PROSEA, Introduction to Bamboos
- 1 General
- 1.1 What is a bamboo?
- 1.2 Choice of species
- 1.3 Origin and geographic distribution
- 1.4 Uses
- 1.5 Properties
- 1.6 Cultural aspects
- 1.7 Problems of interpretation of names
- 2 Botany
- 2.1 Morphology
- 2.2 Anatomy
- 2.3 Taxonomy
- 2.4 Growth and development
- 3 Ecology
- 4 Exploitation and cultivation
- 4.1 History of bamboo exploitation and cultivation
- 4.2 Propagation
- 4.3 Management
- 4.4 Diseases and pests
- 4.5 Harvesting
- 4.6 Yield
- 4.7 Post-harvest handling and processing
- 5 Breeding and genetic resources
- 6 Prospects
What is a bamboo?
Bamboos, commonly grown as woody bamboos, belong to the Gramineae, and form the tribe Bambuseae of the subfamily Bambusoideae. They often have a tree-like habit and can be characterized as having woody, usually hollow culms, complex rhizome and branch systems, petiolate leaf blades and prominent sheathing organs. Moreover, all members possess similar anatomical features in the leaf blades, i.e. fusoid cells and arm cells, which set the bamboos apart from grasses. In tropical Asia and America, several members of this tribe grow into giant bamboos, which are a familiar sight in rural South-East Asia.
Bamboo is frequently confused with rattan and its derived product cane. Bamboo furniture is often referred to as rattan or cane furniture, and vice versa. However, the products are very different. Bamboos, with very few exceptions, have hollow stems which cannot be bent easily unless split. Rattans and canes are always solid and flexible, and belong to the Palmae.
Choice of species
It proved difficult to select useful species to be included as major species in Chapter 2. There are an estimated 1000 or so species of bamboo belonging to about 80 genera in the world (Table 1) of these about 200 species of which are found in South-East Asia and belong to approximately 20 genera (Table 2). Many of the species are indigenous to the monsoon area of South-East Asia. Some species are utilized and widely found in the region, whereas others are present only in limited areas but are extensively used. These species, 45 in all, belonging to 8 genera (Bambusa Schreber, Cephalostachyum Munro, Dendrocalamus Nees, Gigantochloa Kurz ex Munro, Melocanna Trin., Phyllostachys Sieb. & Zucc., Schizostachyum Nees and Thyrsostachys Gamble) are dealt with as major species in this volume.
Minor species are dealt with in Chapter 3, including infrequently used species with limited distribution and species which are currently lesser-known but of potential interest. Some of the latter belong to genera containing major species, and many to other genera such as Dinochloa Büse, Melocalamus Benth., Nastus Juss., Neohouzeaua A. Camus, Racemobambos Holttum, Shibataea Makino ex Nakai and Yushania Keng f.
Lesser-known species not included in the text are listed in Table 3.
Several bamboo species which are important locally such as "bayog" and "laak" (Bambusa spp.) from the Philippines or "kuring" (Gigantochloa sp.) from Indonesia have not been included in this volume because their identity is still uncertain.
Because bamboo classification is far from complete, and research in South-East Asia is still continuing, there will inevitably be changes in the scientific names. Moreover, new information will become available on other aspects as well in the near future.
Origin and geographic distribution
Bamboos occur in the tropical, subtropical and temperate regions of all continents except Europe and western Asia, from lowlands up to 4000 m altitude. Most, however, occur at low to medium elevations in the tropics, growing wild, cultivated or naturalized in a great variety of habitats (Table 2).
Because bamboo classification is far from complete and most genera are still not well understood, it is therefore impossible to provide precise information on their origin. There has been some speculation, however, on possible centres of diversity of bamboos, such as tropical America, Madagascar, and the region including southern China and northern Burma (Myanmar), Thailand and Vietnam. The genera in tropical America (about 20, reasonably well defined) are not found outside the region (McClure, 1973; Soderstrom & Ellis, 1987), whereas all known native species in Madagascar are endemic. The geographical distribution of bamboo is greatly influenced by human activities (Holttum, 1958). Forest destruction, e.g. by logging and building of new roads, has encouraged the spread of native bamboos, which subsequently become abundant and form mixed or pure bamboo forests. Most of the genera included in this volume are native to tropical Asia.
Bambusa is the most widespread genus of bamboos in tropical and subtropical Asia. There are about 37 species in South-East Asia. Of these, 16 species grow wild, each with a limited distribution; 6 species are only found in cultivation (B. balcooa Roxb., B. multiplex (Lour.) Raeuschel ex J.A. & J.H. Schultes, B. oldhamii Munro, B. tuldoides Munro, B. utilis Lin and B. vulgaris Schrader ex Wendland).
There are, however, two species with a wide distribution. Bambusa vulgaris, for example, is pantropical, planted or naturalized in all kinds of habitats, but particularly along river banks; its origin is not certain. The hedge bamboo B. multiplex is widely planted in the tropics, subtropics, and even outdoors in temperate regions as an ornamental or a hedge since it can withstand low temperatures.
Dendrocalamus and Gigantochloa are also native to tropical Asia. They comprise some species which are found solely in cultivation, and some which have limited distribution or are endemic to relatively small areas. There are about 29 species of Dendrocalamus growing in South-East Asia, mainly occurring in the lowlands from the Indian subcontinent to Indo-China and Peninsular Malaysia. D. asper (Schultes f.) Backer ex Heyne is planted throughout in the region, from the lowlands up to about 1500 m altitude; its origin is not known. Gigantochloa, with about 24 species, is mainly confined to the area from Burma (Myanmar), Indo-China to Peninsular Malaysia. It has been recorded that only one species of Gigantochloa in Java is native; the others are believed to have been introduced from the Asian mainland during the migration of people from the north.
Cephalostachyum, Melocanna and Thyrsostachys are mainly found on the mainland of Asia from the Indian subcontinent to Thailand, Vietnam and Laos. Cephalostachyum is an interesting but poorly known genus of about 11 species, 5 of which occur from the Himalaya to northern Burma (Myanmar), whereas the others are found from Burma (Myanmar) to Vietnam, mostly growing in the lowlands, and one species is found in Mindoro (the Philippines). Melocanna seems to have one species only, M. baccifera (Roxb.) Kurz, which is found in Bangladesh, Assam (India), Burma (Myanmar) and Thailand. It has been introduced elsewhere in the tropics. Thyrsostachys is native to Thailand and Burma (Myanmar) and consists of two species. T. siamensis Gamble is one of the most useful bamboos in Thailand. It has been introduced into other countries in South-East Asia.
Schizostachyum is distributed throughout South-East Asia, extending into the Pacific Islands, with its centre of distribution in Malaysia and western Indonesia. There are about 30 species, most of them having a limited distribution.
The genus Phyllostachys is native to China, comprising about 50 species. Some species have been introduced and cultivated in Japan, Europe, North America and the tropical highlands. P. aurea A. & C. Rivière has become naturalized in many parts of the tropics.
Dinochloa, comprising about 20 species, is found from the Andaman Islands and southern Thailand throughout Malaysia, western Indonesia and the Philippines. Species are found scattered in lowland and hill dipterocarp forest, but they become weeds in logged and disturbed areas.
Racemobambos is confined to Malesia including the Bismarck Archipelago and the Solomon Islands, but so far has not been found in Sumatra, Java or the Lesser Sunda Islands. It consists of about 16 species.
Nastus is found mainly in the southern hemisphere from Madagascar to the Solomon Islands, although it has been recorded in the northern hemisphere in Sumatra. It consists of about 15 species.
Bamboo is one of the natural resources of the tropics, and because of its wide distribution, availability, rapid growth, easy handling and desirable properties, has been used widely in the daily life of the local community as a sustainable resource. Bamboos are utilized intensively for a wide range of purposes. "No plant is known in the tropical zone which could supply to man so many technical advantages as the bamboo. The strength of the culms, their straightness, smoothness, lightness combined with hardness and greater hollowness; the facility and regularity with which they can be split; the different sizes, various lengths and thickness of their joints make them suitable for numerous purposes to serve which other material would require much labour and preparation" (Kurz, 1876). Even in this mechanical age, their usefulness continues and is likely to continue, because they are a necessity of life in South-East Asian communities (Holttum, 1958). In recent years bamboos have entered the highly competitive world market in the form of pulp for paper, parquet, plybamboo, and as a canned vegetable. The most significant uses in South-East Asia are for building material, for making various types of baskets, and as a vegetable. Other important uses are as a source of raw material for making paper, for musical instruments and handicrafts.
Bamboo culms have many characteristics that make them suitable for numerous construction purposes (Kurz, 1876; McClure, 1953). Some species are used only for building material (pillars, walls, roofs and floors). When used for pillars, bridges or scaffolding, culms should have a large diameter with thick walls and relatively short internodes. In South-East Asia species suitable for this purpose belong to Bambusa (e.g. B. bambos (L.) Voss, B. blumeana J.A. & J.H. Schultes, B. tulda Roxb. and B. vulgaris), Dendrocalamus (e.g. D. asper) and Gigantochloa (e.g. G. apus (J.A. & J.H. Schultes) Kurz, G. atter (Hassk.) Kurz, G. levis (Blanco) Merrill, G. pseudoarundinacea (Steudel) Widjaja, G. robusta Kurz and G. scortechinii Gamble).
