Exploring microbial diversity in forest litter-based fermented bioproducts and their effects on tomato (Solanum lycopersicum L.) growth in Senegal

Reducing the use of chemical inputs (fertilizers, pesticides) in agriculture while maintaining crop productivity is the main challenge facing sub-Saharan African family farming systems. The use of effective microorganisms (EM) is among the various innovative approaches for minimizing chemical inputs and the environmental impact of agricultural production and protecting soil health while enhancing crop yields and improving food security. This study sought to characterize the microbial biodiversity of local beneficial microorganisms (BMs) products from locally fermented forest litter and investigate their ability to enhance tomato plant growth and development. Beneficial microorganisms (BMs) were obtained by anaerobic fermentation of forest litter collected in four agroecological regions of Senegal mixed with sugarcane molasses and various types of carbon sources (groundnut shells, millet stovers, and rice bran in different proportions). The microbial community composition was analyzed using next-generation rDNA sequencing, and their effects on tomato growth traits were tested in greenhouse experiments. Results show that regardless of the litter geographical collection site, the dominant bacterial taxa in the BMs belonged to the phyla Firmicutes (27.75–97.06%) and Proteobacteria (2.93–72.24%). Within these groups, the most prevalent classes were Bacilli (14.41–89.82%), α-proteobacteria (2.83–72.09%), and Clostridia (0.024–13.34%). Key genera included Lactobacillus (13–65.83%), Acetobacter (8.91–72.09%), Sporolactobacillus (1.40–43.35%), and Clostridium (0.08–13.34%). Fungal taxa were dominated by the classes Leotiomycetes and Sordariomycetes, with a prevalence of the acidophilic genus Acidea. Although microbial diversity is relatively uniform across samples, the relative abundance of microbial taxa is influenced by the litter's origin. This is illustrated by the PCoA analysis, which clusters microbial communities based on their litter source. Greenhouse experiments revealed that five BMs (DK-M, DK-G, DK-GM, NB-R, and NB-M) significantly (p < 0.05) enhanced tomato growth traits, including plant height (+10.75% for DK-G and +9.44% for NB-R), root length (+56.84–62.20%), root volume (+84.32–97.35%), root surface area (+53.16–56.72%), and both fresh and dry shoot biomass when compared to untreated controls. This study revealed that forest-fermented litter products (BMs), produced using litter collected from various regions in Senegal, contain beneficial microorganisms known as plant growth-promoting microorganisms (PGPMs), which enhanced tomato growth. These findings highlight the potential of locally produced BMs as an agroecological alternative to inorganic inputs, particularly within Senegal's family farming systems

Prendre de la hauteur pour caractériser et analyser les paysages agricoles: Application de la télédétection à l'agriculture familiale africaine

A l'interface entre sciences géographiques et sciences agronomiques, mes recherches contribuent à répondre à la problématique générale de l'évaluation spatio-temporelle des performances agronomiques, environnementales et socio-économiques de l'agriculture familiale africaine, en réponse aux changements globaux. Mes recherches s'inscrivent dans un contexte de profondes mutations technologiques parmi lesquelles les outils de télédétection jouent un rôle central. Les données satellitaires ou aéroportées, données d'enquête, d'inventaire ou d'expérimentation sont les fondements de mes recherches, les nouvelles méthodes d'analyses issues de l'intelligence artificielle en sont le ciment. Les travaux présentés ici font la synthèse d'une dizaine d'années de recherche, s'articulant autour de trois composantes : la télédétection comme outil de description, avec un focus particulier sur la cartographie des paysages agricoles et leur diversité; la télédétection comme outil d'évaluation, notamment pour mesurer la production de végétation des paysages agricoles et enfin, la télédétection comme outil de compréhension, au travers notamment d'études portant sur l'analyse des relations entre composantes des paysages agricoles, production de végétation et sécurité alimentaire. Je conduis mes recherches à différentes échelles spatiales, de la parcelle cultivée à la région, et temporelles, du ponctuel aux tendances sur le long terme. Ces différents thèmes de recherche sont illustrés principalement par des exemples d'étude sur des systèmes de cultures annuelles en Afrique de l'Ouest, en condition pluviale, avec un focus particulier sur les systèmes agroforestiers de type parc agroforestier

