Ethnobotanical survey of wild edible plants used by Baka Pygmies in southeastern Cameroon.

Background Forest inhabitants worldwide, and Indigenous Peoples especially, have depended for generations on plants and animals harvested in these ecosystems. A number of Baka Pygmy populations in south-eastern Cameroon became sedentarised in the 1950s, but still rely on hunting and gathering to meet their basic needs. The use of wild edible plants (WEP) by these communities remains largely undocumented. In this study we document the diversity of WEP used by Baka people in dense rainforests in the Mintom region. The area still contains relatively undisturbed forests areas, just south of the Dja Biosphere Reserve, one of the most important protected areas in the Congo Basin. Methods We conducted two ethnobotanical surveys in 2019 in four villages on the Mintom road. In the rst survey, we interviewed a total of 73 individuals to determine WEP usage. In our second survey we specically quantied WEP harvested and consumed daily in a number of households over a two-week period during the major raining season, when use of forest products is highest. Specimens of all recorded plants were collected and identied at the National Herbarium of Cameroon. Results We documented 88 plant species and 119 unique species/plant organ/recipes in 1,519 different citations. A total of 61 genera and 43 families were recorded. Excluding 14 unidentied wild yam species, 17 WEP species had not been reported in previous ethnobotanical surveys of the Baka. Our results showed that cultivated starchy plant foods make up a signicant proportion of their daily nutritional intake.

a lower dietary diversity and consumed more sugar than those living more remotely whose diets contained more WEP and were more balanced in micronutrients. After sedentarization from the 1950s onwards, Baka who supplemented their life in the village with time in forest camps exhibited reduced stress levels helping them maintain a better nutritional status overall [14].
Market economies impact the lifestyle of hunter-gatherers, often by increasing their reliance on cultivated starchy staple foods and decreasing the use of WEP, eroding traditional local knowledge on how to nd, identify and process these plants. For example, only a few Baka elders still mastered the preparation of African oil bean (Pentaclethra macrophylla) seeds, which require several days soaking in running water to eliminate toxic compounds [15]. Bahuchet et al. [16] suspect that knowledge of the use of some WEP has already completely disappeared. Gallois et al. [15] document how the high valuation of cultivated and commercial foods has changed the vocabulary used by the Baka to describe wild foods. The bark of Afrostyrax lepidophyllus is now known as " [bouillon] cubes of the forest" to Baka, re ecting that bouillon cubes are, together with salt, the most bought dietary item by these communities when opportunities arise. In parallel to these social changes, the environment is being degraded at an unprecedented scale. Between 2000 and 2014, 16.6 million hectares of rainforest were lost in the Congo Basin, most (84%) from small-scale, nonmechanized forest clearing for agriculture, alongside selective logging [17].
Documenting the types of plants used by Indigenous Peoples is becoming more urgent as these communities change away from natural diets containing WEP towards domesticated cultigens and processed foods. In this paper, we document WEP use by sedentarised Baka communities in the Mintom region in Cameroon, recording the different usage, and quantifying daily amounts consumed.

Study Case
Pygmy peoples are distributed throughout the Congo basin in Africa. They are several, genetically and ethno-linguistically distinct groups (Bahuchet, 2014), broadly subdivided into western groups such as the Baka and Aka, and Eastern groups comprising Efe and Asua [41]. All live mainly in tropical rainforests as forest foragers and hunter-gatherers although two groups, the Bedzan (Medzan) of Cameroon and the Twa of Rwanda and Burundi, inhabit non-forest areas [42]. Pygmies share distinctive cultural and phenotypic traits such as the "Pygmy phenotype" of small adult body size [43]. The demographic and evolutionary split between Pygmy and non-Pygmy populations is amongst the oldest for modern humans with the divergence estimated from genetic data to be roughly between 60,000 and over 100,000 years ago with the split between Western and Eastern Pygmy groups occurring about 20,000 years ago [44][45][46].
Although the preeminent traditional way of life for these groups remains associated with forest hunting and gathering, most contemporary groups have taken up some form of agriculture. A typical example is the Baka of the Western Congo basin who are distributed in four different countries with the majority living in Cameroon, numbering about 40,000 individuals [47]. From about the 1950's onwards, Baka became sedentarised following missionary activities and the "development assistance" programs by the State after independence [16,47,48]; the adoption of agriculture and semi-sedentary lifestyle has been rather voluntary [49].
Pygmy groups have witnessed the gradual reduction of access to forest resources [50]. After relocation from the forest, Baka have opened their own plots to grow subsistence crops such as plantain, banana, and cassava [47,[51][52][53]. This change in lifestyle has been associated with a marked decline in physical and mental health [54]. Farming has increased in recent years in our study villages, particularly as a result of agricultural programmes initiated by our study partner Zerca y Lejos (ZyL) [55,56], a Spanish NGO working on development and health support to Baka communities in the region. Supplementing their life in the village with time in forest camps has led to reduced stress and has helped them maintain better nutritional status [14]. Hunting, shing, and gathering depend on both the agricultural timetable and seasonal uctuations [47,57].

