Abstract

From the dawn of civilization bamboo has been continuously used in the cultural practices, food habits, house building etc. It has always been considered as an important resource due to its diverse utilities. It is found in a wide variety of soil and climate conditions. Its unique characteristic features make it a perfect solution for the environmental consequences. It plays an important role in carbon sequestration, soil erosion control, water conservation and land escape designing element. This review paper is an attempt to provide information and raise awareness regarding the utilization of bamboo for people and environment.
 

Introduction

      The importance of bamboo to the world economy and its people is enormous. A vast portion of rural people in developing countries depend on bamboo resources for their livelihood and well being. Bamboo is a group of plants that belong taxonomically to the family Graminaeae (Poaceae). It has more than 1,575 species in 75 genera in the world, occurring in a great variety of soil and climate conditions. In India there are 140 species in 19 genera spread over whole India except the Kashmir valley (Gupta, 2008). Tewari (1992) listed 23 genera and 126 species of bamboo from India of which 18 genera and 90 species occur in the north-east states. Melkania (2007) enumerated 63 species of 20 genera of bamboo in the natural forests and degraded and abandoned lands of North Eastern Region. INBAR (2005), reported 145 species belonging to 23 genera. Recently after critical study and scrutiny of literature it was found 20 genera and their 115 species are found in India (Naithani, 2008).

      Besides its diverse use in rural household, industry and building materials, bamboo has the properties to combat the environmental problem. The physical, biological and physiological characteristics of bamboo has made it instrumental in solving many environmental problem such as carbon dioxide sequestration, soil-erosion control, water conservation, bio-energy crops. Its dense rhizome and root system are capable to hold the soils preventing soil erosion and soil runoff.  Large leaf litter content on the soil surface can retain moisture. Charcoal obtained from the bamboo culms can be used for water purifiers. Enormous biomass and desirable fuel quality properties have made it as an alternate source of renewable energy. Using bamboo in different agroforestry models helps in land rehabilitation and improving soil fertility. The ecological functions of bamboo has drawnthe attention of scientific community from all parts of the world. It is being expected that bamboo can play an important role in climate change mitigation. The VIIIth world bamboo congress, to be held at Thialand (September, 2009) has put the ecology and environmental concern of bamboo in its theme interest along with other areas to be discussed. The title of the conference is Bamboo, the Environment and Climate change. The objective of this article is to integrate and enhance the knowledge and awareness of uses of bamboo for ecology and environment.

Role of Bamboo in Carbon Dioxide Sequestration

      There has been huge increase in fossil fuel consumption and CO₂ emissions over the past hundred years causing a dramatic increase in atmospheric CO₂ concentration. This increased CO₂ is believed to be responsible for a significant rise in global temperature. Global-scale climate modelling suggests that the temperature increase will continue, at least over the next few hundred years, leading to glacial melting and rising sea levels (Oelkers and Cole,2008). In an attempt to solve these problems large-scale sequestration of CO₂ from our atmosphere has been suggested. Sequestration of carbon in the terrestrial biosphere has emerged as a means for reducing net carbon emissions. The most common and easy method of carbon sequestration is to simply plant more trees. Plant by their virtue takes CO₂ from the atmosphere and release oxygen. Much of the carbon from the CO₂ is integrated into their biomass and released safely into the soil upon their deaths. Plantation and native vegetation provide an excellent opportunity to optimize the carbon sequestration on these lands.

      The rapid production cycle of bamboo increases carbon sequestration, because fast growing plants absorb carbon dioxide more quickly and more often than trees. The world wide federation (WWF) estimates that an acre of bamboo can store about 6.88 metric tons of carbon per year which is roughly seventy percent more than an acre of hardwoods. Over 90% of bamboo carbon can be sequestered in durable products such as boards, panels, floors, furniture, buildings, cloth, paper and activated charcoal. These products have a very long life span and may retain carbon for several decades. The annual biomass and carbon sink per hectare of many bamboo species are comparative to wood tree crops, such as eucalyptus or teak.  It can sequestrate CO2 in the form of 12 T per hectare of plantation (Tripathi and Bajpai).

Bamboo for Soil Erosion Control

      Soil erosion affects both agriculture and natural environment with impacts on site as well as off site. It is one of the most widespread of today’s environmental problem. The deterioration of soil by the physical movement of soil particles from a given site is as termed soil erosion. Some of the main causes of soil erosion are wind, water, ice, animals and human activities. Erosion results in the degradation of a soil’s productivity in a number of ways: it reduces the efficiency of plant nutrient use, damages seedling, decreases plants’ rooting depth, reduces the soils water holding capacity, decreasing its permeability, increases runoff and reduces it infiltration rate (Troeh, 1991). It was found that grater hoof activity and lower organic matter of the 0-20 mm layer in the high stocking rate paddock caused the soil surface to be more susceptible to erosion. Grazing by removing perennial grasses and pulverizing the surface soil can have a major impact on local water balances and erosion rates respectively within the inter groove areas (Greene et.al 1994). Deng and his team studied five different conversion models to compare the soil conservation efficiency (Deng et. al., 2003). Out of the five models, bamboo grooves intercropped with fodder grass was most in soil erosion. Extensive fibrous root system, connected rhizome system, its comparatively dense foliage, the leaf litter produced on the soil surface, etc. are some the important valuable characteristic features of bamboo for controlling soil erosion. The comparatively dense foliage protects against beating rains, and its habit of producing new culms from underground rhizomes allows harvesting without disturbing the soil (Ben-zhi et.al., 2005).

