Mapping mangrove changes in the Matang Mangrove Forest using multi temporal satellite imageries

The Matang Mangrove Forest is the largest single mangrove forest in Peninsular Malaysia, covering an area of more than 40,000 ha. As a national treasure, it lies under the jurisdiction of both the federal and state authorities. Monitoring temporal changes of mangrove area on a large scale requires a more efficient tool. Remote sensing is often a reliable alternative to ground-survey methods that provides useful source of information and coverage that is timely and complete especially in mangroves areas where accessibility is difficult. In this study, status and changes of land use and land cover in the Matang Mangrove Forest during the past 18 years (1993–1999, 1999 to 2011 and 1993 to 2011) were determined using multi temporal satellites, and threats to the ecosystems were also identified. Classification of land use and land cover approach was implemented using the maximum likelihood classifier (MLC) along with vegetation index differencing (NDVI) technique. Classification accuracy at 85.7%, 90%, and 88.9% with Kappa statistics of 0.82, 0.88, and 0.94 respectively for 1993, 1999 and 2011 image were obtained. The overall change in the area during the 18-year period indicated the loss of mangrove area at 8017.3 ha, while 2998 ha was newly planted or rehabilitated. The present study revealed that Rhizophora apiculata and Rhizophora mucronata are still being preserved, accounting to more than 80% of the total species. Temporal changes of the mangrove for the 18-year period showed that the mangroves were converted to water bodies at 31.1%, dry land forest at 30.6%, oil palm plantation at 18.9%, aquaculture at 11.1%, paddy plantation at 4.9%, horticulture at 3.1%, and urban settlement area at 0.3%. Threats towards the mangrove area were due to erosion, tree harvesting rotation, transitional forest, shrimp ponds, illegal agricultural activities and trespassing. The findings indicated an approach in collecting regular and appropriate mangrove forest area database and detection of activities that violate regulations. This will provide adequate information to the stakeholders in enhancing the management practise and for legislative purposes. Hence, combinations of these approaches has been proven to be adequate in detecting changes in the mangrove area and indicating the nature of the changes which will promote and enhance the management planning process towards sustainability of the Matang Mangrove Forest.