Folk knowledge of wild food plants among the tribal communities of Thakht-e-Sulaiman Hills, North-West Pakistan

Ethnobotanical data of WFPs including vernacular names, parts used, gathering period, gathering areas, collectors and folk food uses are reported in Table 3. A total of fifty-one WFPs from forty-two genera and 28 families were documented. The family Rosaceae was dominant with the largest number of species (7 spp.), followed by Asteraceae (4 spp.), while Apocynaceae, Malvaceae and Rhamnaceae were represented by 3 species each. Based on FC values, the dominant family was Rosaceae followed by Oleaceae, whereas the remaining families with high FC values included Pinaceae, Alliaceae and Moraceae. Most of these taxa are widespread and typically used as wild foods, which have been previously reported in different Eurasian countries [42‐46]. However, a rather uncommon food taxon is Apocynaceae– a family known for its toxicity and medicinal potential. Olea ferrugenia, Amaranthus spinosus, and Ficus palmata exhibited the highest FC values (1.0, 0.93 and 0.69, respectively), whereas in other species FC ranged from 0.59 to 0.01. These and related species have been reported by multiple authors from different parts of the country [42, 47‐54]. Fruits were the most commonly consumed plant parts (31 spp.) followed by leaves (12 spp.), a finding similar to earlier studies [11, 42]. Regarding growth habit, herbs were dominant (43 %) followed by shrubs, trees and climbers (31, 20 and 6 % respectively). The number of species for each growth habit were significantly different, but the FC values of tree species were the highest followed by shrubs.

The WFPs were categorized into three groups, i.e. wild fruits (56 %); wild vegetables (33 %) and wild tea (11 %). In the study area, wild fruits were mostly collected by boys below 25 years of age. It has been previously reported that fruits are a highly consumed food category among WFPs [20, 55, 56]. Wild fruits serve as an alternative to cultivated food during dry seasons and times of famine. In most rural communities of developing countries, wild fruits are the only fruits which are consumed by the local people as they cannot afford to buy commercial fruits [57]. In the present study, the number of wild vegetable species was less compared to other ethnobotanical studies [54, 58]. This might be attributed to less annual rainfall [28], insufficient ingredients used in cooking, and excessive use of dairy products among local communities. Similarly, in the study area, the use of wild vegetables was common among communities residing in the foothills, whereas those with large herd sizes migrated to the mountains and preferred dairy products. The lesser importance of wild vegetables in pastoral communities has also been reported by [59]. Although the use of wild tea species was presently uncommon among local inhabitants, their use was documented as this knowledge is vanishing. Inhabitants of the area use 6 species as alternative teas when commercial teas are unavailable or found only at great distances from their settlements.

In the study area, the transfer of WFP knowledge was from parents to children (vertical) as well as within the community (horizontal), but weaker contacts were developed among different villages. In total, 47, 40, 36, 24 and 24 plant species were documented in Landi Kutherzai, Payor Mela, Jatty Ghbaz, Zindawar and Kurachai villages, respectively. Of these, 31 % (16 spp.) were known to all foothill village informants, while 18 % (9 spp.) were only known in a single village. Among the remaining plant species, 24, 12 and 16 % were common to 4, 3 and 2 villages respectively. Village size, exposure to different ecological zones (seasonal migration–see Table 1) and surrounding flora (See Table 2) may contribute to this variation. For example, Landi Kutherzai and Payor Mela inhabitants which migrate between the foothills and the mountains are exposed to both types of edible floras and thus have more knowledge than the other villagers. The inter- and intra-cultural variations of traditional knowledge are quite helpful in understanding its dynamic nature and patterns of development [60]. Each informant mentioned an average of 17.5 species (11 wild fruits, 6 wild vegetables, and 1.5 wild tea species). Figure 3 depicts the disparities in knowledge of different age groups on the basis of 5 years age differences. The age group 41–45 was more knowledgeable as a result of firsthand experience. Age as an influencing factor on WFP knowledge has also been mentioned in the literature [61]. However, the decrease of knowledge exhibited by the +45 age groups was the result of a reduction in their direct involvement in the collection and consumption of WFPs. Interestingly, the 21–25 years age group showed good traditional knowledge which is a sign of traditional knowledge consistency in the area. These individuals are involved in livestock herding during which they not only eat WFPs, but also collect them for later consumption at home. Younger people with considerable knowledge of WFPs (as a result of similar behaviors) have also been reported by Uprety et al. [20] and others [62, 63]. The minor folk knowledge retained by the age group 26–30 can be explained by the fact that these age group members sometimes left their villages and migrated for labor to towns or overseas to support their families and came back to the villages later. Studying individual ethnobotanical knowledge has the potential to add to the systematic understanding of humanity’s most prevalent and earliest form of knowledge [60].

