1. Introduction
In the last four decades, agroforestry has been promoted as an option to address poverty and food insecurity, as well as to enhance the adaptability of small-scale farmers to social-ecological hazards [
1,
2,
3,
4,
5]. For the former, its potential relies on its contribution to the strengthening of the five pillars of food and nutrition security (FNS): availability, access, utilization, stability, and sovereignty (
Figure 1). Examples in local contexts are: (i) the presence of perennial staple food species in the system, like
Ensete ventricosum,
Musa spp.,
Moringa stenopetala, or
Manihot esculenta, which ensure the availability of food [
6,
7,
8,
9]; (ii) the presence of species that secure cash to farming households, which directly enhance their access to market-based foods, as is the case of
Coffea arabica or
Theobroma cacao [
10,
11]; (iii) the utilization of dimension often enhanced via a diversity of species that offer scarce nutrients, e.g., fruit, leaves, or nuts, as well as the availability of fuel for cooking [
11,
12]; (iv) an increase in the resilience to and reduction in household social-ecological vulnerability, by the diversity of constituting species and their interactions [
5,
10,
11]; and (v) providing options and choices in the means to grow and/or purchase foods items according to the household’s needs in all seasons [
9,
13,
14].
Agroforestry practices (AFPs) vary in their composition, structure, and function, depending on the biophysical, ecological, social, economic, and cultural conditions under which they occur. Hence, taking into account this site-specificity is key before attempting any upscaling. Mbow et al. [
5] emphasized that although agroforestry has a considerable potential to improve food security, ‘’…not all agroforestry options are viable everywhere”. Therefore, before recommending or promoting any agroforestry practice for a certain place or community, it is crucial to characterize and recognize its features, attributes, and performance in view of intra- and inter-year variability.
In Ethiopia, a wide variety of local/traditional AFPs exist, with potential to contribute to the FNS security of the practitioner communities. Different forms of homegardens are reported across the country [
15,
16,
17,
18]. Croplands with scattered trees of
Faidherbia albida are the oldest form of indigenous agroforestry parklands, omnipresent in central and eastern Ethiopia [
4,
19,
20]. The Enset-Coffee gardens,
Coffea arabica planted intermingled with
Enset ventricosum, practiced by the Gedeo people, are well-known to support millions of livelihoods in the most densely populated areas of the country [
15,
21]. The traditional coffee system dominated AFPs in southwestern Ethiopia are a further example of a well-established traditional AFP [
22]. In Yayu, 60 to 80% of rural households rely on these AFPs as the main source of their livelihood [
23]; the area was considered food secure in the last 15 years, despite an increasing human population [
24,
25,
26,
27,
28,
29]. In spite of the potential of the local AFPs to contribute toward FNS, empirical data on this topic are scarce.
For instance, during the last two decades, almost all studies conducted in Yayu mostly focused on the ecology, biodiversity, and conservation of traditional coffee systems [
30,
31,
32,
33,
34,
35,
36], giving lesser attention to their potential for food and nutrient provision to local communities. Therefore, this study aimed to explore the potential of local AFPs of Yayu to contribute to the FNS of rural households. Specific objectives of the study were: (1) the identification of predominant AFPs and their purpose; (2) the plant species composition of each practice; (3) the ethnobotanical knowledge of uses of the various species encountered; and (4) their respective potential for food provision and cash acquisition, as steps towards (5) an appraisal of the five pillars of food security.
4. Discussion
4.1. Agroforestry Practices and Purposes
The three major AFPs, i.e., HG, MCS, and MTF, have their own primary production purposes and specific management, which enable smallholder farm households to diversify their production across the year. Hence, all three are important for sustaining the livelihoods of farmers in Yayu. This was confirmed by the fact that more than 80% of the households in Yayu practice all three agroforestry systems.
However, each practice plays a predominant role. MCS is mainly used to generate money and, for the majority of households, is the main, if not the only, source of cash. Most farmers use MTF to produce food, and HG is used for both a source of food and cash to supplement the other two practices. In the absence of either one or two practices, the importance of HG increases, becoming the main source of food and/or income. Similar findings were obtained by Kebebew and Urgessa [
52] in the Jimma area, southwestern Ethiopia.
Besides these, each AFP provides other benefits. This is especially true in the case of HG, as management practices tend to encourage the production of useful by-products such as fuel, fodder, and timber. Contrarily, MCS and MTF have rather specific purposes, and activities not directly contributing to yield maximization, as in the case of MCS, are discouraged [
38].
In the three AFPs, gender roles differ. Women are mostly in charge of the management and utilization of HG, securing the annual food provision and supplementary cash for the household [
40,
53,
54]. In contrast, the management and benefits of MCS and MTF are mostly controlled by males—generally heads of the households [
53,
55].
4.2. Predominant Species Composition
The highest number of species was found in HG, followed by MCS and MTF. Only 19% of the identified species were found in all practices, and 52% occurred in only one of the three AFP. So, species distribution is practice/system-specific. The number of species in HG is similar to values reported in other studies [
15,
16,
18,
56].
Regarding growth habits, as expected, perennial species were dominant but also shrubs were common, although fewer in MCS and MTF due to the regular clearings carried out to prevent competition.
Concerning the species diversity, based on their origin, about 70% of the species identified were native, confirming that the Yayu area is naturally endowed with high biodiversity [
39]. A higher number of exotic species were observed in HG, followed by MTF and MCS. This confirms that coffee forest production (MCS) is more environmentally friendly than the other two practices. This finding validates those of Muleta et al. [
38] and Gole et al. [
22], who observed that local communities exert their experience in managing the naturally grown coffee for commercial purposes. Nevertheless, there is a remarkable dominance of individual species, especially in MCS and MTF, by
Coffea arabica and
Zea mays, respectively. The dominance of
Zea mays in MTF is consistent with similar reports from the Koga watershed in northwestern Ethiopia [
57]. In contrast, the species frequency distribution in HG is rather flat, as the HG approach has multiple production objectives, i.e., stimulants, fruits, vegetables, roots and tubers, and timber. However, Kebebew and Urgessa [
52] reported that fruit trees were a dominant group of species in HG of Jimma.
4.3. Species Uses and Services
All three practices provide additional uses and services besides food. HG was found to be the most versatile, as it delivers 10 different groups of uses and services. Similar values were observed in Abebe [
8], Senbeta et al. [
39], and Méndez [
46]. The types of uses and services by practice were cross-analyzed, e.g., food uses in HG were inversely correlated with the MTF size, i.e., as the size of MTF increases, the number of food crops in HG plots decreases (
Table A1,
Appendix A). According to the local farmers, this relation is common in the area because those households who produce a sufficiently large amount of cereals from their MTF are less interested in using their HG for growing food. Similarly, the production of ‘stimulants’, specifically
Coffea arabica, in HG, decreases as the households have larger MCS plots (
Table A1,
Appendix A). Both cases show the complementarity that exists among the AFPs of Yayu.
Most uses and services except ‘food’, ‘spices, condiments, and other food and beverage additives’, and ‘shade trees for coffee’ were provided by all AFPs. Local farmers confirmed that ‘fuel’ is mainly a by-product of MCS pruning, weeding, thinning, and clearing. Meanwhile, in HG-specific species, such as
Vernonia amygdalina, are cultivated solely for the production of fuel. The situation is similar with regard to ‘fodder’, where multipurpose trees supplement the hay obtained from the communal grazing lands [
40,
55].
On the other hand, some uses and services are limited to specific practices. For instance, ‘shade trees for coffee’ was observed only in MCS and HG, as
Coffea arabica is hardly present in MTF. Similarly, ‘other services’ such as live fences and hedges are more important for MTF and HG than for MCS, as was reported for the area by Etissa et al. [
56].
