Casuarina junghuhniana Miquel

Casuarina junghuhniana is a fast-growing, deciduous tree 15-25 (max. 35) m tall; trunk diameter 30-50 (max. 65) cm; crown somewhat open. Branching dimorphic with normal woody branches and determinate, deciduous branchlets. Leaves reduced to scales, in whorls of 9-11 (max. 13) that define articulations. Flowers unisexual. Male inflorescence a cylindrical or slightly clavate spike, 3-8 cm long, borne on the apex of a deciduous branchlet; sheathing bracts hairy outside. 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 x 2.5-3 mm. Infructescence a woody conelike structure. Fruit a grey or yellow-brown winged nut (samara), small, 2-3 mm wide and 4-5 mm long including wing. Seed solitary. Casuarina is from the Malay word ‘kasuari’, which indicates the supposed resemblance of the twigs to the plumage of the cassowary bird. One of the common names of Casuarina species, ‘she-oak’, widely used in Australia, refers to the attractive wood pattern of large lines or rays similar to oak but weaker.

Like other Casuarina species, C. junghuhniana is wind pollinated. Shoot growth tends to cease or to be less during the flowering period that coincides with the dry season.

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 in limestone-derived soils.

C. junghuhniana is a pioneer species of deforested land such as rocky slopes and undisturbed areas. Grows naturally on the slopes of volcanoes. Rainfall in its natural habitat is monsoonal with a well-defined summer maximum. It is drought-tolerant and can survive prolonged waterlogging due to its ability to cope with oxygen deficiency. When trees reach a few metres in height they are fire resistant and sprout readily on being damaged by fire.

Indigenous to Indonesia, C. junghuhniana was introduced into Tanzania in 1955 from the Forest Research Institute in Java and then into Kenya. A male hybrid plant was introduced into Thailand around 1900, and its progeny was taken from there to India in the early 1950s.

Seedling with epigeal germination. Mature seeds germinate readily without pretreatment. Germination is good and uniform, completed after 10 days. The germination rate is 50-60%, decreasing rapidly unless kept in dry cool storage. 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. Under favourable conditions seedlings attain 25-30 cm in height within 3 months. Inoculation of the seedlings or cuttings with effective strains of Frankia bacteria is recommended when C. junghuhniana is introduced into a new area.

Seedlings can attain 3 m growth in height per year during the 1st 2-3 years. In plantations with a controlled water regime in Thailand, C. junghuhniana hybrid reaches 20 m in height and 15 cm in diameter in 5 years. 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 x 2-3 m. A mean annual increment of 10-15 cubic m/ha is generally obtainable. Weeding is necessary only during the 1st few years, after which the trees shed large amounts of branchlets to form a thick and dense mat of litter that suppresses weeds. The red-tipped C. junghuhniana is a poor self-pruner; it produces strong root suckers. Pruning in plantations up to a height of 2-2.5 m is often necessary to make the plantations more accessible for general maintenance. Trees respond well to coppicing and pollarding.

Green branchlets are attacked by the Acrididae locust Aularches miliaris and insects of the family Lymantriidae. In dry areas, subterranean termites may 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. Damping-off of seedlings in nurseries is caused by various fungi (Fusarium spp., Phytophthora spp., Pythium spp., Rhizoctonia spp., Sclerotium spp.). Butt and heart rot, caused by Ganoderma applanatum, may infest tree trunk after damage by fire. Schizophyllum commune may cause decay of the sapwood.

Seed storage behaviour is orthodox; can keep viability for up to 1 year at room temperature. 1-1.8 million seeds/kg.

Shade or shelter: A suitable species for planting as a windbreak. Reclamation: Rehabilitates degraded soils. In Java the species has been cultivated in revegetation and rehabilitation programmes dating back to the beginning of the 1900s. It is especially good as a pioneer on landslide-prone soils. In the low lying acid sulphate areas of Southeast Asia and North Australia, C. junghuhniana is grown successfully. Nitrogen fixing: C. 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. Soil improver: Widely planted to improve soil fertility. Branches and foliage are burnt and the ash is spread on village gardens in Timor. Branchlets decompose slowly and provide good mulch. Mycorrhizal fungi further enhance its adaptability in poor soils. Ornamental: C. junghuhniana is sometimes planted as an ornamental. Boundary or barrier or support: In Kenya, farmers plant the tree around fields as a live fence.

Fuel: The wood is highly suitable for firewood and charcoal production. The air-dry density of the wood is 900-1000 kg/cubic m, and the density of charcoal is 650 kg/cubic m. The energy from the charcoal is 34 500 kJ/kg, which is among the highest among firewood species. Fibre: The wood is suitable raw material for kraft pulp. Timber: Very hard, reddish-brown wood, prone to splitting. In Thailand, it is a popular source of construction piles and for fish traps. Also used for pole production. It can be used to make hardboard in a mixture with Dipterocarpus 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 creosote preservative. Other products: Although it is not a fodder species, young trees are browsed by animals.