Species with culms of medium diameter and with relatively thin walls are suitable for the construction of walls, floors and roofs (e.g. Schizostachyum brachycladum Kurz, S. zollingeri Steudel, Gigantochloa levis). In South-East Asia there are several methods of preparation. The commonest and easiest way to make walls is to cut the culms to appropriate length, split them on one side only and then flatten them out; they are either used as such and joined together vertically, or they are woven into a large piece. In the most elaborate method, the culms are split into very thin long strips which are plaited into larger pieces with attractive motifs. This kind of plaited bamboo is also used for partitions and ceilings. In houses with floors raised above the ground, the floor is often made of split bamboo culms of about 5 cm wide, joined together and secured with strips of bamboo culms or other material. In roof construction the culms are split in two and laid in such a way that they resemble corrugated iron. In Bali, bamboo tiles, 30 cm × 5 cm, are used for roof construction. Locally, bamboo culms are used to reinforce cement/concrete structures in China, India, Japan, the Philippines and Indonesia.
Bamboo species with culms of smaller diameter, relatively thick walls (e.g. Gigantochloa apus, G. scortechinii, Schizostachyum zollingeri), and which split easily are used for making various types of baskets (Widjaja, 1984; Wong, 1989). In many parts of East and South-East Asia, local people still prefer baskets made from split bamboo rather than from plastics for carrying vegetables and fruits, poultry or pigs, because braided bamboo "breathes". Although plastics are used ubiquitous, simple carrying baskets and boxes of bamboo are still being produced. In some parts of Indonesia, local people prefer to use thin-walled bamboos (such as Bambusa atra Lindley, B. forbesii (Ridley) Holttum, Schizostachyum brachycladum) for making a fine basket, as this saves having to split the bamboo beforehand.
Bamboo shoots ("rebung") are an important vegetable in East and South-East Asia. A shoot is the new growth of the rhizome apex into a young culm and consists of young internodes protected by sheaths. After removing these sheaths, the shoot is cut into small pieces or shredded and then cooked in boiling water. The pieces are then used as a vegetable ingredient for various dishes such as pickles, fried meat or vegetables, meat or vegetables cooked in coconut milk. In general the shoots emerge during the rainy season and the desired shoot is the one which grows from the rhizome buried deep in the soil. In many parts of South-East Asia, shoots are consumed locally, but in Thailand a large-scale canned bamboo-shoot industry has developed. In general, young shoots of many bamboo species are edible, but only a few bamboos produce superior shoots, i.e. Dendrocalamus asper, Gigantochloa levis, G. albociliata (Munzo) Kurz and Thyrsostachys siamensis. In China, superior bamboo shoots are produced by Phyllostachys pubescens Mazel ex H. de Leh., Dendrocalamus latiflorus Munro and Bambusa oldhamii.
For centuries the Chinese have used bamboo in paper making (e.g. Phyllostachys pubescens). In South-East Asia (e.g. Indonesia, the Philippines and Thailand) paper mills have been established using some bamboo species as raw material, such as Bambusa bambos, B. blumeana and Dendrocalamus strictus (Roxb.) Nees). In India, the principal species used is D. strictus.
Bamboo musical instruments have been developed by most tribes in South-East Asia. There are 3 types, i.e. idiophones (percussion or hammer instruments), aerophones (blown instruments) and chordophones (stringed instruments). Apparently, bamboo musical instruments have been known in South-East Asia for a long time, because flutes are known to every tribe. Filipinos, Indonesians and Thais have stringed instruments, although the number of strings varies. Species of the genus Schizostachyum are the most suitable for making aerophones (like "kan" or "sompotan"), because of small diameter culms, long internodes and thin walls. The main species used for making idiophones (e.g. "angklung") and chordophones are Gigantochloa atroviolacea Widjaja, G. atter, G. levis, G. pseudoarundinacea and G. robusta; sometimes Dendrocalamus asper and Gigantochloa apus are also used. The large-diameter culms of G. atroviolacea are used for making bass drums and bass horns.
Another important use of bamboo is in the handicraft industry. Table mats, handbags, hats and other woven bric-à-brac can be made of bamboo. The best developed bamboo handicraft industry is the weaving of bamboo splits. In weaving the bamboo splits, many different patterns have been created. However, there are some handicrafts made of unsplit bamboo. Usually this kind of handicraft consists of engravings on the outer part of the culm or the rhizome. The species employed in woven handicrafts are mostly species with long and flexible fibres such as Bambusa atra, Gigantochloa apus, G. scortechinii, and Schizostachyum latifolium Gamble. Species that are easily engraved are Bambusa vulgaris, Dendrocalamus asper and Schizostachyum brachycladum.
People of South-East Asia living in bamboo-rich areas have long used bamboo culms to make their furniture. Recently, bamboo furniture has become popular, and elite bamboos are sought after. A number of species of Bambusa, Dendrocalamus and Gigantochloa are commonly used in the furniture industry (Widjaja, 1980). Two of the favoured species are Gigantochloa atroviolacea and Dendrocalamus asper, whose culms are straight and smooth.
Hedge, wind-break, ornamental
Some bamboos are used as a living hedge or wind-break when planted close together such as Thyrsostachys siamensis and Bambusa multiplex. Several species (e.g. Bambusa multiplex, B. vulgaris, Schizostachyum brachycladum) are planted as ornamental. The thorny bamboos (e.g. Bambusa bambos) are often planted around fruit orchards, vegetable fields, smallholdings or villages to protect them from intruders (e.g. wild animals).
Culms of Dendrocalamus asper, for instance, are also used as containers for collecting water or palm juice, for pipes and troughs, etc. Unsplit internodes, e.g. of Schizostachyum brachycladum, are used as pots for cooking vegetables, meat, rice or glutinous rice. The internode is usually lined with banana leaf before being filled with uncooked food, and is placed over a fire. Glutinous rice with coconut milk cooked in a bamboo internode ("lemang") is a popular dish in South-East Asia.
Forest destruction has allowed some bamboo species to become abundant; they are a major source for native people to develop cottage industries of chopsticks, satay sticks and incense sticks (e.g. Gigantochloa scortechinii).
Fish traps are made of split bamboo joined together with either rattan strips or bamboo strips.
Bamboo rafts are usually made from culms with medium diameter and relatively thin walls.
Bamboo leaves are often used as fodder. Large and smooth leaf blades are used for wrapping food (e.g. Chinese "bak chang" made of glutinous rice). In Indonesia, large leaves are also used to make "tangerang" hats for working in rice fields or tea plantations.
Bamboo culms are used for various poles, e.g. carrying poles, vegetable and fruit props, fishing rods, outriggers, boating poles, posts and fences.
- Moisture content. The moisture content (m.c.) of bamboo culms is important and can influence mechanical properties. It is determined by the weight of the water in the culm, expressed as a percentage of the dry weight of the culm: (weight - dry weight)/dry weight × 100%. The moisture content of mature culms of fresh bamboo ranges from 50-99% and of immature culms from 80-150%, whereas for dried bamboo it varies between 12-18%.
- The moisture content of culms increases from bottom to top, and from 1-3 years; it decreases in culms older than 3 years. It is much higher in the rainy season than in the dry season.
- Density. Density is given at a certain moisture content in kg/m3. For example, it ranges from 600-900 kg/m3 at 12% moisture content for Dendrocalamus strictus. Specific gravity is sometimes given calculated for 0% moisture content and is a dimensionless parameter.
- Fibre saturation point. The fibre saturation point is the point at which there is no more free water in the culm, but the cell walls are still saturated with water. Apparently, fibres and parenchyma have different fibre saturation points, leading to different values. The fibre saturation point is given as a percentage and is 20% for Dendrocalamus strictus.
- Shrinkage. Unlike wood, bamboo begins to shrink directly after harvesting, but it does not continue uniformly. Shrinkage affects both the thickness of the culm wall and the diameter (Liese, 1985). Drying green mature bamboo to about 20% moisture content, leads to a shrinkage of 4-14% in the wall thickness and 3-12% in diameter. Shrinkage is slightly more in the radial direction than in the tangential diameter (about 7% compared with 6%), but differences between the inner and outer wall are greater; shrinkage in the longitudinal direction is less than 0.5%.
The mechanical properties generally used for bamboos are the same as those for wood, and values are given at a certain moisture content. All values for strength properties increase with a decreasing moisture content and are positively correlated to specific gravity. The parameters for bending strength and compression strength refer to the whole culm of the bamboo and not to split bamboos. However, some authors have tested the mechanical properties of split bamboos as well.
- Bending. For (static) bending strength the following parameters are used:
- Modulus of elasticity (in N/mm2) indicates the ratio between the bending stress in the material and the relative deformation caused by this bending stress; it is a measure of rigidity; thus higher values indicate more rigid material. The modulus of elasticity is directly related to the amount of fibres, thus in a culm the value of this parameter decreases from the outer side to the inner side. The normal range for air-dried culms is 17*000-20*000 and for green culms 9000-10 100 N/mm2.
- Modulus of rupture (= fibre stress at maximum load, maximum fibre stress, ultimate bending stress, stress at breaking point) indicates the stress necessary to bring about failure of the tested material when bent (in N/mm2). The normal range is 72-94 (without nodes), 84-120 (with nodes) N/mm2. The modulus of rupture is approximately 0.14 × density (in kg/m3) for dry bamboo (12% moisture content), 0.11 × density for green bamboo (Janssen, 1990).
- Compression. For compression the following parameters are used:
- Compression strength parallel to grain (maximum crushing strength, ultimate compression stress) indicates the stress applied parallel to the direction of the fibres necessary to bring about failure ("crush") in a sample (in N/mm2). Normal ranges: 21.6-38.8 (bottom), 26.6-41.4 (middle) and (17.4-)31-49.9 (top) N/mm2. The compression strength parallel to grain is approximately 0.094 × density for dry bamboo (12% moisture content) and 0.074 × density for green bamboo (moisture content 60% or more) (Janssen, 1990). Compression strength perpendicular to grain is sometimes given, but is not very common.