4.4. Food Production Potential
MTF and HG were found to be the main food-supplying practices. The number of all edible species identified (80) was considerably higher than in other areas with a similar ecological profile in Ethiopia, e.g., 23 by Senbeta et al. [
39] in Yayu, 59 by Abebe [
58] in HG of Sidama. However, differently from these studies, which considered only native species, the present study included both native and exotic species.
HG has the larger share of active foods species (82.5%) compared to 1.5% in MCS and 20% in MTF. The dominant active food species in MTF are
Zea mays,
Sorghum bicolor,
Eleusine coracana, and
Eragrostis tef, which are ingredients of the traditional food
Enjera (main source of carbohydrates). Other second-order species are
Vicia faba and
Pisum sativum, which are leguminous providers of protein. Similar values were observed in the Jimma zone [
52] and the upper Blue Nile basin [
57].
Noticeable is the low supply of staple foods by MTF during the ‘food gap’, the window of time between seasons. This is generally filled with food cultivated in HG [
40,
53], including species such as
Ensete ventricosum, which is available throughout the year [
6,
7,
8,
59], and
Colocasia antiquorum,
Dioscoreaal alta, and
Solanum tuberosum, which are available during the ‘food gap’ specifically, and are complemented by leafy vegetables such as
Brassica oleraceae spp. and
Brassica carinata [
40,
55,
60,
61].
Concerning the presence of ‘active-foods’, MTF is dominated by cereals but lacks vegetables and fruits, which are mostly provided by HG, endowed by a broader diversity of active food species from different food groups, e.g., Carica papaya, Prunus persica, Daucus carot, Cucurbita pepo, Capsicum frutescens, Brassica oleracea, Brassica carinata, etc., which are also key sources of micronutrients.
4.5. Income Generation Potential
Household economic capability to acquire food in the market is key for the food access pillar [
62,
63]. As shown, 95% of the monetary income in Yayu comes from selling
Coffea arabica harvested from MCS. This cash is used not only to buy food but also to cover other expenditures [
40,
54].
However, this high dependency on
Coffea arabica creates a concomitant cash shortage. Alternatively, HG provides a diversity of merchantable products, e.g., dairy products, fruit, livestock, spices, and even other cash crops that are sold throughout the year, but especially during that ‘cash gap’. The findings of Etissa et al. [
56] confirmed this. Similarly, in MTF, with
Catha edulis being harvested several times throughout the year, can generate a continuous flow of cash, and in the case of annual crops, whenever surplus is achieved it may also be sold. An interesting paradox occurs with
Eragrostis tef, the most valued staple, which sometimes is sold to buy cheaper staples like
Zea mays and
Sorghum bicolor.
Regarding the species richness of each marketability category, most species cultivated in HG, such as Catha edulis, Musa paradisiaca, Mangifera indica, and Rhamnus prinoides, were actively sold in the area. Contrastingly, MCS and MTF were dominated by non-marketable tree species in number but not in area. This is likely due to the priority given to Coffea arabica in MCS, and to annual crops such as Zea mays and Sorghum bicolor in MTF. In general, the non-marketed species exceeded the marketable categories, suggesting a potential of improvement via conservation, transformation, and/or marketing.
4.6. Relationships among Household and Agroforestry Attributes
The correlation analysis conducted between attributes of the household and agroforestry practices (see
Table A1,
Appendix A) disclosed that altitude and proximity to market are the two most important household attributes, which influencing the species composition and richness of a given AFP in Yayu. As the traditional coffee production system causes minimum damage on the existing vegetation and as it exists in a biosphere reserve, the residual influence of the original vegetation on the current species composition of AFPs was expected. The original vegetation is mainly a result of the local topography and ecological factors. These results agree with those of Addi et al. [
64], who focused on the correlation of natural vegetation composition and altitude in southwestern Ethiopia, and those of Bajigo et al. [
17], who observed a similar association of altitude with woody species diversity in HG of the Wolayita zone.
