Local indigenous knowledge about medicinal plants in and around Kakamega forest in western Kenya

Introduction

Although community development goals are not always consistent with biodiversity conservation objectives¹ there are often many opportunities for mitigating negative effects by tapping into local indigenous knowledge with reference to certain aspects of environmental use and conservation². Indeed, application of knowledge and values of communities that are resident within or around key biodiversity areas has been gaining increasing global popularity as significant elements in enriching and improving strategies for conserving biodiversity³. This is because integration of such indigenous knowledge into conservation programs facilitates cross-borrowing of ideas, promotes constructive engagement, and instills a sense of common ownership and responsibility towards achievement of a synergy of goals². This echoes the concept of social capital³ that, apart from amassing local support and goodwill, adoption of local indigenous knowledge in conservation may also promote and provide sustainable insurance against conflicts of purposes. This results in increased chances of achieving the dual goal of biodiversity conservation stewardship as well as community development. For instance, Studies have shown that rainforest ethno-botanical checklists prepared by communities living in or near them tend to be more exhaustive because they are based on practical day-to-day uses that are firmly ingrained in local cultural norms and values⁴.

Like in many parts of the developing world, there is a growing upsurge in demand for herbal and other traditional remedies for various ailments among communities in Kenya. This is due either to increasing cost of conventional modern medicine or, or inadequacies in public health service delivery. However, the bulk of “technical” information on traditional cures is still disparate and privately held, with limited accessibility to the public or in peer-review domain⁵.

This study sought to set in motion a process for comprehensive and systematic documentation of plants of medicinal value for Kakamega forest, with a view to consolidating indigenous knowledge about them and making these available to the wider community around the forest itself as well as other stakeholders, in the process of underscoring highlighting ecosystem and other socio-economic services offered by Kakamega forest to society. The study also sought to highlight any plant species in the forest that may have medicinal value that are also of conservation concern, either as endangered or as a problem species.

Materials and methods

Study area: Kakamega forest lies in western Kenya between 00°08′30.5′′ – 00°23′12.5′′ N and 34°18′ 08′′ – 34°57′26.5′′ E from 1520–1680 m above sea level^6,7. The mean annual rainfall is 2000 mm, with long rains in April/May and short rains in September/October⁶ while mean annual temperature is 20°C. Due to anthropogenically-driven fragmentation over many decased, its main closed-canopy area now occupies only 60% (85 km²) of its original area (Figure 1). The forest is Kenya’s only true tropical rainforest (BirdLife International, 2004) and constitutes one of Kenya’s 61 Important Bird Areas (IBAs) due to many endemic birds species found in it (BirdLife International, 2004). Apart from birds, it also has remarkable biodiversity richness, hosting several species of mammals, reptiles, amphibians, invertebrates and plants^8,9. It is currently under increasing threat of loss to agriculture and settlement by the increasing local human population. The neighbourhood of the forest, where the western Kenya Bantu ethnic community called Luhya reside, is densely populated with an average density of 250 persons per kilometer^10,11.

Figure 1. Map of Kakamega forest (This figure has been reproduced with kind permission from Otieno and co-authors¹²).

The study was carried out within the three main blocks of Isecheno-Yala-Ikuywa group of fragments (south), Buyangu-Salaza-Kisere blocks (north) and the detached Kaimosi fragment (see Figure 1). The sections were covered in two field seasons of 11 days each, first during April–May while the effects of the long rains were still evident and many plants bore fruit (wet season) and then late July when full fruiting is reduced and some leaves are shed off (dry season). This was to control for any rainy-season effects.

Sampling strategy: A key informant was identified from each block/area of the forest during each sampling week, to be interviewed about the medicinal plants as outlined in Kothari¹². The key informant was selected on the following criteria: (1) seniority of age in the community (not less that 50 years old); (2) local residency for a period not less than 20 years; (3) appreciable knowledge of forest plants in the local dialect and well versed with their use(s). Current or previous experience as herbalist was preferable but not essential. Such selection was based on prior consulation with the local community leaders.

Data was collected through field excursions using interviews that employed structured questionnaires guided by a mix of closed- and open-ended questions for the key informants. This was combined with free-style discussions, actual field excursions and visits with the respondents. For data consistency, the same informants were involved each sampling season in each area. In addition, eventually there was a joint focused group discussion¹² with all the key informants to synergize the information gathered. Information captured and recorded included include: 1) Local name of plant in question; 2) Disease/condition cured by plant; 3) Plant part(s) used for the cure; 4) Preparation method; 5) Common (English) name of plant. These were determined from standard field guides; 6) Scientific name.

Data analysis

A checklist of all observed plants of medicinal values was compiled, including their indigenous, common and scientific names; condition(s) cured; methods of preparing and administrating them to a patient; as well as the age and gender of the target patients (see link to data file below). All the lists generated by the different key informants were scrutinized and synchronized into a final one at the joint focused group discussion¹³. With help from the informants/respondents, each plant was observed in its natural habitat and a digital image taken using a digital camera. Further, for each medicinal plant, a small part (preferably with leaves) was collected while fresh and digitally photographed for identification and pressed for herbarium. Plants whose common (English) and scientific names were not immediately identifiable in the field were taken for specialized identification at the East African Herbarium in Nairobi.

Results

A total of 40 key species of medicinal plants used by the people around Kakamega forest were identified and recorded (see Appendix). The plants fall into 24 positively identified families while the family of the remaining one species Bequartiodendron oblanceolata was not clearly discerned (Table 1). The most dominant families were Asteraceae, Fabaceae and Lamiaceae, each representing 10.3% each of all plants.