- Shear strength is the stress necessary to make surfaces slide over each other parallel to the direction of the grain (in N/mm2). Shear strength in bamboo is higher than in wood, but the hollowness of bamboo causes problems in this respect. Normal ranges: 6.0-9.5 (bottom), 6.1-11.3 (middle) and (5.4-)7.6-12.6 (top) N/mm2. The shear strength is approximately 0.021 × density for dry bamboo (12% moisture content) (Janssen, 1990).
Strength parameters for (static) bending and compression, as cited above, are commonly determined for round bamboo samples, but they can all be determined for split bamboo as well. Some authors specify how tests to determine these values are performed. Bending tests can vary in that loads are applied at different points, at the node or internode, at samples from different positions along the culm, and at different ages of the culm.
Loading at a node or at the centre of an internode influences the outcome of values: the modulus of rupture is up to 20% less when loaded at the centre of an internode, but can also be slightly more (up to 10%). However, these rather large differences are not very frequent; the modulus of elasticity is always larger, approximately 10%, for tests with loads at the centre of internodes (Limaye, 1952). The modulus of rupture is least in the middle part of the culms, sometimes there is a slight tendency to increase with increasing height along the culm. This trend holds better for the modulus of elasticity, but is not valid for all tests known from literature. Compression parallel to grain is rather similar for samples taken at different heights along the culm; presence of nodes hardly influences the value of this parameter (Atrops, 1969). Values for strength parameters are sometimes expressed in MPa (Mega Pascal), which is equal to N/mm2. For the parameters commonly given in N/mm2, some authors use kg/cm2 as unit of measure; l kg/cm2 equals 0.098 N/mm2.
- Major chemical components. The major components of bamboo culms are cellulose, hemicellulose and lignin; the minor components include resins, tannins, waxes, and inorganic salts (Liese, 1985). Cellulose and hemicellulose, also called holocellulose, are the solid residue of the total polysaccharide fraction that remains after extraction of minor components and lignin by mild oxidation. Hemicellulose is extracted from holocellulose with a 17.5% NaOH solution, the residue being cellulose, sometimes referred to as α-cellulose. Pentosans are the main constituents (80-90%) of hemicellulose of bamboos. In cold water some dyes and tannins can be dissolved, while hot water extracts more substances from bamboo culms, such as starch and some toxic substances. Alcohol-benzene 1 : 2 (1/3 ethanol and 2/3 benzene) extracts almost all substances not belonging to the cellulose groups and lignin. Ether is used to extract alkaloids which do not dissolve in water.
- Pulp and paper manufacture. The chemical composition of bamboo is of special interest to the pulp and paper industry. The following components are generally cited (in %, i.e. percentage of the oven-dry weight; only for ash percentage of moisture-free weight): holocellulose (61-71%), pentosans (16-21%), lignin (20-30%), ash (1-5(-9)%), silica (0.5-4.0%, being part of the ash); solubility in cold water (1.6-4.6%), hot water (3.1-7.0%), alcohol-benzene (0.3-5.3(-7.8)%), 1% NaOH (15-30(-39)%) and sometimes ether (0.2-1.8%). Hemicellulose contributes to the strength of paperpulps. Higher lignin content implies more chemicals to be used for pulping to extract the lignin to a certain content. Greater alcohol-benzene and water solubility also imply increased consumption of chemicals in pulping. The 1% NaOH solubility indicates the amount of low molecular weight carbohydrates consisting mainly of hemicellulose and degraded cellulose; as such, it may indicate the degree of decay, e.g. by fungi, heat, and oxidation. Silica is the main constituent in ash; silica will ultimately present problems for the pulp and paper-making process. The silica content of bamboo culms is generally higher than that of wood, viz. 0.5-4.0% and most of it is deposited in the epidermis. Since bamboo contains more impurities than wood, cooking is more costly and the pulp yield is less.
- The percentage of pulp extracted from the culm is 40-50%.
- Edible young shoots. For the chemical composition of young shoots the following components are given in g or mg per 100 g edible portion: water 89-93 g, protein 1.3-2.3 g, fat 0.3-0.4 g, carbohydrates 4.2-6.1 g, fibre 0.5-0.77 g, ash 0.8-1.3 g, Ca 81-96 mg, P 42-59 mg, Fe 0.5-1.7 mg, vitamin B1 0.07-0.14 mg, vitamin C 3.2-5.7 mg, glucose 1.8-4.1 g. Energy value 118-197 Joules; HCN content: 44-283 mg/kg.
Since time immemorial, bamboos have exerted profound influence on the life and cultures of Asian people. For example, bamboos always figured in local paintings, legends, songs, folklore, etc. Since prehistoric time, bamboo has been used as one of the weapons for hunting and fighting. In Peninsular Malaysia, the Temiar and Semoi make their traditional hunting weapons such as blowpipes from two internodes of bamboo. For both peoples, the blowpipe has both a symbolic and a practical value: the possession of a blowpipe is a sign that a man has reached adult status so that he is able to join hunting parties and become a full member of the community. In Irian Jaya, people make their arrowheads from small bamboo species of Racemobambos and of Nastus, and the arrow shafts from small, straight, thin bamboo culms of Schizostachyum species.
Bamboo is also employed in traditional ceremonies; for example, in Bali the yellow variety of Schizostachyum brachycladum is used during the burial ceremony because yellow is considered the sacred colour of Hinduism. The roof of traditional houses and rice barns in Toraja, Sulawesi (Indonesia) is made from the green variety of the same species. "Garong" baskets are made of several internodes of another Schizostachyum species tied together with split bamboo or rattan; the baskets are filled with rice wine during the Gawai festival in Sarawak, Malaysia (Sandin, 1963).
From the earliest times peoples have used a bamboo knife to cut the umbilical cord at birth. This custom occurs not only in South-East Asian countries but also in Japan, China and India. As well as being used to cut the umbilical cord, the bamboo knife is also used for circumcision by the Muslims in Indonesia and Malaysia (Kurz, 1876).
Problems of interpretation of names
The identification and naming of bamboos in South-East Asia present many problems because classification of bamboos is not complete. The botanical names applied in this volume and their identification are based on several sources such as previous bamboo literature, herbarium specimens and field observations.
Vernacular or local names are not considered very important for identifying bamboos because they are often not reliable. Therefore, great caution is required in the interpretation of vernacular names.
Because bamboo can be found almost everywhere, especially in tropical and subtropical Asia, and is readily available for various purposes, research on various aspects of bamboo is also considerable in the region. The information accumulated from such research is supposed to provide a background for similar research conducted in other areas; therefore it should be transferable. However, if the bamboo species are not correctly identified, and if voucher specimens are not made or cited, the result has little value. If bamboo researchers wish to cooperate, as recommended by the Third Bamboo Workshop 1988, then they should be able to communicate with each other on the same correctly named bamboo species. This means that research should have a firm taxonomic base. In order to be able to give the correct scientific name for a bamboo species, a complete herbarium specimen is required.
Collecting bamboos is time consuming and requires patience and skill. Most researchers do not bother to make full collections and like to take short cuts. Vernacular names have been used to find out scientific names by consulting literature citing both vernacular and Latin names. Some researchers have relied on cited names from checklists; very often they have uncritically gathered or cited taxonomic information from second-hand sources (i.e. literature accumulated from previous taxonomic works). Many of the published accounts from such research have been disregarded in this Prosea volume, because the names given are doubtful.
Most of the information on morphology presented here is based on the work of previous authors. Kurz (1876) was the first botanist to provide a general impression of bamboo morphology, and later Gamble (1896) extended the work of Kurz with his monograph of Indian bamboos. These two works are followed by an excellent account by Holttum (1958) on the Malayan bamboos. The terminology and definitions are mostly taken from McClure (1966).
(see Fig. 1)
Although bamboos are generally thought of as erect, in fact they vary in habit. A distinction can be made between clump-forming, single-stemmed and climbing bamboos. In South-East Asia they may be large and erect (e.g. some Bambusa spp., Dendrocalamus spp. and Gigantochloa spp.), small, slender and erect (e.g. Thyrsostachys spp. and some Schizostachyum spp.), erect with drooping or pendulous tips (e.g. Schizostachyum spp.), slender and scrambling (e.g. Nastus spp., Racemobambos spp.), or climbing (e.g. Dinochloa spp.). In scrambling bamboos, the culms grow to considerable height and bear many branches at each node; the lower culm part is straight and erect, whereas the upper part cannot support itself and scrambles or leans on nearby vegetation. Superficially this habit resembles a climber, but a proper climbing bamboo has culms which cannot support themselves and therefore twine around tree trunks.
The clump-forming (or tufted) bamboos, represented by the genera Bambusa, Schizostachyum, Gigantochloa and Dendrocalamus are predominant in the tropics, while non-clump forming or open bamboos like Phyllostachys predominate in the temperate zones.
The rhizome is of great importance in bamboos, because there is no central trunk as in trees, and the rhizome becomes the foundation of the plant. The bamboo rhizome has been described as a segmented, complex subterranean system (Holttum, 1958; McClure, 1966). There are two basic types of rhizomes: pachymorph (determinate, sympodial) and leptomorph (indeterminate, monopodial). The native bamboos of South-East Asia have a pachymorph rhizome system, in which each individual rhizome has short internodes and an apex that will continue to grow and become a culm. In this type of rhizome, the basal part ("neck") is short, narrower and more slender than the upper part. The culms are usually close together, and form a densely tufted clump. In Melocanna baccifera the slender "necks" elongate for up to 1 m, so that culms are distant and form a very open or diffuse clump. Many of the temperate bamboos have a leptomorph rhizome system. Here the rhizome is long and slender and usually hollow, and the apex extends and grows horizontally. Each internode has a solitary bud giving rise to either a culm or a rhizome. The clump has a spreading habit.
