Potentialités Des Agroforêts Contre Les Changements Climatiques En Zone D’écotone Forêt-Savane Du Cameroun

L’agroforêt fait partie du paysage agraire dans l’Arrondissement de Ndikiniméki dans la région du centre Cameroun, malheureusement sujette à de nombreuses pressions. En dépit des travaux menés sur les agroforêts du Centre et du Sud Cameroun, peu se sont intéressés à sa contribution dans la lutte contre le réchauffement climatique. L’objectif de la présente étude est de démontrer l’efficacité des agroforêts dans la sécurité alimentaire des populations, la conservation de la phytodiversité et dans la lutte contre les changements climatiques. Pour ce faire une analyse participative a été réalisée avec 74 exploitants d’agroforêts répartis dans cinq villages. Des inventaires botaniques ont été réalisés dans chacune de ces agroforêts. Les données recueillies ont fait l’objet d’analyses diverses (calcul des indices écologiques, de diversité, de biomasse et des tests statistiques). Les agroforêts jeunes (moins de 15 ans) et vieilles (supérieur à 45 ans) sont les plus importantes dans la zone. La classe de superficie supérieure à 1500m² vient au premier rang avec 32%. Les cultures vivrières les plus fréquentes dans les agroforêts sont les tubercules (Manihot esculanta), les légumineuses (Phaseolus vulgaris) et le maïs (Zea mays). La cacaoculture est la plus répandue des cultures de rente de la zone avec une fréquence de 0,73. Le safoutier (Dacryodes edulis) et le manguier (Mangifera indica) viennent au premier rang des fruitiers exotiques. La richesse spécifique est évaluée à 72 espèces reparties en 63 genres et 29 familles. Parmi les familles écologiquement importantes nous avons les Moraceae (FIV=26,96%) et Apocynaceae (FIV=25,66%). Les indices de diversité de Shannon sont les plus importants dans les agroforêts de Ndokononoho et Oundjock. Mangifera indica (64,80 t/ha) et Dacryodes edulis (41,23 t/ha) sont les espèces qui ont les biomasses les plus importantes de la zone. La biomasse ligneuse totale dans la zone est estimée à 4261,72t pour un stock de carbone total de 2003t, ce qui correspond à un stock total de CO2 de 7351,03t CO2 qui rapporterait aux exploitants un crédit carbone de 44.026.788,87 Franc CFA. Ces résultats attestent de l’efficacité de ces agroforêts dans la lutte contre le réchauffement climatique et pouvant servir dans l’orientation et l’application des politiques du mécanisme REDD++ sur le plan local et régional. The agroforest is part of the agrarian landscape in the Ndikinimékisuddivision in the central region of Cameroon, unfortunately subject to many pressures. Despite the works carried out on the agroforests of Centre and South regions of Cameroon, few have paid attention to its contribution to the fight against global warming. The objective of this present study is to demonstrate the effectiveness of agroforests in the food security of the populations, the conservation of phytodiversity and in the fight against climate change. To do this, a participatory analysis was carried out with 74 agroforest farmers in five villages. Botanical inventories were carried out in each of these agroforests. The data collected were analyzed in various ways (calculation of ecological, diversity and biomass indices as wells as statistical tests). Young groforests (less than 15 years old) and old (over 45 years old) are the most prominent in the zone. The surface area class exceeding 1500 m² comes first with 32 %. The most common food crops in the agroforests are tubers (Manihot esculanta), legumes (Phaseolus vulgaris) and maize (Zea mays). Cocoa farming is the most common cash crop in the zone with a frequency of 0.73. Safoutier trees (Dacryodes edulis) and mango trees (Mangifera indica) are ranks first among the exotic fruit trees. Species richness is estimated at 72 species in 63 genera and 29 families. Among the ecologically important families, we have the Moraceae (FIV=26.96%) and Apocynaceae (FIV=25.66%). The Shannon’s diversity indices are the most important for the Ndokononoho and Oundjock agroforests. Mangifera indica (64.80 t/ha) and Dacryodes edulis (41.23 t/ha) are the species with the most important biomass in the zone of the study. The total woody biomass in the area is estimated at 4 261,72t for a total carbon stock of 2003t, which corresponds to a total CO2 stock of 7 351.03t CO2 which would bring operators a carbon credit of 44 026 788.87 Franc CFA. These results justify the effectiveness of these agroforests in the fight against global warming and can be used as a guide and the implementation of the policies of the REDD ++ mechanisms at the local and regional levels

