Dynamiques spatiales récentes du Parc National du Banco (PNB) et stratégies de gestion communautaire durable de ses ressources forestières (District d’Abidjan en Côte d’Ivoire)

La dynamique spatio-temporelle récente de la forêt du Parc National du Banco (PNB), situé à l’intérieur des limites administratives du district d’Abidjan en Côte d’Ivoire, est cartographiée à partir de la comparaison post-classificatoire des classes de deux images multispectrales Spot 1 et 2 prises en janvier 1992 et 2002 et après validation par un inventaire de la végétation, réalisé durant l’été 2008 sur 196 points, suivant des transects nord-sud et est-ouest et des relevés ponctuels. D’un côté, une enquête socio-démographique (250 personnes choisies aléatoirement dans 6 villages riverains) ont permis de cerner les points de vue des acteurs locaux sur l’avenir du PNB. De l’autre côté, les observations de terrain réalisées autour et à l’intérieur des limites administratives du PNB ont également permis de vérifier et de valider les résultats cartographiques. Les résultats des inventaires montrent la présence d’une grande diversité végétale malgré l’anthropisation des marges de ce milieu forestier. Les analyses surfaciques des types de végétation, cartographiés à partir de l’image de la scène Spot (2002) centrée sur le parc, montrent une prédominance des formations forestières avec environ 4 000 ha soit 68 % de la superficie du PNB contre 1 746 ha soit 31 % en 1992. Les exploitations majeures de la végétation se localisent sur les marges du parc. En revanche, à l’intérieur du parc, les plantations forestières des années 1940 et les forêts « naturelles » connaissent une densification de leur végétation. Les résultats des enquêtes sur la perception des populations indiquent que 67 % des personnes interrogées estiment que l’amélioration de la politique actuelle de gestion du PNB et son aménagement constituent des moyens adéquats pour sa conservation et son développement durable.The recent space-time dynamics of the forest of the National Banco Parc, located inside the administrative limits of the district of Abidjan in Ivory Coast, caracterised by the post-classifying comparison of the classes of two multispectral images Spot 1 and 2 catches in January 1992 and 2002 (scene of 60 X 60 km² centered on the town of Abidjan, analyzes of three multispectral channels, XS1, XS2, XS3, pixel 20 m). Floristic inventories, carried out during the summer 2008 out of 196 points, according to a North-South and East-West transects, as well as socio-demographic investigations (250 people chosen by chance in 6 bordering villages) and of the observations of ground made it possible to check and correct the cartographic results and to determine the points of view of the local actors on the future of the PNB. The results of the inventories show a great vegetable diversity. The surface analyses of the types of vegetation charted starting from the image of under scene Spot (2002) centered on the park show a prevalence of the forest formations with approximately 4 000 ha either 68% of the surface in 2002 against 1.746 ha or 31% in 1992. The major exploitations of the vegetation are located on the margins of the park. On the other hand, inside the forest plantations of the 1940’s and the “natural” forests know positive evolutions. The results of the investigations into the perception of the populations also state that 67% of the questioned people estimate that the improvement of the current policy of management of the PNB and its installation constitutes adequate means for its conservation and its durable development

Dynamique forestière et pression urbaine dans le Parc national du Banco (Abidjan, Côte d’Ivoire)

Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua Kouté Sagbé and north-Agban Attié and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB

Dynamique forestière et pression urbaine dans le Parc national du Banco (Abidjan, Côte d’Ivoire)

Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua Kouté Sagbé and north-Agban Attié and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB

Dynamique forestière et pression urbaine dans le Parc national du Banco (Abidjan, Côte d’Ivoire)

