Ecosystem restoration remains high on development agendas worldwide. In the Sahel, including Senegal, knowledge gaps remain on how the underlying policy and regulations for rights and ownership influence farmers' incentives for upscaling land restoration. We contribute to filling these gaps by i) analysing agroforestry related policy and regulations, and ii) assessing key stakeholders (foresters, animators, and farmers) perceptions in Kaffrine, Kaolack and Fatick regions using semi-structured interviews. The results show that tree rights and use procedures are determined by the Forestry Code and vary according to the status and location of the tree. However, the Forestry Code was found to be inappropriate for managing agroforestry systems where farmer managed natural regeneration (FMNR) is practiced, hence creating barriers to its adoption. Contrasting perceptions and potential solutions emerged. While the field animators and farmers find the tree use procedures burdensome and constraining for the practice of FMNR, most foresters find them not burdensome and appropriate for environmental protection. As solutions, animators and foresters suggest farmers' sensitization, capacity building, and rewards, whereas the farmers call for an easing of tree use procedures and a reduction of taxes and permit fees. These results suggest farmer-centric and inclusive policy reform of tree rights in Senegal.

Tamarindus indica is a priority local forest food tree in the Sahel. It is an important source of income for many rural families. It is still in the wild, apart from a few specimens of the accessions recently introduced into the landscape of Sahelian villages. The objective of the present study is to investigate the performance and efficiency of three accession grafts and the effect of grafting to shorten the juvenal growth and fruiting periods for improving woody species diversity in agroforestry parklands and diversifying the sources of income of small producers. The design was a randomized complete block with 5 replications. Each block was composed of 5 grafts of three accessions (Niger 309, TB3, Sweet Thailand) and 5 seedlings propagated from wild tree seeds. Growth parameters (height, collar diameter, canopy width and primary branch number) were measured on all plants. The evaluation of fruiting potential was made on 5 plants of each accession in the first year and 10 plants in the second year. Cost–benefit analysis were carried out to assess the financial viability and economic profitability of planting these accessions of T. indica. The results show that Sweet Thailand accession had the best growth performance compared to Niger 309 and TB3. Fruiting of the three accession grafts started in the second year after planting, in contrast to seedlings which started to bear fruit from the fourth year. TB3 grafts had higher average fruit production in 2017 and 2018 (120 and 640 kg ha−1, respectively). The cost–benefit analysis shows that planting of the three accession grafts is financially viable and economically profitable. The results of the present study indicated that planting these three accessions might play an important role in food security, the resilience of small-scale farmers and the improvement of biodiversity in the landscape.

Description of the subject. We present a literature overview of innovation platform practices in Africa, combined with case studies of sub-national platforms established in Senegal and Burkina Faso. Objectives. The main objective was to understand how the facilitation process of innovation platforms can become more effective. Two specific objectives were to study RAMSES II innovation platform cases in Senegal and Burkina Faso where we observed and reflect on the facilitation of agroforestry innovation platforms. A final objective was to position the case results in a literature overview of IP experiences in Africa. Method. Information on innovation platforms was collected by combining an analysis of RAMSES II agroforestry innovation platform cases and an innovation platform literature review. Results. The study illustrates how the organizational position of the facilitating research agents contributed to shaping platform agendas, functions, and outcomes. This process hinges on the deployment of legitimacy claims, which appeal to technical expertise and scientific narratives, in this case on agroforestry. Institutional embeddedness is shown to be a critical aspect of agency in innovation platform multi-actor processes, contributing to framing local understandings of agroforestry and to channel collective efforts. Conclusions. The institutional identity of facilitating research agents and their relationship to members of a platform requires a more open and process oriented role. Coordination and facilitation roles can also be taken up by other members of the platform. This enhances the platform’s ability to ground their agendas into local needs and priorities. It also enhances sustainability, as active membership during the project period prepares platform members to continue after project closure.

