Global Scenario of Acrocarpus fraxinifolius Wight & Arn. - A future tree of Agro forestry

Acrocarpus fraxinifolius portrait one among the mainstay of agro forestry in Asian tropics. The lofty tree fortified a substantial impact in every horizon of life. The evergreen, deciduous tree of Fabaceae family stands tall about 30-60 m endowed with unique properties which idiosyncrasies it in the plant kingdom. Surpassing the adverse climatic conditions, A. fraxinifolius serves as a shade tree for tea and coffee plantation and epitomises as a multipurpose avenue tree culminating to the culture of agro forestry. Mundani in bloom is a spectacular appearance bestowed with scarlet crimson red flowers attracting infinite migratory birds and insects. The ancestral gene with indelible memory gravitate this extraordinary majestic tree to aestivate and adapt to strongest survive.


INTRODUCTION
Acrocarpus fraxinifolius Wight & Arn possessing a botanical synonym Acrocarpus combreliflorus Teysm & Binn emanates from the tropical regions of Asia and is known as the native of Asian tropics. Its natural and biological distribution covers India, China, Burma, Borneo, Sumatra, Indonesia, Vietnam, and Bangladesh. This exotic species is planted around the globe and is extensively known as acrcarpo, Mundane, Clapboard tree (Lorenzi et al., 2003).
It is considered as one among the tallest trees in India. The Taxonomic Classification of A. fraxinifolius includes family Fabaceae and subfamily Caesalpinioideae.
Though A. fraxinifolius is a leguminous tree, but is devoid of nitrogen fixing ability in root nodules. It is a single species with molecular relatedness with Cerotonia. Acrocarpus is a rapid growing, evergreen or deciduous tree. Pink Cedar is attributed with dense wood, resistance and maneuverabality.

ECOLOGY AND HABITAT a. Geographic Distribution
A. fraxinifolius is observed as a part of tropical evergreen and sub-evergreen forest. In India it covers the evergreen forests hill slopes (up to 1200 meters) of Western Ghats (Troup, 1921;Rai, 1976), tropical semi-evergreen forests of the eastern Himalayas and propounded as the dominant tree species (Puri, 1960).
Annually it grows up to 1.3-3 m and can reach to a height of 50-60 m with a diameter 0.90-2.40 meters (Whitemore and Otarola, 1976). A comprehensive distribution of Acrocarpus is monitored in Nilgiris, Coorg, North and South Kanara, Anamallis, Tirunelvi and Kerela in Southern India. The tree is also grown as a shade tree for coffee plantation in tropical Africa, in Coorg and south kanara districts of Karnataka. The lofty tree is also considered suitable for tea plantation.
The species are also cultivated in the high rainfall zone of Himachal Pradesh between 600-1200 m elevations (Ghildyal, 1989). The species also covers the eastern Himalayas, in West Bengal, Bhutan, Sikkim, Assam and Meghalaya between 600-1200 m.

b. Climatic factor
Mundani occurs at high rainfall, relatively cool highland areas (Laurie, 1974) and flourish at an altitude ranging from 0-2000 m, precipitation from 500-3000 mm and average temperatures 14-26 °C (Martinez et al, 2006). In India and Myanmar it occurs in regions with an annual precipitation of over 2000 mm. It is sensitive to drought and frost. Being a shade tree the temperature varies from 35 °C to 42.5 °C and the minimum from 2.5 °C to 17.5 °C. The tree adapts to wide variation in rainfall (1900-5000 mm).

c. Soil Type and pH
Acrocarpus grows best in deep, well-drained, clay-loam soils with a pH of 4-7 and also thrives in acid soils and limestone areas (Cheng, 1985). In Mexico Mundani grows in vertisol type soils with average drainage and a pH of 6.9-7.5

BOTANY OF ACROCARPUS FRAXINIFOLIUS
Young leaves of Mundani are characterized by their bright red appearance. Flowering of trees occur after the shedding of leaves. The bark surface is rough, pale grey and brown in colour. The leaves are spirally arranged, bipinnately compound with 3-5 pairs of pinnae and 4-7 pairs of leaflets per pinna. Flowers are bisexual with pedicel 4-10 mm long flowers.

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Flowers of A.fraxinifolius are petal free, oblong, 5-9mm long, dark red, short and hairy in appearance. Fruits contain elongated and flattened pod of 8-17 cm long. Epigeal germination is observed in seeds (Chavelas and Devall, 1988). Orthodox storage behavior at low temperature is exhibited by the seeds (Hong et al., 1996).

PROPERTIES OF ACROCARPUS FRAXINIFOLIUS
The heartwood of exotic tree is hard and strong attributed with pale, pinkish bright red to reddish brown colour having darker streaks which is well distinguished from the pale yellowish sapwood, adding to furniture and cellulose production (Lorenzi et al., 2003). The density of Acrocarpus varies from 0.44 to 0.68 g/cm 3 according to the age, the site and the origin (Simpson, 1996;Carvalho, 1998;Honorato et al., 2005). It has physical resemblance with ash and walnut wood (Anibal et al.,) and is propagated as an ornamental tree (Whitmore and Otarola, 1976). In tropical Africa and India, grown as a shade tree for coffee plantation (Rocas, 2010). Mundani is attributed with inter locked grain and the wood texture is coarse.

GENETIC PROPAGATION OF Acrocarpus:
A germplasm bank and a seed orchard had been established by 1986 in Arunachal Pradesh in India. Kenya and India are the major seed-exporting countries.

XYLOPHAGES ORGANISMS INVADING Acrocarpous fraxinifolius:
Young trees of Acrocarpus are susceptible to biological invasion by termites. Serious defoliation of young seedlings is contributed by grasshoppers and caterpillars. Damping off is a prominent disease reported in Acrocarpus. It is also invaded by Armillaria mellea. High rainfall and dry season leads to mortality of these exotic trees. Netria species have a paramount impact on shoots attributing to the decay of trees. In Mexico trees are defoliated by leaf cutter ants (Atta sps). Trees are invaded by termites after being infected by unidentified fungi (Combe and Gewald, 1979).

ADVANTAGES AND USES OF ACROCARPUS PLANTATION:
1. Acrocarpus wood act as a source for fodder, firewood for charcoal production, apiculture, timber, furniture, gum and resin. 2. The wood is used to produce pulp for paper and has also been recommended for reinforcing river banks, stabilize terraces and used in agro forestry systems (Orwa et al., 2009) International Letters of Natural Sciences Vol. 30

CONCLUSION
A. fraxinifolius can be termed as the tree for the future. The cultivation and plantation of this leguminous arboreal will contribute to wood necessary and will attribute to preserve the forest and thousands of habitat and vegetal species.