ABSTRACT
A combination of social survey and direct field observation were used to identify plant species whose stems and/or roots were sourced for barks in the twelve senatorial districts of four core Yoruba-speaking states of Nigeria. Five communities were selected from each senatorial district and in each community, ten respondents were selected and interviewed. Also two major market centers were selected in each district and in each market center, ten botanical vendors were randomly selected and interviewed. All the interviews were conducted with the aid of semi-structured matrix. Voucher specimens of plant species identified were collected from both the community and market surveys. The extractive method(s) utilized on each species were observed and the species abundance was determined. A total of 115 species were used as sources of bark including roots of 20 species, stems of 51 species and a combined stems and roots of 43 species. The extraction methods utilized in these botanicals were mostly predatory or annihilative. Most of the debarked botanicals were indigenous species, uncultivated with poor regenerative abilities. Ecological strategies that would enhance the conservation of these botanicals were proposed.
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URL: https://scialert.net/abstract/?doi=rjb.2008.17.22
INTRODUCTION
The Yorubas are a distinct tribe and with a population of over 35 million constitutes the second largest tribe in Nigeria. They are mainly situated in the southwestern part of the country consisting of Lagos, Ogun, Oyo, Osun, Ekiti and Ondo states. Considerable proportions of Yorubas are also present in Kwara, Kogi and Edo states of Nigeria. The Yorubas are known worldwide for the preservation of their culture, which they passed from one generation to another. Part of this culture is the use of botanicals for the maintenance of their health (Kayode, 2002).
As a result, plants parts are often extracted from the mother-plants and used in the preparation of local pharmaceuticals. This extraction, according to Momma (1994) could be classified into two types: the predatory or annihilation extraction in which collection of plant parts lead to the destruction of the source and the non-predatory or gathering extraction in which, though gathering plant parts is involved but the source is still protected.
At present, indiscriminate harvesting of plant bark is rampant in the southwestern Nigeria (Fasola and Egunyomi, 2002) where unfortunately there is a gross dearth of literature on the inventory of the species affected. Thus this study is aimed at providing information on the species and recommends ecological strategies that could enhance their conservation.
MATERIALS AND METHODS
Five rural communities, which are still far from urban influence, were selected from each of the three senatorial districts in each of the four core Yoruba-speaking states of Ogun, Oyo, Ondo and Ekiti.
In each community, ten elderly individuals who had maintained domicile for a continuous period of 30 years or more, were selected and interviewed with the aid of a semi-structured matrix (Kayode, 2003).
Respondents were asked to identify the species whose stem and/or root barks were used ethnobotanically. The occurrences of the identified plant species were determined within a 500 m radius from the community using the abundant scale defined by Kayode (1999) as follow: less than 5 individuals as Rare, 5 to 10 as Ocassional, 11 to 30 as Frequent, 31 to 100 as Abundant and over 100 individuals as Very Abundant. Five radii were taken in each village. Also, two major market centers were identified in each senatorial district. At each market center, botanical vendors were identified and samples of the botanical barks been sold were obtained. Market surveys in each state were carried out at 2 months interval for 12 months.
Voucher specimens were collected during the community and market surveys and were taken to the Herbarium of the Department of Plant Science, University of Ado-Ekiti, Ado-Ekiti, Nigeria for proper identification.
RESULTS
The respondents cut across sex, age, educational and religious status thus suggesting that these features were not regarded as prequisites to the consciousness of respondents on the pharmaceutical potentials of plant barks. The fact that there were more female respondents (52%, Table 1) than male could be attributed to the ready availability of women during field sampling and their wide knowledge of the pharmaceutical potentials of plant species which was borne out of the African tradition that saddled women with the maintenance of health of household members. The respondents who were of diverse religious beliefs were mostly illiterates (80%, Table 1) and depended on the environment in meeting most of their needs.
Respondents in the various communities demonstrated similar indigenous knowledge about the pharmaceutical abilities of plant species. Thus, suggesting that the indigenous knowledge on plant species is an integral part of the Yoruba culture that is passed from one generation to another. Barks were sourced from the roots of 20 plants species that belong to 16 different families (Table 2). Only two species (10%) were cultivated species in the study area and include Citrus sinensis (L.) Osbeck and Elaeis guineensis Jacq. E. guineensis is the major source of palm oil and provides the raw materials for other non-wood products such as basket, broom, shade and fuel in the study area. Similarly, barks were sourced from the stems of 51 species belonging to 25 different families (Table 3). Only six of these species (i.e., 12%) were cultivated in the study area. They are Bligha sapida K.D.Koenig, Chysophyllum albidium G. Don, Cola acuminate (P. Beauv.) Schott and Endl., Cola nitida (Vent.) Schott and Endl., Psidium guajava L. and Tectonia grandis L.f. Apart from T. grandis, the fruits of these species have commercial value in the study area. T. grandis was found to be cultivated in taungya plantations of governmental agencies and few religious organizations as shade trees.
Table 1: | Socio-economic classification of respondents in the study area |
*: % calculated to the nearest whole numbers |
Table 2: | List of plant species whose roots are extracted as source of bark |
Table 3: | List of plant species whose stems are extracted as source of bark |
Table 4: | List of plant species whose roots and stem are extracted as source of bark |
Table 5: | Relative occurrence of identified plant species |
Though the fruit of Parkia biglobosa (Jacq.) R.Br. ex G. Don was equally valued for its culinary and commercial purposes yet the cultivation of this species was still limited to the preservation of the wildlings.
Both the roots and stems of 43 species belonging to 26 families (Table 4) served as sources of barks. Five of these species (i.e., 12%) were been cultivated due to their commercial value in the study area. These species are Artocarpus heterophylla Lam., Citrus aurantium L., Citrus aurantifolia (Christm. and Panzer) Swingle, Cocos nucifera L. and Mangifera indica L. Although the fruit of Garcinia kola Heckel is equally of commercial value yet its cultivation is still limited to the preservation of the wildlings. Results from the relative abundance test (Table 5) revealed that only 5% and 4% were on abundant and very abundant scales, respectively, over 80% of the plant species identified were rare on the abundance scale.
DISCUSSION
Most of the debarked species were indigenous tree species thus supporting the previous assertions by Kayode et al. (1997) and Kayode and Kadeba (2001) that in Nigeria, preferences for tree species were skewed towards the local species than the exotics. The respondents were quite familiar with the ethno medicinal values of these species. Kayode (2005) enumerated the myriads of constraints that hindered the cultivation of these local species in the study area. These include the poor regenerative abilities of the local species.
The rare species, especially those species whose stems and roots served as sources of barks are vulnerable to extinction. Field observation revealed that most of the debarking was indiscriminately carried out. Quite often circular debarking was embarked upon. Such circular debarking, as previously observed by Cunningham (1988), often leads to the death of the plant. It is expected that the rapid removal of the forests that served as the reservoir and repository of genetic diversity would further complicate the present situation. The Nigerian forest is being removed at an alarming rate of 300 000 ha per annual (Repetto, 1988; Kayode, 1993) while reforestation and afforestation rates are less than 5% of the rate of deforestation (Odebiyi, 1990).
The results from this study had revealed that the bark extraction of these species could be described as been predatory or annihilative. Momma (1992, 1994) had previously asserted that when the rate of regeneration is slower than the capacity to extract, the integrity of the mother-plant is no longer protected; extraction ad infinitum could no longer be guaranteed hence the extraction is annihilative. It is therefore necessary to embark on the conservation of these species in the study area. Perhaps, it might be necessary for each senatorial district to have a botanical garden where most of these debarked species could be cultivated and preserved. Research efforts would be required to determine the relative regenerative capabilities of the debarked species. Some of the debarked species should be domesticated and public enlightenment on the dangers involved in species diversity loss should be carried out. Individuals and communities should also be mobilized to participate actively in tree planting activities. Most of the debarked species were known to have strong anti-malaria properties thus supporting the previous assertion by Kayode (2005) that malaria is the most prevalent disease in the study area, thus, biological efforts aimed at minimizing the incidences of malaria would help in the conservation of these species.
REFERENCES
- Fasola, T.R. and A. Egunyomi, 2002. Bark extractivism and uses of some medicinal plants. Nig. J. Bot., 15: 26-36.
Direct Link - Kayode, J. and O. Kadeba, 2001. Indigenous fuelwood tree species in rural areas of Ekiti State, Nigeria. Afr. Scientist, 2: 111-116.
Direct Link - Kayode, J., 2002. Ethnobotanical survey and conservation of plant species used for curing malaria in Edo and Ekiti States of Nigeria. NISEB J., 2: 247-252.
Direct Link