Correct timing of phenology is crucial for the survival and growth of species in arid areas with long dry seasons. Nevertheless, knowledge on genetic variation and adaptive patterns in phenology in deciduous African dryland species is limited. Here we study the variation in phenology of diploid and polypoid A. senegal trees from rangewide populations growing in a common garden trial in Senegal and test correlations between population phenology and climate at the site of origin. The leafing, flowering and fruiting phenology was monitored during 17 months and compared to detailed observations of the rainfall in the common garden during the period. We found that A. senegal trees in general started development of leaves prior to the beginning of the rainy season with flowering and fruiting initiation occurring during the rainy season. The results lead us to conclude that is was not the rain per se that initiated leaf development. We also conclude that phenology in A. senegal is under genetic control, because significant differences could be observed among populations and ploidy levels when grown at the same site. In general, early leaf flushing trees had a longer growing period and performed better in terms of growth at the tested site and the results thus support that leaf phenology influence fitness. We further found that differences among trees in phenology seem to be associated with differences in climate at their site of origin, because the timing of leaf development in the common garden and the timing of the rainy season at the site of origin was significantly correlated for the diploid trees (not for tetraploids). However, it was diploid trees from sites with a late arriving rainy season that developed leaves earliest in the year. The environmental cues that control leafing phenology and the associated physiological mechanisms therefore still need to be identified in order to understand how the variation among populations has evolved, its relationship to local adaptation and the implication for smart transfer of seed sources as mean to mitigate changing growing conditions related to global warming.

The beneficial effect of Faidherbia albida on the yield of certain associated crops has been demonstrated for long and is often characterized by a distance-decay pattern. While several approaches have tested the spatial extent assessment of tree influence, none of them has been designed either to capture the directional variations or to address the park effect at the landscape scale. Recently, Roupsard et al. (2020) proposed an approach based on multispectral (MS) UAV (Unmanned Aerial Vehicle) imagery and geostatistics to bridge this gap. In the present study, we extended their study by proposing a new application of their approach to groundnut crop and validation for millet crop. In addition, we tested improvements of the method, using several MS images along the crop cycle. In a typical F. albida parkland (Niakhar, Senegal), groundnut and millet under-crops of agroforestry plots of approximately 1-ha and 2-ha respectively, have been harvested. On each plot, groundnut and millet traits were measured at three different positions from six F. albida trees (under crown "S"; crown edge "B" and far from the crown "H"). We found that F. albida improves the haulm yield of the groundnut crops under its crown by about 50%. However, unlike its strong effect on millet, it does not significantly affect the groundnut pod yield. Through geostatistical analysis of multi-spectral, centimetric-resolution images obtained from the UAV flights carried out during the wet season, we observed that F. albida affects the groundnut NDVI signal up to 9.8-m and the NDVI of millet up to 18-m. We found statistically significant, positive correlations between groundnut pod yield and MSAVI2, NDVI (r2 = 0.73; RMSE = 9.8) first, and between groundnut haulm yield and MSAVI2 (r2 = 0.85; RMSE = 5.81). For millet, the multiple linear regression model is able to explain 74% of the millet yield variability (RMSE=20.48) using millet+weed MSAVI2 and NDVI. We used the regression model to upscale groundnut pod and haulm yield maps at the whole-plot scale. Compared with groundtruth, the error was only by 8% and 13% for groundnut pod and haulm yield, respectively. Using a geostatistical proxy for the sole crop, the crop-partial Land Equivalent Ratio (LERcp) was estimated at 1.02 for pod yield and 1.05 for haulm yield.

Droughts are extreme events that have major impacts on communities, ecosystems and economies due to slow onset and complex processes. Land and ecosystem degradation increase the risks of loss and damage during droughts, whereas well-adapted practices and policies can enable society to (re)build resilience. This review highlights actions needed to connect and fill gaps in the present systems for ecological and hydrological monitoring, governance, and alignment of economic incentives at regional, national and local scales. Stopping the slow-burning fuse of drought damage requires improved tracking and reversal of the observable slow-onset nature of hydrological and socio-economic drought. International scientific and technical cooperation to better map and quantify changing loss and damage risks could provide evidence-based action triggers.

Arbuscular mycorrhizal (AM) fungi constitute promising biofertilizers for the deployment of a sustainable agriculture. However, the evaluation of mycorrhizal benefits in the field is poorly documented, notably in fruit tree orchards, and concerns exclusively growth performance and nutrition. Here, we evaluated the persistence of beneficial effects of AM fungal inoculation on two jujube (Ziziphus mauritiana Lam.) cultivars (Tasset and Gola) inoculated in nursery conditions and subsequently transferred in the field until fruit production. The growth-promoting effects on jujube observed in nursery was still maintained 18 months after planting, with significant higher rates of survival and an increase of fruit production for inoculated jujube cultivars. Nevertheless, AM-mediated responses were dependent on cultivar. No major disturbance of native AM fungal community was associated with AM fungal inoculation but a stimulation of AM fungal colonization is probable. The use of mycorrhizal inoculation with the R. irregularis IR27 strain hold promise for the development of efficient jujube orchards under semi-arid conditions.

Farmer Managed Natural Regeneration (FMNR) is a simple and inexpensive practice for restoring vegetation cover on degraded land, unlike reforestation. Current knowledge on the socioeconomic factors that may influence its adoption is limited. The objective of this study is to analyze the socioeconomic determinants of FMNR adoption by communities. 197 households were surveyed. The probit model was used to identify the socioeconomic determinants of adoption. The results show that ethnicity, access to external support, receptivity to technological innovations, mode of land acquisition and the importance of production are determining factors in the adoption of FMNR. According to farmers, FMNR contributes to improving soil fertility and soil moisture conservation (21% and 17% of farmers, respectively). According to them, the FMNR improves the supply of wood (18 %) and non-timber forest products (13 %). The main constraints to the scaling up of this practice are, respectively, illegal logging (42%), animal roaming (29%), and the difficulties of using animal traction in a farm having many trees/shrubs (12 %). These results provide an overview of the considerations to be integrated for the success of FMNR as a strategy to strengthen the resilience of communities and ecosystems to climate disturbances.

Leaf morphology, total leaf nitrogen (N) content and carbon and nitrogen isotope ratios of Acacia senegal trees vary among ploidy levels and geographic origins. Leaf morphology was significantly correlated with carbon isotope composition (δ13C) among diploid trees, while a significant correlation was observed with nitrogen isotope composition (δ15N) among tetraploid trees. Leaf morphology and ploidy level can influence plants' ability to adapt to climatic conditions. Here we study Acacia senegal that has multiple ploidy levels and grows across a geographic range of mainly dry environments. We test if and how ploidy level and climate at the site of origin influence leaf shape and ratios of stable carbon and nitrogen isotopes of A. senegal. The study is based on leaves collected from 225 A. senegal trees representing 16 populations across the species range, grown in a common garden trial in Senegal. Leaf morphological parameters were measured, and ploidy level, total leaf nitrogen (N), carbon isotope ratios (δ13C) and nitrogen isotope ratios (δ15N) were determined. Three levels of ploidy were found, namely diploid, triploid and tetraploid, but at highly different frequencies among the 16 origins. Leaf morphology varied significantly among both geographic origins and ploidy levels, with especially triploid trees having distinct leaf shapes. Tetraploids displayed high δ13C and low δ15N values compared to diploids. For diploids, leaf length and number of leaflets were correlated with precipitation and latitude, respectively. Leaf morphology and isotopic discrimination in A. senegal vary according to ploidy level and geographic origin. Our analysis suggests that the differences likely reflect adaptation to different environments, but the patterns tend to differ between diploids and tetraploids.

