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

Abstract

Background: Deforestation 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 people's perceptions on environmental changes, between Littoral (Cameroon estuary) and Southern (mouth of the Nyong River and Mpalla village) regions of Cameroon.

Methods: The data from both locations were obtained through conducting household interviews and field observations.

Results: In 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.

Conclusions: Findings 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.

Figure 1

Map showing the location of study area and the seven selected sites.

Figure 2

Photographs illustrating different mangrove uses in Cameroon: (A) Mangrove poles obtained from Rhizophora spp. are used for fish smoking ready to sell in the local market (Youpwe). (B) Use of Rhizophora small timber for precarious house building at Youpwe. (C) N. fruticans leaves used for walls covering at Epassi. (D) 'Shuttle' crafted from Rhizophora prop roots at Mpalla village (Kribi). (Photographs by ANA).

Figure 3

Mangrove land degradation in Cameroon: (A) Sand extraction within mangrove forest. The background shows uncut sparse adults trees. (B) Elevated areas of previously cleared mangrove stands waiting for housing. (C) Clear-felled corridor within the mangrove used for wood transport or as access path. (D) Complex of cut branches and prop roots (Rhizophora spp.) left in situ. (Photographs by ANA).

Figure 4

Principal Component Analysis of the perceived causes of mangrove degradation. It can be observed that each sample site in the Cameroon estuary (i.e., Epassi, Youpwe and Bois de Singes) is located close to its major degradation threat perceived. Nevertheless, the four sites on the top right corner (Mpalla, Milende, Bwabe and Ngueh) are seen less influenced by those four recognized mangrove threatening factors. Each star indicates the position of its respective sampling site in the PCA plane with reference to the perceived causes of mangrove degradation. The length of each vector line represents the importance of that particular variable's contribution to the PCA axis. The circle represents the graphical illustration of the correlation between the variables and the principal components. (This analysis does not take into account data obtained from field observation).

Figure 5

Flow chart showing the causes of mangrove degradation as well as remedies (conceptual proposals) for its proper conservation and management strategies in Cameroon. Each source of information is represented by different types of arrows. The causes as well as consequences of large (Littoral region) or little (Southern region) degradation of mangrove forests are also differentiated.