Background
Wild edible plants (WEPs) are ‘safety nets’ for many communities during lean seasons [
1‐
3] and in times of conflict [
4,
5]. They have been essential assets in the fight against malnutrition and hunger in many societies [
6‐
8] and of benefit to modern communities and in the future [
9,
10]. However, WEPs have witnessed continued localized habitat destruction and overexploitation [
11,
12], attributable to various anthropogenic and natural factors [
13,
14]. Such factors compromise the sustainable use of WEPs as safety nets for many communities across the globe [
15].
Within Africa, threats to WEPs pose challenges to about 80% of the rural populations that derive food from the wild [
16]. The threats inhibit the optimal regeneration of WEPs and their use as food by such communities [
17,
18]. While some threats have adverse effects on the local abundance of WEPs, changes in lifestyle and consumption patterns, among other socioeconomic and cultural reasons, also explain the declining use of WEPs [
19,
20]. The impacts from such threats are primarily felt by poor rural people [
16,
21], thus negatively affecting the role of WEPs as ‘safety nets’ for rural African populations vulnerable to malnutrition and hunger [
22,
23].
Turkana County in northwestern Kenya is one of the affected regions in Africa. It is inhabited by the Turkana people, among others, whose traditional livelihood strategy is nomadic pastoralism [
24,
25]. Accordingly, their primary diet comprises animal products like meat, milk, and blood. They derive plant-based vitamins and herbal medicines primarily from WEPs [
20,
26,
27]. Some communities have diversified their livelihood strategies into trade, such as the sale of
Aloe vera [
28,
29], honey harvesting [
25,
30], artisanal gold mining [
31], poultry keeping [
32], basket weaving [
33‐
35], hide processing [
36], local brewing [
37], fishing [
38,
39], and crop cultivation [
25,
40].
Of the 47 counties in Kenya, Turkana County has the highest poverty and malnutrition rates [
41]. Only 3.2% of its population hold food stocks that can last more than one month [
42]. Against the national poverty headcount rate of 36.1%, it has the highest poverty rate of 79.4% (about 80% of Turkana people are considered poor) [
42]. The county also has the highest food poverty rate at 66.1%, compared to the national average of 32% [
42]. With WEPs known to aid in food and nutritional security [
43], assessing their threats and management options could be a significant step in sustainably utilizing them in such a setting as Turkana County.
Turkana people have relied on locally constituted management methods like seasonal grazing (via migration with livestock) and clear designation grazing fields [
44]. These, however, could not be sufficient in countering contemporary threats, including those of anthropogenic climate change. Managing valuable resources such as WEPs for sustainable use is crucial to local communities. We define ‘sustainable use’ as the case when WEPs are harvested within the limits of their carrying capacity for self-renewal and the manner of harvest does not degrade the environment in other ways [
45].
We sought to understand the threats and management options that could aid the sustainable use of WEPs in northwestern Kenya. To achieve this, we used an integrated participatory approach to combine FGDs results with field plot surveys guided by three research questions: (i) Which threats do WEPs face in Turkana County, and how do they vary across different socioeconomic and environmental settings? (ii) How do indigenous communities’ perceptions of these threats compare with field survey results? (iii) What are possible effective management options and how do they differ across socioeconomic and environmental settings?
Discussion
We assessed threats facing priority woody WEPs from local community perspectives involving FGDs and field plot surveys in an integrated participatory approach. We also assessed management options with the potential to counter the adverse effects of these threats from the point of view of FGD participants. From the FGDs, we most importantly found climate change, invasive species, and overstocking/overgrazing to be among the highest-ranking threats facing WEPs in Turkana County. Our findings from the field plot surveys revealed that overstocking/overgrazing, selective harvesting/overharvesting, and invasive species were the top-ranking threats. Field plot surveys and FGD rankings of threats showed strong positive linear relationships. We found mitigation of climate change, preservation of local knowledge, and selection, propagation, processing, and marketing to be the highest-ranking management options for the priority woody WEPs.
Our FGDs and field observations results on threats correspond to those from similar studies conducted in southern Ethiopia that put agricultural land expansion, fuelwood collection, uncontrolled fire setting, overgrazing, and overharvesting as highly ranked threats to WEPs [
17,
63‐
65]. The different socioeconomic and environmental settings of the studied community units can explain the observed differences in the scoring of threats facing WEPs: For example, inhabitants of the three community units derived their livelihoods differently. While livestock keeping was predominant in Nasiger and Atala Kamusio, crop farming dominated in Lopur [
48]. The extensive irrigated croplands astride the banks of River Turkwel in Lopur partly explained why this community scored the threat of agricultural expansion highest. Efforts by the Kenyan government to expand agricultural land for irrigated crop farming since 2015 [
48] could jeopardize the future of WEPs in the region.
