Ndongo Din

Assessing forest products usage and local residents' perception of environmental changes in peri-urban and rural mangroves of Cameroon, Central Africa.

BackgroundDeforestation is one of the most ubiquitous forms of land degradation worldwide. Although remote sensing and aerial photographs can supply valuable information on land/use cover changes, they may not regularly be available for some tropical coasts (e.g., Cameroon estuary) where cloud cover is frequent. With respect to mangroves, researchers are now employing local knowledge as an alternative means of understanding forest disturbances. This paper was primarily aimed at assessing the mangrove forest products usage, along with the local peoples perceptions on environmental changes, between Littoral (Cameroon estuary) and Southern (mouth of the Nyong River and Mpalla village) regions of Cameroon.MethodsThe data from both locations were obtained through conducting household interviews and field observations.ResultsIn the Cameroon estuary (Littoral region), 69.23% of respondents (mostly elders) could distinguish two to four mangrove plants, whereas the informants (65.45%) in the mouth of the Nyong River and Mpalla village (mostly young people interviewed from the Southern region) are familiar with only one or two commonly found mangroves. Also, more respondents from the Cameroon estuary are depending on mangroves for fuelwood (Rhizophora spp.) and housing (Rhizophora spp., Avicennia germinans (L.) Stearn and Nypa fruticans (Thumb.) Wurmb.) purposes, in contrast to Nyong River mouth and Mpalla village. Although local people perceived wood extraction as a greater disruptive factor, there are several causes for mangrove depletion in the Cameroon estuary. Among others, over-harvesting, clear-felled corridors, sand extraction and housing were found important. Furthermore, a decline in mangrove fauna composition (in terms of fishery products) was recorded in the Littoral as well as Southern regions. However, the causes of such perceived negative changes were not similar in both cases.ConclusionsFindings of this study highlight the need to improve sustainable management of the mangrove ecosystems through afforestation (in large impacted areas), selective removal of senescent tree stems and branches (in little damage stands), regulating sand extraction and housing activities, and creating awareness and law enforcement.

Early growth stages and natural regeneration of Avicennia germinans (L.) Stearn in the Wouri estuarine mangroves (Douala-Cameroon).

To strengthen the regeneration and management of Cameroons coastal ecosystems, the biological characteristics of seedlings of Avicennia germinans (L.) Stearn and associated species were analysed from January 1999 to December 1999 in the mangroves under different environmental conditions. Site factors such as temperature, conductivity, salinity and pH were studied in relation to species distribution, and showed significant variation within species. These factors were strongly correlated in the case of A. germinans. The phenology of Avicennia extends throughout the year. Structural parameters of the trees, seedlings and of associated species have been determined. The survey of plant populations shows that A. germinans species represent more than 95% of the total seedlings of the study area, in spite of their variable density. A correlation was found between seedling diameter and height. The intra-specific competition is high and the percentage of seedlings that reach maturity is extremely low (less than1%). Seedlings are over-scattered and weakly aggregated (Green index: GI = 0.023). Floristic diversity is greater and A. germinans zones appear to be the diversification centre of taxa in the mangroves.

Impact of Urbanization on the Evolution of Mangrove Ecosystems in the Wouri River Estuary (Douala Cameroon)

Cameroon mangroves are protected over 20 years by both Management of Forest and Fauna and Environmental Management Legal Framework laws. However, these juridical tools are not efficient in the field regarding the rate of mangrove forest depletion around coastal cities in the country. This work aims to identify the main factors of mangrove degradation and to assess their effects on the dynamics and evolution of this ecosystem in relation with city development. Key abiotic parameters are favorable for mangrove progression. Natural disasters and anthropogenic activities have been identified as responsible of mangrove ecosystems depletion. Wood harvesting, urban settlement and infrastructures, sand extraction, petroleum exploitation, coastal erosion, and climate change appear to be the most important factors of mangrove degeneration. Secondary destructive factors such as dwellings, sustenance agriculture, collection of Non-Timber Forest Products, digging, landfill, dyke construction and large clear-felling also contributed widely to mangrove degradation. The realization of state projects had heavily impacted the evolution of mangroves in the Wouri river estuary. In the absence of law and specific regulation implementation strategies, populations have taken advantage of the authorities’ tolerance to invade all mangroves areas around the Wouri river estuary. The management of Cameroon mangrove ecosystems faced the population conception of considering mangroves as an ordinary forest. Mangrove degradation along the Wouri river estuary does not seem raising advocacy in spite of the fact that this especial ecosystem could never change its coastal nature place like other artificial generated forests.