There are various sampling methods recommended for ethnobotanical study, such as- i) Direct or participant observation, ii) Checklist interview, iii) Group interview iv) Field interview, v) Plant interview, vi) Market survey [30-32].

In present study, data have been collected in the field following group interview, field interview and plant interview techniques. During the interview, the information has been noted in the documentation data sheet along with their scientific name, local name, Chakma name, family, plant parts used, illness treated and using information. Audio recording has been done with a digital voice recorder.

1. Group interview

In group interviews the ethnobotanist conducts interviews with several informants at a time. Apart from being very difficult to organize a group of practicing herbalists (‘Baiddya’) from several different areas of CHT due to the poor communication system.

2. Field interview

This is also referred to as a ‘bagging interview’ [30]. The field interview consists of walking in one or more vegetation zones with an informant, collecting and taking notes on plants and their uses. The plants are shown to the researcher by the informants who described its use. The advantages of the field interviews include the facts that informants get to see the plants in their natural state, thus minimizing the risk of misidentification, and that the context of the interviewitself can lead to the discovery and discussion of new important questions [31].

3. Plant interview

In a variation of the field interview technique, plants can be collected in the field, brought back to the village, and presented to informants [30]. Data about the plant uses can then be obtained. This method is known as the ‘Plant Interview’ technique.

The first step was to contact the headman (as Chairman) and karbari who were considered as the best informant and most influential person of the tribal communities in his area and to ask their help to find the herbalists who have knowledge of medicinal plant uses and regarded as professional practitioners in the area. Before selecting the herbalist’s local people of that area were also consulted. With satisfactory information about the informants seven herbalists havebeen selected. Some students from indigenous communities who are studying at Chittagong University were also helped to select and make the initial contacts with the informants. Several sites from the study area have been randomly selected according to informants’ consensus and visited to collect the voucher specimens and information of plant.

The plant interview technique has been also used to obtain medicinal plant use information. Where informants were too busy or too old to accompany the author to the field, that technique has been used and freshly collected plants have been brought to the informants. From these collections the informants identified some of the plants by their local name and described their use. These conversationshave also been documented and recorded with the help of a voice recorder. This method is less time consuming than field interviews and the plant interview allows more informants to be included in a given period of time [31]. One disadvantage of the technique is that small sections of large shrubs and trees may not be readily identifiable by informants, who often rely on such morphological, architectural, or ecological characters as plant height, crown shape, branching pattern and habitat for positive identification. One technique adopted to overcome the problem was to present colour photographs of the plants when available.

The group interviews techniques have also been used to collected information from several informants at a time. One disadvantage that the herbalists are secretive in the presence of other herbalists. They believe that if they share knowledge with other herbalists, they may lose economically in their profession.

The interview is a dynamic process involving spoken interactions between two or more people. Its value as a tool of inquiry depends on the context in which it takes place and on the interviewer’s skills [31]. Ethnobotanical information was obtained through informal interviews conducted during the same period with knowledgeable individual’s particularly elderly man and women. All of the people that were interviewed belong to the lower income group and do not have particular jobs, but carry out different kinds of work throughout the year: cattle ranching, laying bricks, selling plants, etc. Several techniques have been used for interviewing to gather ethnobotanical data: Mostly Semi structured and Open- ended interview techniques have been adopted. A documentation data sheet has been prepared based on Alam [32], Alcorn [30], Cotton [33] and Martin [34] (Figure 1).

Figure 1: Sample of documentation data sheet.

All voucher specimens have been collected during documentation and preserved at the Chittagong University Herbarium (CTGUH). Voucher number has attributed at the end of each species name within the bracket (Table 1). The specimens have been identified consulting with the experts, through several herbarium studies by comparing herbarium specimens and studying available literatures. The description and the current nomenclature have been compared with recent book-“Dictionary of Plant Names of Bangladesh [20].

Table 1: Plant species used by the Chakma indigenous community for traditional health remedies.