In terms of invasive species, although receiving average to high scores across the communities, no differences among the community units could be detected. The dominant invasive species in northwestern Kenya,
Prosopis juliflora [
66,
67], was perceived by all three community units as a threat to the priority woody WEPs. This species was highlighted by the FGDs as highly invasive, a fodder to livestock although known to destroy teeth of goats, and is used for charcoal to try and manage its spread. We also observed the species in the field surveys.
Climate change was perceived by the FGD participants in terms of a range of indicators that they experienced in the region (Additional file
1: Table s2). We acknowledge that these could be subjective and that structured scientific investigations could help reveal the extent of the impact of climate change or variability on WEPs in the region. WEPs have the potential to cushion a community against the negative impacts of climate change [
68‐
70], climate change can also threaten their sustainable use [
14,
64]. Further, overstocking/overgrazing could also inhibit optimal production of WEPs while at the same time inhibiting the regeneration potential as the seedlings or propagules get stampeded, overgrazed/overbrowsed [
71,
72].
Our results on the potential management options for priority woody WEPs indicated that mitigation of climate change, preservation of local knowledge about WEPs, and carrying out selection, propagation, processing, and marketing of WEPs in the region were perceived as plausible. While the communities called for documenting local knowledge about the WEPs and passing that knowledge to current generations, they also understood that climate change should be mitigated and that scientists could help in selecting WEPs, propagating them on a large scale, processing/improving on traditional preservation methods to add value, and availing them in the market for sustainable income generation.
Implementing management options such as mitigation of climate change [
73,
74], controlling harvesting [
75], establishing protected areas [
76‐
78], and nutritional and genetic profiling [
79] have been proposed to protect WEPs, and some places implemented with notable successes [
80,
81]. In particular, Feyssa [
81] in Ethiopia showed how important indigenous knowledge and its intergenerational transfer could aid the management and conservation of WEPs. Marketing has also been reported as a potential management strategy of WEPs elsewhere [
82] because communities that derive an income from the sale of fruits from WEPs will also consider them more valuable and worthy of conservation. Moreover, propagation and cultivation are also reported elsewhere as potential ways to use WEPs sustainably [
83‐
85].
In more recent work, Borelli [
86] emphasized the need for an integrated conservation approach to better manage WEPs. This would entail cooperation across sectors and diverse stakeholders in the WEP’s value chain(s). Indeed, we noted that local communities knew the threats facing their WEPs, as indicated by a strong positive linear correlation with our field plot survey scores, and should, accordingly, be integrated into the formulation of WEP management options. Their voice in the implementation of management options should be borne in mind by scientific communities and policymakers alike since they have used their management options to sustainably utilize their resources throughout history.
Among the possible management options mentioned by FGD participants, some could be implemented through local community initiatives, while others would require interventions from external bodies. For instance, the conservation of WEPs in sacred areas (cemeteries, churches, cultural gathering sites), controlling harvesting for food and fodder, cultivation of WEPs, regulation of charcoal burning, and preservation of local knowledge about WEPs could fit within local community action plans (personal communication from FGD participant). On the other hand, the assessment of nutritional value and toxicity, the establishment of protected areas, selection, propagation, processing, and marketing require external intervention but with local collaboration. Some measures, such as raising public awareness about the benefits of WEPs, mitigation of climate change, and monitoring and inventorying WEPs, can only be achieved by closely engaging with local communities, policymakers, and any actors attempting to influence the management of WEPs. Involving local communities in implementing any management option is imperative.
We understand that cost implications always play a big role in implementing any management options for threats facing biodiversity [
87]. However, it is beyond the scope of our study to address the question of cost implications in deploying any of the management options to ensure sustainability in the conservation efforts of WEPs. It is important to map the extent of potentially suitable habitats for the WEPs so that conservation and management options can be implemented site-specific. How future climate change scenarios might exacerbate the already existing threats would also be important to determine moving forward.
Even though these findings agreed well with most studies on threats to biodiversity across the region, it is important to note that the relative significance varied with environmental and socioeconomic gradients at local scales. Local differences in threats and management options are therefore worth considering in developing sustainable management solutions for WEPs to bring them back into dietary diversification programs sustainably [
14,
88].
Conclusion
Climate change, invasive species, and overstocking/overgrazing threaten the sustainable use of WEPs in Turkana County, Kenya. How threats are perceived to affect WEPs depends on socioeconomic and environmental gradients across communities. Our integrated participatory approach, combining local community perceptions and field plot assessments, revealed close links, but some threats were ranked strikingly differently across the three study community units.
Across all the study communities, the most plausible management options for the WEPs were mitigation of climate change, preservation of local knowledge, and selection, propagation, processing, and marketing. We propose a detailed cost–benefit analysis of the assessed management options, bringing on-board all stakeholders in the WEP value chain, which should be a prerequisite before conservation plans are implemented. It is also important to establish the extent of the suitable habitats of the WEPs. Such an overview could improve the success of conservation and management interventions.
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.