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

Assessment of Physical-Chemical Drinking Water Quality in the Logone Valley (Chad-Cameroon)

Unsafe drinking water is one of the main concerns in developing countries. In order to deal with this problem, a cooperation project was set up by the ACRA Foundation in the Logone valley (Chad-Cameroon). Water supplies were sampled throughout the villages of this area mostly from boreholes, open wells, rivers and lakes as well as some piped waters. The samples were analysed for their physical-chemical and microbiological quality in order to identify the contamination problems and suggest appropriate solutions. Results of the assessment confirmed that in the studied area there are several parameters of health and aesthetic concern. Elevated lead levels were detected both in aquifers and in surface waters, confirming that further investigations of the occurrence of lead contamination in the Logone valley are warranted. In addition, many groundwater sources are negatively impacted by parameters of aesthetic concern, such as turbidity, iron and manganese. Even though they do not affect human health, elevated levels of these parameters cause consumers to abandon improved water supplies, often in favour of surface water sources that are microbiologically contaminated. The use of alternative sources, improvement of water supply structures and water treatment are possible solutions to improve the quality of drinking water in the Logone valley

Is drinking water from 'improved sources' really safe? A case study in the Logone valley (Chad-Cameroon).

Within a cooperation project coordinated by the Association for Rural Cooperation in Africa and Latin America (ACRA) Foundation, water supplies were sampled across the villages of the Logone valley (Chad-Cameroon) mostly from boreholes, open wells, rivers and lakes as well as from some piped water. Microbiological analyses and sanitary inspections were carried out at each source. The microbiological quality was determined by analysis of indicators of faecal contamination, Escherichia coli, Enterococci and Salmonellae, using the membrane filtration method. Sanitary inspections were done using WHO query forms. The assessment confirmed that there are several parameters of health concern in the studied area; bacteria of faecal origins are the most significant. Furthermore, this study demonstrated that Joint Monitoring Programme (JMP) classification and E. coli measurement are not sufficient to state water safety. In fact, in the studied area, JMP defined 'improved sources' may provide unsafe water depending on their structure and sources without E. coli may have Enterococci and Salmonellae. Sanitary inspections also revealed high health risks for some boreholes. In other cases, sources with low sanitary risk and no E. coli were contaminated by Enterococci and Salmonellae. Better management and protection of the sources, hygiene improvement and domestic water treatment before consumption are possible solutions to reduce health risks in the Logone valley

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

Assessment of Physical-Chemical Drinking Water Quality in the Logone Valley (Chad-Cameroon)

Unsafe drinking water is one of the main concerns in developing countries. In order to deal with this problem, a cooperation project was set up by the ACRA Foundation in the Logone valley (Chad-Cameroon). Water supplies were sampled throughout the villages of this area mostly from boreholes, open wells, rivers and lakes as well as some piped waters. The samples were analysed for their physical-chemical and microbiological quality in order to identify the contamination problems and suggest appropriate solutions. Results of the assessment confirmed that in the studied area there are several parameters of health and aesthetic concern. Elevated lead levels were detected both in aquifers and in surface waters, confirming that further investigations of the occurrence of lead contamination in the Logone valley are warranted. In addition, many groundwater sources are negatively impacted by parameters of aesthetic concern, such as turbidity, iron and manganese. Even though they do not affect human health, elevated levels of these parameters cause consumers to abandon improved water supplies, often in favour of surface water sources that are microbiologically contaminated. The use of alternative sources, improvement of water supply structures and water treatment are possible solutions to improve the quality of drinking water in the Logone valle

Is drinking water from ‘improved sources’ really safe? a case study in the Logone valley (Chad-Cameroon)

Within a cooperation project coordinated by the Association for Rural Cooperation in Africa and Latin America (ACRA) Foundation, water supplies were sampled across the villages of the Logone valley (Chad-Cameroon) mostly from boreholes, open wells, rivers and lakes as well as from some piped water. Microbiological analyses and sanitary inspections were carried out at each source. The microbiological quality was determined by analysis of indicators of faecal contamination, Escherichia coli, Enterococci and Salmonellae, using the membrane filtration method. Sanitary inspections were done using WHO query forms. The assessment confirmed that there are several parameters of health concern in the studied area; bacteria of faecal origins are the most significant. Furthermore, this study demonstrated that Joint Monitoring Programme (JMP) classification and E. coli measurement are not sufficient to state water safety. In fact, in the studied area, JMP defined 'improved sources' may provide unsafe water depending on their structure and sources without E. coli may have Enterococci and Salmonellae. Sanitary inspections also revealed high health risks for some boreholes. In other cases, sources with low sanitary risk and no E. coli were contaminated by Enterococci and Salmonellae. Better management and protection of the sources, hygiene improvement and domestic water treatment before consumption are possible solutions to reduce health risks in the Logone valley

Persistence of insecticidal activities of crude essential oils of three aromatic plants towards four major stored product insect pests

Essential oils of aromatic plants with insecticidal properties are more and more considered as alternative insecticides to protect stored products. Many banned insecticides have high persistence which allow them to occur at several levels of trophic chains. The aim of the present work is to analyse the persistence of insecticidal activity of crude essential oil of three most used local aromatic plants : Annona senegalensis Pers. (Annonaceae), Hyptis spicigera L. (Lamiaceae) and Lippia rugosa L. (Verbenaceae) towards the four majors stored product insect pests: Sitophilus zeamais Motsch., Sitophilus oryzae L., Callosobruchus maculatus Fab. and Tribolium castaneum Herbst. This research revealed that H. spicigera essential oil was the most active towards S. oryzae with a LD50 = 20.18ppm. T. castaneum was the less sensitive insect to the three essential oils tested. During a period of 24 hours L. rugosa essential oil was the most persistent, showing mortalities for S. zeamais of 80%, S. oryzae more than 60%, C. maculatus 100% and T. castaneum_50%. The two other oils tested were not as persistent as L. rugosa. This important persistence of the essential oil of L. rugosa could be explained by its high content of oxygenated compounds compared to that of the other oils. This most interesting essential oil is therefore a suitable one for popularisation in strategies of pest management in storage

Effect of sorghum cultivars on population growth and grain damages by the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae)

In northern Cameroon, the rice weevil, Sitophilus oryzae L. (Coleptera: Curculionidae) is a major pest of Sorghum bicolor (Poaceae) during storage. This staple crop is currently damaged by many insects and others pests during storage. To reduce the post-harvest losses due to S. oryzae, many control strategies are performed. An important step to achieve successful control is to isolate and characterize the noxious activity of rice weevil present on the sorghum variety currently stored. The present study shows that the two main ecotypes of S. bicolor, the "djiigari" ecotype is very susceptible to the 7 weevils strains isolated in the region. In a period of 100 days a single female of one of the most prolific strains produces 24 adults and more than 57% of grains are attacked. In the "safraari" ecotype, the level of attack is very low. This suggests that efforts should be made to advice the farmers to prefer "safraari" ecotype in order to avoid post harvest losses due to S. oryzae