dc.description.abstract | Tropical mangrove forests are located in the tropical and subtropical regions, and they connect our land and people with the sea, providing various ecological and socioeconomic services for humans. At the same time, mangrove forests in many parts of the world are declining at an alarming rate-possibly. Monitoring spatiotemporal distribution of mangrove forests is thus critical for natural resource management. Therefore, the research objective are: (i) mapping mangrove forests in the four regions around the world: West and Centre Africa, Southeast Asia, Australia and Central America using Landsat data from 1988 to 2014; (ii) identifying mangrove forests cover change (gain and loss) in three past decades; and (iii) predicting changes of mangrove forests in the future. The data were processed through five main steps: (1) data pre-processing including atmospheric correction and image normalization; (2) image classification using supervised classification approach (Support Vector Machine – SVM); (3) accuracy assessment for the classification results; (4) change detection analysis; and (5) change projection analysis.
In all four cases of study, mangrove area have increased or decreased seriously. In West and central Africa: The loss of mangrove forests from 1988 to 2014 was approximately 16.9%, while only 2.5% was recovered or newly planted at the same time; Australia –Western: the overall changes in the area is decreased of mangrove forests very dramatically (loss about 20.85% of mangrove forests) from 27 years study. And Central America – Gulf of Fonseca: the overall change within the study area during this 26 years indicated the loss of approximately 16.24% of mangrove forest, while a small proportion of mangrove forests in the region (4.32%) was newly planted or rehabilitated while Southeast Asia - in Sundarbans delta: the overall change of mangrove forests was increased approximately 15.3% of total mangrove forests area. The decline of mangroves due to the deforestation, overexploitation, natural catastrophes deforestation and mangrove rehabilitation programs. Urbanization has caused environmental issues including habitat loss, reduction of biodiversity, and increased coastal erosion.
For mangroves change projection, this research was projected changes until 2027 within the in-situ area that was selected in four sites of study by using Probabilistic Landscape Modelling and Simulation Tool (ProLAMS) which integrates the remote sensing data and geographic information data for landscape modeling and prediction by using probabilistic simulation approach. The results shown that the total area of mangrove forests increased a little bit when compared with classification results in 2001 and 2014. However, mangroves area was remain unchanged or slightly decreased in the future. Mangrove prediction result effected by the input variables as well as the parameters used within the model. Thus, institutional or policy interventions may be taken into account to improve management of mangrove forests in the regions. The overall efforts in this study demonstrate the effectiveness of the proposed method used for investigating and predicting the spatiotemporal changes of mangrove forests.
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