BABOOL - AN IMPORTANT TREE

DR. S.M. ALAM
(feedback@pgeconomist.com)

Mar 7 - 13, 2011

Gum acacia (babool) or gum acacia, hashab (Arabic), gum arabic tree with botanical name Acacia nilotica of family leguminosae is an important forest tree of Indo-Pak subcontinent.

In tropical parts of Africa (Sudan and Senegal) as well as Pakistan and India, Acacia nilotica trees are highly valuable sources of fuel, timber, fodder, tannin, and honey. The plant is exceeding by drought tolerant.

In Pakistan, it is one of the most important species in social and farm forestry. Acacia nilotica is a moderate sized tree that grows up to 15 meters and in very unfavorable locations is only a shrub. It has an umbrella-shaped crown and is easily identified by its bright yellow, and sweet-scented flower heads.

The natural life of the tree is usually 25-30 years. The prickles typically grow in trees at each node-the central one recurred, the two lateral (sometimes absent) upward. Flowers are in whitish spikes. During the hot season, the tree appears in full leaf and provides a good shade to the people of the locality and passerby. The tree can survive, even the most adverse conditions - hot, dry wind and sandstorms on the poorest soils of rock and sand. This species is ideal for reclamation of refractory sites and shifting sand dunes.

It is important forest resource of the Republic of Sudan, which supplies about 80 percent of the world's gum arabic. The principal plantations are in the Sudan and Senegal, where the local farmers harvest the crop for supplementary income. In addition, it is now cultivated in India, Pakistan and Nigeria. The species is very common in Sindh and Punjab and to some extent in the other areas of Pakistan. It can grow under temperatures vary from 43 to 48o C. The tree is very drought resistant. It can grow under sub-desert conditions, where annual rainfall is a low as 200 mm, with 8 - 11 dry months in the year, but prefers 300 450 mm rainfall. It will also survive with annual rainfall as high as 800 mm. It grows easily from seed.

This is a fast growing tree under favorable soil irrigation. It grows on a variety of soils. It prefers alluvial soil, but grows well even on heavy, black cotton and clay soils as well. It is generally propagated by seed and rarely by seedlings. The tree tolerates high temperature. In rural areas of Pakistan and India, the pods are fed to goats and other animals. The trees are extremely thorny and could become a major problem for the users. This species should be introduced only to those arid areas, where the need for firewood is absolutely critical and most essential. Babool trees preserve environment, clean air impart beauty and give shade, provide fuel-wood and timber, protect soil, stop erosion and increase soil fertility. It is highly suitable for agro- forestry systems and is already widely grown in combination with watermelon, millets, forage grasses and other crops.

It can be used in desertification control to reestablish a vegetation cover in degraded areas as well for sand dune fixation and wind - erosion control.

The wood is a very common as fuel on the Indo-Pak sub-continent and large quantities are consumed as firewood and charcoal by the villagers. It has also been used extensively to fuel locomotives and river steamers, and it powers the boilers of some small industries as well. The calorific value of sapwood is 4,800 kcal per kg, while that of heartwood is 4,950 kcal per kg. The wood is heavy (specific gravity, 0.67 - 0.68) and the trees coppice occasionally. Average production of wood from natural forests is about 5 m3 per ha. It has been reported that the yield of wood from gum plantations, where the trees are widely spaced is low, with annual increments of about 0.5 - 1.0 m3 per ha.

But, if the trees are grown at a density suitable for firewood production the yield should be much greater.

The hard, tough wood is resistant to termites, impervious to water, and is famous for railroad ties (sleepers), tool handles, carts boats and oars. It is an attractive wood, good for carving the turnery, and is still used for boat building, as it was in ancient Egypt. It is also one of the best mining timbers in Pakistan. The leaves and pods are widely used as fodder and in arid regions of Pakistan constitute the chief diet for camels, goats, and sheep. Pods and foliage contain as much as 15 per cent crude protein and important feed during the rainy season and early dry season for these animals/cattle.

The bark and pods are widely used in the leather industry; their tannin content varies from 12 to 20 per cent, leaves of the trees are regarded as a nutrition food for goat, camel and sheep. This is available almost all throughout the year. It is a great nitrogen fixer. Acacia nilotica is probably the earliest commercial source of gum arabic, which is used in foods and beverages though this valuable commodity now comes mainly from Acacia senegal. The gum is still used in the manufacture of matches, inks, paints, and confectionery in pharmaceutical preparations throughout the world. It has a wide range of industrial application. The seeds are dried and preserved for human consumption as vegetables. Pods are affected by insects, which can severely affect the viability of seed, and the roots are susceptible to attack by termites during extreme droughts. Young plants may be severely damaged by goat, sheep, and other animals during their grazing in the field. This species may form thorny thickets and could become a serious pest. Both Australia and South Africa have policies to eradicate further introduction of "this noxious thorny weed". It was concluded that gum acacia is a very useful fuel wood tree in the country.