Conservation et valorisation de la biodiversité dans les agroforêts de la zone périurbaine de la ville Bafia (Région du Centre au Cameroun)

Résumé Les agroforêts qui font partie du système de production agricole dans le département du Mbam-et-Inoubou sont malheureusement en dégradation. L’objectif global de ce travail est d’évaluer le niveau de conservation de la biodiversité des agroforêts Bafia dans la perspective de leur aménagement. Pour se faire, une étude participative et réitérative a été effectuée avec 100 exploitants répartis dans 7 villages. Des inventaires botaniques ont été réalisés dans chacune de ces exploitations. Les données recueillies ont fait l’objet d’analyses diverses (calcul des indices écologiques et de diversité, tests univariés et multivariés). L’analyse ressort que les agroforêts Bafia ont une biodiversité végétale importante. Les agroforêts de plus de 45 ans sont les plus importantes dans la zone (40,92%) et la classe de superficie de 0,5 à 1 ha est majoritaire (54,36%). Sur l’échantillon total, 53% des paysans utilisent une main d’œuvre familiale, et les cultures les plus fréquentes sont les légumineuses alimentaires et les tubercules. La richesse spécifique est évaluée à 61 espèces réparties en 55 genres et 28 familles. Sur le plan agro-écologique, Elaeis guineensis se révèle plus important avec un IVI (Importance Value Index) global de 25,02 tandis que Ceiba pentandra vient en premier rang des espèces locales avec un IVI de 13,72. Les Palmaceae ont le FIV (Family Importance Value) le plus élevé de la zone avec 34,73. Nyamson 3, Lablé et Nyamson 1 ont les exploitations les plus diversifiées. La Classification Ascendante Hiérarchique (CAH) montre quatre groupes de parcelles agroforestières. Les agroforêts de case Bafia montrent d’une part leur efficacité dans la conservation de la diversité végétale, d’autre part dans la sécurité alimentaire des ménages. Mots clés : Biodiversité, agroforêts de case, développement durable, sécurité alimentaire Abstract Agroforests which are part of the agricultural production system in Mbam-et-Inoubou division are unfortunately deteriorating. The overall objective of this work is to assess the level of conservation of the biodiversity of the Bafia agroforests in view of their management. To achieve that goal, a participatory and reiterative study was conducted with 100 operators distributed in 7 villages. Botanical inventories were carried out in each of these farms. The data obtained were subjected to various analysis (calculation of ecological indices of diversity, univariate and multivariate tests). The analysis shows that the Bafia agroforests have significant plant diversity. Agroforests of over 45 years are the most important in the area (40.92 %) and size class from 0.5 to 1 ha is the majority (54.36 %). From the total sample, 53 % of the farmers use family labour, and the most common food crops are legumes and tubers. Species richness is estimated at 61 species distributed in 55 genera and 28 families. In the agro-ecological point of view, Elaeis guineensis is most important with an overall IVI (Importance Value Index) of 25.02 while Ceiba pentandra comes first of local species with an IVI of 13.72. The Palmaceae have the greatest FIV (Family Importance Value) in the zone with 34.73. Nyamson 3, Lable and Nyamson 1 have the most diversified farms. The ascending hierarchical clustering (AHC) shows four groups of agroforest plots. The box Agroforests of Mbam-et-Kim and Mbam-et-Inoubou divisions on the one hand shows their effectiveness in conservation of plant diversity and on the other hand in households’ food security. Keywords: Biodiversity, box agroforests, sustainable development, food security

Effects of substrate and mycorrhizal inoculum on stem segment cuttings of Pterocarpus erinaceus Poir. (Fabaceae) in the Guinean savannah highlands of Cameroon