Water Conservation and Bamboo

      Water is an important natural resource. An important use of water in our country is for irrigation. Irrigation accounts for about 70% of total water withdrawals worldwide. Besides, water is also required in large amounts for industrial and domestic consumption. Due to population and rapid economic growth, water use has increased over recent decades in most of the nations except for a few industrialised country (Sharma,2001). Observational records and climate projections provide abundant evidence that fresh water resources are vulnerable and have the potential to be strongly impacted by the climate change, with wide ranging consequences for human societies and ecosystems. Soil moisture reduction due to precipitation changes could affect natural systems in several ways. There are projections of significant extinction both plant and animal species. Water availability surface water sources or shallow underground water wells depends upon the seasonality and inter-annual variability of stream-flow, and a secured water supply is determined by seasonal low flows (Bates et. al., 2008). Traditional and modern water harvesting techniques, water conservation and storage, and planting of drought resistant and early maturing crops are being practised to mitigate the impact of climate change and water. Bamboo is considered as an alternate for water conservation, due to its physiological properties.

      Bamboo germplasm enjoys a wide diversity in India, in particular north-east region. It plays important role in water conservation and water source protection. The green bamboo covering the mountains of north-east states helps to protect the water resources, and bamboo forests help to conserve water. The litter deposits on the soil surface of the forest cover reduces the evaporation of underground water and hence maintain the moisture conserving water more in comparison to other forest species. As discussed in soil erosion section, the strong subterranean shoots and rhizome system is capable of conserving water and strengthening the riverbank. In China, where there is the case of water-loss and soil erosion, or where the bank of rivers, lakes and reservoirs are easy to be washed away, bamboo is planted to protect them from water loss and soil erosion. The water quality of Yangtze River is better than that of Yellow river due to alpine bamboos cover surrounding the river. According to a report from Environmental bamboo foundation, Nyuh Kunning, Ubud, it has been found that the water table (Underground water level) rises up within a few years of bamboo plantation. In some cases new springs also appear, reason may be bamboo being the C₃ plants. Trees conserve on an average 35-40% of rain water in comparison, bamboo saves up to 90%. It shows the effective potential of conserving water.

      Other side of bamboo, how it helps in water conservation is the use of bamboo in drip irrigation system. In this system, water distribution is done with the use of bamboo channel and bamboo supports. Water from the natural streams located at higher elevation is supplied with the use of bamboo channels, supported with bamboo poles (Borthakur, 1992; Dabral, 2002).  It is interesting to mention that with the advancement of research and technology in the field of bamboo, now bamboo resins and fibres are used for clothes making and it needs popularization. Convention cotton requires over 10,000 cubic feet of water per acre to grow, where as bamboo tolerates drought extremely well and only requires minimal rain water. Moreover, bamboo fibre doesn’t hold odour and so it can be used over and over without frequent washing. This is really a great way to conserve water.
 

Charcoal Production

      Bamboo charcoal can be produced with the help of pyrolyser. A local pyrolyser can be made with the help of metal oil drum in the form of kiln. Pyrolysis of bamboo chips in an oil drum to produce charcoal takes on an average of four to five hours. The charcoal produced is cooled, powdered, and sieved to uniform size to get charcoal powder. Bamboo charcoal has high calorific value and it is a good alternative for fire wood for heating and cooking purposes. Other than these, it has wide application in food and environment based industry (CIBART and INBAR).

      It plays important role in environment protection. According to a report by FAO also posted on the website of bamboo network (www.bamboonetwork.org), bamboo charcoal can used as a water clarifier and absorber of poisonous gases and moisture. It can be used as shield to protect from electromagnetic waves. The indoor pollution caused by poisonous materials would be absorbed if the panels were made of bamboo charcoal instead of other common materials such as plastic, asbestos etc. It is also used in sugar refining and waste treatment.

Bamboo as a Potential Bio-Energy

      The total mass of living organisms is a given area or volume is called biomass; recently dead plant material is often included as dead biomass. Energy derived from biomass are known as bio-energy (Bates et. al.,2008). Bioenergy continue to play an important role both in the domestic and industrial sector in India, as it is an agricultural- based economy. Biomass is the main source of energy for a large number of small, rural, and cottage industries along with the majority of rural households. In rural sector biomass energy (bio-energy) is used for firing of clay items, drying, baking, steam raising and distillation. In industrial sector it is used in textile mills, brick kilns, mini cement plants, steel re-rolling and lime kilns. Rural and industrial application of bioenergy calls for the developmentof environment friendly and economically viable system, process control and raw materials for the efficient use of bioenergy. Biomass gasifier system has all these qualities. In this system, solid fuel is converted into gaseous fuel in presence of limited  supply of oxygen. The resulting gas mixture can be directly in an oven/ burner and fed into a a diesel engine to generate electricity (Palit and Made, 2007). Bamboo may have potential as bioenergy for use in industrial sector and rural domestic everyday use. 