Study site
The study region is located in the eastern part of the The climate is equatorial and humid. Rainfall averages between 1,500 and 2,000 mm per year, and some precipitation is common even during the dry seasons [58]. Mean annual temperature is 25 °C, uctuating slightly between seasons. The climate is composed of four seasons: a major dry season is from December to March, a minor rainy season from March to May, a minor dry season in August, and a major rainy season from September to November [15].
The terrain of the region is sloping with gently rolling hills ranging between 250 to 800. The major vegetation type is a mixture of evergreen and semi-deciduous forests [59]. According to Sonké (1998), three broad categories of forests can be distinguished in the Mintom area: forests on rocks, forests on rm soil, and aquatic or hydromorphic forests. Forests on rm soil are divisible into primary and secondary forests.

Data collection
Ethical approval was not required in this study, although it meets the guidelines of the Social Research Association [60]. Permission to undertake eld work in our study area was granted by the Ministry of Interviews were conducted between January and March 2019 following a pre-prepared open-ended questionnaire. To facilitate communication with the villagers, each interviewer was assisted by a Baka guide from each village, who spoke both French and the Baka language. The guide verbally translated our questionnaire from French to Baka language (Supplementary Appendix 1). Questions were asked to all members of an interviewed household jointly and every answer was noted. General information was rst gathered on name, village, ethnic group, age and sex of the respondents. Questions related to plant (wild and domesticated) use were "to what extent food usage (mode of use) was associated to which plant species" rather than asking "which plants were used for which food usages". For each mode of use cited (vegetable, spices, drink, …) were recorded the vernacular Baka name of the plant, plant parts used, the technic of harvesting (cutting, digging, …), distance from the village for collecting the plant and period of collection during the year. Whilst a "quotation" lists any plant/usage combination by any household irrespective how often it is cited by different people, "recipes" represent unique species / plant organ / usage combinations. A rarefaction analysis by stepwise addition of informants was conducted to estimate how the addition of informants increased the number of plant species and recipes.
Harvested edible plants, including agricultural plants and WEP were quanti ed daily for 14 days between 22th October and 07th November 2019 in Assok and Doum. This period encompassed the major rainy season, when mobility into the forest for hunting and gathering is highest amongst the seasons [15]. Each item destined to be consumed was weighted, and the vernacular names and use were recorded.
Plant specimens listed by informants were collected with assistance from the Baka guides. Some plants, mainly trees, were identi ed in the eld but all others were deposited at the National Herbarium of Cameroon (HNC) in Yaoundé. At the HNC, all specimens were rst sterilized with alcohol at 90 °C, dried with hot air and then kept at 20 °C for 3-4 days and sprayed with insecticides. Specimens were identi ed to the genus level and, whenever possible, to the species level by comparing them with specimens in the herbarium, local eld and identi cation guides [36,59,[61][62][63] and online databases [64][65][66][67].
Diversity indices used are those often used to assess the diversity in systematic botany or forest ecology [68] such as the Shannon-Weaver index [69], the Simpson index [70], and the regularity or the equitability index of Pielou [71]. The Shannon Weaver index (H') allows to assess the diversity level of each group taking into account the proportion of each plant in the group. The Simpson index (D) measures the probability for two citations withdrawn randomly from a given group, to belong to the same plant or recipe [72]. The regularity or the equitability index of Pielou measures the diversity level reached by a group compared to its maximal level of diversity. It compares two groups which have different number of individuals [73]. An ANOVA was used to determine the variance in the number of products harvested and consumed in different households. Data analysis was performed using R version 3.5.1 [74]. We also identi ed 119 recipes, i.e. unique species / organ / usage combinations. Rarefaction analysis shows that the information collected did not reach a saturation plateau (Fig. 1).

