The Utilization and Conservation of Indigenous Wild Plant Resources in the Limpopo Province, South Africa

3.1 Diversity of useful wild indigenous plant resources

The present study documented a total of 50 useful plant species belonging to 32 botanical families, mainly the Fabaceae (28%, n = 9) and Cucurbitaceae (13%, n = 4), that are harvested by rural communities inhabiting the Limpopo Province of South Africa (Table 1). These families are repeatedly recorded in various ethnobotanical studies conducted in South Africa [45, 46] and elsewhere [46, 47, 48], as being highly represented with a greater number of plants exploited by indigenous people to meet their livelihoods. Cucurbitaceae and Fabaceae are not only widespread in communal lands of the Limpopo Province but they also comprise many plants commonly known as foods and natural medicine. Therefore, their predominance in this study came as no surprise. According to de Albuquerque [49], indigenous people highly value and experiments on plants that are more accessible or locally abundant. However, plant species from the rest of the botanical families were rarely harvested for their products, perhaps due to their less adaptation in a wide range of altitudes across the aforementioned province. As such, they are less susceptible targets of the local people to experiment with.

3.2 Plant utilization categories

The consumption of wild plants is an ancient African tradition which serves multiple purposes. In the present study, analysis of ethnobotanical uses categories indicated that more taxa were exploited exclusively for medicinal (n = 32) and food (n = 10) purposes. Some of the commonly harvested medicinal plants documented include Elaeodendron transvaalense (Burtt Davy) R.H.Archer (HIV/AIDS), Hypoxis hemerocallidea Fisch., C.A.Mey. and Avé-Lall. (Gonorrhea and HIV/AIDS), Leonotis leonurus (L.) R.Br. (asthma and chest pain), and Lippia javanica (Burm.f.) Spreng. (asthma, rhinitis sinusitis, and tuberculosis), used as therapies for the mentioned ailments (Table 1). Therapeutic applications of these species are well supported by scientific studies [36, 50, 51], thus partly explaining their utilization by people of the Limpopo Province. Plant-based medicines such as Alepidea amatymbica Eckl. and Zeyh, Brackenridgea zanguebarica Oliv., Celtis africana Burm.f., Encephalartos transvenosus Stapf and Burtt Davy, Mundulea sericea (Willd.) A. Chev, Rauvolfia caffra Sond., and Sclerochiton ilicifolius A. Meeuse were considered as having mysterious and magical powers used to expel evil, fight opponents, and as luck charms (Table 1). For the food plant category, all the species were reported to be either eaten as leafy vegetable with porridge (Momordica balsamina L., Momordica boivinii Baill, and Vigna unguiculata L.) or exploited for their edible fruits (Berchemia discolor (Klotzsch) Hemsl, Dovyalis caffra (Hook. F. and Harv.) Hook. F, Grewia bicolor Juss., Pappea capensis Eckl. and Zeyh, Vangueria infausta Burch, and Ximenia caffra Sond.). The consumption of these plants by indigenous people in the Limpopo Province is primarily attributed to multiple factors including food scarcity, nutri-medicinal value, and local cultural practices.

Other categories that had explicit use were for provision of livelihoods such as firewood (n = 2; Vachellia karroo Hayne and Vachellia rehmanniana Schinz), water storage (n = 1; Breonadia salicina (Vahl) Hepper and J.R.I. Wood.). Vachellia karroo and V. rehmanniana are preferred as firewood species due to both their local availability and long burning period, which provide lasting heat and light [41].

The remaining plants, namely, Anthocleista grandiflora Gilg (used to cover maize grains to encourage germination when malt is prepared, and female bodies during rituals, and as medicine for high blood pressure), Boscia albitrunca Gilg and Gilg-Ben (eaten as food and HIV/AIDS medicine), Colophospermum mopane Kirk ex Benth (firewood and fodder), Dichrostachys cinerea (L.) Wight and Arn. (construction of huts and livestock enclosures, and firewood), and Sclerocarya birrea (A. Rich.) Hochst (used to treat female infertility, fodder, valued for rituals ceremonies as a way of appeasing the ancestors and for making traditional beer) fell under the multiple-use category and were cherished for the mentioned livelihoods. Plants belonging to this category are more likely to be overharvested due to their multiple cultural values [52, 53].

Overall, all the above-stated use groups is a reflection of a close relationship between the local people and their natural environment, which has led to the development of a rich knowledge based on plants, plant-use, and related practices [54]. Comparisons of our finding regarding the most dominant plant use category concur to that noted by other researchers in South Africa [55, 56], and other African countries such as Ethiopia [57], Lesotho [58], and Botswana [59]. Contrary findings were noted in Kenya [47], Brazil [60], and India [61]. This may be the result of cultural differences in knowledge of the plant resource uses. Nonetheless, it should be stated that a larger number of wild plants used as medicines and foods for human was expected in this review, first due to the fact that traditional medicine is highly rooted in many cultures of the Limpopo Province [38, 62, 63], and second because rural people in this province grew-up eating wild edible plants and their majority live below the poverty line [64]. Thus, it is acceptable to postulate that the use of plant resources for food and medicinal purposes by indigenous people of the Limpopo Province will increase tremendously in the foreseeable future. This is because the indigenous communities have enticements to utilize and conserve wild plants when their livelihoods depend on gathering of their products.