      The large amount of biomass produced by bamboo provides it a very attractive source of bioenergy and can be considered as a renewable source of energy (Fielden, 1999). Scurlock et. al., (2000) studied a limited range of bamboo species (nine bamboo samples) for its characterisation with respect to their fuel quality. It was found that bamboo shares a number of desirable fuel characteristics with certain other bioenergy feedstocks. Moisture content , ash value, volatile content, fixed carbon content, heating values, alkali index, C H N S & Cl analysis, ash elemental (% dry matter, ash elemental (% ash, 600^oC) were the parameters on which bamboo was analysed for its fuel quality. Most of these parameters give positive and desirable results for the bamboo to be used as The net calorific value of bamboo is comparatively higher than the other woodd species like beech, spruce, eucalyptus and poplars in the range of 18-3 to 19.7 MJ/ Kg (Gielis and Oprin, 2001). From a combustion perspective, this is a very low N content and would be beneficial in terms of minimal fuel bound nitrogen conversion to NO_x if bamboo were used as a broiler fuel. Bamboo can be suitably be used for co-firing fuel because of its lower N contents than many coals used for power production. It has other NO_x benfits caused by the differences in flame structure and temperature that reduce thermal NO_x formation. The lower sulphur content also gives positive result for its fuel efficiency. The low ash and chlorine contents of the bamboo samples make them attractive for use in biomass combustion application for electricity production. The waste products from bamboo processing for other purposes may also be suitable for energy recovery using biomass gasifier. It can be used as bio-energy in the form of briquettes, charcoal and activated carbon form also. In Northern laos it was reported that among the different seven species of bamboo: Bambusa tulda, Bambusa pallid, and Dendrocalamus membranaceus show the greatest potential as bio-fuel. The result was again based upon moisture content (%), density (g/cm³), ash content(%)  and energy content (MJ/Kg) (Dannenmann et. al., 2007). Department of science and Technology and National Mission on Bamboo Application of Government of India has also underlined the importance and granted fund for the establishment of bamboo gasifier to produce electricity in the villages of North East Region of India (Anonymous). 

Bamboo Agro-forestry and Land Rehabilitation

      Agroforestry is an agricultural model in which herbaceous plant and woody perennial trees are grown together. The combinations are such that the both partners should not competefor nutrition and also they are not allelopathic to each other. In recent years, agroforestry of different models have been popularised due to its win-win situation both from the proactive and ecological view. From the ecological point of view, agroforestry are recommended for management, maintenance and improvement of soil fertility (Nath et.al., 2009).

      Bamboo has its ability to grow in various types of soils. It performs well in arid, degraded and eroded land. Growing of bamboo can conserve the soil, prevents water flow and rehabilitate the land. The enormous biomass of bamboo particularly the leaf litter has ability to regenerate the soil. Bamboo plantation can be instrumental for land repair and maintenance (Ben Zhi, 2005). With its evergreen canopy, large biomass accumulation and abundant litterfall, bamboo has been playing a great role in rehabilitation of degraded land. Bamboo based agroforestry models provides a conducive temperature and improvement in othe climatic factorsfor the intercrops. It increases the photosynthetic capacity and productivity. The litterfall increases the organic matter, nitrogen, phosphorus, potassium and other macro & micro nutrients. In India different bomboo-agroforestry models have been successfully established which includes bambbo + ginger (Jha & Lalnumawia,2004), bamboo + soyabean (Sheshadri, 1985) bamboo + turmeric, bamboo + Pigeon pea (Shanmughareland Francis, 2001). Sole bamboo plantation have also been used to rehabilitate the land in different parts of the world (Christanity et. al., 1996 Takamatsu et. al.,1997), for illustration, in India Dendrocalamus strictus shows positive land rehabilitating and restoring ability. The net productivity was found to be similar to that of native dry forest within a short span of time (Singh et. al., 1999).

Conclusion

      From the above it may be concluded that bamboo has its promising feature in the field of its uses in ecology and environment. People and farmer should be trained and informed about the environmental utilization of bamboo for increasing the much needed ground water, soil conservation, environmental improvement and bamboo properties as a sustainable utilization.  For the wide spread use of bamboo as a potential bio-energy the proroductivity should be increased in comparison to other less efficient bioenergy candidate crops. As a bio-energy resource it can meet both thermal as well as electrical energy requirements and thereby can give energy security to the rural people (Tripathi & Bajpai). Till now much of the research focus is on its biological characteristics, propagation, clump management and other value added products. Along with these there is a subsequent need of research to understand the mechanism of its ecological functions and utilization. 

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