Pterocarpus erinaceus Poir is a woody species of the Sudano-Guinean to Sudano-Sahelian zones with very high food, medicinal and commercial potential leading to the overexploitation. This study aimed to contribute to the domestication of this species using stem segment cuttings. The sand/sawdust and black soil/sawdust substrates were inoculated with 0.10, and 20 g of mycorrhizae. The split plot with 4 repetitions was used as the experimental method and set at 10 cuttings per unit. The experience revealed that the appropriate substrate and dose of mycorrhizae for the budding of stem segment cuttings (SSC) were the sand/sawdust mixture (25.00 ± 18.34 %) and 10 g (23.75 ± 5.63 %) respectively. Satisfactory result was recorded in 10 g (4.18 ± 2.52 cm) dose of mycorrhizae for the height of the aerial axes with abundant number of leaves per aerial observed in the sand/sawdust substrate (2.36 ± 0.48). Concerning the rooting ability of the cuttings, adequate substrate for the number of newly formed roots is the sand/sawdust mixture (25.00 ± 18.34 %) while the dose of 10 g of mycorrhizae favoured the appearance of roots (23.75 ± 14.07 %). The best substrate for the length of newly formed roots is the sand/sawdust mixture (10.64 ± 7.14 cm) and 10 g of mycorrhizae improved the length (9.82 ± 6.40 cm) for Senegal rosewood. Given the above results, we can admit that the improvement of certain parameters (budding, rooting) in P. erinaceus is possible by vegetative propagation

Adsorption of essential oil components of Xylopia aethiopica (Annonaceae) by kaolin from Wak, Adamawa province (Cameroon)

Essential oils of aromatic plants are nowadays cited as suitable tools for better protection of stored grains from insect pest attacks. These chemical insecticides are less attractive to producers because of their low persistence and difficulty to use as pure product There is therefore a need to formulate them as an easy handling chemical with better persistence. The present work aimed to study the formulation through adsorption of active components of Xylopia aethiopica Dunal (Annonaceae) essential oil on kaolin. X aethiopica essential oil was obtained by hydrodistillation in a Clevenger type apparatus unit Essential oil obtained was analysed by a GC-FID and a GC-MS. The adsorption measurements were performed with collected two kaolin fractions (F1 <100 mu m; F2 <50 mu m) and two kaolin fractions after H2O2 treatment (F3 <50 mu m; F4 <2 mu m). The kaolin was characterized by XRD, XRF, FTIR; its specific surface area was determined by the B.E.T method. The amount of essential oil adsorbed was inversely proportional to the particles size. Treatment of kaolin with hydrogen peroxide increased the adsorption capacity of essential oil components. The components adsorbed in highest amounts were sabinene, beta-pinene, alpha-pinene and beta-phellandrene. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved

A review of Cameroonian medicinal plants with potentials for the management of the COVID-19 pandemic

Since the outbreak in December 2019, in Wuhan (China) of COVID-19, approved drugs are still lacking and the world is seeking effective treatment. The purpose of this article is to review the medicinal plants with potential to be used as complementary therapies against COVID-19. Bibliographic information was searched in several databases (Google Scholar, PubMed, Scopus, ScienceDirect, PROTA, ResearchGate and GLOBEinMED), to retrieve relevant papers on (1) plants used to manage common symptoms of COVID-19, (2) plant secondary metabolites with confirmed inhibitory effects on COVID-19 and (3) plants exhibiting pharmacological activities of relevance for COVID-19 management. A total of 230 species was recorded as potential source of ingredients for the fight against the 2019 novel corona virus. Of these species, 30 contain confirmed antiCOVID-19 secondary metabolites, 90 are used traditionally to manage at least 3 common symptoms of COVID-19, 10 have immunostimulant activity, 52 have anti-inflamatory activity, 14 have antiviral properties and 78 species are documented as used to treat malaria. A PCA analysis showing cluster formatting among the recorded species indicates 4 groups of species and an array of possibility of using individual species or a combination of species for their complementary effects. The authors argue that Cameroonian medicinal plants can be of potential contribution to the fight against COVID-19. Further applied research is needed to provide more scientific evidence for their efficacy, to establish standard formulations and clinical studies as part of efforts to develop therapies for COVID-19