3.3 Plant habit and used plant part/s

The growth form analysis of 50 documented useful plant resources revealed that trees (62%, n = 31), herbs (30%, n = 15), and shrubs (13%, n = 4), respectively, were harvested for their products in the present study. These are the common plant habits exploited by indigenous people in South Africa [55, 65] and other African countries [57, 66] to meet their various needs. It should be stated that the supremacy of trees in the present study is attributed to multifaceted factors including cultural beliefs attached to them (i.e., provision of rain) and their utilization in local ritual ceremonies and a wide range of products (i.e., medicines, foods, fodders, fruits, and firewood, among other provisions) they provide to local communities. Equally, herbaceous taxa were considerably represented mainly due to numerous values they provide (Table 1). However, the shrubby species, namely, Aloe falcata Baker, Kleinia longiflora DC, Leonotis leonurus (L.) R.Br. and Lippia javanica (Burm.f.) Spreng were only harvested for therapeutic purposes, which probably explain their lower preference by local communities of the Limpopo Province. Generally, sustainable harvesting of products from the afore-stated growth forms should be promoted in the Limpopo Province for the sake of both conservations of the plants and livelihoods of local people.

The actual impact of wild plant harvesting depends on the specific growth form or type of resource that is removed [67]. Different plant exudates from herbs, shrubs, and trees recorded in the current study were obtained by local communities to meet their livelihoods, with fruits, followed by leaves, bark, and roots, respectively, being the most preferred. Other plant parts were used to a lesser extent (Figure 1). The widespread use of leaves and fruits by indigenous people to meet their different needs is well documented in ethnobotanical literatures [68, 69, 70]. Their high uses in this study are mainly attributed to their economic value (i.e., source of cash generated from the sale of fresh fruits) and use as food supplements by many rural communities in the Limpopo Province. Other factors that contributed to high exploitation of fruits are their local abundance in many free access communal lands of this province and the fact that they are consumed raw without any processing.

Leaves were the second most commonly used plant part and were mainly exploited as medicines and vegetable (Table 1). Consumption of leaves for these livelihoods is locally believed to be ascribed to their efficacy as remedies and rich nutrients. From a conservation standpoint, the high harvesting of leaves is less destructive to the survival of plants [71, 72]. The opposite of this can be said for bark and roots. High usage of these organs exclusively as medicines in this study is directly linked to the traditional beliefs that they store more healing power than any other plant part [44, 73]. This belief, however, has a great potential to encourage their extensive harvesting, which in turn will make the targeted plant species vulnerable to overexploitation. The rest of morphological plant parts did not appear to be of great value to the indigenous people of the Limpopo Province (Figure 1).

3.4 Conservation status of plant species

The present study revealed that all 50 plant resources documented are listed on the South African National Red Data List of Plants, with the majority (82%, n = 41) appearing as Least Concern. This finding has a positive conservation implication mainly because more widespread and abundant species in the wild are included in this category [36]. Therefore, it is acceptable to state that most useful taxa in the Limpopo Province might be still fairly abundant within the wilderness.

However, 12% (n = 6) of Red Data listed plants recorded in this study are of conservation concern with the following status: Critically Endangered (Brackenridgea zanguebarica Oliv.), Endangered (Alepidea amatymbica Eckl. and Zeyh.), Near Threatened (Drimia sanguinea (Schinz) Jessop, Eucomis pallidiflora Baker. subsp. pole-evansii (N.E.Br.) Reyneke and Elaeodendron transvaalense (Burtt Davy) R.H. Archer) and Vulnerable (Dioscorea sylvatica Eckl.). The rest as either Not Evaluated (4%, n = 2) or have Data Deficient (2%, n = 1) status. It is worth stating that most of the abovementioned species are constantly reported by plant resource harvesters in the Limpopo Province as very difficult to find in their natural habitats, with prime rationale being excessive exploitation for commercial purposes [35, 74]. Another factor put forward by indigenous people of the Limpopo Province that jeopardize these plants is gathering by outsiders and other local people who are not trained on both the traditional harvesting of useful wild plants and approaches to conservation.

3.5 Traditional plant conservation strategies

Interestingly, this study also revealed that the indigenous people of the Limpopo Province, who depend on the recorded wild plant resources for survival, have evolved ways of managing them (Table 1). Generally, traditional leaders (i.e., chiefs and headmen) are the ones managing the utilization of these resources via traditional rules and regulations, and this is common practice in other provinces of South Africa [75] and other African countries [76]. On the contrary, Kepe [77] found that in areas that are held as common property by all villagers in Mkambati area of the Eastern Cape Province (South Africa), people do not have to ask for permission to collect wild plant resources. In the present study, anyone who breaks the traditional management strategies were fined a certain amount of money and restricted to harvest wild plant resources for a specified period of time. Overall, the traditional approaches used in this study to conserve plant diversity encompass the following;