A young shoot is a new growth of the distal end of a pachymorph rhizome or of a lateral bud of a leptomorph rhizome. It consists essentially of a short, massive, little-differentiated stem packed with nutrients and protected by numerous two-ranked, rigid sheaths (Holttum, 1958). This new growth develops slowly at first, then elongates rapidly, forming a new culm. The structure of a young shoot is often very characteristic in recognizing a bamboo species.
A bamboo culm is separated by horizontal partitions ("nodes") into joints ("internodes"). Most culms have cylindrical and hollow internodes and this, together with the dense, hard, thick (or thin) walls and nodes, gives the culm great mechanical strength. The diameter of the culm depends on the species and the environment, and varies between 0.5-20 cm. The diameter of the mature culm is already determined by the diameter of the young shoot. The internodes are usually glabrous and smooth, or rough and hairy when young, becoming glabrous at maturity. In some species the internodes are covered with white substance or wax when young. Midculm internodes are generally longer than the lower or upper ones; they are delimited by a sheath scar, which marks the insertion of the culm sheath or culm leaf to the culm. The nodes may be swollen, and the lower ones often bear aerial roots. The culm is usually not a reliable characteristic in recognizing a bamboo species. However, it is very characteristic for certain species. For example, Bambusa vulgaris culms are not straight and the nodes are slanting, and Dinochloa culms are nearly always zig-zag.
Young shoots and young culms are protected by modified leaves which embrace the developing internodes, and usually fall off when the culm becomes mature. A culm leaf consists of a sheath proper (culm sheath), a blade, a ligule, and sometimes one or two auricles. The blade is attached to the sheath along the narrow top part of the sheath. The ligule is a growth from the top of the sheath, membraneous with entire or serrate apex and with or without bristles, and the auricles are the lateral extension of each side of the blade base. The structure of the culm sheath is very important for recognizing bamboo species. The inside is smooth and shiny; when young the outside or the back is usually covered with irritant hairs which may be white, pale brown, golden brown or black. The sheaths also vary in colour and may be green, bluish or purplish-green, or yellow tinged with orange. The shape of the culm blade and the position of its attachment to the sheath (erect or deflexed) also vary.
Branches are a characteristic feature of bamboos. Each internode bears a branch bud (primordium) just above the culm leaf scar. The branch buds are arranged on alternate sides of the culm, and may be found from the lowermost node upwards or from the midculm node upwards. Branches develop while the culm is still growing, or they develop only after the culm reaches its full height. In South-East Asian bamboos, the branch bud is solitary. The branch system is often very characteristic of a bamboo genus. In Schizostachyum, for example, branches are many at each node, equal or subequal in size. In Dinochloa, the primary branch axis of the branch bud is dormant but produces short secondary branches from its basal nodes. If the apex of the culm is damaged, the dormant primary branch axis of each node will grow and elongate to replace the main culm. The array of branches that may develop at a single culm node is called branch complement.
Each of the ultimate branchlets bears 8-18 leaves, except for Shibataea kumasasa (Zollinger) Nakai. They differ from the blade of the culm leaf by having a petiole and a pronounced midrib. Each leaf blade is connected to the sheath at the base of the petiole. In general the leaf blade is not useful for recognizing bamboo species. The ligule is usually very short and entire, but may be very long and deeply laciniate. Auricles may be present at the top of the sheath, and are often furnished with very long bristles.
Inflorescence and flower
Being members of the grass family, bamboos typically have a compound inflorescence consisting of many flowers. Bamboo flowers or florets are usually very small (2-15 mm long); each floret comprises a lemma, a palea, three lodicules (sometimes absent), 3 or 6 stamens, and an ovary with 1 or 3 stigmas. Usually 2 or more (rarely one) florets are borne along jointed branchlets together with one to several glumes below the florets. The whole structure is called a "spikelet". These spikelets are arranged in an inflorescence. Basically, there are two types of inflorescences (McClure, 1966). The first is the "semelauctant" type, indicating a determinate inflorescence with spikelet borne in a raceme or a simple panicle, emerging and dying almost simultaneously. The second is the "iterauctant" type, indicating an indeterminate inflorescence. In the latter type, the basic unit is a pseudospikelet with the distal portion resembling a true spikelet and the basal portion bearing buds, each of which is supported by a sheath and bears another sheathing organ called a prophyll. These buds will eventually develop into pseudospikelets, the process continuing almost indefinitely until the culm's reserves are exhausted. In South-East Asia the semelauctant type of inflorescence is characteristic of Racemobambos, Nastus and Yushania, whereas the iterauctant inflorescence may be found in the other genera.
Basically the bamboo fruit (caryopsis) does not differ from the caryopsis of other members of the grass family. It consists of a pericarp enclosing the seed; the seed itself consists of endosperm and an embryo comprising a radicle, a plumule and a scutellum. In four Asian genera, namely Dinochloa, Melocanna, Melocalamus and Sphaerobambos, the pericarp of the fruit is thick and fleshy and is traversed by several vascular bundles; its ground tissue is mainly parenchymatous with cells containing numerous small globular starch grains. In this type of fruit the endosperm is much reduced and the embryo has a large scutellum containing a large number of starch grains that function as food storage.
Because many bamboos produce seeds infrequently, published records on bamboo seedlings are very fragmentary (Arber, 1934; McClure, 1966; Soderstrom, 1981). A bamboo seedling consists of a primary root and a primary culm. The primary root, developed from the radicle, is a slender, unsegmented axis. The primary culm, which develops from the plumule, is a segmented axis. The coleoptile, a sheathing structure protecting the growing apex of the embryo, can be observed at the base of the primary culm. It is usually very short. Each node of the primary culm has a sheath, and the first 2-3 sheaths do not possess blades. These precede the first developed culm sheath in which the blade is broad and horizontally positioned. The situation can be observed in seedlings of e.g. Dendrocalamus strictus (Troup, 1921), Melocanna baccifera (Stapf, 1904), and Schizostachyum zollingeri (Wong, 1981).
A bamboo culm consists of approximately 50% parenchyma, 40% fibres and 10% conducting cells (i.e. vessels and sieve tubes). Parenchyma and conducting cells are more frequent in the inner part of the culm, fibres more frequent in the outer part. In the internode the cells are axially oriented whereas the direction of the cell elements in the nodes is arranged perpendicular to the internode to provide the transverse interconnections. The amount of fibre increases from bottom to top while the parenchyma content decreases.
Vascular bundles in bamboo culms consist of the xylem with 1-2 smaller protoxylem elements and two large metaxylem vessels (diameter 40-120 μm) and the phloem with thin-walled, unlignified sieve tubes connected to companion cells. The metaxylem vessels and phloem tissue is surrounded by sclerenchyma sheaths. At the peripheral zone of the culm, the vascular bundles are small and numerous, at the inner part larger and fewer. The total number of vascular bundles decreases from outer to inner parts within the culm, and from the bottom to the top. The type of vascular bundles can be differentiated into 4-5 types, depending mainly on the size and degree of isolation of the sclerenchyma sheaths associated with the vascular strands (Liese, 1980, 1987).
Bamboo fibres are characterized by sclerenchyma cells surrounding the vascular bundle and are separated by parenchyma but they sometimes converge, forming bundles of sclerenchyma. Fibre length may vary considerably with species. It often increases from the periphery of the culm to a maximum at about the middle, and decreases toward the inner part. The fibres are 20-40% shorter in the inner zone. An even greater variation exists longitudinally within one internode. The shortest fibres are found near the nodes, the longest fibres in the middle part of the internode. Polylamellate wall structures of fibres lead to an extremely high tensile strength (40-320 N/mm2 from the inside to the periphery of a culm). Anatomical features of fibres often cited are: (average) length (L, in mm), diameter (D, in μm), lumen diameter or lumen width (l, in μm) and wall thickness (w, in μm). The pulp and paper industry uses parameters derived from these anatomical features, i.e. slenderness ratio (L/D), flexibility ratio (l/D × 100) and Runkel ratio (2w/l); the Runkel ratio should be 1 or less to be acceptable for this industry. As these ratios can easily be calculated from the anatomical features (using the same units of measure, e.g. mm), they will not be mentioned separately for species described in this volume. Ranges for the different anatomical features based on information from the literature for South-East Asian bamboos are: fibre length 1.45-3.78 mm, fibre diameter (11-)14-22 μm, lumen diameter 2-7 μm and wall thickness 4-9 μm (The Committee for Bamboo, 1984).
The taxonomy and classification of bamboos are far from satisfactory. This is because the herbarium specimens available do not represent the bamboos of the world; moreover, they are often inadequate to represent the species. Most herbarium specimens are leafy or flowering branches. They show nothing of the complex periodic flowering behaviour nor elaborate vegetative morphology (such as rhizome system, culm leaf structure and branch architecture). Moreover, because many bamboos flower infrequently, they are often ignored completely by plant collectors.
Munro's monograph on world bamboos (1868) has become and remains to this day the foundation of all later works. He recognized 120 species belonging to 21 genera which are divided into three groups, based on the number of stamens and lodicules, and fruit structure. Later Bentham (1883) used Munro's system as a basis for his bamboo classification, with four subtribes largely based on fruit structure. Gamble (1896), in his monograph on Indian bamboos, adopted Bentham's system without modification. In the following century, Holttum (1946, 1956), regarding the existing system of classification as somewhat unnatural, proposed a new scheme based primarily on ovary structure, dividing the genera into four groups. He emphasized (1956), however, that further work on the detailed structure of the ovary and fruit in all genera was necessary to place his tentative scheme on a firm footing.
More recently, two new systems of bamboo classification have been proposed: one by Clayton & Renvoize (1986) and the other by Soderstrom & Ellis (1987). In their treatment of the Gramineae, Clayton & Renvoize (1986) recognize 49 bamboo genera in the tribe Bambuseae, which are placed in three subtribes, namely Arundinariinae Benth., Bambusinae Presl, and Melocanninae Reichenb. Their system of classification is based mainly on a suggestion by Holttum (1956), that the ovary appendage might be used as a primary criterion. In 1987, Soderstrom and Ellis published and proposed a system of classification which relies greatly on characters of the leaf anatomy, along with those from the spikelet, flower, and fruit. They recognize about 54 genera divided into nine subtribes, and 5 genera of uncertain placement. The subtribes are Arthrostylidiinae Soderstrom & Ellis, Arundinariinae Benth., Bambusinae Agardh, Chusqueinae Soderstrom & Ellis, Guaduinae Soderstrom & Ellis, Nastinae Soderstrom & Ellis, Neurolepidinae Soderstrom & Ellis, Shibateinae (Nakai) Soderstrom & Ellis, and Schizostachydinae Soderstrom & Ellis (which has now become a synonym for Melocanninae Reichenb.). Since then there have been further taxonomic studies on some genera belonging to different subtribes. Stapleton (1991, 1994) has proposed a new subtribe, Racemobambosinae, to accommodate Racemobambos, which has no place in Soderstrom & Ellis' system. Clark (pers. comm.) does not recognize the subtribe Neurolepidinae, and suggests including the only genus, Neurolepis, in Chusqueinae. Based on the latter system of classification and on these recent studies, the tribe Bambuseae can provisionally be summarized as indicated in Table 4.
Because bamboos are of great importance in Asia, research on all aspects (including taxonomy) has been concentrated there. In 1876, Kurz published "Bamboo and its use" containing original information on species occurring in South-East Asia. Gamble's monograph covers species from India, Sri Lanka, Burma (Myanmar) and Malaysia, and later (1910) also the Philippines. Later, Merrill (1923) also wrote accounts of bamboos from the Philippines. E.G. Camus and A. Camus (1923) published in "Flore Générale de l'Indo-Chine" (vol. 7) an account of bamboos of Indo-China. Backer's work covers Javanese bamboos (1928). In 1958, Holttum produced a critical and excellent account of Malayan bamboos, and in 1967 published on species from New Guinea.
Some works on local flora concerning bamboos are merely the account of species (Brown & Fisher in Brown, 1951; Lin, 1968; Santos, 1986). Critical taxonomic work on South-East Asian bamboos started in the 1980s. Revisions of bamboo genera are being carried out, and complete specimens have been collected for this purpose. Since then, many new species and a few new genera have been published (Dransfield 1981, 1983a, 1983b, 1992; Widjaja 1987; Wong 1982, 1993a, 1993b).
Growth and development
New rhizomes are produced from the previous years' rhizomes. Culms are produced annually from the youngest rhizomes mostly, thus new culms develop near the previous year's culms (Chaturvedi, 1990; McClure, 1966). Annual production may be 5-10(-20) culms per clump for vigorous arborescent species, while in the more shrubby species 50-100 culms may be produced annually per clump (Troup, 1921). Natural clumps may consist of more than one original seedling. In Thailand, it is reported that large yields of culms occur in alternate "on" and "off" years (the production in the "on" years being 2-3 times higher than in "off" years) (Smitinand & Ramyarangsi, 1980).
The total average length of culms is 15-20 m, but in certain species like Schizostachyum caudatum Backer ex Heyne it is only 8 m whereas in Dendrocalamus asper it may reach 30 m. The internode length increases from the base towards the middle part of the culm and then decreases further upwards. The average length of internodes for most species is about 35 cm, but it may reach as much as 150 cm (as in Schizostachyum lima (Blanco) Merrill). Culms reach their full height 60-120 days after emergence of the young shoot. The shoots elongate at an average rate of 10-30 cm per day, but in Bambusa tulda the rate may reach 70 cm per day. The elongation of shoots of tropical bamboos appears to take place mostly during the night. Not all shoots sent up by the rhizome will reach maturity.
The development of branches begins after the culm reaches its full size. In most species of Dendrocalamus, Gigantochloa and Bambusa, the first branches emerge from the upper third of the culm continuing from the middle part; these are followed by more branches from the uppermost part. After all the apical branches have emerged, branches start to develop on the lower part of the culm of Bambusa. In some species, branches are found 1-1.5 m above the ground, in others they may emerge just above the ground.
Flowering and fruiting
It has long been known in China and India that in many bamboos plants of the same species flower stimultaneously, at intervals of 20-120 years, and then all culms die, to be replaced by seedlings. There are, in fact, three main flowering types:
- gregarious: a whole population flowers over a period of 2-3 years and then dies, although the rhizomes may still be alive (flowering cycle of e.g. Bambusa bambos 32-45 years, Dendrocalamus strictus 20-65 years, Melocanna baccifera 30-45 years);
- sporadic: individuals flower seasonally or occasionally, and only the flowering culms die afterwards, while the rhizomes continue to live (e.g. Gigantochloa scortechinii);
- continuous: individuals produce flowers all year round, the culms which produce flowers do not die (most Schizostachyum species).
The extent of flowering of the gregarious type tends to be later and less on good sites and under proper management; congested clumps show more extensive flowering. Grazing and the incidence of fire increase the intensity of flowering and bamboo forests near villages also exhibit a greater flowering intensity (Dwivedi, 1990).
Pachymorph species produce more fertile seeds than leptomorph bamboos (Liese, 1985). The viability of bamboo seed is short and mostly does not exceed 35 days in Melocanna baccifera and 21 months in Thyrsostachys siamensis.
After gregarious flowering, seeds germinate at the beginning of the rainy season and the best germination is obtained on bare soil. After germination the ground is carpeted with seedlings.
In South-East Asia, bamboos may be found in a wide range of habitats from lowland to mountain forests in both the dry and humid tropics, on wastelands, swamps, and dry or regularly flooded river banks. There are no records of bamboo occurring in mangrove forest. However, very little has been published on the ecology of bamboo.
South-East Asia has various climates, ranging from per-humid to semi-arid tropical and subtropical. Some bamboo species are characteristic for the drier tropics and subtropics, whereas others are found in the humid tropics only. Dendrocalamus strictus, for example, is found abundantly in the region including the Indian subcontinent, southern China (southern Yunan) and Vietnam, where the dry season is pronounced. It may be found in mixed forest or as pure bamboo forest. Thyrsostachys siamensis, for instance, is a native in the drier areas covering central Thailand and Vietnam, and also Burma (Myanmar). It is often found in pure bamboo forest as well. Although both species usually grow in the drier areas, they perform well when planted in the humid tropics. Most species of Schizostachyum are encountered in the humid tropics, for instance, in lowland and hill dipterocarp forest. Most species of Racemobambos and Nastus usually grow in the montane forests of the humid tropics.
Bamboo species of the humid tropics rarely form pure bamboo forest, but they may become dominant in overlogged forest. Dinochloa species, for example, are usually found in lowland and hill dipterocarp forest. However, after the forest has been disturbed by logging, they become abundant as weeds, causing much concern that they may prevent the regeneration of commercial timbers (Liew, 1973). In Peninsular Malaysia, with a humid climate, three bamboos (Dendrocalamus pendulus Ridley, Gigantochloa scortechinii and Schizostachyum grande Ridley) commonly dominate the landscape in areas where forest has been logged or cut. This phenomenon has been observed in Indonesia and southern Thailand as well.
Bamboos are remarkably adaptable to any kind of soil. For example, Bambusa vulgaris, a pantropical species, grows on a wide range of soils. However, bamboos perform best on well-drained rich soils; on poor soils, culms are shorter and have a much smaller diameter. Dendrocalamus elegans (Ridley) Holttum is found, however, only on limestone hills in northern Peninsular Malaysia and southern Thailand. Other species, such as Dinochloa obclavata S. Dransf. and Racemobambos rigidifolia Holttum, both from Sabah (Malaysia), are confined to forest on ultramafic rock.
An inventory of the bamboo resources in Peninsular Malaysia revealed that bamboos occur significantly more often in logged-over areas than in undisturbed forest. Logging creates a light-abundant environment favourable for bamboos (Nor & Wong, 1987).
Exploitation and cultivation
History of bamboo exploitation and cultivation
For centuries, people of tropical Asia have been utilizing bamboos collected from the wild, as well as from species already domesticated. In Thailand, young shoots of Thyrsostachys siamensis were collected from the wild for local consumption only, but recently they have become very popular and they are now canned for export. Most shoots are still collected from bamboos growing in the wild.
Paper mills have been built in areas where Dendrocalamus strictus, a bamboo producing good quality pulp, grows abundantly. In Peninsular Malaysia, Gigantochloa scortechinii becomes abundant in logged forest. In the past it was used only for making rough baskets for carrying vegetables, but recently this bamboo has become a major wild-growing resource for developing cottage industries. Bamboo here is often overexploited, giving rise to a shortage of raw material, which is a serious problem in the local cottage industry. In the past, local people exploited these wild bamboos in a sustainable way. In Indonesia, in particular in eastern Java and southern Sulawesi, Bambusa bambos has been overexploited because it is a major resource for paper mills. A similar situation has developed in Sumbawa where it is used as a raw material for a developing chopstick industry.
Some bamboos have been planted for centuries in parts of Asia for local use. In Java, for example, useful bamboo species are only found in cultivation and were presumably introduced from mainland Asia. They are planted around villages, often becoming naturalized and growing spontaneously. Traditionally, villagers have used bamboos on a more or less sustainable basis, renewing their gardens by planting new plants.
In several areas of South-East Asia, plantations of bamboo have been established for various purposes. In Thailand, plantations for shoot production (mainly Dendrocalamus asper) are located in Prachinburi Province (4465 ha). Plantations for culm as well as shoot production are found at Chiang Mai, Kanchanaburi, Songkhla, Khon Kaen, and Phitsanulok. Species included are Bambusa bambos, B. blumeana, B. burmanica Gamble, Dendrocalamus asper, D. brandisii (Munro) Kurz, D. strictus, Gigantochloa albociliata and Thyrsostachys siamensis. In Indonesia, there is a plantation of Dendrocalamus asper, D. giganteus Wallich ex Munro, D. latiflorus and Gigantochloa pseudoarundinacea in Lampung (1100 ha), and a 50 ha plantation of Dendrocalamus asper for culm production has been established at Mojokerto (East Java).
Various methods are used to propagate bamboos: generative propagation by seed and vegetative propagation by rhizome cuttings, culm cuttings, branch cuttings, layering, and tissue culture (Bamboo Information Centre, 1990; Institute of Forest Genetics and Tree Breeding, no date; McClure, 1966; Othman et al., 1990; Ramanuja Rao et al., 1989).
Unfortunately, the availability of seed for propagation is unreliable because of the tendency of most bamboos to flower gregariously. Hence this method is very risky for large-scale establishment of plantations. Rhizome cuttings and culm cuttings are the most widely used methods of vegetative propagation. Rhizome cuttings seem more appropriate for the bamboos that do not form clumps, while culm cuttings are used for the clump-forming species (The Committee for Bamboo, 1984; Uchimura, 1978). For vegetative propagation, it is essential that viable buds be present. Moreover, the conditions for dormancy break and prolonged dormancy (in the case of transport after the propagule has been severed from the mother plant) still have to be determined (McClure, 1966).
Propagation by seed
This method of propagation depends on seed availability. Some bamboos only flower at long intervals and when flowering they rarely produce viable seeds (McClure, 1966). When seeds are available, mass propagation can be established readily: as soon as they are mature the fleshy-type fruit and the grass-type seed will germinate readily in a moist medium in a nursery, if sown immediately after gathering. The viability of the seed decreases if it is not kept under suitable conditions. For most species, viability lasts only up to about 2 months. Seed longevity could be prolonged up to 60 days in Melocanna baccifera by storing the seed in dry sand (Banik, 1994). Seeds may retain their viability for a much longer period of time (up to 2 years) when stored under cool conditions (Huberman, 1959). For instance, Thyrsostachys siamensis seeds remained viable even after 27 months when stored with a low initial moisture content of 6-10% at low temperatures (-5°C and 2-4°C) (Ramyarangsi, 1990).
After germination, seedlings should be transplanted into individual containers. When 0.75-1 m tall, the plants can be planted out in the field. The advantage of using seed in bamboo propagation is that it can be transported easily and it gives a broad genetic base to the plantation.
Propagation by rhizome cuttings
Rhizome division is traditionally the best way to propagate bamboo vegetatively. Local people prefer this method of propagation because young clumps are quickly produced. For propagation by rhizome cuttings or offsets, 1- and 2-year-old culms are used. They are cut at least at 0.3 m, and the culm with the attached rhizomes is separated from the mother plant and planted (Vongvijitra, 1990) either directly in the field during the rainy season or first in the nursery (Lantican et al., 1987). One drawback of this method is the risk of impairing the health and vigour of the mother plant when preparing many offsets (Uchimura, 1978). Other problems are the transport of the bulky material, which is susceptible to drying out, and the high labour costs involved in collecting the offsets for mass propagation on a large scale (Sharma, 1982). Shoots are produced after 2-3 months, followed by the formation of roots. After 6 months, young plants in the nursery are ready for transplanting to the field.
Propagation by culm cuttings
It is suggested that in order to obtain good propagules, 2-year old culms should be cut before or after they have started to produce shoots. In West Java, the local people have observed that the best mother plant for propagation is a culm which has produced shoots twice or is 2 years old. Either the whole culm or culm segments can be used as vegetative propagules. If the whole culm is used, it is buried. This will stimulate the alternating buds to produce young branch shoots, which gradually transform into stronger culmlets which at the same time form roots. McClure & Kennard (1955) suggested that 2-year-old culms will produce the highest percentage of planting material. It has been found, however, that 1-year-old culms of tropical bamboos give the highest percentage of plantlets.
The second method involves culm portions bearing 1 or 2 nodes taken from culms at the age of 6 months to 2 years, usually 1 year, depending on the species. The part of the culm best suited for making the cuttings differs per species. It is reported that one internode of a culm bearing 2 buds or branches will form 2 developed young plants rapidly. The branches are pruned to a length of 10-20 cm and foliage is removed. Cuttings are planted horizontally at a depth of 5-10 cm; 1-noded cuttings can be planted obliquely with the node buried. Prior to planting, growth hormones may be applied to the cut surface to improve survival and growth (Sharma, 1982; Uchimura, 1978). After 2-3 months, young shoots emerge and will form the main culms, followed by the formation of roots.
Two-noded cuttings may be planted horizontally, level with the ground, and a hole is made in the internode and filled with water; this method is successful for Bambusa vulgaris. The dormant buds sprout at the nodes (Sharma, 1980).
Although rhizome cuttings are traditionally the preferred mode of vegetative propagation, culm cuttings have the advantage that more cuttings can be obtained from one clump and the costs of transport, handling and labour are lower.
Propagation by branch cuttings
Branch cuttings seem to be promising for future mass propagation, for instance of Bambusa vulgaris and Dendrocalamus asper. In Thailand, this method is very suitable for establishing of large-scale plantations of Dendrocalamus asper (Vongvijitra, 1990). Branches with 3 nodes are collected from 1- to 2-year-old culms; care should be taken not to injure the dormant buds. The presence of root primordia is essential for successful propagation, induction of root primordia in situ may well be possible (McClure, 1966). They may be treated with 100 ppm indoleacetic acid (IAA) and propagated in sand (Lantican et al., 1987). Normal branch cuttings develop roots after only 3-6 months and rhizomes after 12-15 months. Propagules bearing roots, rhizomes and shoots are considered essential for successful establishment and development of bamboo plantations. Artificial induction of roots and rhizome formation at branch base is possible by chopping the culm tops and removing newly emerging culms yielding "pre-rooted and pre-rhizomed" plants (Banik, 1987).
Several methods can be applied for propagation by layers. Either a whole culm or only that part of the culm bearing branches is bent down to the ground into a shallow trench and fastened in place by hooked or crossed stakes; sometimes it is notched below the branch-bearing nodes. It is then covered with soil or some other suitable medium. However, this is a rather cumbersome method and is probably useful only for very small bamboos. Stump layers may be prepared by cutting off one or more culms in a clump, leaving 1-2 nodes with a bud or a branch complement. The stumps prepared in this way are then covered with a suitable mulch. The third method is a form of air layering in which a culm is kept erect, and may or may not be notched below each branch complement. The base of the branch complements in the midculm section is surrounded by a suitable propagating medium, held inplace by a receptacle (McClure, 1966). When roots and shoots develop at the nodes, the buried or covered parts are separated from the mother plant, the internodes cut, and the layers planted separately. Layering of Bambusa vulgaris and Dendrocalamus giganteus showed only 10% success (Banik, 1987; Lantican et al., 1987; Liese, 1985; Sharma, 1982), whereas Melocanna baccifera did not respond to any layering method (Banik, 1987). Air layering in Dendrocalamus asper appeared to be fairly successful in Indonesia (up to 50%).
Tissue culture is becoming increasingly important, but results from experimental research are available on a small scale only. In India, large numbers of somatic embryos of Dendrocalamus strictus and Bambusa bambos were obtained by culturing mature embryos and explants from seedlings grown aseptically (Usha Rao et al., 1990). Plantlets have also been obtained from nodes of mature plants of Bambusa vulgaris and Dendrocalamus strictus, and precocious rhizome induction is possible to accelerate plantlet growth in the field (Ramanuja Rao & Usha Rao, 1990).
In order to manage bamboo stands properly, three aspects should be taken into consideration: management of natural regeneration, maintenance, and fertilizer application.
Management of natural regeneration
Protection of natural regeneration is an important measure to be taken. A detailed study in Bangladesh on the natural regeneration of Bambusa tulda and Dendrocalamus longispathus Kurz showed that seedling mortality was high because of suppression and competition by weeds. Almost all seedlings died within 7-12 months under complete shade. The dead mother clumps provided partial shade to the seedlings, and this condition seemed to favour the regeneration process. Burning or clear-felling the mother bamboo clumps within 1-3 months after seed germination was found to stop the regeneration process by killing all the bamboo seedlings. The effect was less negative if burning was done 6-9 months after seed germination (Banik, 1990), since bamboo seedlings generally produce an underground rhizome within 4-6 months after germination (McClure, 1966; Troup, 1921). Therefore, felling of dead culms in the early stage of the regeneration process should be discouraged because the dead clumps considerably benefit the regenerating bamboo crop and lead to a well-developed stand with healthy clumps (Ahmed, 1954; Seth, 1954). Thinning of the naturally regenerated seedlings of both species yielded 700-1000 seedlings/m2 and enhanced seedling survival and development after 12 months (Banik, 1990).
Ideally, bamboo stands should be managed on a yearly basis, not only for harvesting but also for maintenance. Usually, the felling cycles are 3-4 years. Systematic and regular exploitation increases the production of the bamboo stock.
In the management of bamboo forests, maintenance cannot be overlooked: all efforts are aimed at encouraging the formation of healthy and vigorous clumps for high production of new culms. Over-mature and other non-marketable culms should be cut out to preserve maximum vigour and productivity of the rhizomes and culms (Huberman, 1959). Culms should be cut close to the ground to prevent the remaining stumps congesting the clump and reducing productivity.
