Mangrove forest zonation by using high resolution satellite data
Sr. Suvit Vibulsresth,Dr. Surachai Ratanasermpong,
Dr. Darasri Downreang,Chaowalit Silapathong
Remote Sensing Division,
National Research Council of Thailand
Bangkok 10900
Abstract
Mangrove forest is one of the valuable resources, as a multiple economic, ecological, scientific and cultural resource now and for future generations. It was in 1987 that remote sensing technique was applied in this area and the results from classification of LANDSAT-MSS data were used as base-line information for the mangrove land use zoning into 3 principal zones: Preservation, Economic A and Economic B zones which cover the area of 427 Sq. m 1,997 sq. km and 1,300 sq. km respectively for the whole country.
In this study high resolution data of LANDSAT-TM and SPOT-PLA which can provide more effective information than LANDSAT-MSS, were used for mangrove forest land use zone monitoring. These satellite data were recorded in late 1988. It was found that for the selected test site of Eastern Seaboard of Thailand: 1) The FCC of TM bands 4-5-3/R-G-B with linear seaboard enhancement technique differentiates mangrove forest from other vegetations, 2) SPOT-PLA shows better shrimp farming pattern and built-up area and 3) the combination of TM4-TM5-PLA/R-G-B via digital classification could satisfactory depict the mangrove forest zonation which corresponds to the dominant species.
Introduction
Mangrove forest is one of the most important coastal ecosystems. Since the last 10 years, a number of mangrove forest area has been destroyed mainly by human activities. In Thailand, mangrove forest area was seriously reduced from a total of 2,873 sq, m, in 1974 to 1,964 sq. km in 1986. Therefore in 1988, to alleviate the deterioration situation, the zonation of mangrove forest land use was performed with the aid of LANDSAT-MSS image interpretation. Three zones of mangrove land use were defined as preservation zone, Economic A and Economic B zones, covering areas of 427 sq.km 1,997sq.km and 1,300 sq, km respectively.
However, the zonation of mangrove forest corresponding to species distribution,that is one of the dominant characteristics of mangrove forest has never been successively carried out of LAND-SAT data. In this study, high resolution data of LANDSAT-TM and SPOT-Panchromatic are used to classify. The species zonation of mangrove forest are at Khlung test site in Chanthaburi.
Description of the study area
Khlung, a district of Chanthaburi province, is in the south-eastern Thailand. This coastal zone is predominated by 2 seasons, wet (May-October) and dry (November-April), with the means annual temperature of 26.5 C.
The mangrove forest of Khlung can be classified according to its species distribution into 3 major zones (Vibulsresth, et.al. 1985) as follows (Fig.1) :
- Class I. Dominated by Rhizophoraceace (Rhizophora mucronate, R. apiculata and Bruguiera sp) which are distributed along the coast line and river banks. Some Avicennia sp. Can also be found in the area that the soil is more sandy.
- Class II. This class is dominated by the dwarf pure stand of Ceriops tagal. It is found in the inner zone next to class I where the physical condition is poor with bad soil and long period of flooding. In the transition zone between class I and class II Xylocarpus sp. and Acrostic hum aurum are often found.
- Class III. This class is further inland and is composed of many species such as Lumnitzera spp. Excoeccaria sp. Xylocarpus sp. and Melaleuca leucodendron (on sandy soil) etc. The soil in this zone is more stiff and flooded during exceptionally high tide.
Figure 1 Dominant species zonation of mangrove forest
of khlung, Chanthaburi.
(After Vibulsresth et. al., 1985)