La problématique de la conservation de la forêt ivoirienne et de ses ressources est au centre des préoccupations des pouvoirs publics depuis les années 1960. Ainsi, la Côte d’Ivoire a-t-elle mis en place un réseau d’aires protégées, notamment plusieurs parcs nationaux, pour conserver ses massifs forestiers et leurs biodiversités. Situé à Abidjan, le Parc National du Banco (PNB) et sa périphérie connaissent de profondes mutations environnementales depuis quelques décennies. Ces mutations liées principalement aux activités humaines et à l’urbanisation rapide du district d’Abidjan provoquent une dégradation du massif forestier du PNB. Cette recherche vise à décrire et à analyser les différentes menaces liées à la pression urbaine, notamment les risques de déforestation et de pollution qui exposent certaines zones du PNB. Pour atteindre ces objectifs, l’analyse de l’évolution de la végétation, des types d’occupation du sol, des recompositions territoriales et des jeux des différents acteurs est mise à profit pour comprendre les dynamiques environnementales de la forêt du Banco et sa périphérie. L’inventaire et la cartographie des types de risque ainsi que leurs impacts sur le PNB permettent d’identifier les zones les plus vulnérables aux pressions anthropiques et à l’urbanisation. L’étude des types de pressions humaines sur la forêt du PNB est menée à travers des observations de terrain pour détecter les changements spatiaux des dernières années. L’étude s’appuie également sur une photographie aérienne de 1955 et une image satellite Spot prise en 1998. La photographie aérienne a été acquise auprès du Centre de Cartographie et Télédétection (CCT-Abidjan) et de l’Institut Géographique National (IGN-Paris). L’image satellite a été obtenue grâce au programme ISIS de Spot Image. Ces données ont permis de cartographier l’occupation du sol en 1955 et 1998 et de comparer l’évolution de la végétation à travers une analyse diachronique.Les résultats de l’étude montrent que dans les années 1955, le paysage du PNB et sa périphérie était dominé par la forêt malgré la présence de quelques tâches urbaines. La forêt couvrait une superficie de 5462 ha tandis que la forêt secondaire occupait une surface de 9220 ha. Ces deux formations forestières représentaient près de 90 % du paysage de la zone d’étude. En 1998, 3450 ha de forêt et 434 ha de plantations forestières constituent la végétation du PNB. Bordé de quatre communes, le Parc National du Banco subit les conséquences de l’urbanisation galopante. Cette croissance rapide du district d’Abidjan a engendré de nombreux problèmes environnementaux, notamment la multiplication des quartiers précaires qui bordent le parc au nord, à l’est et au sud, l’insuffisance des équipements et infrastructures de transport, d’assainissement et de logement. Ainsi, le PNB est-il devenu l’exutoire des déchets solides et liquides des ménages abidjanais. Les eaux pluviales communales, notamment à Abobo au nord, Adjamé à l’est et Yopougon au sud sont également évacuées dans le parc. De multiples unités industrielles, des activités informelles et de nouveaux quartiers résidentiels bordent le PNB qui fait déjà face depuis des décennies aux aménagements divers (création d’autoroutes, de voies express, d’infrastructures et d’équipements nécessaires à la satisfaction de la demande urbaine en eau, électricité, etc.). En outre, de nombreuses zones du PNB font l’objet de revendications foncières, notamment le nord-est et le sud du parc. Ces zones contestées se situent dans les villages d’Anonkoua Kouté et de Sagbé au nord, Agban-attié et Agban-village au sud-est, et Andokoi au sud-ouest. Pour répondre aux problèmes liés à l’action des populations dans le PNB et sa périphérie, les gestionnaires ont mis en place une série de mesures alternatives pour améliorer sa conservation. En effet, dans le but de le protéger davantage et de le faire participer au développement économique des populations, ses administrateurs ont mis en place une politique de gestion participative. Cette stratégie permet d’associer les populations locales à sa conservation. L’association de celles-ci à cette gestion communautaire des ressources forestières permet de les responsabiliser en les impliquant dans les missions de surveillance, de valorisation et d’aménagement. La mise en valeur du parc notamment à travers l’écotourisme, le développement d’activités alternatives à l’attention des braconniers et des exploitants illégaux font également partie des nombreuses stratégies mises en place pour sauver cet écosystème menacé. L’écotourisme est ainsi devenu le fer de lance de la politique de gestion participative des administrateurs publics du PNB.Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua Kouté Sagbé and north-Agban Attié and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB