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Rhizophora mucronata Lam.

Rhizophoraceae
Asiatic mangrove

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.


  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Toxicity
  5. Description
  6. Germplasm
  7. Distribution
  8. Ecology
  9. Cultivation
  10. Harvesting
  11. Yields and Economics
  12. Energy
  13. Biotic Factors
  14. References

Uses

The wood (sp. grav. 0.81), durable except in the ground, and difficult to saw, is used for construction, fish traps, house frames, piling, and poles. Thousands of tons of mangrove woodchips are exported annually from Indonesia, Sabah, and Sarawak for pulp and for rayon manufacture (NAS, 1980a). Fruits may be eaten, after scraping off the outside and boiling with wood ashes, according to some skeptical accounts (Burkill, 1966). The Wealth of India describes the fruit as sweet and edible, the juice made into a light wine. Young shoots are cooked and eaten as a vegetable (C.S.I.R., 1948–1976). Bark, used for tanning and dye, may be removed from stems for sale as firewood. Leaves are the source of a black or chestnut dye (Burkill, 1966). Mangrove extract is used for maintaining oil-well drilling muds within a desired range of flow (C.S.I.R., 1948–1976). Planted along coastal fish ponds to stabilize the banks.

Folk Medicine

Reported to be astringent, Asiatic mangrove is a folk remedy for angina, diabetes, diarrhea, dysentery, hematuria, and hemorrhage (Duke and Wain, 1981). Leaves are poulticed onto armored fish injuries (Watt and Breyer-Brandwijk, 1962).Indochinese use the roots for angina and hemorrhage. Malayans use old leaves and/or roots for childbirth. Burmese use the bark for bloody urine, Chinese and Japanese for diarrhea, Indochinese for angina (Perry, 1980).

Chemistry

Wood contains 4.4% resin, 63.4% cellulose (List and Horhammer, 1969–1979) and 1.5% ash (Watt and Breyer-Brandwijk, 1962). Tannin may vary in dry bark from ca 13–50%, leaves contain 9.1%, green fruits 12.0%, and ripe fruits 4.2%. Spent mangrove bark, after tannin extraction, can be used as a source of furfural (C.S.I.R., 1948–1976). Spent bark from North Borneo yields an ash assaying 18% lime (70% CaCO3).

Toxicity

Honey collected from the flowers is said to be poisonous (C.S.I.R., 1948–1976).

Description

Evergreen tree 25(–30) m high, 70 cm in diameter, with numerous branching arching stilt roots. Bark brown or blackish, smoothish, with horizontal fissures. Leaves opposite, elliptical to oblong, 8–15 cm long, 5–10 cm wide, acute, entire, without visible veins, thick and leathery, glabrous, black-dotted beneath. Petiole 3–5 cm long. Stipules paired, leaving ring scar. Flower clusters axillary, 2–3 times forked, with 3–8 flowers ca 15 mm long. Bell-shaped hypanthium with 4 pale yellow, pointed leathery sepals and 4 cream-colored petals 9 mm long. Stamens 8, stalkless, anthers 6–8 mm long, 4 opposite sepals and 4 opposite petals. Ovary half-inferior, conical, 2-celled, with 2 ovules in each cell, 2-lobed style. Berry ovoid or conical, 5–7 cm long, brown, leathery. Seed 1, viviparous, becoming cigar-shaped, to 40 cm long and 2 cm in diameter (Little, 1983).

Germplasm

Reported from the Africa, Hindustani, Indonesia-Indochina, and China-Japan Centers of Diversity, Asiatic mangrove, or cvs thereof, is reported to tolerate diseases, insects, pests, salt, and waterlogging (NAS, 1980a; Little, 1983). (2n = 36)

Distribution

Old World tropics from South and East Africa to Madagascar, Seychelles, Mauritius, southeastern Africa to southern China, Ryukyu throughout Malaysia to northeastern Australia, Melanesia, and Micronesia. Not widely introduced in Hawaii (Little, 1983).

Ecology

Estimated to range from Tropical Moist to Rain through Subtropical Moist to Rain Forest Life Zones, Asiatic mangrove is estimated to tolerate annual precipitation of 10 to 80 dm, annual temperature of 20 to 26°C, and pH of 6.0 to 8.5. Hou (1958) suggests that this is the only Malayan mangrove which can survive complete daily inundation. Little (1983) describes the habitat as brackish and saline salts of depositing shores and marshes. Of the Asian species this one is most likely to be found in deep soft mud.

Cultivation

According to the NAS (1980a), planting is usually not needed because natural regeneration is so successful. In Avicennia and Rhizophora, direct seeding results in ca 90% survival. Drying the seedlings in the shade a few days before planting seems to make them much less attractive to crabs, perhaps due to a buildup of tannin.

Harvesting

In Tamil Nadu, natural regeneration is abundant and plantations for fuel are managed on 30-year rotations. Clear fellings of Rhizophora may be replaced by Avicennia (Hou, 1958). Species of Rhizophoraceae, growing only from the tips of the branches, are often killed by indiscriminate lopping of branches(NAS, 1980a).

Yields and Economics

Virgin mangrove stands are reported from Mindanao, where there were 149 trees/ha over 25 cm DBH with 130 m3/ha. Planted forests 40 years old are projected to yield 400 m3/ha, an average of only 10 m/ha/yr (Hou, 1958). Cannell (1982) cites data on a mangrove forest dominated by Rhizophora, Ceriops, and Sonneratia, averaging 11 m tall, with an LAI (leaf area index) of 3.7–4.2. The stemwood and bark on a DM basis weighed 74.4 MT/ha, the prop roots 61.2 MT/ha, the branches 15.8, the foliage 7.4, the fruits 0.3, for a total standing aerial biomass of 157 MT/ha. The CAI (current annual increment) of stem wood, bark, and branches was 20 MT/ha/yr, foliage 6.7, fruits 0.3. These data, taken from a mangrove on Phuket Island, Thailand, regenerated following clear felling, Suggest annual productivity may attain 20 MT/ha/yr in Asian mangroves.

Energy

Mangrove was the main fuel in the Philippines until World War II (NAS, 1980a). One great advantage in the eyes of firewood dealers is the ease with which, the wood is split. With a calorific value higher than oak, it burns with even heat. Five tons of mangrove firewood is said to equal three tons of Malayan coal, two tons of Indian or Japanese. It makes an excellent charcoal, rather high in sulfur (Burkill, 1966). Wood affords good fuel with high calorific value (4,888 cal, 8,799 Btu) and makes high quality charcoal. In Bangkok, mangrove charcoal, which burns steadily, giving off intense heat without sparking, sells for twice the price of other charcoal (NAS, 1980a).

Biotic Factors

Crabs, great enemies of the seedlings, may damage starting plantations. Browne (1968) lists the following: Crustacea, Sesarma spp.; Coleoptera, Poecilus fallax; and Mammalia, Macaca irus.

References

Complete list of references for Duke, Handbook of Energy Crops
Last update Friday, January 9, 1998 by aw