Evaluation of the Aerial Biomass of Three Sahelian Species in the Ferlo (North Senegal): Acacia tortilis (Forsk.) Hayn essp. Raddiana (Savi) Brenan, Acacia senegal (L.) Willd and Balanites aegyptiaca (L.) Del

International audienceIn a context of climate change characterized by rising temperatures, increased greenhouse gases and frequent droughts, the Sahel is presented as one of the most vulnerable areas to the adverse effects of climate change. The Sahel is presented as one of the most vulnerable areas to the adverse effects of climate change. The objective of this study is to assess the above-ground biomass and carbon stock of three Sahelian species: Acacia raddiana tortilis (Forsk.) hayne ssp. raddiana (savi) Brenan, Acacia senegal (L.) Willd and Balanites aegyptiaca (L.). The study was carried out in northern Senegal commonly known as Ferlo. Biomasses of the populations of the three target species were first assessed by harvesting the entire epigenetic part of the species and then modelled by correlation using dendrometric parameters measured on each individual of the sample. Two models, mono-specific and multi-species, were used. The results obtained showed that the diameter at breast height (x) and the parameter best correlated to the epigeal biomass (y). The dry biomass of woody plants was 31.4 ± 15.2 kg/tree for B. aegyptiaca, 30.6 ± 13.2 kg/tree for A. senegal and 26.2 ± 11.1 kg/tree for A. raddiana; i.e. carbon equivalents of 14.75 - 14.38 - 12.31 kg/tree respectively. The amount of carbon contained in the above-ground woody biomass is estimated at 4.48 t/ha. The carbon equivalent, atmospheric CO2 is estimated at 16.44 tons of CO2/ha and based on the actual density of Ferlo (108.08 ± 49.79 ind/ha) the sequestered carbon of the area is estimated at 1777.008 tons of CO2. The comparison between the models developed in this study and the multispecific or mono-specific models from the literature showed substantial differences. This study contributes to a better understanding of the contribution of Sahelian woody species to carbon sequestration and the results could be used in the framework of adaptation to climate change

Dendrochronological Potential and Impact of Climate Factors on Radial Growth of Two Species in the Sahelian Zone: <i>Boscia senegalensis</i> (Pers.) Lam. ex Poir and <i>Sclerocarya birrea</i> (A. Rich) Hoscht (Ferlo Nord/Senegal)

International audienceThe objective of this study is to analyze the dendrochronological potential of two Sahelian species (B. senegalensis and S. birrea) and to evaluate the relationships between their growth rings and the climate. The study was conducted in 2016 in the Ferlo area of Senegal. The biological material consists of wood slices, taken from the trunks of these adult woody species at 0.30 m and 1.30 m from the ground after they have been felled. The technique used to examine the slices consists in identifying their rings, establishing their structures, inter-dating them and studying the relationship between the identified rings and climatic factors. The results showed that the species had thin, clear, highly visible and sharp rings. The limit of growth is marked by a line of parenchyma. Intradatation series carried out on the chronologies made it possible to estimate the ages of the individuals, which vary from 10 to 38 years for B. senegalensis and from 29 to 50 years for S. birrea. Their average growth rates are estimated at 0.906 mm/year and 0.89 mm/year respectively. The chronological sequences are 29 years (1987-2016) for B. senegalensis and 38 years (1964-2012) for S. birrea. The results revealed that there is no significant correlation between the growth chronologies of B. senegalensis and the climatic regressors (temperature and precipitation). In contrast, the ring-climate relationship shows that in S. birrea winter precipitation positively influences ring growth while temperature has no effect on ring growth in this species. This study provides a better understanding of the response of forest ecosystems to possible climate change, particularly in the current context of sustainable forest management

Effet de l'application de différentes doses de fertilisants organiques sur la croissance et le rendement de la tomate (Solanum lycopersicum)

International audienceL'objectif de cette étude est d’évaluer les effets de l'application de différents fertilisants organiques (fumier de vache, litières de Balanites aegyptiaca (L.) Del., Boscia senegalensis (Pers.) Lam. ex Poir. et Sclerocarya birrea (A. Rich.) Hochst) sur les paramètres de croissance et de rendement de la variété F1 Mongal de la tomate (Solanum lycopersicum L.) en conditions semi-contrôlées. L’étude a été effectuée à la ferme agricole de l’Université Gaston Berger de Saint Louis au Nord du Sénégal entre avril et juin 2018. Le dispositif expérimental utilisé est en blocs aléatoires randomisés avec quatre (04) répétitions, huit (08) traitements et trois (03) doses (0,2%, 0,5% et 0,8%). Les traitements appliqués sont : T0 (témoin sans apport de fertilisant), T1 (litière de Balanites aegyptiaca), T2 (litière de Boscia senegalensis), T3 (litière de Sclerocarya birrea), T4 (fumier), T5, T6 et T7 (mélange à proportion égale (½+ ½) de fumier et chacune des trois (03) litières). Après application des différents fertilisants organiques, une durée de décomposition de 15 jours a été observée avant semis dans des pots de 1,5 kg. Après 60 jours de croissance, les résultats obtenus ont montré que les effets sur la croissance de la tomate varient en fonction de la dose et de la qualité de la matière organique apportée. Les litières de B. senegalensis appliquées seules ou en combinaison avec le fumier et la litière B. aegyptiaca utilisée seule ont amélioré significativement certains des paramètres étudiés (hauteur, surface foliaire, biomasse sèche aérienne et couleur du feuillage) aux doses de 0,5% et 0,8%. Les meilleurs effets ont été induits par la plus forte dose (0,8%) de B. senegalensis. La litière de S. birrea n’a pas eu d’effets significatifs sur les paramètres de croissance et de rendements de la tomate. Le fumier n’a montré aucun effet sur les paramètres de croissance de la tomate par rapport au témoin sans fertilisant. Ainsi, la litière de B. senegalensis dans les conditions de cet essai, a montré un grand potentiel pour l’amélioration des paramètres de croissance et de rendement de la tomate

Répartition spatiale de la végétation herbacée autour des mares temporaires : influence des facteurs anthropiques et topographiques à WIDOU THIENGOLY (Ferlo, Nord-Sénégal)

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