Of the 40 plants, 22 were shrubs, 13 trees, 3 lower plants such as herbs or forbs, and 2 climbers (Figure 2). Twenty-six of the medicinal plants occurred inside the forest itself and 14 occurred outside. One of the medicinal plants (Prunus africana) is also listed in the IUCN Red List as Vulnerable to extinction. The majority of the medicinal plants identified (95%) were indigenous and only 5% exotic.

Figure 2. Proportion of plant forms represented by the medicinal plants identified.

The diseases reported to be cured by the medicinal plants identified in the study varied widely but were grouped into 14 categories including use in treatment of a number of livestock diseases (Figure 3). Ninety percent of the diseases cured are those that affect humans and about ten percent for livestock diseases. Most of the human diseases cured using the plants, fell into the categories of digestive or peptic; respiratory, vector-borne; and reproductive ailments (Figure 3). Furthermore, these ‘cures’ are applicable for both genders and almost all age groups except in 17% and 7% of the cases where the ‘cures’ are applicable to adults and elderly people only, respectively.

Figure 3. Overall distribution of categories of disease claimed to be cured using medicinal plants identified.

In preparing the ‘cures’ from the plants, the local people mainly use leaves, roots and barks, but in a few plants, the ‘cures’ are derived from flowers, fruits and young shoots (Figure 4). Additionally, since many of the plants are used for curing digestive or peptic, respiratory or vector-borne ailments, the majority of them are administered orally.

Figure 4. Percentage instances of use of the various parts of the medicinal plants identified.

Discussion

The results of the study demonstrate that apart from Kakamega forest’s already well known position as a significant Kenyan rainforest in terms of the rich biodiversity, eco-system service provider and as a remarkable tourist site, it is also important to the local community as a repository for ethno-pharmacological resources that play a crucial role in supplementing the government’s effort in providing healthcare at the grass-root level. This also includes remedies for the treatment of livestock diseases. Unfortunately, much of the indigenous knowledge about these plant-based remedies, however, is still restricted to only a minority among the local population, particularly the elderly. Furthermore, these elderly knowledge holders are only those who have ancestry to a select number of families with long histories of the practice of traditional medicine. Traditionally, such indigenous knowledge, which is often regarded as spiritual, is closely guarded by such families, and is only passed on down the generation line to members of the family who use the knowledge and skills as a form of livelihood when they serve society as traditional medical consultants. In the process, such families wield immense respect in the society.

In-depth discussions with the key informants and a cross-section of some respondents among the local residents further revealed that even when the consultants prescribe treatment to their patients, only the already-prepared form of the cure is provided by the “medicine man” rather than revelation about the plant from which it is obtained, or how the concoctions are prepared. Nevertheless, this system is slowly changing and in recent years, some flexibility appears to be emerging, with the “medicine men”, including the ones interviewed in this study, are quite willing to provide information about the traditional cures in exchange for financial inducement or compensation. The wider society is also getting increasingly skillful in identification, preparation and administration of plant-based remedies at the local level⁴.

With the increasing cost of healthcare from modern facilities occasioned by global economic challenges which make medication expensive and out of reach to most rural dwellers in developing countries¹⁴, there is an increasing need to identify more affordable alternatives for the treatment of common ailments that affect rural human populations. For this reason, promotion of the use of natural remedies derived from various locally based resources such as medicinal plants, should form an important priority of governments’ strategies to make healthcare accessible to the rural populations in a more affordable way.

Wider availability of such knowledge, including from such research projects as these when published and distributed, would go a long way in improving access to basic healthcare. In addition, to protect the local community from exploitation of their indigenous medicinal knowledge by “external” prospectors and their agents for commercial purposes, a modality for a locally-based medicinal plant enterprise including charges for demonstrations, medicinal plant checklists and herbal medicine preparations sold to willing buyers, could be established and proceeds shared with or amongst the local stakeholders.

For instance, already underway is a project known as the Kakamega Forest Integrated Conservation Project, which involves a section of the local people in collaboration with the International Centre for Insect Physiology and Ecology (ICIPE). Part of this project involves commercial cultivation of two of the medicinal plants (see link to data file) Mondia whytei and Ocimum kilimandscharicum on farms. The income generated benefits the farmers and helps to supplement their subsistence needs. From ICIPE’s science park in Nairobi, an extract from Ocimum kilimandscharicum is used to make a commercial product called Naturub, which helps to relieve nasal congestion, colds, flu, insect bites, aches and pains¹⁵.

Similarly, there is a commercial medicinal product extracted from the roots of one of the plants in the forest. The product is named Mondia Tonic and is produced from extracts of the roots of Mondia whytei (see link to data file) and this is used as an appetizer, a flavoring agent, a stimulant or for mineral supplementation¹⁵. Such initiatives, if structured to incorporate indigenous knowledge of the local community, would be a further boost to economic empowerment of the community by using part of the returns from tha market to compensate them for such knowledge.

Conclusion

In conclusion, there is sufficient indigenous knowledge among the community around Kakamega forest about medicinal plants, to contribute not only to sustainable provision of grass-root health care but also a potential to share this knowledge beyond western Kenya. This knowledge also has a potential for boosting economic empowerment of the people around Kakamega forest. A tertiary potential benefit is incorporation of the knowledge into policies to guide conservation action for the rainforest and its biodiversity. This crucial benefit has further significant implications for mitigation of climate change impacts that would otherwise result in destruction or loss of this important water catchment for many rivers in western Kenya.

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