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the exploitable areas were detected, trees were felled in a radius of several hundreds
meters. The waterways are being diverted or simply blocked. The immediate consequence is the drying of all the area to be harvested and also the whole rear portion
which was fed by these pathways. Mangrove characteristic species are very sensitive to daily flooding by tides; stopping the water flow always triggers in short term,
the degeneration of the forest composition and structure.
Sandpits change the structure and physiognomy of mangrove ecosystems.
Attempts to regenerate mangroves observed in many quarries show that the
destruction of mangrove forests due to this activity may be reversible if brackish
water supply is restored degraded substrates. The new progressive series is always
lead by Nypa fruticans but had never evolved to a climaxic mangrove forest.
3.4.3 Landed Distribution
Mangrove forests are experiencing long-term and severe decline (Valiela et al. 2001;
Alongi 2002). The causes of such losses include the coastal land-use development
leading to losses due to over-harvesting (Walters et al. 2008; Nfotabong-Atheull
et al. 2009), expanded agriculture (Hossain et al. 2009), and conversion into shrimp
farming ponds (Guimarães et al. 2010), to name but a few. From 1974 to 2009, mangrove forest area had decreased 53.16% around Douala concurrent with a substantial
increase of settlements (60%), roads (233.33%), agriculture areas (16%), non-mangrove areas (193.33%), and open water (152.94%) (Nfotabong-Atheull et al. 2013).
Deforestation appears to be 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.
While the drivers causing this depletion/deforestation vary from one region to
another, there is a general consensus that anthropogenic activities are the root drivers of this change. In addition, while the dilemma of mangrove ecosystem conversion for aquaculture is recognized as the greatest threat to mangrove forests, globally
pollution, agriculture and urbanization seem to be making headway among developing countries. Furthermore, exploitation of mangroves for fuel wood, charcoal production, construction, and other uses have been identified as an important pervasive
and intrusive threat to this ecosystem (Dodman et al. 2006), particularly within
coastal developing countries, where local communities depend on the exploitation
and use of these resources for their livelihoods (Focho et al. 2001).
Douala is the first most populous city in Cameroon, with a population that grew
rapidly from 1,352,833 inhabitants in 1987 to 2,510,263 people in 2005 (Cameroon
National Institute of Statistics 2009). The characteristic urban anarchic development, accompanied by demographic pressure in the peri-urban areas and emphasized by increase in poverty contributed hardly to forest depletion. This growth rates
indicate an intense human pressure on the urban landscape. This expansion was
therefore the driving factor for the “colonization” of new lands in spite of their
physically hostile nature (Fig. 3.11).
3 Impact of Urbanization on the Evolution of Mangrove Ecosystems…
the exploitable areas were detected, trees were felled in a radius of several hundreds
meters. The waterways are being diverted or simply blocked. The immediate consequence is the drying of all the area to be harvested and also the whole rear portion
which was fed by these pathways. Mangrove characteristic species are very sensitive to daily flooding by tides; stopping the water flow always triggers in short term,
the degeneration of the forest composition and structure.
Sandpits change the structure and physiognomy of mangrove ecosystems.
Attempts to regenerate mangroves observed in many quarries show that the
destruction of mangrove forests due to this activity may be reversible if brackish
water supply is restored degraded substrates. The new progressive series is always
lead by Nypa fruticans but had never evolved to a climaxic mangrove forest.
3.4.3 Landed Distribution
Mangrove forests are experiencing long-term and severe decline (Valiela et al. 2001;
Alongi 2002). The causes of such losses include the coastal land-use development
leading to losses due to over-harvesting (Walters et al. 2008; Nfotabong-Atheull
et al. 2009), expanded agriculture (Hossain et al. 2009), and conversion into shrimp
farming ponds (Guimarães et al. 2010), to name but a few. From 1974 to 2009, mangrove forest area had decreased 53.16% around Douala concurrent with a substantial
increase of settlements (60%), roads (233.33%), agriculture areas (16%), non-mangrove areas (193.33%), and open water (152.94%) (Nfotabong-Atheull et al. 2013).
Deforestation appears to be 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.
While the drivers causing this depletion/deforestation vary from one region to
another, there is a general consensus that anthropogenic activities are the root drivers of this change. In addition, while the dilemma of mangrove ecosystem conversion for aquaculture is recognized as the greatest threat to mangrove forests, globally
pollution, agriculture and urbanization seem to be making headway among developing countries. Furthermore, exploitation of mangroves for fuel wood, charcoal production, construction, and other uses have been identified as an important pervasive
and intrusive threat to this ecosystem (Dodman et al. 2006), particularly within
coastal developing countries, where local communities depend on the exploitation
and use of these resources for their livelihoods (Focho et al. 2001).
Douala is the first most populous city in Cameroon, with a population that grew
rapidly from 1,352,833 inhabitants in 1987 to 2,510,263 people in 2005 (Cameroon
National Institute of Statistics 2009). The characteristic urban anarchic development, accompanied by demographic pressure in the peri-urban areas and emphasized by increase in poverty contributed hardly to forest depletion. This growth rates
indicate an intense human pressure on the urban landscape. This expansion was
therefore the driving factor for the “colonization” of new lands in spite of their
physically hostile nature (Fig. 3.11).
3 Impact of Urbanization on the Evolution of Mangrove Ecosystems…