Botanical Identification of Irvingiaceae Species
In total, we collected botanical vouchers of eight different Irvingiaceae species used by the Baka: five species of Irvingia, referred to under the collective term “mangues sauvages,” two species of Klainedoxa, and one species of Desbordesia (Table 1). We were therefore able to collect representatives of all of the Irvingiaceae species present in Cameroon, except I. smithii Hook. f., which is very rare in Cameroon and only known from one location along the border with Congo Brazzaville (Harris 1996; Kenfack et al. 2007).
Local Classification of Bush Mangoes
The naming conventions for the bush mangoes among the Baka includes both species-specific identifiers and more general group names (Fig. 2). Confusingly, the name used for one particular species may also apply to a group. In Baka language, payo refers to the specific species I. excelsa, but also to a group of similar-looking bush mangoes that includes pekè (I. gabonensis), gangendi (I. wombulu), and kòmbèlè (I. robur). Typically, , I. grandifolia is not considered to be payo, probably because the fruits are much smaller (Fig. 3).
The two Klainedoxa species are grouped under the general term, , which is also used specifically for the very commonly occurring K. gabonensis (Fig. 4). Because of its smaller fruits, the less common bondulu (K. trillesii) is considered to be the “younger brother” of K. gabonensis. Finally, ntuo (Desbordesia insignis) is considered to be a separate entity.
The Baka distinguish the different species based on their taste, fruit size, the shape of their leaves, and the habit of the trees. For instance, I. robur (Fig. 5) is said to have larger fruits and seeds than I. gabonensis, whereas I. excelsa is said to have stronger kernels than I. gabonensis, which makes their processing more difficult.
Due to its bright pink stipules and young leaves, D. insignis can be distinguished from a large distance. The pink crowns of these trees are clearly visible in Baka villages along logging roads (Fig. 6).
Habitat and Domestication
All species of Irvingiaceae occur naturally in primary forest, but when the Baka cut forest for agricultural fields, they spare these trees because they provide them with valuable fruits. It is therefore common to find Irvingiaceae trees as emergent in secondary forests, in shrubland around villages, and along logging roads. However, the large majority of Irvingiaceae fruits and kernels are gathered in the forest, either secondary or (selectively logged) primary forest. In contrast to Irvingiaceae trees in the forest, of which the fruits are available for everyone, trees that grow on or near agricultural fields are seen as property of the owner of the field, who may prohibit fruit collection by other Baka. According to our informants, only Desbordesia insignis was sometimes planted from seed, while all other species were considered as wild. However, during our forest walks, some informants collected Irvingiaceae seedlings to plant closer to their home, which suggests that other bush mango species may be deliberately planted as well.
The Baka differentiate four seasons: the major dry, the minor rainy, the minor dry, and the major rainy seasons. The time when bush mangoes fruit is a key period in their yearly calendar. It is often used as a temporal marker when referring to past events ., the “bush mango season,” specifically refers to the fruiting period of I. excelsa (payo) and I. gabonensis (pekè) in June–July, as the other Irvingiaceae species ripen in other times of the year (Fig. 7).
The importance of the bush mango fruiting season is reflected in the mobility patterns of the Baka: between June and August, many families go on collecting trips into the forest to gather Irvingia fruits. From children to elders, all family members are involved in gathering the fruits and seeds. In this period, families may spend several weeks to months in the forest, staying at a forest camp or shifting between several camps depending on the availability of Irvingia trees in the surroundings. While all Irvingiaceae have massive fruiting periods, I. excelsa and I. gabonensis were the species most commonly eaten and sold in the four study sites, and said to be the most abundant in the forest.
Local Preparation and Uses of Irvingiaceae
In general, all Irvingiaceae fruits are collected from the ground. Only the fruit pulp of I. gabonensis is consumed raw; the fruits of the other species are so bitter that only the kernels are eaten. The Baka open the fruits with a machete and take out the fatty kernels, either at the place the fruits were collected or back in the camp (Fig. 8). The kernels of all eight Irvingiaceae species are eaten raw during collecting, especially by children. The adults also collect the kernels in wicker rattan baskets lined with Marantaceae leaves. This process of fruit collection and removal of the kernels takes a considerable amount of effort. The Baka consider the Irvingiaceae to be one of the most difficult wild foods to gather, because of the time needed to extract the kernels. They have to knock the hard seeds several times with a machete before they split and the kernels can be taken out. Piles of decaying opened fruits are frequently seen along forest paths.