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Results and Discussion

The investigation and documentation of the knowledge of herbal practice was conducted from the Chakma indigenous community of Rangamati district of Bangladesh. A total of 50 plant species in 49 genera under 34 families were documented. Most frequently used family in context to the number of species is Araceae followed byEuphorbiaceae, Acanthaceae, Verbenaceae, Liliaceae, Amaranthaceae, Convolvulaceae, Fabaceae and Apocynaceae respectively.

Among the 50 plants species, the most utilized plant parts for the preparation of herbal medicine is leaf, which is, 73% followed by fruit 6%, Root 7%, bark 6%, stem 4% and flower 4% respectively (Figure 2). When root and the whole plant are used for the preparation of herbal medicine, are considered as the destructive way of using plants because it needs to destroy/uproot the whole plant. But leaf, fruit, flower or other aerial parts can be used without destroying the whole plant. So, using the plant parts without destroying the whole plant is a significant way to conserve them.

Figure 2: Percentage of plant parts used by the Chakma for their preparationof medicine.

By analyzing the ethnobotanical data, it was observed that the Chakma are conservative in plant use and they have the knowledge of sustainable use of plants. Because most frequently utilized plant’s part is leaf (73%) for the preparation of herbal medicine, which is a non-destructive way of use. Moreover, it refers that leaves in many species may store high concentration of bioactive compounds [35]. In addition it is easy to collect, store, transport, and help the species in conserving it without destroying the plants. The percentage of destructive and non-destructive way of plant use is shown in Figure 3.

Figure 3: Destructive and nondestructive plant use as medicinal perspective.

A total of 28 diseases/ illness were documented, which resulted Fracture 25%, Tumor or cancer 20%, cough 15%, skin disease 10%, snake bite 10%, piles 8%, jaundice 8%, Harnia 4% (Figure 4).

Figure 4: Percentage of plant species used for various diseases/illness.

The most frequent citied modes of preparation were extract, paste, juice and infusion respectively. As far as the techniques of preparation of medicine are concerned, these do not resemble those specified in present day organized pharmaceuticals practices. In some preparations, households, utensils (cup, knife, pot) and naturally available materials (sticks, pieces of stone etc.) have been used.

The dose and duration of application of these medicinal preparations are varied from informant to informant. Most of the cases they were took one to three teaspoonfuls extract, occasionally they were took a glass or one cupful. Time and duration is also varied, most frequently extract was took for one to three days. In case of some complicated diseases/illness, the duration may be longer.

The informants in the present study are within 25 to 75 years old (Table 2). During the survey, most of the information documented from the male informants. The percentage of male is 71% and the female is 29%. The present study revealed that only one healer was below 50 years (Table 2). The present generation lost the interest to continue their parental profession because it does not provide them proper financial support to their livelihood (Uddin, 2010) and the older practitioners die without passing their specialist knowledge. This knowledge, however, is dwindling rapidly due to movement towards a more modern lifestyle, agricultural practices, cultural changes within the community, housing colonies, and education system. These changes are leading to not only the destruction of habitats of medicinal plants but also the declining of traditional knowledge and medicinal plant species in the area. Similarly, the threat to traditional knowledge observed in other parts of the world [36] is also due to a lack of interest of the younger generation.

Table 2: Age and number of plant information collected from the informants.

The Rangamati district is rich in biodiversity, and to conserve this it is necessary to create public awareness about conservation of wild ethnobotanical plants. It is suggested that- 1) collection should be made by trained and experienced plant collectors who can identify the ethnobotanical plants properly and aware of preservation of plants and their plant parts. 2) During the collection of leaves, flowers and fruits, the whole plant should not be uprooted. 3) A completeban by the proper authorities should be imposed on the collection of rare and endangered species and 4) Research institutes and university researchers should carry out research on these species to conserve and improve their genetic constitutions. 5) Local people’s knowledge should be associated to prepare a conservation strategy. In addition, attempts must be made to encourage the documentation of plants so they are readily accessible to a larger number of the populace.

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Acknowledgement

The authors express their deep sense of gratitude to the informantsand the Bengali men and women who helped in different ways during the field work.

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