In this article we will discuss about:- 1. History of Bamboos 2. Habitat and Distribution of Bamboos 3. Uses.
History of Bamboos:
Bamboos are integral not only to the culture of India but that of the entire Southeast Asia. The wide range of their uses qualifies this group of species to be the one foremost associated with the mainstay of rural life and culture in our country.
Its versatility has led to the coinage of such terms as “bamboo culture”, “green gold”, “poor man’s timber”, “friend of the people” and “cradle to coffin timber”. In fact, bamboo can be used as a substitute of timber in many respects.
Bamboos belong to the grass family Poaceae (Gramineae). In India, there are 125 indigenous as well as exotic species of bamboos belonging to 23 genera. Bamboo forests occupy an area of 10.03 million ha, roughly 12.8% of the total forest area in the country.
They are found in almost all the states of the country, from the tropical to the temperate regions and the alluvial plains to the high mountains, the only exception where they do not occur naturally is Kashmir.
The principal bamboo genera occurring in India are Arundinaria, Bambusa, Chimonobambusa, Dendrocalamus, Dinochloa, Gigantochloa, Indocalamus, Ochlandra, Drepanostachyum, Phyllostachys, Pleioblastus, Pseudoxytenanthera, Schizostachyum, and Thamnocalamus.
More than 50 per cent of the bamboo species occur in Eastern India – Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura and West Bengal. Other areas rich in bamboos are the Andamans, Bastar region of Madhya Pradesh and the Western Ghats.
Habitat and Distribution of Bamboos:
Bamboos grow from sea level, in the tropics, to 4000 metres above sea level, in the temperate region. Although, bamboos are more common to the tropics, they also occur naturally in subtropical and temperate zones of the world, except in Europe.
The geographical distribution of bamboos is governed largely by the conditions of rainfall, temperature, altitude and soil. Most of the bamboos require a temperature from 8 degree celcius to 36 degree celcius, a minimum annual rainfall of 1000 mm and high atmospheric humidity for good growth.
They form an important constituent of many deciduous and evergreen forests. In nature bamboos seldom occur as pure crops, but are generally found as an understorey in tropical evergreen, tropical moist deciduous, tropical dry deciduous, montane sub-tropical, montane wet temperate and Himalayan wet temperate forests.
Generally, the genera Bambusa and Dendrocalamus are found under tropical conditions, whereas Arundinaria and its allies occur in the temperate region and are by far, most common on high elevations in the western and eastern Himalayas. Dendrocalamus strictus is predominant in dry deciduous forests, while Bambusa bambos flourishes best in moist deciduous forests.
The most important bamboo of the semi- evergreen forests of the Andamans in Gigantochloa rostrata. In the eastern region, i.e., West Bengal, Assam and north-eastern Himalayas, the commercially important bamboos are Bambusa tulda, Dendrocalamus hamiltonii and Melocanna baccifera.
Bamboos are usually found in moist valleys, sheltered depressions, along steams and the lower hill slopes, but occasionally also occur on higher slopes and hill tops.
They usually occur mixed with or under tree species, except in case when they form secondary brakes, and then, they are more or less pure. Though many species form brakes, those of Arundinaria, Ochlandra, Melocanna and Bambusa bambos are typically more extensive. Where shifting cultivation is practised, the bamboo brakes are more common.
The distribution and site factors of some commercially important bamboos occurring in India are:
Uses of Bamboos:
Bamboo is considered to be the most efficient natural resource as far as strength vis-a-vis cost. Strength of the bamboo depends upon the species, climatic factors and its moisture content.
Bamboo is strong, though not stronger than timbers like Sal and Teak. Seasoning is a essential pre-requisite for maintaining the appearance and strength of bamboo products and structures. Unseasoned bamboo is highly susceptible to insects and fungal attack, decay and mechanical degradation.
Seasoning of bamboos has to be done properly and carefully as rapid drying results in splitting. To prevent cracks during seasoning green bamboos may be split into halves. The bamboos are best dried by air seasoning under overhead cover for 2-3 months. Kiln drying under controlled conditions can be done successfully in about 2-3 weeks.
Bamboo can be cut and split easily with hand saw. Strips of any measurement can be made with knife. Immature bamboos are soft and pliable and can be moulded to desired shape. Bamboo takes polish and paint well.
