6.1. Diversity, use, and domestication strategies of plant species in association with cocoyam
The floristic diversity observed in cocoyam-based cropping systems in Benin, encompassing a total of 48 associated species, confirms the agroecological richness previously reported in traditional or integrated farming systems (Baudron, 2024). This diversity reflects the complex interactions among ecological factors, farming practices, and socio-economic dynamics. As highlighted by Esquivel et al. (2021) and Guinet et al. (2023), variability in agroecological contexts strongly influences the composition and structure of agroecosystems. Areas characterized by high rainfall and fertile soils tend to support greater species richness, while degraded or low-rainfall zones exhibit more limited floristic assemblages.
The dominance of Musa species in taro associations underscores their nutritional, economic, and cultural importance, as confirmed in several African studies (Akouègnon et al. 2014 ; Tchoma et al. 2020). Likewise, the strong representation of Fabaceae reflects their ecological plasticity and functional role in soil fertility—traits identified by Houéhanou et al. (2016) as key determinants of agroforestry sustainability. However, the association of taro with high-value forest trees (Vitellaria paradoxa, Khaya senegalensis, Parkia biglobosa, etc.) raises concerns about potential conflicts over land use in contexts of increasing pressure on woody resources (Camille 2021).
From a socio-economic perspective, agroforestry emerges as a critical lever for rural resilience by enhancing food security, income diversification, and economic stability (Schroth et al. 2011 ; Sagastuy & Kause 2019 ; Ruf 2018). Such systems facilitate adaptation to land degradation and climatic variability while promoting carbon sequestration and biodiversity conservation. The effectiveness of these practices, however, depends on contextual factors such as land availability, planting density, and canopy size, which influence competition and the productivity of associated crops (Yousefi et al. 2024).
The analysis of plant uses highlights the multifunctionality of associated species : leaves, wood, and fruits are the most exploited organs, primarily for medicinal, nutritional, and artisanal purposes (Agbodjento et al. 2023 ; van Noordwijk et al. 2022). These findings support those of Winara et al. (2022), who emphasized that plant diversity simultaneously contributes to household nutrition, health, and livelihoods. The predominance of medicinal uses, as previously noted by Talukdar et al. (2020) and Adjatin et al. (2012), underlines the central role of traditional knowledge in the local management and domestication of plant resources.
Analysis of domestication levels reveals a gradient of human intervention ranging from wild to fully cultivated species (Vodounhê et al. 2012). This diversity of statuses illustrates a progressive and adaptive domestication process shaped by local needs, resource availability, and the socio-cultural value of species (Gbedomon et al. 2017 ; Brown, 2018 ; Locqueville et al. 2023). The coexistence of wild and domesticated forms within the same agroecosystem confirms the pivotal role of smallholder practices in in situ biodiversity conservation (Adjatin et al. 2012 ; Salako et al. 2018).
However, the overexploitation of woody species and the growing pressure on plant resources may threaten ecological sustainability. As emphasized by Donovan (2017) and Turner-Skoff & Cavender (2019), the multiple benefits derived from trees may paradoxically encourage overuse, leading in some cases to the depletion or local disappearance of certain species (Nuenschwander et al. 2010). These results call for the implementation of sustainable management strategies and community-based conservation mechanisms integrating the ecological, economic, and cultural dimensions of domestication.
In summary, the diversity and structure of plant associations in taro-based systems reflect a dynamic balance between production, conservation, and the sustainable use of plant resources. Recognizing farmers’ knowledge and supporting local domestication initiatives appear to be key levers for strengthening agroecological resilience and food security in tropical contexts.
6.2. Prioritization of species in association with cocoyam
In recent years, increasing attention has been devoted to the conservation and prioritization of wild plant species in Benin. Previous studies have focused on non-timber forest products (Vodouhê et al. 2009), wild edible plants (N’Danikou et al. 2011), crop wild relatives (Idohou et al. 2013), neglected and underutilized species (Dansi et al. 2012), and woody species. However, none have specifically addressed plant species associated with cocoyam (Colocasia esculenta) cultivation. Conservation measures targeting these associated species are essential to ensure their long-term availability in cocoyam-producing agroecological zones. Given the increasing threats posed by human activities, land-use change, and environmental degradation, enhancing the sustainability and effectiveness of conservation actions is urgent, as species currently considered of low concern may become highly threatened in the near future (Agbani et al. 2018).