Simulating light quantity and quality over plant organs using a ray-tracing method to investigate plant responses in growth chambers

Ray-tracing models enable the assessment of light quantity and quality intercepted by plant organs, supporting biological studies in growth chambers with varying light conditions. However, their validation within canopies and clear usage methods remain limited. This work establishes a reliable method for using these models. The method includes i) accounting for the intensity and spectrum of light sources in the calibration procedure; ii) a generic calibration strategy using a few well-placed light measurement points based on chamber geometry. It evaluates the method to simulate light phylloclimate at the organ scale across biologically relevant wavebands of contrasted widths and properties. Using the SEC2 light simulation framework, three virtual experiments were conducted in a growth chamber, with and without rose plants. Inputs included chamber geometry, material optical properties, lamp emissions, and digitised plant mock-ups. Simulations were compared with spectral measurements at various chamber positions and sensor orientations, both without plants and inside a canopy. Results showed high accuracy in replicating spatial light variability, with RMSE ranging 0.011 to 0.021 and 0.014–0.038 μmol m-2s-1nm-1 across different wavebands and sensor orientations, for vertical and horizontal transects, respectively. Applying this approach to a case study demonstrated its effectiveness in formulating new biological hypotheses regarding the role of local light in regulating bud outgrowth. This was achieved by highlighting differences in phylloclimate induced by variations in plant architecture. This work thus provides a comprehensive framework for facilitating the application of ray-tracing models in growth chamber studies

Co-designing zoonotic diseases prevention practices when people depend on wild meat

In the face of the escalating frequency of diseases emergences originating from wildlife, the development of reliable strategies for controlling zoonotic diseases transmission at the interface between wildlife and human is becoming a global priority. Rural communities whose subsistence is based on hunting for wild meat extraction are natural targets of such interventions, because of their regular contacts with wildlife. To date there have been few attempts at building preventive sanitary strategies taking into account the socioeconomic and institutional constraints in which wild meat systems operate. The study presented here, conducted in eastern Gabon, aimed at conceiving risk-reduction strategies of zoonotic diseases transmitted from wildlife in a two-phase approach, namely (1) an assessment phase, based on a survey on risk knowledge and practices conducted with members of communities living on wild meat, and (2) a co-design phase based on focus group discussions to identify acceptable prevention strategies aimed at limiting the contacts creating the major risks of exposure to zoonoses infections. The use of participatory methods aiming at eliciting issues and solutions from the participants, enabled the conception of strategies that were adapted to the context and well accepted by stakeholders at different stages, namely the track, capture, transport of wild animals, the butchering of carcasses, cooking and consumption process. However, some limitations to the effective application of the strategies can be anticipated notably because of (1) the current low and biased perception of zoonotic risks by wild meat actors, and (2) the economic incentives for maintaining risky behaviors like the capture and trade of live animals and the consumption or sale of animals found dead or displaying signs of disease infection

Short-term impacts of selective logging on forest elephants

Although forest elephants (Loxodonta cyclotis) are known to use logged forests, the impact of selective logging on this critically endangered species has never been well established. Considering the potential of some logged areas to serve as other effective area-based conservation measures, aligning with the Convention on Biological Diversity's 30/30 initiative, we aimed to assess the short-term impacts of logging on three population parameters: the presence, abundance, and activity of forest elephants. Combining camera traps and dung surveys before and after logging operations, we assessed the response of forest elephants in a certified timber concession in Gabon. Encouragingly, we found no negative effects of logging on the three population parameters studied. There was no discernible change in the presence of elephants after logging, and their abundance actually increased (relative abundance index from 1.56 to 2.59; p-value 0.0139) at one of the study sites. Activity patterns were also unaffected, showing sustained activity during daylight hours. We also identified the logging-associated factors that have significantly influenced forest elephant's abundance. Notably, logging intensity, as measured by the average number of trees harvested per hectare, and road density were positively correlated with the number of forest elephant observations (logging intensity effect: 0.2992, p-value 0.035; road density effect: 0.3628, p-value 0.060). As global conservation goals evolve, this research provides important insights into the coexistence of well-managed industrial activities and the conservation of endangered species, highlighting the need to include responsibly managed timber concessions in future conservation strategies. It also underscores the importance of wider adoption of sustainable practices such as low-impact logging, promoted by certification schemes such as FSC or PEFC, to secure the future of central African forests and their unique wildlife

The impact of access to agricultural advisory services on input use and farm performance: Evidence from Senegal

Performant agricultural advisory services (AAS) in Africa are crucial for improving the agricultural productivity and food security of the farm households. Yet, evidence-based study on the impacts of AAS on farm performance are scarce, especially in West African countries. This study evaluates the impact of access to AAS on input use and farm performance in Senegal, employing the instrumental variable and control function approaches accounting for selection bias. The approaches are also employed to several sub-samples to see if the impacts are heterogeneous across crop types and fertilizer use, and matching techniques are applied to test the robustness of the results. Results show that the highest positive impact of AAS is on yield, while the impacts on gross margin and improved seeds uptake are very modest. Access to AAS has no effect on fertilizer uptake. It also finds that AAS impacts positively cereal production and farmers using no fertilizer but has no effect on the legume and horticultural crop production and on farmers using fertilizer. Given the Senegalese government and donors have put a lot of effort into developing an efficient AAS system, a consideration of the identified weaknesses is required to improve its efficiency. [EconLit Citations: Q12, Q16]

When farmers' knowledge matters: Improving epidemiological understanding of Peste des petits ruminants in northern Nigeria

Peste des petits ruminants (PPR) is an endemic disease of sheep and goats in Nigeria and represents a major threat to the livelihoods of smallholders. Understanding the epidemiology of this disease and its management by livestock farmers is essential for developing appropriate surveillance and control programmes. This study aimed to enhance the knowledge about PPR by conducting a large-scale survey in 52 villages in Plateau, Bauchi and Kano states in the northern part of Nigeria. Our approach involved holding focus group discussions with farmers, both men and women, to collect their knowledge about the disease and to understand their perspectives on its management. The results showed that farmers use several different terms to refer to diseases that are likely to be PPR, and that these same terms might also be used to refer to diseases caused by other infectious agents. Farmers rarely call on veterinary services to prevent the disease and vaccination is seldom practiced. Disease control is attempted using conventional treatments, with or without veterinary supervision, or using traditional therapies. There is limited or poor implementation of good farming practices such as biosecurity measures. This study has increased our understanding of PPR and its management in areas with limited public and private veterinary services. In addition, it has also fostered trust between scientists and communities, paving the way for future participatory action research programmes

Variabilité du rendement de l'anacardier (Anacadium occidentale L.) dans la région du Poro, nord de la Côte d'Ivoire

En arboriculture, comprendre les facteurs de variabilité de la production intra- et inter-vergers est une étape essentielle pour augmenter les rendements. La présente étude évaluait l'impact des caractéristiques des vergers et des arbres sur la production de noix de cajou en 2022 et en 2023. Douze vergers issus de trois tranches d'âge ont été sélectionnés dans quatre zones. En 2022, la production par arbre a varié entre 0 et 14,21 kg de noix de cajou, avec une moyenne de 2,87 kg par arbre. En 2023, la production par arbre a varié entre 0 et 20,88 kg, avec une moyenne de 5,78 kg par arbre. Indépendamment de l'année, les vergers de plus de 15 ans ont obtenu des rendements significativement plus élevés. Une relation linéaire positive (R² = 0,48) a été observée entre le rendement et l'envergure. Cet effet a été plus marqué en 2023 qu'en 2022, qui a été une année de faible production. Les variations de rendement observées entre arbres et entre parcelles s'expliquent par les différences de dimension des arbres, les conditions climatiques variables et l'âge des vergers