Results
Interviewed women (n = 21) reported the use of 69 species and 86 recipes, men (n = 46) described 77 species and 100 recipes and couples (n = 6) a total of 51 plants and 59 recipes. Diversity indices (Table 1) indicate an overall high diversity. Average usage densities were 1.2 plants/informant and 1.6 recipes/informant. Values were highest among couples, high for women alone, and low for men alone with a signi cantly higher citations/informant ratio (ANOVA, df = 2 F = 19.06, p < 0.001) and Shannon index (ANOVA, df = 2, F = 5.9, p = 0.003) for citations given by women versus men. The same holds for recipes (ANOVA, df = 2, F = 40.55, p < 0.001 and df = 2 F = 11.47, p < 0.001, respectively.  Table 2. Ten types of plant organs were used with tubers, fruits and leaves the most used ( Fig. 2A). Six types of use were quoted (Fig. 2B) with yams, (Dioscorea spp.) being the most consumed, followed by fruits and ingredients. In general, tubers and yams were more often quoted as consumed in the mentioned recipes.  (Fig. 4).

Discussion
Our results indicate that as many as 88 different plant species -including 14 putative, not identi ed wild yam species -were consumed by the 73 interviewed Baka families. A total of 119 recipes were used as WEP. Despite this relatively large number of items identi ed in our study, the rarefaction analysis indicates that the number of species recorded is not likely to represent all the WEP diversity used in the study area. This is typical for studies where sampling is not conducted across all seasons, as indicated in an ethnobotanical survey in the Bamenda Highlands in western Cameroon [75]. Although we asked information on WEP use throughout the year, it is likely that the use of some species elude the memory if they are only rarely consumed in a season other than when the interview was conducted. Except the 14 unidenti ed wild yam species, 17 WEP species had not been reported in any other ethnobotanical survey for the Baka [15]. A total of 51 plant usages were also unreported before.
The stated number of plants in our study is strikingly higher than the number reported in the grassland with some remaining patches of montane and submontane forests of the Lebialem highlands in southwest Cameroon, where only 26 WEP were documented from 300 respondents distributed in 15 communities [76]. Our number of WEP is also double the number of the Bamenda highlands study, that was conducted at the same time of the year as our study and which revealed 41 plant species by questioning 121 individuals [75]. There are two likely causes for the larger WEP diversity in our study site. First, the site south of Dja Biosphere reserve is more intact compared to the Lebialem highlands and the Bamenda highlands where relatively high human population density has resulted in severe biodiversity degradation [75]. In our study site there is some indication that WEP are over-exploited near settlements as the inhabitants of three out of four villages needed to travel more than one kilometre for collection and harvesting. The distance between the location of harvested common species and the village indicates the scarcity of the resource. Second, Baka have inhabited the forested areas for millennia, relying on a hunter-gatherer lifestyle. Their extensive traditional knowledge of WEP is likely re ected in the high number of plants used. In contrast, the inhabitants of the Bamenda highlands are mainly from the non-Pygmy  [26,77,79].
The most species rich genus was Dioscorea, the wild yams, with possibly 20 species. This includes Dioscorea mangenotiana, a vigorous annual climber that possesses a long-lived root which can attain as much as 60 kg in weight [36]. WEP are a major part of Baka cultural identity, and wild yams in particular play a speci c role in their cosmology. Yams are considered as a link between humans, elephants, and the "jengi" spirit, because these three share this symbolic food [9,10]. For this reason, wild yams have been considered "Cultural Superfoods" [80], which also relates to the notion of a cultural keystone species [81]. The nutritional importance of wild yams is highlighted by the exploitation through "paracultivation", whereby growth of wild yams is managed in their natural environment and over-exploitation is largely avoided [36]. The relatively high number of wild yam species in our study concurs with those assumptions; but is in contrast to the observation by Gallois et al. [15]. Although they report that Baka prefer wild yam when readily available, they seem not to be easily available in their study area, explaining the relative low consumption of wild yams observed there. Similarly, Hirai et al. [82] report of only three species at the northern periphery of the Boumba-Bek National Park in the East Region of Cameroon (D. mangenotiana, D. burkilliana, D. praehensilis). Wild yams store starchy reserves in aerial or underground tubers and are the most important source of carbohydrates for many hunter-gatherers of African forests [36]. In Africa, Cameroon has with 17 probably species the highest yam diversity [83], followed by 12 in Gabon [84] and Congo Brazzaville [85], 11 in Central African Republic [86], and 9 in Congo Kinshasa [36].
We could only identify six species whilst 14 putative species, which the Baka distinguish with separate names, remained unknown. These should be a prime target for future work and also establish whether there are undescribed species in our study area.
Foods other than wild yams are also important sources of macro-and micronutrients and energy for millions of people in the Congo Basin. Enquiries conducted in different regions in Cameroon [26,75,[87][88][89][90], Côte d'Ivoire [91] and in the Democratic Republic of Congo [92,93] revealed the high proportion of WEP fruits and seeds. The importance of fruits or seeds is linked to their high nutritive value and also to the production and long-term storage of derived products (oils for example). Edible wild fruits play a key role in the wellbeing of rural communities in developing countries in Africa and elsewhere, since they replace domestic vegetables during shortage periods [e.g. 94]. The daily consumption of some of these fruits may offer protection against some ailments and oxidative stress [95]. The main fatty acids of Baillonella toxisperma oils are oleic, stearic and palmitic acids. The fact that the biochemical characteristics and fatty acid pro le are comparable to common vegetable oils shows that the B. toxisperma oil is a potential source of valuable oil which might be used for edible, cosmetic, pharmaceutical and other industrial applications [96]. Etong and Mustapha [97] found that the oil of the bush mango Irvingia gabonensis contains six major fatty acids. Oil extracted can be useful both domestically and industrially. Amongst vegetables, the widely used species of the Gnetum genus are rich in proteins, minerals and amino acids [98]. Amongst spices, Afrostyrax lepidophyllus has antioxidant, anti-in ammatory, and anti-xanthine oxidase activity [99].  [15]. In their study, starchy foods were cited in 93% of dietary recalls.
Amongst the BaYaka Pygmies from Congo, knowledge of WEP is widely shared amongst people regardless of relatedness, whilst knowledge of medicinal plants is mainly kept between spouses and relatives [18]. It is, therefore, surprising to nd such strong sex-speci c differences in the information given by men and women in our study site. About double as many men reported WEP details than women. We noted that Baka women talk scarcely when they are accompanied by their husbands. But when they have an opportunity to be alone Baka women were much more open and provided more information than men on the same subject (high diversity of usages), which explains the higher information densities of plants and recipes, the higher values of the Shannon and Pielou indexes for plants and recipes and the weak values of the Simpson index for plants. All these ndings highlight the importance of gathering information from all member of a given family during ethnobotanical surveys.