The strength of the culms, their straightness and lightness, combined with hardness, range in size, hollowness, long fibre and easy working qualities, make the bamboos suitable for a variety of purposes.
Whether it is the tender shoots, used for pickles and curries, the slivers, used for tooth picks and meat barbecues, ribs for fans or slats for sun screens, or the dried culm as the sturdy lathi and for construction of the so called bamboo houses, the versatility of bamboo is legendary.
The thousand and one uses for bamboos have long been known and established.
Some of the Traditional Uses are:
Agricultural implements, anchors, arrows, back scratchers, baskets, beds, blinds, boats, bottles, bows, bridges, brooms, brushes, buildings, caps, cart-yokes, caulking material, chairs, chicks, chopsticks, coffins, combs, containers, cooking utensils, cordages, dustpans, fans, fences, fish-traps, fishing-nets, fishing rods, flag-poles, floats for timber, flutes, flower-pots, food, food-baskets, fuel, furniture, hats, handicrafts, haystack stabilisers, hedges, hookah- pipes, joss-sticks, kites, ladders, ladles, lamps, lance staves, lanterns, lining of hats and sandals, masts, match-sticks, mats, musical instruments, nails, net floats, ornaments, props, paper, pens, polo mallets, rafts, rayon pulp, roofing, sails, scaffoldings, scoops, seed-drills, shoes, shuttles, slats, sports goods, sprayers, stools, sticks, tables, thatching, tobacco pipes, toys, tool handles, traps, trays, tubes, umibrella- handles, walking-sticks, walls, vessels and wrappers.
Structural Utilisation of Bamboos:
Bamboo has been traditionally in use in building construction from times immemorial. It is used in foundation, frames, floors, walls, partitions, ceilings, door and windows, roofs and for reinforcement in cement concrete.
Although, there are more than 125 species of bamboo reported to be occurring in India, 20 important species have been tested so far for their physical and mechanical properties. The mean values and ranges of specific gravity, ultimate bending and compressive strength (MOR and MCS) of bamboo in green condition are given below.
The classification of timber species for structural use in building is done on the basis of modulus of rupture (MOR) and modulus of elasticity (MOE) while for other structural uses like piles and mine use, timbers have been classified on the basis of modulus of rupture (MOR), modulus of elasticity (MOE) and maximum crushing stress (MCS).
Similarly, bamboos have been classified on the basis of MOR, MOE and MCS in green condition in three groups as given below. The limits of these properties for the three groups have been fixed keeping in view the corresponding limits for wood and spread of ultimate bending and compressive strength of bamboos.
Suitable species for constructional use are given below along with some traditional timber species falling in these groups.
For facilitating proper designing in bamboo safe working stresses of these species have also been worked out.
Uses Deserving Specific Mention:
1. Bamboo Parquet: (Block flooring):
The term parquet is applied to flooring in which strips, 3.81 cm X 6.71 cm, are cut and laid out in geometric patterns.
2. Laminated Bamboo:
The bamboo culms are cracked, spread out and flattened into sheets, with suitable binding and filling material. Then the sheets are combined, lapped, arranged, glued, treated and pressed to the desired form. They are then cut and trimmed to the desired size and shape and finally given finishing touches, according to one’s fancy.
3. Bamboo-Reinforced Concrete:
Bamboo reinforcement was first used in China in 1919 in concrete piles in railways. It is also used for construction purposes.
4. Artificially-Shaped Bamboo:
Bamboo can be made to grow into square, rectangular and triangular shapes for low cost housing, handicrafts, decoration items and cottage industries. Japan has successfully grown artificially-shaped bamboos. Production is simple, like moulding hollow blocks, but needs practice.
Banslochan or Tabashir is a siliceous secretion found in the internodes of the culms of various species of bamboos. It occurs in fragments or masses, up to 2 cm thick. It is used as a cooling tonic and aphrodisiac; also in the treatment of asthma, cough and other debilitating diseases.
It is superior to many other charcoals for use in electric batteries; in India, used for pharmaceutical purposes. Jewellers prefer bamboo charcoal.
The dried, mature bamboo leaves are used for deodorizing fish-oil in Asian countries.
8. Soil Conservation:
Many bamboos are quite useful for soil conservation due to their intricate rhizome system and roots.