Mangrove Forest Distributions and Dynamics in Madagascar (1975–2005)
Open Access
- 26 March 2008
- Vol. 8 (4), 2104-2117
- https://doi.org/10.3390/s8042104
Abstract
Mangrove forests of Madagascar are declining, albeit at a much slower rate than the global average. The forests are declining due to conversion to other land uses and forest degradation. However, accurate and reliable information on their present distribution and their rates, causes, and consequences of change have not been available. Earlier studies used remotely sensed data to map and, in some cases, to monitor mangrove forests at a local scale. Nonetheless, a comprehensive national assessment and synthesis was lacking. We interpreted time-series satellite data of 1975, 1990, 2000, and 2005 using a hybrid supervised and unsupervised classification approach. Landsat data were geometrically corrected to an accuracy of ± one-half pixel, an accuracy necessary for change analysis. We used a postclassification change detection approach. Our results showed that Madagascar lost 7% of mangrove forests from 1975 to 2005, to a present extent of ~2,797 km2. Deforestation rates and causes varied both spatially and temporally. The forests increased by 5.6% (212 km2) from 1975 to 1990, decreased by 14.3% (455 km2) from 1990 to 2000, and decreased by 2.6% (73 km2) from 2000 to 2005. Similarly, major changes occurred in Bombekota Bay, Mahajamba Bay, the coast of Ambanja, the Tsiribihina River, and Cap St Vincent. The main factors responsible for mangrove deforestation include conversion to agriculture (35%), logging (16%), conversion to aquaculture (3%), and urban development (1%).Keywords
This publication has 14 references indexed in Scilit:
- A World Without Mangroves?Science, 2007
- Global carbon sequestration in tidal, saline wetland soilsGlobal Biogeochemical Cycles, 2003
- Standardizing the calculation of the annual rate of deforestationForest Ecology and Management, 2002
- Mangrove Forests: One of the World's Threatened Major Tropical EnvironmentsBioScience, 2001
- A near-real time forest-cover map of Madagascar derived from SPOT-4 VEGETATION dataInternational Journal of Remote Sensing, 2000
- Origins of mangrove ecosystems and the mangrove biodiversity anomalyGlobal Ecology and Biogeography, 1999
- Mangrove mapping in North-Western Madagascar using SPOT-XS and SIR-C radar dataHydrobiologia, 1999
- A remote sensing based methodology for mangrove studies in MadagascarInternational Journal of Remote Sensing, 1998
- Use of mangroves by traditional fishermen in MadagascarMangroves and Salt Marshes, 1997
- Image reconstruction by parametric cubic convolutionComputer Vision, Graphics, and Image Processing, 1983