—11; bracteoles mucronate, 1.7—2.0 mm long; perianth lobes 0.7—1.7 mm long; filament 3.0—3.5 mm long. Female inflorescence in the axil of scale leaves on permanent shoots, cone-shaped, ellipsoid, truncate, 1—2 cm long, reddish; bracts 18—20-seriate, broadly obtriangular; bracteoles oblong-obovate, rounded or very obtuse, thick, 5—6 mm x 2.5—3.0 mm. Fruit a samara, small, 2—3 mm wide and 4—5 mm long including wing. Seedling with epigeal germination.

Mature seeds germinate readily without pretreatment. The germination rate is 50—60%, decreasing rapidly unless kept in dry, cool storage. The cotyledons are folded initially, later extending and becoming oblong. Under favourable conditions seedlings attain 25—30 cm in height within 3 months. As the main stem elongates, side branches develop from the upper axils of scale leaves. They are upright, giving the crown a slender, conical shape. Young trees continue to develop a conical crown; with age it tends to flatten.
Seedlings can attain 3 m growth in height per year during the first 2—3 years. In plantations with a controlled water regime in Thailand the Casuarina junghuhniana hybrid reaches 20 m in height and 15 cm in diameter in 5 years. In Markhanam, Tamil Nadu, India, hybrid trees reach a height of 5 m in 20 months.
Shoot growth tends to cease or to be less during the flowering period which coincides with the dry season. Like other Casuarina spp., Casuarina junghuhniana is wind-pollinated.
Casuarina junghuhniana fixes atmospheric nitrogen by nodulation with actinomycete bacteria of the genus Frankia. The nodules are woody and perennial and can form large masses in the root system. Mycorrhizal fungi further enhance its adaptability to poor soils.

Casuarina junghuhniana is rather variable. In its easternmost area of distribution, 2 forms occur, locally known as black and white casuarina, respectively.
Casuarina junghuhniana has coarse and fine branchlet variants. The forms with coarse branchlets may occur on exposed sites and are notable also for their rough, deeply-furrowed corky bark which is unusual for Casuarina spp. Casuarina junghuhniana hybridizes readily with Casuarina equisetifolia L. in cultivation, but not in the wild. The male hybrid introduced to Thailand has good form with straight stem and symmetrical conical crown. It is popular for commercial forestry and as an ornamental.

Casuarina junghuhniana grows naturally on the slopes of volcanoes at altitudes of 1500—3100 m but also at lower altitudes in dry places. In eastern Indonesia, especially on Timor, it occurs from near sea level up to 550 m altitude.
Rainfall in the natural habitat is monsoonal, with a well-defined summer maximum and a reported annual range of 700—1500 mm. Mean maximum temperature of the hottest month ranges from 25—28°C, mean minimum temperature of the coldest month from 19—22°C. It is drought-tolerant and can survive prolonged waterlogging. Near Bangkok commercial plantations in salt-marsh areas are sometimes inundated with saline water. When trees reach a few metres in height they are fire resistant and sprout readily after being damaged by fire. Casuarina junghuhniana grows on a wide range of soils, from light volcanic and sandy soils to heavy clays. It is tolerant of a wide pH range, from 2.8 in acidic clays to 8.0 in limestone-derived soils.

Propagation is by seed, shoot cuttings or air layering. Seed is sown onto germination beds. Seedlings are pricked out into polythene bags when 3—5 cm tall. For mass propagation, shoot cuttings are more suitable than air layering. Young shoots 1—2 mm in diameter and 10—15 cm in length are rooted with the help of hormones, either indole-4-butyric acid (IBA), indole-4-acetic acid (IAA) or naphthalene-1-acetic acid (NAA). Under 50% shade, rooting takes 3—4 weeks.
Inoculation of the seedlings or cuttings with effective strains of Frankia is recommended when Casuarina junghuhniana is introduced to a new area. Some Frankia strains of Casuarina equisetifolia are effective on Casuarina junghuhniana. When Casuarina junghuhniana or Casuarina equisetifolia are already being cultivated in an area, it is usually sufficient to mix topsoil collected from the plantations into the potting media. A spacing of 2 m x 2—3 m is used for commercial plantations for poles.

Weeding is necessary only during the first few years, after which the trees shed large amounts of branchlets to form a thick and dense mat of litter that suppresses weeds.
Casuarina junghuhniana is a poor self-pruner, and produces strong root suckers. Pruning in plantations up to a height of 2.0—2.5 m is often necessary to make the plantations more accessible for general maintenance. Trees respond well to coppicing and pollarding.

