Perceptions, usages et vulnérabilité des ressources végétales ligneuses dans le Sud-Ouest du Burkina Faso

Au Burkina Faso, les populations rurales dépendent fortement des ressources végétales ligneuses pour la satisfaction de leurs besoins quotidiens. Dans un contexte de pression anthropique croissante, l’évaluation de la vulnérabilité des espèces s’avère un impératif majeur pour permettre la préservation et la gestion durable de ces ressources. Pour ce faire, des enquêtes semi-structurées ont été menées chez les Sénoufo, un des groupes ethniques dominants du Sud-Ouest du Burkina Faso. La vulnérabilité des espèces citées par les personnes enquêtées a été évaluée sur la base d’un indice de vulnérabilité (Iv) établi à partir de six paramètres. Au total, 73 espèces ont été citées pour lesquelles l’artisanat, le bois de feu et la construction se révèlent être les principales causes de vulnérabilité. Certains aspects des croyances traditionnelles s’avèrent cependant favorables à la conservation des ressources végétales ; ainsi, par exemple, certaines espèces sont interdites à la combustion. Cette étude montre que la combinaison des inventaires de terrain et des enquêtes ethnobotaniquesest indispensable comme approche fiable pour l’identification des espèces menacées

A Combination of Metabolomics and Machine Learning Results in the Identification of a New Cyst Nematode Hatching Factor

Potato Cyst Nematodes (PCNs) are an economically important pest for potato growers. A crucial event in the life cycle of the nematode is hatching, after which the juvenile will move toward the host root and infect it. The hatching of PCNs is induced by known and unknown compounds in the root exudates of host plant species, called hatching factors (HFs, induce hatching independently), such as solanoeclepin A (solA), or hatching stimulants (HSs, enhance hatching activity of HFs). Unraveling the identity of unknown HSs and HFs and their natural variation is important for the selection of cultivars that produce low amounts of HFs and HSs, thus contributing to more sustainable agriculture. In this study, we used a new approach aimed at the identification of new HFs and HSs for PCNs in potato. Hereto, root exudates of a series of different potato cultivars were analyzed for their PCN hatch-inducing activity and their solA content. The exudates were also analyzed using untargeted metabolomics, and subsequently the data were integrated using machine learning, specifically random forest feature selection, and Pearson’s correlation testing. As expected, solA highly correlates with hatching. Furthermore, this resulted in the discovery of a number of metabolite features present in the root exudate that correlate with hatching and solA content, and one of these is a compound of m/z 526.18 that predicts hatching even better than solA with both data methods. This compound’s involvement in hatch stimulation was confirmed by the fractionation of three representative root exudates and hatching assays with the resulting fractions. Moreover, the compound shares mass fragmentation similarity with solA, and we therefore assume it has a similar structure. With this work, we show that potato likely produces a solA analogue, and we contribute to unraveling the hatch-inducing cocktail exuded by plant roots

Relationships between soil seed banks and above-ground vegetation along a disturbance gradient in the W Park trans-boundary biosphere reserve, West Africa

Aims: Vegetation succession depends on the availability of suitable propagules in the soils, thus knowledge of soil seed banks is essential for formulating effective strategies for restoring the vegetation of degraded sites. The W National Park, the only trans-boundary biosphere reserve in West Africa, is being extensively fragmented and degraded in recent decades. The aims of this study were to assess the reserve’s soil seed banks, their relationships with standing vegetation and bundle of disturbances, and their potential significance for vegetation restoration. Methods: The size and composition of the above-ground species vegetation were assessed in nine plots of 1 ha each representing a range of habitats with differing disturbance severity (low, intermediate and high). A total of 702 soil samples were taken from three layers (0-3, 3-6 and 6-9 cm) and soil seed bank was analyzed using the seedling emergence technique. Important Findings: Generally, seeds of non-woody taxa dominated in samples from all soil depths and habitats of all disturbance severities. The mean soil seed density was 17.8, 24.4 and 26.3 seeds dm-3 in samples from the least, intermediate and most disturbed sites, respectively, and highest in the upper soil layers in all cases. The results indicate that there is limited potential for restoring woody vegetation solely from soil seed banks, and that woody species in the region rely more on recently shed seeds trapped in the standing dead biomass and litter on the ground than soil seed banks for regeneration. Thus, human intervention is needed to accelerate forest recovery, mainly through alleviating anthropogenic impacts on the ecosystem (for instance, avoiding destruction of new seeds by intense fire), and site manipulation to improve environmental conditions for seedling establishment and growth

Relationships between soil seed banks and above-ground vegetation along a disturbance gradient in the W National Park trans-boundary biosphere reserve, West Africa

Aims Vegetation succession depends on the availability of suitable propagules in the soils, thus knowledge of soil seed banks is essential for formulating effective strategies for restoring the vegetation of degraded sites. The W National Park, the only trans-boundary biosphere reserve in West Africa, is being extensively fragmented and degraded in recent decades. The aims of this study were to assess the reserve’s soil seed banks, their relationships with standing vegetation and bundle of disturbances and their potential significance for vegetation restoration. Methods The size and composition of the above-ground species vegetation were assessed in nine plots of 1 ha each representing a range of habitats with differing disturbance severity (low, intermediate and high). A total of 702 soil samples were taken from three layers (0–3, 3–6 and 6–9cm) and soil seed bank was analyzed using the seedling emergence technique. Important Findings Generally, seeds of non-woody taxa dominated in samples from all soil depths and habitats of all disturbance severities. The mean soil seed density was 17.8, 24.4 and 26.3 seeds/dm3 in samples from the least, intermediate and most disturbed sites, respectively, and highest in the upper soil layers in all cases. The results indicate that there is limited potential for restoring woody vegetation solely from soil seed banks, and that woody species in the region rely more on recently shed seeds trapped in the standing dead biomass and litter on the ground than soil seed banks for regeneration. Thus, human intervention is needed to accelerate forest recovery, mainly through alleviating anthropogenic impacts on the ecosystem (for instance, avoiding destruction of new seeds by intense fire), and site manipulation to improve environmental conditions for seedling establishment and growth. Other ways of restoring forests than through the soil seed bank (e.g. sowing seeds collected elsewhere, and planting tree seedlings) could also be relevant

Conceptualising farming systems for agricultural development research: cases from Eastern and Southern Africa

In the context of broad scale system changes (e.g. climate change) and the prioritisation of impact-at-scale development, there is a particular need for farming systems research (FSR) to improve our understanding of the links between systems at multiple scales. Drawing on three empirical case studies of large-scale agricultural interventions in eastern and southern Africa, we highlight problems that arise from conceiving and justifying interventions on the basis of the simple aggregation of farms into large collective systems. We review changes in the approach and concepts of FSR and point to the value of farming systems concepts that go beyond these aggregations, and find ways to capture the multi-level system dynamics that link on-farm decision making to broader political, social, and environmental changes. Recent attempts at more accurately conceptualising the domain of FSR, and drawing distinctions between ‘farms’, ‘systems’, and ‘systems of farming’, represent a useful contribution to such work