The offseason availability of WFPs through drying and storage are valuable practices as they provide food stability and therefore food security throughout the year [64]. Inhabitants of the study area store 16 % (8) of WFP species, including Allium sp. (Fig. 4), Olea ferruginea, and Sideroxylon mascatense for use during the winter season; therefore, these species have significantly higher FC values than non-storable species (Mann–Whitney-U-Test for independent samples, p < 0.0001). We found that 29 % (14 spp.) were exploited for additional cultural uses, for example, as fodder (Grewia tenax, G. villosa, Celtis australis), fuel and timber (Pinus wallichiana, P. gerardiana), as well as for multiple purposes (Olea ferruginea and Sideroxylon mascatense). The additional qualities of WFPs enhance their local preference as significantly higher FC values were recorded for such species (Mann–Whitney-U-Test for independent samples, p = 0.016). Furthermore, significantly higher FC values were also obtained for species with medicinal uses (Mann–Whitney-U-Test for independent samples, p = 0.001). The present results follow the general rule that the more versatile a plant, the more widespread its usefulness [65]. The medicinal importance of WFPs (given their role in the prevention of illnesses) has been explained in detail by [3, 15]. The manifold uses of these plants demonstrate their local importance for subsistence and as cultural heritage [66, 67].

In our documentation of WFPs, we observed that 14 % (7species) were sold in markets. The species with marketable potential, such as the species Pinus gerardiana, Caralluma tuberculate, and Ziziphus jujube (Fig. 5) were more important in the minds of local inhabitants (Mann–Whitney-U-Test for independent samples, p = 0.002), as they provide opportunities for supplementing family income and such species have attracted worldwide attention [12]. Among all WFPs, 16 % (8 species) were rarely available in the study area. The unavailability of these species was generally due to the unsuitable edaphic and climatic conditions (Lactuca dissecta, Notholirion thomsonianum, Pistacia khinjuk), although over-exploitation for marketing purposes was also responsible (Caralluma tuberculata). Sustainable use of such economically important species, however, could make a valuable contribution to the income of indigenous communities [68, 69]. Additionally, it is believed that food botanical studies are vital for the conservation of cultural history, local identity and tradition dishes of a region [27]. The importance of traditional ecological knowledge in the conservation of biodiversity has been recognized by the United Nations Convention on Biological Diversity that calls for the recognition and protection of traditional knowledge [70]. In this study, 14 % (7 species) of WFPs were semi-cultivated (i.e. present in both wild and cultivated forms), including Ficus palmata and Punica granatum. The domestication of species is the most important cultural development in the past 13,000 years of human history [14]. The wild species of Allium, Punica granatum, Cicer nuristanicum and Ficus palmata collected from the present study area may be quite useful for genetic cross-over with their domesticated sister species in order to not only improve crop yields, nutrient levels, disease resistance, and the ability to withstand adverse climate change, but also broaden the genetic diversity of present crops to fulfill the requirements of the 21st Century [10, 11, 71].

The seasonality patterns of WFPs demonstrate that May, June, July, and August are regarded as the peak months, during which 33 % (17 spp.), 37 % (19 spp.), 39 % (20 spp.) and 25 % (13 spp.) are obtained, respectively. Likewise, January, February, November, and December are included as off months in which no WFPs are obtained. For fruits and vegetables the peak months are July, October and June, in that order. Similarly, the duration of availability of fruits is generally about only a month whereas for vegetables it lasts 2–5 months (Table 3). Overall, the majority of the species are available during the summer, i.e. hot-dry season which correlates well with shortages of cultivated food resources. The same phenomenon has been reported by Campbe [72], who explained that people need supplementary foods during periods of food shortages. The supply chain in the area was short (except for Pinus gerardinana) with collectors/wholesalers selling either to retailers or directly to consumers. The collectors/wholesalers (mostly young boys) were responsible for bringing the WFPs to the market with little or no additional costs, where retailers and consumers can purchase them. The same details are mentioned by Karaan et al. [73] in relation to the marketing and supply chain of indigenous fruit markets in Tanzania, Zimbabwe and Zambia.

Multiple methods of data collection were used (as explained above) for understanding the characteristics of WFPs. Detailed interviews demonstrate that Pinus gerardiana is the most important species in the area; however its FC value does not convey its actual importance. The reason for this is that Pinus gerardiana is not merely a WFP in the minds of locals; it also makes a tremendous contribution to their livelihood. Similarly, Punica granatum was appreciated as a quite important fruit in detailed interviews but its FC value does not represent this. Punica granatum is regarded less as a wild plant and more as a cultivated one, which causes it to be less cited. Conversely, Notholirion thomsonianum was recorded with a high FC value (0.31) in freelisting but less attention was given during the detailed interviews. On the other hand, the interviews suggested that wild tea species have no importance in the area but its separate freelisting made it a category that highly influenced their FC values. Despite the importance of different quantitative tools, semi-structured, detailed interviews are the best way of exploring the actual importance of ethnobotanical species [65]. Reyes-García et al. [74] stated that the value obtained through a freelisting does not necessarily correspond to its practical value as they found that some species frequently mentioned in freelisting exercises were rarely used. Multiple methods have to be employed for determining the present uses of plants as different indices do not, in all cases, measure the plants’ uses but rather their knowledge [65].

This study investigated foothill and mountain villages that were separated on the basis of altitude, flora, rainfall, diversity and density of vegetation. This study reports a significantly higher number of species 61 % (31 spp.) in the foothills as compared to the mountains 39 % (20 spp.); however, the FC values of mountain species were significantly higher than for those in the foothills. A large proportion of informants do not migrate to the mountains, and as a result they remain unaware of the edible flora of these areas. Previous studies have mentioned that convenience and experience make the immediate vicinity a favorable collection site [55]. Moreover, the use of wild plants is primarily based on the utilization of species belonging to the closest ecological environments [75, 76]. Two possible factors may account for the high FC values: the selection of the best species among the diverse flora in the mountains and more dependence on natural food entities due to the inaccessibility of markets. Furthermore, there was a prevailing local belief that the mountains have more spiritual potential than the foothills which may influence local inhabitants to give more preference to mountainous species. Weckerle et al. [55], while examining ritual species in the Hengduan Mountains of Southwest China, explained the local perception regarding the availability of the best quality ritual species in high mountains due to a strong association of the mountains with god.

To the best of our knowledge, after an extensive literature survey [42, 47‐53, 58, 77‐131], 73 % (37) species recorded in this study had previously been reported by various investigations in Pakistan, whereas 27 % (14 spp.) are newly reported WFPs and thus represent an addition to the knowledge of the wild edible flora of the country. The average FC values of the newly reported WFP species were significantly lower than the overall FC, which indicates that they are not very important in the area. However, some species which do have high FC values and thus represent important WFPs, such as Salvia moorcroftiana (FC: 0.47), Notholirion thomsonianum (FC: 0.31) and Cotoneaster pruinosus (FC: 0.22), had not yet been reported for the country. Several studies reported the use of these species for different purposes in other areas, including the medicinal use of Salvia moorcroftiana [77, 78, 132, 133] and Notholirion thomsonianum [125]. This may probably be due to specific cultural knowledge of each community, a phenomena that has been reported in other studies [45, 75]. Some species such as Viscum cruciatum, Cicer nuristanicum and Berberis calliobotrys may not have been reported in other areas due to their restricted occurrence in the country [134]. The newly documented species were collected from diverse habitats ranging from waste land to pine forests, by different collectors (women, men, kids), and during different seasons (Table 3). Moreover, they represented a broad range of WFPs including wild fruits (Berberis calliobotrys, Cotoneaster pruinosus), wild culinary vegetables (Notholirion thomsonianum, Cynoglossum lanceolatum), wild salad greens (Cirsium arvense, Salvia moorcroftiana), wild tea species (Limonium cabulicum, Spiraea canescens), and wild relatives of cash crops (Cicer nuristanicum, Allium sp.). This information may broaden the existing wild food spectra and might provide insight into food diversification. In the context of the recent rapid decline in traditional knowledge across the globe [135‐137], exploration of new WFPs is quite encouraging.