In this study, we applied the prioritization framework developed by Brehm et al. (2010) and successfully implemented by Idohou et al. (2012) to identify cocoyam-associated species requiring conservation attention across different agroecological zones. Twelve priority species were identified and ranked by importance : Vitellaria paradoxa, Morinda lucida, Khaya senegalensis, Parkia biglobosa, Albizia zygia, Rauvolfia vomitoria, Anogeissus leiocarpa, Sarcocephalus latifolius, Vitex doniana, Cola nitida, Caesalpinia bonduc, and Newbouldia laevis. These species were subsequently assessed for domestication and conservation potential.
According to Abessika et al. (2024), V. paradoxa and K. senegalensis face high and continuous exploitation pressures due to the demand for shea butter and khaya wood, limiting their natural regeneration. Both species are widely recognized as conservation priorities in West Africa (Vodouhê et al. 2011 ; Sop et al. 2013 ; Assogbadjo et al. 2012 ; Lokonon et al. 2019 ; Hounsou-Dindin et al. 2022) and are listed as Vulnerable on the IUCN Red List for Benin (Adomou et al. 2011). P. biglobosa is similarly threatened by habitat loss and poor regeneration resulting from agricultural expansion and deforestation (Boffa, 1999), despite its recognized importance in traditional agroforestry systems (Sopkon, 1999 ; Yabi et al. 2013).
Medicinal species such as M. lucida and R. vomitoria are subject to intense harvesting, which hampers their development and regeneration (Laila, 2019). Likewise, A. leiocarpa and A. zygia are considered vulnerable due to overexploitation, habitat degradation, and the high value of their timber, with unsustainable harvesting exceeding reforestation efforts (Ouédraogo et al. 2017 ; Kouassi et al. 2018). C. nitida and N. laevis are overharvested for their medicinal and ritual significance, while V. doniana suffers from excessive harvesting of its leaves, fruits, and wood, limiting regeneration (N’Danikou et al. 2015). Although C. bonduc and S. latifolius currently show greater adaptability to tropical environments, continued exploitation could eventually endanger these species.
These findings highlight the need for strategies that promote both the development and protection of these valuable indigenous resources to prevent further biodiversity loss. Species prioritization revealed a tendency among farmers to favor multipurpose species, particularly those associated with cocoyam cultivation, as they meet multiple subsistence needs. Farmers generally value species offering several uses because they maximize returns on labor invested in resource collection. As the abundance of high-value plants increases, less-valued species tend to be neglected (Gaoue et al. 2017). Similar patterns have been reported in Mali (Faye et al. 2010), Togo (Padakale et al. 2015), and Tanzania (Wagner et al. 2019), where preferred agroforestry species provide multiple products and services, contributing significantly to household income. Farmers’ preferences, however, often vary with social class and farming experience (Moore et al. 2014).
There is no single standardized method for developing conservation priority lists, as each approach depends on its specific objectives. The framework used in this study is methodologically flexible and integrates multiple ecological and socio-economic criteria. Unlike approaches applied by Teso et al. (2012), Crespo (2016), and Khoury et al. (2013) in Spain, Venezuela, and the United States, respectively, it requires substantial data and time due to its complexity and the variety of indicators considered. Moreover, data scarcity for many wild and underutilized species remains a limiting factor.
The results derived from this method may not fully reflect local perceptions of conservation priorities, as scientific assessments often differ from community-based evaluations. Such discrepancies can undermine the acceptance and effectiveness of conservation measures (N’Danikou et al. 2011). To address this gap, it is essential to integrate local knowledge systematically into the prioritization process through participatory approaches that combine scientific and community perspectives. This inclusive strategy can produce co-constructed priority lists, strengthen local ownership of conservation initiatives, and enhance the long-term sustainability of implemented actions.