Culms of Bambusa blumeana are often cut at a height of 2-3 m, i.e. just above the dense growth of spiny branches. Removal of the spines and the cutting of culms close to the ground increased the number of shoots that appeared each year, reduced shoot mortality and reduced the number of deformed culms, as shoots no longer had to work their way through the thicket of spines (Bumarlong, 1980). Green culms produce new sprouts after cutting (coppice). If dry culms are not removed from a clump, the coppice shoots produced in such a clump may also cause congestion. Coppice shoots are thinner than the culms and are sometimes referred to as switches (Chaturvedi, 1990).
The protection of the forest from grazing and fire is essential to proper bamboo forest management. Furthermore, earth should be mounded or heaped around the bamboo culms each year before the rainy season. A light shade from overhanging trees enhances bamboo growth (Chaturvedi, 1990). However, bamboo areas managed for shoot production require more light than those for culms used in construction (Liese, 1985).
The optimum spacing for productivity is very important in the management of bamboo plantations, but very little research has been done on this subject.
Newly planted areas should be weeded. Young bamboo plants cannot compete with weeds like Mikania cordata (Burm.f.) B.L. Robinson and Pennisetum polystachion (L.) Schultes.
Thinning of culms is important in bamboo plantations either for shoot production or for culm production. Congestion is a specific problem for clump-forming bamboos; culms are so densely packed that new culms do not develop well. Congested clumps result from damage, especially at the periphery, by grazing, fire, insects, but also by improper management like cutting indiscriminately around the periphery, continual removal of young tender shoots or digging up culms with the rhizome attached. In time, a dense mass of dead rhizomes prevents the living rhizomes from spreading outwards. The latter develop within the clump, where the new culms are also produced year after year, resulting in congestion, with the new culms bending in all directions in their effort to penetrate the dense mass of older culms (Troup, 1921). To relieve congestion, it is recommended to either (1) to cut out all congested culms, even if that leaves only the current year's culms (Chaturvedi, 1990), (2) to cut two tunnels at right angles in a clump and thin the remaining segments (Sharma, 1980), or (3) to clear-fell part of the clump in the form of a horseshoe and thin the remaining sections (Sharma, 1980; Suwannapinunt, 1990).
The thinning design for shoot production differs from that for culm production, because light is essential for shoot development. Hence, 4-5 culms that are 1-3-years old should remain uncut, e.g. 2 culms that are 1 year old, 1 culm that is 2 years old and 1-2 culms that are 3 years old. During the rainy season, a mulch with bamboo and grass leaves is recommended to encourage shoots to sprout. Shoots produced in this way are usually sweeter and more tender than those without mulching.
Traditionally, people never apply fertilizers to their bamboo groves. It has been demonstrated, however, that fertilizer application increases the production of shoots and culms. In the case of Thyrsostachys siamensis, Dendrocalamus asper and D. strictus the application of 15-15-15 NPK fertilizer resulted in a significant increase in yield of culms and shoots by applying 100,100 and 200 kg/ha of fertilizer respectively (Suwannapinunt & Thaiutsa, 1990). In China, compound fertilizer of N, P, K and Si applied in furrows at 375 kg/ha gave a yield increase of about 7.9 t/ha of culm, being nearly 47% (Fu et al., 1991).
Diseases and pests
Little information is available on diseases and pests of living or harvested bamboos.
In bamboo nurseries damping off by Rhizoctonia solani is the major disease, although it can be effectively controlled by fungicidal application (Mohanan, 1990). In young bamboo plantations, fungal attack of rhizome buds may affect both culm production and rhizome proliferation. Culm rot and culm sheath rot are the other important diseases affecting culm production in plantations. In Bangladesh, bamboo blight is one of the serious diseases affecting the growing culm; it is caused by the sheath rot pathogen of rice, Sarocladium oryzae (Boa, 1987). Witches' broom disease is common in South-East Asia. However, there are no reports of this disease affecting culm and shoot production.
Furthermore, bamboo mosaic virus (BoMV) is another important disease attacking leaves, shoots and young culms. It causes shoots to harden resulting in poor quality for consumption and canning.
The most common pests of bamboo in South-East Asia affect the shoots by boring and sucking sap. Oregma bambusae can be a serious pest of bamboo shoots. Although uncut bamboo culms are usually healthy, culm borers (e.g. Cyrtotrachelus dux, C. longimanus) may affect culms because their larvae bore long tunnels that pass internally through several internodes (Singh, 1990). Infestation is usually worse when culm density is high. The bamboo hispine beetle (Estigmena chinensis) is the most important pest affecting bamboo stands in natural forests.
The most important pests of harvested culms are borers (Dinoderus ocellaris, D. minutus and D. brevis) which usually attack culms with high starch content (Singh, 1990).
Since more emphasis is being placed on bamboo as a suitable plant for resource-poor farmers, the potential for disease and pest damage is bound to increase (Boa, 1994).
Bamboo should be harvested in accordance with the part to be used (culm or shoot), the age and the season. For culm production, harvesting is carried out during the dry season or is started at the beginning of the dry season, to prevent culms being attacked by borers. Moreover, during the dry season the starch content is at its lowest (Sulthoni, 1987). The 1-2-year old culms are suitable to be harvested for handicraft purposes and for pulp production. The 3-year-old culms are mostly suitable for building material, furniture and other cottage industries (e.g. chopsticks).
There are two methods of harvesting culms: clear-felling (or clear-cutting) and selective felling. With clear-felling the entire clump is cut down, which causes the clump to produce smaller culms in the following year. It is not advisable to use this method when aiming at sustainable production of culms. With selective felling, only suitable culms of a certain age are harvested. By regulating the harvest correctly, it is possible to increase yield. In addition, a regular cutting system might influence the flowering behaviour of a bamboo stand. The selective felling method is generally used for exploiting and maintaining bamboo clumps. Various techniques for selective felling are applied to promote a higher productivity of clumps: i.e. the horseshoe technique, tunnel technique, M-shaped technique, and V-shaped technique.
With regard to felling intensity, it is essential to retain a number of culms for mechanical support of new shoots and to maintain the rhizomes in full vigour (Huberman, 1959). It is noted, however, that it may be rather difficult to approach the harvestable bamboos without sacrificing a few young culms growing on the periphery (Varmah & Bahadur, 1980). Recommendations regarding the felling intensity are: 50% of the old culms (Troup, 1921), or leaving at least 6 mature culms older than 1 year if the clump contains at least 12 mature culms (Varmah & Bahadur, 1980). Other sources state that all bamboo culms of 3 years and older should be cut, as they no longer provide mechanical support for new shoots because shoots are not formed close to old culms (Chaturvedi, 1990; Suwannapinunt, 1990). For sustained yield management in Malaysia, the recommended harvesting intensity per clump in a 3-year cutting cycle is about 70% i.e. leaving about one-third of the culms in the original clump (Ahmad & Haron, 1994). Shoots are harvested during the rainy season and preferably cut off before they emerge above the soil, when they are still fresh and tender.
Annual yields of bamboo culms vary according to species, environmental conditions and management. It is reported that the productivity of Thyrsostachys siamensis in Thailand, which mostly occurs on low-fertility soils, is on average 1500 culms/ha per year. The annual production of this bamboo is 9-15 t/ha in "on" years and 3-5 t/ha in "off" years. The growing stock (being the total fresh weight of living culms in a stand) of this bamboo ranges from 33.4-109.2 t/ha. The productivity of Bambusa bambos in Thailand is 5000-8000 culms/ha per year, and the annual production is approximately 24.7 t/ha during "on" years and 5-8 t/ha in "off" years, with a growing stock of 88 t/ha (Smitinand & Ramyarangsi, 1980). In the Philippines, natural stands of Bambusa blumeana may produce 960-1600 culms/ha per year (The Committee for Bamboo, 1984). In India, with a growing stock of Bambusa bambos of approximately 32 t/ha the annual production is about 3.5 t/ha (Lakshmana, 1994). However, data on yield are in general rather scarce.
Yield records for shoot production are also very rare. It is reported from Thailand that the production of Dendrocalamus asper shoots in 1984 in Prachinburi Province amounted to about 38*000 t. Although there are no actual figures for bamboo shoots harvested from natural forests, it is estimated that several hundred thousands t of bamboo shoots are harvested annually in Thailand (Thammincha, 1987). About 14*000 t were exported in 1985 from Thailand to Japan, United States, Hong Kong and Western Europe (Thammincha, 1990).
Post-harvest handling and processing
Bamboo culms become degraded during transport and storage due to attack by staining and rotting fungi, and insects (beetles, borers, termites). The durability of bamboos mainly depends on climatic conditions. Untreated bamboo may last 1-3 years when exposed directly to the atmosphere and soil, but up to 7 years when protected. Because of its low durability, treating with preservative is necessary. Two methods can be used to enhance the durability of bamboos: non-chemical methods and chemical methods (Liese, 1981).
- Non-chemical methods. The non-chemical methods are those traditionally used by the people in South-East Asia and include curing, smoking, lime painting, tar painting and submerging in water or mud. Curing involves leaving harvested culms with branches and leaves still attached in the open air. The leaves continue to transpire, so the starch content of the culms falls. It is said, however, that culms treated this way are not resistant to borers but only to termites and fungi. The second traditional method is to smoke bamboo culms above the fire. This is considered an effective treatment against insects as well as fungi. Painting of culms with lime is widely used for walls and said to be effective against fungi. Sometimes culms are painted with tar mixed with sand, or plaster with cow dung mixed with lime to prevent attacks by fungi and insects. The fifth non-chemical method commonly used in South-East Asia is to submerge culms in either stagnant or running water, or mud for several weeks. This method is said to confer resistance to borers but not to termites and fungi. Submergence in water may result in the bamboo becoming stained.