Kernels from all Irvingiaceae are also roasted. They may be first dried in the sun for several days or on a grid above the fire. They may also be roasted on an aluminum sheet or a pot cover, which allows the Baka to use the kernels shortly after gathering. The Klainedoxa species are more frequently consumed raw or roasted, but rarely included in more elaborate dishes. In contrast, the Irvingia species are often processed further. Once roasted, they are pounded in a wooden mortar or ground into a powder on a wooden board with a dried bùku fruit (Strychnos aculeata Soler.). The powder can then be mixed with water and salt and boiled into a sauce, which is eaten with starchy food such as cooked cassava, plantain, or yams. This powder is also added to more elaborate dishes, such as stews with green leaves from wild plants (e.g., Gnetum spp.) or cultivated vegetables (e.g., cassava leaves), meat, fish, or combinations of these. The kernels are appreciated for their flavor and fat.
The Baka also prepare a paste or cake from Irvingia kernels for longer storage. Only the kernels from I. excelsa and I. gabonensis were reported to be used in this manner. After the Baka collect great quantities of kernels, they dry them for 2 or 3 weeks and then store them on a rack above the fire. They then roast the kernels and pound them in a mortar, which produces an oily dough from which the oil often separates. They line a pot with banana leaves, pour the dough and separated oil on top, and mix the two together. The resulting cake is allowed to dry in the sun for 2 days, so that the oil is re-absorbed into the dough. This cake, known as mupekè, can be kept for 1 or 2 years without spoiling. When it is needed, they scrape off a small portion of the cake and use the resulting powder in dishes (Fig. 9).
Irvingiaceae trees also have other uses, such as firewood (Desbordesia insignis) or medicine. I. robur and I. excelsa were reported to be used for treating stomach pain, and Klainedoxa trillesii was used to treat diarrhea. I. gabonensis was reported to cure malaria. For all of them, the medicine was prepared similarly: the bark was scraped, the powder added to water and drunk. The bark from Klainedoxa gabonensis and I. grandifolia was used in rituals before hunting expeditions, in order to bring luck to the hunter. The exact means by which the barks are used in these rituals were not shared by our informants.
Importance of Bush Mango Species in Dietary Recalls
Although eight different Irvingiaceae species are collected for their fatty kernels, only two local names were reported in the dietary recalls in the four villages: pekè and payo, of which the latter was most frequently reported as consumed in the past 24 h (Table 2). However, during the interviews, we did not ask whether the informant was referring to real payo (I. excelsa) or one of the other three other species known under this collective name (I. gabonensis, I. wombulu, and I. robur), as we did not understand at that time that the term was sometimes used for all four of these species. Regardless, pekè (I. gabonensis) is the most preferred Irvingiaceae species. When asking 100 Baka informants about their preferred wild edible plants, I. gabonensis was the only Irvingiaceae species that appeared on the list, and was ranked seventh of the most favored wild food plants (Gallois et al. 2020).
None of the Klainedoxa species was mentioned in these recalls, but during the trips in which we collected voucher specimens, we frequently encountered areas where large amounts of Klainedoxa fruits had been processed. Desbordesia insignis also was absent from the dietary recalls, but whether this was because our fieldwork seasons did not coincide with its fruiting season or because its kernels were eaten only as a forest snack remains unclear.
Merchants from West and North Cameroon regularly come to Baka villages by car or motorcycle to buy Irvingia kernels. During the 14 days income surveys, only payo (Irvingia spp.) and pekè (I.gabonensis) were reported as being sold to middlemen, either to foreigners from other parts of Cameroon or to Nzimé, who also buy the kernels for their own consumption. During focus group discussions, the Baka specified that I. excelsa and I. gabonensis were the most commonly sold, while I. wombulu and I. robur were sold less frequently. The price paid for the kernels varied among villages, individual collectors, and merchants. In Elonda, a two-liter container of dried kernels (the equivalent of 1 kg) was sold in 2019 for USD 1–5 (600–3000 XFA), while a 2 kg cake of I. gabonensis kernels for about USD 6. Overall, in the 14-day income recalls, the total revenue earned reported for all the 221interviewed participants from both sale and wage labor was about USD 983, of which about two-thirds was from selling NTFPs (Fig. 10 and Table 3). The sale of Irvingia kernels represented the highest share (36%) of the income provided by wild-collected plants. Of these, most (34%) were reported as payo, which might refer to four different species, including I. excelsa. Overall, the sale of Irvingia kernels provided about 9.5% of the total income earned by the Baka during these 14 recalled days.
Recently, commercial timber companies have started to log Desbordesia insignis trees. The other Irvingiaceae are not yet felled for the hardwood trade in this area. However, some Baka informants reported that a destructive form of bush mango gathering was taking place during the peak fruiting season of I.gabonensis. Baka harvesters searching for quick cash entered the protected Dja faunal reserve, a UNESCO World Heritage Site located about 30 km from our study area, and cut several trees to be the first to collect the fruits and sell the kernels. This has led to conflicts between Baka and park rangers.