Conclusions
Surveys carried out among Baka people living south of the Dja Biosphere Reserve revealed 88 edible plants species including 14 putative but not identi ed wild jam species (genus Dioscorea). This genus was with six identi ed and 14 putative species the most species rich genus in the study, emphasizing their nutritional and cultural importance for Baka. Compared to the Bamenda Highlands in western Cameroon, the Baka WEP diversity was more than double. Excluding the 14 unidenti ed wild jam species 17 WEP species have not been reported in any other ethnobotanical survey including on Baka [15]. The importance of the study area for WEP diversity is also highlighted by the fact that 18 out of the 30 'key' NTFP in Cameroon [77] were quoted by Baka. The increasing in uence of market economies on the lifestyle of hunter-gatherers since sedentarization from the 1950s onwards is exempli ed by the high proportion of starchy food in daily nutritional intake observed here and elsewhere [15]. Baka still harvest and use a wide variety of WEP, giving the opportunity to further document Baka´s knowledge of WEP especially as biological resources and indigenous knowledge are diminishing with high destruction and a growing disinterest among the younger generation [75]. Fostering this knowledge will be important for sustainable development and achieving food security.

Declarations
Forests, Trees and Agroforestry. Additional funding was provided by the SIFCO, through CAFRAM. No funding body has no direct role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.

Availability of data and materials
Plant specimens were deposited in the National Herbarium of Cameroon, Yaoundé Ethics approval and consent to participate: Before conducting interviews, prior informed consent was obtained from all participants. No formal ethics approval was required.

Consent for publication:
Not applicable   Collection distance for the most popular WEP from villages.