A number of diseases are found associated with Casuarina junghuhniana. Damping-off of seedlings in nurseries is caused by various fungi (Phytophthora sp., Pythium sp., Fusarium sp., Sclerotium sp. and Rhizoctonia sp.). Butt and heart rot, caused by Ganoderma applanatum, may infest tree trunks after damage by fire. Schizophyllum commune may cause decay of the sapwood.
Green branchlets are attacked by the Acrididae locust Aularches miliaris and insects of the family Lymantriidae. In dry areas subterranean termites can destroy young plants by eating their roots. In Thailand they are controlled by spreading a small quantity of a mixture of equal amounts of lime and salt in the planting hole.

Plantation-grown trees can be harvested throughout the year. In Thailand a harvesting cycle of 5 years is used for poles and fuelwood planted at a spacing of 2 m x 2—3 m.

In the highlands of Tanzania trees from a woodlot yielded 14.7 m³ stacked wood at age 4.3 years, and those planted along contour strips in an agroforestry trial produced 180 kg air-dry fuelwood per tree at age 3.5 years. In general, a mean annual increment of 10—15 m³/ha is obtainable.

In Thailand felled trees are transformed to poles by removing side branches. The length of poles is cut proportionately to the diameter, i.e. 3 m pole length for 7.5 cm diameter, 4 m pole length for 10 cm in diameter. Off-cuts from stems or branches are excellent firewood for the pottery industry. No special handling is required if the products are marketed as poles, piles or firewood. The wood, however, has a tendency to split when sawn.

The Australian Tree Seed Centre, Commonwealth Scientific and Industrial Research Organization (CSIRO), Division of Forestry and Forest Products in Canberra has assembled germplasm from throughout the natural distribution of Casuarina junghuhniana and from derived occurrences in Kenya and Tanzania. The Forestry Seed Centre in Kenya and the National Tree Seed Project in Tanzania collect and conserve seed from locally cultivated trees.

Activities on tree improvement work appear to be limited to a small progeny trial in southern China established with seed mainly from Kenya and Tanzania, and from a small number of trees from Timor. International provenance trials have been established to examine genetic variation.

Due to its fast growth, its nitrogen-fixing capacity, its wide adaptability, ease of propagation and excellent fuelwood quality, Casuarina junghuhniana has the potential to be planted for a range of purposes in the semi-arid to humid tropics, under both lowland and highland conditions.

Chittachumnonk, P., 1983. Silviculture of Casuarina junghuhniana in Thailand. In: Midgley, S.J., Turnbull, J.W. & Johnston, R.D. (Editors): Casuarina ecology, management and utilization. Proceedings of an International Workshop, 17-21 August, 1981, Canberra, Australia. Commonwealth Scientific and Industrial Research Organization (CSIRO), Melbourne, Australia. pp. 102-106.
National Research Council, 1984. Casuarinas: nitrogen-fixing trees for adverse sites. National Academy Press, Washington, D.C., United States. 118 pp.
Okorio, J., Byenkya, S., Wajja, N. & Peden, D., 1994. Comparative performance of 17 upperstory tree species associated with crops in the highlands of Uganda. Agroforestry Systems 26: 185-203.
Pinyopusarerk, K. & Boland, D.J., 1990. Casuarina junghuhniana - an Indonesian species of promise for the tropics. In: El-Lakany, M.H., Turnbull, J.W. & Brewbaker, J.L. (Editors): Advances in casuarina research and utilization. Proceedings of the Second International Casuarina Workshop, January 15-20, 1990, Cairo. Desert Development Center, American University in Cairo, Cairo, Egypt. pp. 202-212.
Turnbull, J.W., 1990. Taxonomy and genetic variation in Casuarina. In: El-Lakany, M.H., Turnbull, J.W. & Brewbaker, J.L. (Editors): Advances in Casuarina research and utilization. Proceedings of the Second International Casuarina Workshop, January 15-20, 1990, Cairo. Desert Development Center, American University in Cairo, Cairo, Egypt. pp. 1-11.

K. Pinyopusarerk

Pinyopusarerk, K., 1997. Casuarina junghuhniana Miquel. In: Faridah Hanum, I & van der Maesen, L.J.G. (Editors): Plant Resources of South-East Asia No 11: Auxiliary plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea