Essai d’analyses de la conception paysanne de l’évolution, de la gestion et de l’utilité du Parc National de Mozogo-Gokoro (Cameroun) en vue de son aménagement

Cet essai d’exploration du milieu humain riverain du Parc National de Mozogo-Gokoro est une démarche visant sa conservation et son aménagement, en exploitant des indicateurs facilement compréhensibles. Une enquête socio-économique à orientations écologiques a été réalisée afin d’apprécier la perception paysanne de l’évolution spatio-temporelle, compositionnelle et structurale du parc, de son utilité, et de sa gestion avec confrontation des résultats à la vision de l’administration forestière locale. Les résultats ont montré que c’est un écosystème qui a subi une forte pression anthropique, et l’effet de la sècheresse avec une trajectoire régressive. Plusieurs espèces animales et végétales sont signalées en disparition ou en diminution dans le Parc, reflétant un recul de la biodiversité. Son utilité est illustrée par la diversité des ressources (Produits Forestiers Non Ligneux, bois de service et d’énergie) prélevées ou dont le besoin a été exprimé par la population riveraine, indiquant par ailleurs une gestion non conforme à la réglementation. Des orientations d’aménagement, découlant de cette perception, ont été proposées afin d’atténuer la dynamique régressive amorcée et causée par l’absence d’un plan de gestion participative, renforçant sa protection intégrale.Mots clés : Enquête, dynamique spatio-temporelle, perception, population, végétation, protectio

Acute toxicity of monocalm 400sl (monocrotophos) and profenalm 720ec (profenofos) on Oreochromis niloticus (Linnaeus, 1758)

Objective: This study aimed at assessing acute toxicity of Monocalm 400SL (monocrotophos) and Profenalm 720EC (profenofos), two organophosphorous pesticides widely used in the Far North region of Cameroon, to fight against insects and mites parasitizing cotton, rice, maize, sorghum, beans and potatoes. Methodology and results: A 48 h static acute toxicity test was carried out, to determine the LC50 of commercial formulations of monocrotophos (Monocalm 400SL) and profenofos (Profenalm 720EC) on the freshwater Oreochromis niloticus and its behaviours, during the exposition. The fishes were exposed to increasing concentrations of the two pesticides, in a non-renewed medium. The numbers of dead fishes were recorded, after 48 h and the behaviours observed, during the exposition. The 48h-LC50 values, estimated by probit analysis, were of 20.42 and 0.046 mgL-1, for monocrotophos and profenofos, respectively. Lowest Observed Effect Concentration (LOEC) means were of 10 and 0.02 mgL-1, for monocrotophos and profenofos, respectively. Elsewhere, fish behaviours such as slow opercular movements, loss of balance, increased surfacing activities, loss of pigmentation; increased aggression and erratic swimming were observed, during exposition to the pesticides. Conclusion and application of results: Monocrotophos was found to be slightly toxic and profenophos highly toxic to Oreochromis niloticus. Water contamination with these products can represent a great threat for fish and aquatic invertebrates. So it is recommended to apply these pesticides with caution.Keywords: Acute toxicity; LC50; monocrotophos; profenofos; Oreochromis niloticus

Diversity of used plant species for producing charcoal and its trade-off in Far-North Region, Cameroon

 The Northern Regions of Cameroon belong to sudano-zambesian region. In these regions, woody species are scarce compared to Guinean-Congolese Region and they undergo the human pressure like abusive exploitation of plants. In order to contribute to valorization of phytogenetic resources and contribute to struggle desert progression in sahelian region, a study on plants diversity which are used to produce charcoal and its trade-off was carried out in Far-North Region of Cameroon. Census of plants species was made on the basis of semi-structured surveys through the producers of charcoal and identification of tree trunks on the sites of charcoal production. Data of trade of charcoal was collected by direct observation and a semi-structured survey questionnaire in Maroua. In total, 25 species grouped in 17 genera and 8 families have been recorded. Acacia and Combretum were the richest genera with four species each. They were quoted as multipurpose species which can be used elsewhere as fruits, timbers, medicinal plants or essential oils and exudates. In Maroua almost, 98 % of households use charcoal for heating. In the absence of the charcoal, up to 60 % of those use firewood, 18.46 % use domestic gas and 18.46% use kerosene. Because of poverty and unemployment, people of primary education are mostly charcoal sellers.  INTERNATIONAL JOURNAL OF ENVIRONMENTVolume-6, Issue-2, Mar-May 2017, Page: 19-29</p