The trees in agroforestry plots create spatial heterogeneity of high interest for adaptation, mitigation, and the provision of ecosystem services. But to what distance, exactly, from the tree? We tested a novel approach, based upon geostatistics and Unmanned Aerial Vehicle (UAV) sensing, to infer the distance at which a single agroforestry tree affects the surrounding under-crop, to map yield, litter (i.e. stover) and compute crop-partial Land Equivalent Ratio (LERcp) at the whole-plot level. In an agro-silvo-pastoral parkland of semi-arid western Africa dominated by the multi-purpose tree Faidherbia albida, we harvested the pearl-millet under-crop at the whole-plot scale (ca. 1 ha) and also in subplot transects, at three distances from the trunks. We observed that the yield was three times higher below the tree crown (135.6 g m(-2)) than at a distance of five tree-crown radii from the trunk (47.7 g m(-2)). Through geostatistical analysis of multi-spectral, centimetric-resolution images obtained from an UAV overflight of the entire plot, we determined that the 'Range' parameter of the semi-variogram (assumed to be the distance of influence of the trees on the Normalized difference vegetation index (NDVI)) was 17 m. We correlated the yield (r(2) = 0.41; RRMSE = 48 %) and litter production (r(2) = 0.46; RRMSE = 35 %) in subplots with NDVI, and generated yield and litter maps at the whole-plot scale. The measured whole-plot yield (0.73 t ha(-1)) differed from the one estimated via the UAV mapping by only 20 %, thereby validating the overall approach. The litter was estimated similarly at 1.05 tC ha(-1) yr(-1) and mapped. Using a geostatistical proxy for the sole crop, LERcp was estimated 1.16, despite the low tree density. This new method to handle heterogeneity in agroforestry systems is a first application. We also propose strategies for extension to the landscape level.

Opuntia tuna est une espèce bien adaptée dans la zone des Niayes au Sénégal. Sa prolifération assez rapide est due en partie à une sous exploitation suscitant ainsi un envahissement de quelques espaces agropastoraux. Dans une perspective de valorisation et de meilleure gestion de l’espèce, cette présente étude a été conduite pour comprendre les formes d’usages et de gestion de la plante par les populations locales afin de la promouvoir pour renforcer leur résilience. L’étude a porté sur cinq villages de la zone nord des Niayes auprès de petits exploitants de maraichers. Des enquêtes qualitatives par entretiens et groupes de discussion ont été conduites. Elles ont porté sur le niveau de connaissance, les pratiques et usages connus du cactus, les contraintes liées à sa présence, les solutions adoptées ou envisagées et le niveau de perception sur sa valorisation. Les résultats ont révélé de nombreux usages de la plante et de ses produits. Plus de la moitié des personnes enquêtées utilise le cactus dans le domaine agricole. L’élevage, la pharmacopée et l’alimentation sont d’autres secteurs également concernés par l’usage du cactus. Les analyses ont montré que la plupart des personnes enquêtées (94%) admettent un degré d’envahissement très élevé de Opuntia tuna. Le niveau d’envahissement pourrait être liée à la zoochorie selon 38% des hommes et 33% des femmes. La bonne adaptation de l’espèce dans la zone serait également un facteur de prolifération selon 33% des hommes et 23 % des femmes. Afin de pallier la prolifération rapide du cactus les maraichers ont développé des stratégies de gestion telles que le brulis, la coupe et le dessouchage. Une meilleure gestion de cette espèce qui présente de nombreux usages pour les maraichers de la zone des Niayes est nécessaire. De tels usages de l’espèce, valorisés davantage pourrait contribuer de façon significative à la diversification des sources de revenus des communautés locales et au développement durable de la zone des Niayes.

Agro-silvo-pastoralism is a highly representative Land Use in Africa, often presented as a strategical option for ecological intensification of cropping systems towards food security and sovereignty. We set up a new long-term observatory (“Faidherbia-Flux”) to monitor and model microclimate, energy and C balance in Niakhar (central Senegal, rainfall ~ 500 mm), dominated by the multipurpose tree Faidherbia albida (12.5 m high; 7 tree ha-1; 5% canopy cover). Faidherbia is an attractive agroforestry tree species in order to partition fluxes, given that it is on leaf during the dry season (October-June) and defoliated during the wet season, just when crops take over. Pearl-millet and groundnut crops were conducted during the wet season, following annual rotation in a complex mixed mosaic of ca. 1 ha fields. Early 2018, we installed an eddy-covariance (EC) tower above the whole mosaic (EC1: 20 m high). A second EC system was displayed above the crop (EC2: 4.5 m if pearl-millet, 2.5 m if groundnut) in order to partition ecosystem EC fluxes between tree layer and crop+soil layers. Sap-flow was monitored from April 2019 onwards in 5 faidherbia trees (37 sensors). The ecosystem displayed moderate but significant daily CO2 and H2O fluxes during the dry season, when faidherbia (low canopy cover) was in leaf and the soil was evaporating. At the onset of the rainy season, the soil bursted a large amount of CO2. Just after the growth of pearl-millet in 2018, CO2 uptake by photosynthesis increased dramatically. However, this was largely compensated by high ecosystem respiration. Surprisingly in 2019, although the crop was turned to groundnut, the fluxes behaved pretty much the same as with pearl millet in 2018: comparing annual balances between 2018 and 2019 we obtained [454, 513] for rainfall (P: mm yr-1), [3500, 3486] for potential evapotranspiration (ETo: mm yr-1), [0.13, 0.15] for P/ETo, [470, 497] for actual evapotranspiration (E: mm yr-1), [2809, 2785] for net radiation (Rn: MJ m-2 yr-1), [1686, 1645] for sensible heat flux (H: MJ m-2 yr-1), [-3.2, -2.8] for net ecosystem exchange of C (NEE: tC ha-1 yr-1), [-11.8, -11.1] for gross primary productivity (GPP: tC ha-1 yr-1) and [8.6, 8.3] for ecosystem respiration (Re: tC ha-1 yr-1). The energy balance (Rn-H-LE) was nearly nil indicating that the EC system behaved reasonably. E was very close to P, indicating that little or no water would recharge the deep soil layers. Now comparing the dry (2/3 of the year) and wet (1/3) seasons: surprisingly, NEE was more effective during the dry season [-3.9, -1.7]. This was the result of Re being much lower on a daily basis as well as cumulated over the entire seasons [57, 84], whereas GPP was similar [-10.8, -12.1]. We found a good match between E measured above the whole ecosystem (EC1), and the sum of tree transpiration (T, measured by sapflow) + E measured just above crops + soil (EC2) throughout the wet and dry seasons. The “Faidherbia-Flux” observatory is registered in FLUXNET as SN-Nkr and is widely open for collaboration.

This study is a contribution to the characterization of traditional agroforestry parklands in Lower Casamance. It aims at determining the diversity of species and the tree size structure in these parklands, as well as at identifying the threats to their sustainability, in order to assist decision making on natural resource conservation. To this end, 45 plots of 50 × 50 m size were inventoried. In each plot, an exhaustive inventory of trees was performed, including species identification, height measurement and estimates of regeneration and mortality rates. Additionally, 116 stakeholders were interviewed about their management practices, the revenue they obtained from agroforestry parklands, and their opinion on the future of these parks. A total of 2739 Elaeis guineensis palm trees and 3948 trees from other species were observed in the 11.25 ha studied. Hence a relative density of 40.96 individuals of E. guineensis ha −1 . The 63 species belonged to 51 genus within 23 botanical families. The analysis of tree communities indicated a strong role of human management on the species composition of parklands, with cultural value trees near the villages and wood production trees further away, and with some sites having more trees with medicinal uses. The distribution of tree sizes of E. guineensis and estimates of mortality and regeneration rates indicated that the population of palm trees is ageing and regeneration is too low to compensate mortality. Based on interviews, palm production is decreasing in the area, and causes of decline identified by the farmers were salinization, drought, illegal cutting, and bush fires, i.e., both natural and anthropogenic causes. In view of the importance of these parklands for the local economy and food security, better management of E. guineensis parklands is required to ensure their sustainability.

