Abstract:
The vegetation of the Lower U Minh is an important ecosystem as it contributes to preserrve the nature while providing many bebefits. It is also used as an excellent indicator for identifying early signs of ecosystem change in the entire area. In order for that, however, an effective method should be used to re-evaluate the change occurred during the past years. Use of remote sensing is the most effective method that serves for this purpose which was also used in the present study. In order to identify the vegetation change over a 40 years of time since 1975, three Landsat (TM) satellite images (1975, 1995 and 2015) were taken to develop the base maps which were then compared to identify the vegetation change of the national park. Using the base maps, six different vegetation types were identified using unsupervised and supervised classifications to build vegetation classification map with an overall accuracy of 86.33% and a kappa coefficient of 0.81. The results showed that multi-temporal Landsat images with the average resolution bear the ability to assess the vegetation coverage changes. Though the total extent of the National Park has not been changed during the study period, the extents of its vegetation types changed in different manners. The grass cover changed from 155.57 ha in 1975 to 643.24 in 2015 while extent of water changed from 315.24 ha to 194.92 ha during the same period. The extents of the grass cover and water were 884.95 and 697.60 ha respectively in 1995. The Melaleuca forest cover of different ages was also changed in significant manner during the study period.