- Chemical methods. The chemical methods for preservation are more effective but not always applicable and economical. There are 5 major chemical methods of preservation. The first is fumigation of culms with methyl bromide or other chemicals. The second method is brushing and spraying or paint-coating using borax and boric acid (1:1), varnish or melamine. This method is used against borers and mould, but is considered not very effective. The third method is butt treatment. The base of a freshly cut culm with branches and leaves still attached is placed in a container of preservative that will penetrate the vessels of the bamboo. This method is applicable only for short culms. The fourth method is the open-tank method, in which culms are soaked in a preservative for a few days. The age of the bamboo and the permeability of the skin determine how quickly the solution permeates the culm. It is therefore suggested that this method is more suitable for split bamboo than for whole culms. A higher concentration of the preservative is required to soak green culms than to soak dried bamboo. There are a few modifications of the open-tank preservation method i.e. hot dipping treatment or cold dipping treatment. These treatments are successfully applied by using 20% copper sulphate and zinc chromate followed by 20% sodium bichromate. The fifth method of preservation is the boucherie method. In essence, this method is forcing preservative to penetrate a culm by gravity. The preservative is dripped from a container which is placed higher than the culm through a pipe connected to the butt-end of the bamboo. The boucherie method has been modified by applying pneumatic pressure over the preservative fluid, thereby significantly reducing the treating time. This method can only be used on green bamboo or bamboo with a high moisture content. A successfully applied solution is a mixture of boric acid and borax (1:1).
Culms for pulp and paper making
Formerly, culms were first crushed and then chipped; however, in new mills only chippers are used. Pulping is mainly carried out through the sulphate method using caustic soda and sodium sulphide in the cooking liquor. It produces unbleached pulp that can be used for making paperboards, wrapping and bag papers. Bleached pulp is used for producing a wide range of writing, printing and wrapping papers, newsprint and paperboards. For the production of 1 t of unbleached pulp, 2 t of clean, chipped bamboo are required. To produce 1 t of bleached pulp, 2.5 t of air-dried bamboos (4 t fresh) are needed (Liese, 1981; The Committee for Bamboo, 1984).
Degradation of bamboo shoots occurs during transport, due to browning caused by physiological activities. Active carbon from bamboo is effective for keeping bamboo shoots fresh (Hosokawa & Minamide, 1994). Young shoots of many bamboo species contain cyanogenic glucosides, which cause a bitter taste. Cooking freshly cut shoots in boiling water (changing the water 1-2 times) removes the bitter taste. In West Java, villagers bury bamboo shoots in mud or running water for 3-4 days before further preparation (Widjaja, 1987).
Breeding and genetic resources
In South-East Asia, the breeding of bamboos is still in its infancy. In China, hybridization experiments among native species (e.g. Dendrocalamus latiflorus × D. hamiltonii Nees and D. latiflorus × Sinocalamus stenoauritus W.T. Li) are carried out as part of selection and breeding programmes for shoot production (Zhang & Chen, 1994). The scope of the species selected for this purpose, however, is very limited because of the irregularity of flowering. Most of the cultivated bamboos producing good quality culms and shoots are believed to be the result of selection and domestication by mankind. These bamboos are usually homogeneous and show little morphologic and genetic variation. Because these bamboos flower and fruit infrequently, they are traditionally propagated by rhizome, culm and branch cuttings. The progeny, therefore, is usually identical. On the other hand, there is a large intraspecific variation in many wild-growing species and even in some cultivated species.
Tissue culture is very promising for the breeding of bamboos through hybridization using protoplasts and through in-vitro flowering (Mascarenhas et al., 1990).
Bamboos in South-East Asia provide a rich source of genetic variation which has not yet been investigated intensively.
Germplasm collections have been established in various parts of South-East Asia such as in Kanchanaburi and Chiang Mai (Royal Department of Forestry, Thailand), Lampung (private enterprise, Indonesia), various botanical gardens (Xishuangbuana, Nanjing, Bogor, Singapore, Hong Kong), Los Baños and Baguio (Ecosystems Research & Development Bureau, the Philippines), Kepong (Forest Research Institute of Malaysia), Forest Department of Brunei, Lae (Papua New Guinea), Peradeniya (Sri Lanka), Kerala (Kerala Forest Research Institute, India), and Calcutta and Dehra Dun (India).
Management of the wild resource
The world demand for bamboos has increased recently, and this goes hand-in-hand with the increasing use of modern and sophisticated technology for processing bamboo products for traditional and modern society. On the other hand, bamboo is still and will continue to be used by local people who use it on a more or less sustainable basis. Local bamboo stands are usually planted around villages and are readily available. In many parts of Thailand, the northern part of Peninsular Malaysia, and several areas in Indonesia, bamboos can be seen dominating the landscape. In India, Thailand and southern China, culms have been harvested for a long time from wild-growing bamboos, mainly for use in paper manufacture. In other places, culms have been collected for local needs such as house construction or for making household utensils. Bamboos from these wild populations have been exploited for use in cottage industries established by local people or communities (often supported or funded by the government), to produce items such as chopsticks and handicrafts for export. There is a great potential of bamboos from these wild populations, because of their abundance and the various end-uses for the culms. To maintain the sustainability of the wild resource, however, management of the wild population is essential.
In South and South-East Asia, large-scale plantations of some bamboo species (such as Dendrocalamus asper, Thyrsostachys siamensis) have been initiated to meet the demand of bamboo industries (especially plywood, parquet, furniture and canned shoots). Because bamboo has the ability to grow on various soils, some species have been planted for use in agroforestry in China (Huang & Hueng, 1991), reforestation and reclamation of degraded land. The prospects for bamboo cultivation are promising but there are various problems to be solved before the success of establishing a large-scale bamboo plantation will be guaranteed (e.g. selection of species, propagation, cultivation methods).
For centuries, South-East Asian bamboo products have been sold and shoots have been consumed locally. These products were produced by local people from culms obtained from farmers or bamboo growers. Usually, the culms were harvested on a sustainable basis, and in most cases the availability of raw material was sustained as well. Therefore, on a small scale, the trade in bamboo will continue to be reasonably promising. These local industries provide a small but steady income to local people who have marginally survived the competition with the plastics industry.
In recent years, the number of bamboo products on sale in the western hemisphere, most of which are imported from South-East and East Asia, has been increasing. There are no precise data on the international demand for these products. However, it seems likely that the global prospects for the bamboo trade are promising. China, for instance, yearly exports considerable quantities of small poles for horticultural purposes.
Research priorities and development
Because bamboos have many unique features and multiple uses, they provide a wide range of topics meriting investigation. In South, South-East and East Asian countries, research on many aspects of bamboos such as biology, properties, propagation, silviculture and utilization is being carried out to improve the contribution to the rural community and to support agriculture, forestry and horticulture. These research programmes have received financial support mainly from the International Development Research Centre (IDRC, Canada), the United Nations Industrial Development Organization (UNIDO, Vienna, Austria) and the Food and Agriculture Organization of the United Nations (FAO, Rome, Italy). Since the first International Bamboo Workshop in Singapore in 1980, initiated and supported by IDRC, various international and national conferences and workshops have been organized to exchange information. Research needs, priorities and development have always been the main topics of discussion, and have recently been summarized by the International Fund for Agricultural Research (IFAR) (Williams, 1991). A new network, the International Network for Bamboo and Rattan (INBAR) has been established as an outgrowth of a network initiated by IDRC (Canada) to identify and support research on bamboo and rattan. Researchers have always disagreed about the correct scientific name of bamboo species mentioned in the above research programmes. The establishment and use of the correct names, therefore, is essential in order to be able to exchange information.
The priorities for bamboo research and development are as follows:
- Survey existing resources:
- to work on critical taxonomic accounts as a basis for further development of the resources; this can be implemented either by revising each South-East Asian bamboo genus or by making an inventory in each country;
- to document the habitat, acreage, population density, uses and economic potential of the species of each genus revised, and to evaluate the biodiversity of the bamboo resources of each country;
- to explore the genetic diversity of bamboo from the wild to enable the selection of promising species and intra-specific variation.
- to establish methods of management of sustainable resources in natural stands and in plantations in order to improve methods of propagation, planting, maintenance and harvesting;
- to explore the use of bamboo species in agroforestry and for reforestation programmes in deforested and degraded areas, areas prone to flooding and marginal land;
- to investigate the nature of the vigorous spread of bamboo species in logged forests in order to control this spread, since it otherwise will become weedy and this prevents the regeneration of important timber tree species.
- Utilization and socio-economics:
- to expand the extent of post-harvest technology;
- to investigate the potential use of other parts of the culm (e.g. leaves, sheaths);
- to evaluate the employment opportunities for local people in cottage industries using bamboo as raw material collected from natural stands;
- to investigate various aspects for further development (e.g. properties, morphology, propagation, plantation, preservation) of species which locally have great economic potential but are still little known;
- to expand the extent of marketing systems locally and internationally for local industries such as cottage industries and handicrafts.
- Breeding and genetic improvement:
- to expand the selection of species for breeding programmes and genetic improvement.
- to expand the extent of germplasm collection and to promote in-situ conservation;
- to identify bamboo species on which local people depend, and to protect them from over-exploitation for larger industries.
With the rapidly extending research activities on bamboos in Asia, global scientific information and training on various aspects of bamboos are very important. Bamboo Information Centres have been established, one in China and one in India; both are funded by IDRC. Training on various subjects has been initiated, especially in China and India, and it should be extended to South-East Asian countries. Research priorities may vary for each country in South-East Asia. In Thailand and its neighbouring countries (Vietnam, Laos, Cambodia, Burma (Myanmar)), for example, where bamboo is utilized extensively, the inventory of bamboo resources is not widely carried out. However, such an inventory is essential for the further research and development of various important bamboo species in the region as a whole.