Similarly, the market has a considerable influence on the type of species grown and their purpose of management under each AFP of Yayu. For instance, in Yayu, households located near to the market had better species richness than those farther away. In facts, both negative and positive influences of the market on different traits of AFPs have been reported. For instance, in line with the present study, the authors of Reference [
8] reported a positive correlation between the species richness of agroforestry plots and proximity to markets in the Sidama zone in Ethiopia. In contrast, Reference [
65], studying HG diversity in Indonesia, revealed that HG near to markets tended to be dominated by a few commercial crops. In Yayu, the major reason for the higher species richness in HG near to markets may be the dominance that
Coffea arabica already has on MCS, while the others are purposefully managed to meet household and market demands.
Gender also correlates with the richness of some species groups, depending on the purpose of management, plot location, and labor demand of the species. For example, cultivating legumes and cereals in MTF plots requires higher cropping and guarding labor, which the female-headed households often lack. According to the local people, the females in those households are often widows or divorced mothers. These avoid labor-demanding crops in their MTF plots and convert a share to cash-generating tree species such as
Eucalyptus grandis and give the rest to sharecroppers [
53]. On the other hand, the HG plots of female-headed households were rich in food groups such as vitamin A-rich dark green vegetables and tuber and root crops, which are of great importance for the food security of these households during shortage times. A study conducted on the driving forces of changes in the structure of traditional HG agroforestry of southern Ethiopia reported a more significant relation between women and food crops than between women and cash crops grown in HG [
66].
In general, the migrant and resettled households had AFP plots that were less rich in native useful species, including edible ones, than the native households, except for the actively-marketed species. This because they have relatively less knowledge about the type and uses of native plant species. According to the local people, the resettled households change the species of their AFP into merchantable exotic species more frequently than the natives. This implies that the impact of migration has a considerable impact on the environment, especially on non-marketable species. Lemenih et al. [
67] confirmed the negative relationship between migration and environmental management as a lack of formal or informal structure and poor social capital with respect to the native environment.
4.7. The Five Pillars of Food Security
This study demonstrated that each AFP has considerable potential, but differentiated contribution toward the five pillars of FNS of small farming households of Yayu. MTF primarily contributes to the ‘availability’ pillar by serving as the main supply of the annual food. MCS is solely to contributor to the ‘access’ pillar by generating the annual cash the household uses to purchase food and other food-related inputs from the market. The HG plots of smallholders usually are used to fill the seasonal and unexpected food and cash supply gaps by producing crops with different harvesting seasons, which ultimately enhance the stability of the above two pillars. Furthermore, the diversity in all three AFPs plays an important role for the ‘utilization’ pillar by providing fruits, vegetables, fuel, and fodder, which ultimately increases the access of the household to diverse and healthy foods. The final pillar, ‘sovereignty’, is mainly assured by the HG as its management and selling of products are mostly controlled by the female family members, who manage the type of food prepared for the household.
5. Conclusions
Yayu agroforestry practices (AFPs) constitute a remarkable case study concerning potential local-based efforts to improve food and nutrition security (FNS). The local farmers use three different AFPs, namely homegarden (HG), multistorey-coffee-system (MCS), and multipurpose-trees on-farmland (MTF), with different spatial and temporal arrangements, structures, and compositions. Each has a main purpose, i.e., MTF for food production, MCS for cash generation, and HG for both. Inter- and intra-practice variations exist with respect to species composition and utilization. Making the best use of their differences, farmers manage and utilize these practices in a synchronized way to sustain their livelihoods.
Based on the correlation analysis, it is concluded that the species composition, structure, and mode of utilization of a given AFP in Yayu is a function of household attributes such as elevation, proximity to market, gender, and settlement history.
This study also acknowledges the existence of a knowledge gap regarding the detailed contributions of AFPs to the current FNS of smallholder farm households in Yayu. Thus, empirical research should assess the FNS status of smallholder farm households to relate this with the observed attributes of each AFP. As shown, the Yayu area is endowed with untapped resources of edible and marketable plants, whose contributions should be explored in depth, particularly of those within local AFPs, toward the enhancement of FNS as well as the living standards of smallholder farm households of Yayu and other similar areas.