A Map of the Mangroves of Madagascar

An Introduction to the Mangroves of Madagascar: The Historical State of the Ecosystem

The largest area of mangroves in Eastern Africa is found in Madagascar. This area contains 332,000 hectares of mangroves, meaning it covers 3,000 to 4,000 square kilometers of land. Mangrove forests range along the Tsiribihina River, which is one of the largest waterways in the country. This region is between the tropical and subtropical regions of the world. Species of trees, shrubs, or ground ferns that are more than a half-meter high make up the mangrove forests. Rainfall ranges from 750 to 1500 millimeters per year. Unfortunately, the mangroves have started dwindling.

Leah Falcon

Current Human Impacts on the Mangroves

Humans continue to play a large role in the decline of the mangroves of Madagascar. The ecosystem is threatened by urban development, overfishing, and the development of land for agriculture. Also, people have found new agricultural lands for rice and shrimp farming. Mangrove forests provide many benefits for the local human populations, including wood and forest products. The buying and selling of these goods help the coastal communities by contributing to the national economy.

People also affect the ecosystem indirectly through climate change. “As drought and storms reduce local communities’ agricultural production, and ocean acidification and coral bleaching degrade fisheries, people harvest even more mangroves to compensate," notes one source on conservation and sustainable development. "Meanwhile the mangroves themselves are suffering from climate change and can hardly afford the extra harvesting” ("Conservation & Sustainable Development"). Cimate change is also responsible for an increase in storm surges, which

In addition to the ways humans impact the ecosystem, the mangroves also directly impact the local communities. Mangroves act as nurseries for a variety of fish, crustaceans, and mollusks. These micro ecosystems are important for Madagascar’s fisheries, as fishing is one of the country’s primary industries. Climate change is also responsible for an increase in storm surges, which result in a greater number of devastating natural phenomena, like tsunamis and hurricanes. The vegetation of the region acts as a barrier, protecting human lives and property from natural disasters. With mangrove forests declining in Madagascar, there is less vegetation to be a barrier or to host the variety of bird and fish species that are unique to the area.

















Leah Falcon

To Improve and Maintain Positive Human Impacts on the Mangroves

In order to maintain a positive balance between the ecosystem and humans, two strategies emerge. The first is to increase the amount of protected areas within the ecosystem. These protected areas should be multipurpose, focusing on biodiversity conservation as well as improving human welfare. Joint efforts of the World Wildlife Fund, the National Marine Institute, and the National Park Service have set up the New Protected Areas (NPAs), including the Menabe-Antimena protected area. So far these protected areas have been extremely effective. Supporting good site management and reasonable exploitation of site resources, these protected areas improve the overall balance between people and this unique ecosystem.

The second way to maintain positive human impacts on the mangrove ecosystems is to develop various other conservation strategies. These include monitoring and evaluating human activities that affect the mangroves, and increasing awareness and education among local inhabitants of the ecosystem, including the Malagasy people whose lives are tied to the mangrove ecosystem in many ways. Building on local knowledge about sustainable practices for fishing and harvesting the mangrove wood, it is possible to reduce human stresses or and increase the restoration of degraded areas. Additional goals include managing activities that affect mangroves sediment elevation and managing the landward retreat of the ecosystem by replicating it in other protected areas. Using a combination of these strategies, the mangroves of Madagascar will again fall into a category of ecosystems with positive human impacts. 

Mangrove Forest Cover Change in Madacascar from 1975 to 2005

In their 2008 study, Chandra Giri and Joseph Mulhausen used GeoCover Satellite data, in combination with other maps of the mangrove forest area, for the years 1975, 1990, 2000, and 2005 to track and analyze the rate of change of the ecosystem. Using this data, they produced this map showing the extent of the mangrove forests in 2005. 

This satellite data shows dense mangrove areas (dark red) and open mangrove areas (dark green).

Using time series analysis, the researchers then mapped the change over time of the mangroves from 1975 to 2005. They estimated a net loss of 7% for this ecosystem, which is considerably less deforestation than mangrove forests in South and Southeast Asia, which have suffered up to 25% deforestation rates. The rate of deforestation was not uniform through time, nor across the country. 

The Future of the Madagascar Mangroves

 The future prospects of the Madagascar mangroves are not looking too well.  The depletion of these mangroves is not only due to natural disasters, but also due to human impact.  The economic and commercial interests of humans have caused humans to overlook the importance of these mangrove forests.  These tropical environments lack the informative coverage that other ecosystems have about their deterioration. The Madagascar mangroves provide fishing resources and coastal protection to the area.  These mangroves are huge supporters of marine biodiversity.  The closer humans are to this ecosystem, the bigger the impact on these forests.  This is because humans feel compelled to exploit the natural resources that the mangroves have to offer.   Traditionally, it was local communities that managed the mangroves but over time these mangroves have begun to be controlled by state governments. Subsistence fishing was the most common form of fishing, but because of governmental control, these mangroves have adapted a more commercialized form of fishing in order to obtain a higher economic gain and ultimately make these ecosystems more “useful”.  Many coastal mangroves are being destroyed and scientists are not discarding the possibility of the “extinction” of mangroves because they are aware that this is very likely to happen.  But until this happens, people should try their best to value the services and resources that that mangroves have to offer without destroying or exploiting them for economic gain or other less important reasons.

References

Clausen, A., Rakotundrazafy, H., Ralison, H. & Andriamanalina, A. (2010, September). Mangrove Ecosystems in Western Madagascar: an analysis of vulnerability to climate change. Retrieved from http://www.abcg.org/action/document/download?document_id=372.

Cleveland, C. (Ed.). (2014, October 19). Mangrove ecology. Retrieved November 24, 2014, from http://www.eoearth.org/view/article/159955/

Conservation & Sustainable Development. (n.d). Retrieved November 16, 2014, from http://www.macfound.org/press/publications/adapting-to-the-effects-of-climate-change-in-madagascar/

East African mangroves. (n.d.). Retrieved November 23, 2014, from http://www.eoearth.org/view/article/151864

Giri, C. & Muhlhausen, J. (2008). Mangrove Forest Distributionsand Dynamics in Madagascar (1975-2005). Sensors, 2008, 8, 2104-2117. Retrieved from http://www.mdpi.com/1424-8220/8/4/2104.

Giri, C., & Muhlhausen, J. (2008, March 27). Abstract. Retrieved November 16, 2014, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3673408/

Madagascar & Western Indian Ocean office. (n.d.). Retrieved November 16, 2014, from http://wwf.panda.ord/who_we_are/wwf_offices/madagascar/?uProjectID=MG0933

Mangrove Conservation in Western Madacascar: A Vulnerability Assessment. Retrieved from http://wwf.panda.org/who_we_are/wwf_offices/madagascar/?uProjectID=MG0933.

Oceana | Protecting the World's Oceans. (n.d.). Retrieved November 16, 2014, from http://oceana.org/en/explore/marine-places/madagascar-mangroves

Strengthening the Network of 'New Protected Areas' in Madagascar, Notably New Protected Areas with Mangrove Ecosystems. Retrieved from http://addis.unep.org/projectdatabases/01082/project_general_info.

Valiela, I., Bowen, J., (n.d.). BioScience. Retrieved November 25, 2014, from http://bioscience.oxfordjournals.org/content/51/.

Leah Falcon