A wide program of fruit tree planting, notably jujube trees, has been implemented in the framework of the pan-African Great Green Wall (GGW) project to improve food security in arid and semiarid regions. However, the success of such initiatives is highly limited by a low tree growth and high tree mortality rates due to transplant shocks from tree nursery to field. The positive impact of mycorrhiza-based ecological engineering strategies on jujube trees were previously demonstrated in nursery conditions, but field monitoring is necessary to evaluate their sustainability in terms of plant growth and survival. In the current study, local (Tasset) and exotic (Gola) jujube cultivars were tested for their response to mycorrhizal inoculation with the non-native arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis IR 27 and fertilization with rock phosphate. The environmental impacts of both treatments were assessed by characterizing the native AM fungal community in a 13-month-old jujube orchard. Field results demonstrated higher rates of survival and a relative stability of nursery-driven plant benefits of inoculated jujube trees, as well as a potential higher persistence of AM fungal inoculum for the exotic cultivar. The native AM fungal community associated with the local cultivar was the most diverse, but Glomeraceae was predominant in both cultivars. The mycorrhiza-based ecological engineering strategies proposed in this work affected both AM fungal communities, notably Glomeraceae and Gigasporaceae members, but in a higher extent for the local jujube cultivar. Results highlight the strong benefits of mycorrhizal inoculation at the very early stages of tree seedling growth in nursery and their stability in the first year of plantation. Nevertheless, a deeper assessment of mycorrhizal inoculum persistence and spread, and a wider characterization of soil and root microbiome need to be implemented in further field monitoring to better evaluate the environmental impacts.

PurposeAgriculture must transform as climate change progresses. The international community has promoted climate-smart agriculture (CSA) as a set of solutions. Previous analyses of opportunities for scaling up CSA have not looked closely at building political and social support for policies, practices and programs. The purpose of this paper is to fill that gap in the case study country of Senegal.Design/methodology/approachThe study applies the conceptual definitions, operationalizations and assessment targets from the political will and public will (PPW) approach to social change. Semi-structured interviews and documents constitute the sources of data and information.FindingsThe analysis identifies opportunities to generate political will for supplying an enabling environment for the widespread adoption of CSA. On the public will side, the analysis identifies opportunities to generate and channel demand for CSA.Research limitations/implicationsResearchers investigated some definitional components more completely than others due to resource and access constraints. Further, the context specificity of the components limits generalizability of certain findings.Social implicationsSocial structures may need to change for successful adoption of certain CSA innovations, but improved agricultural outcomes are likely to result.Originality/valueThis examination of crucial elements for scaling up CSA efforts constitutes the most extensive application of the PPW approach to date, thus providing an example of this generalizable method.

Recently, a new approach to extension and climate information services, namely Participatory Integrated Climate Services for Agriculture (PICSA) has been developed. PICSA makes use of historical climate records, participatory decision-making tools and forecasts to help farmers identify and better plan livelihood options that are suited to local climate features and farmers' own circumstances. This approach was implemented in 2016 in two sites in Senegal and Mali, with 57 and 47 farmers, respectively. At the end of the growing season, these farmers were surveyed to explore their perceptions on the use of the approach. In Senegal and Mali, respectively 97% and 76% of the respondents found the approach 'very useful'. The approach enabled farmers to make strategic plans long before the season, based on their improved knowledge of local climate features. Moreover, evidence demonstrates that PICSA stimulated farmers to consider and then implement a range of innovations which included: (i) changes in timing of activities such as sowing dates, (ii) implementing soil and water management practices, (iii) selection of crop varieties, (iv) fertiliser management and (v) adaptation of plans for the season (farm size, etc.) to the actual resources available to them. The study also demonstrated the potential of farmer-to-farmer extension in scaling up the approach, which is of great interest especially in the current context of limited extension services in the West African region.