Relationship between environmental factors and structure of mangrove forest at protected zone of Mui Ca Mau National Park, Vietnam

The Mui Ca Mau National Park in Vietnam is a coastal ecosystem consisting of Protected Zone, Marine Conservation and Buffer Zone. Over the years, patches of mangrove communities have evolved in the Protected Zone. The formation of community patches may be a reflection of the variability of the environmental factors prevailing in the habitat at National Park. This study was conducted in order to understand the relationships of mangrove forests and their environment in Cau Mau National Park. Eight sampling sites representing eight ecological communities were selected along gradients from the seashores to the inlands of the Protected Zone. At each sampling sites, two transects perpendicular to each other were laid out from which mangrove plant samples were taken. Samples of soils and surface water were taken from each sampling sites for physico-chemical analysis of abiotic variables. Species of aquatic animals were recorded from interview of people who are collecting unprohibited mangrove species. Policies on protected areas in Vietnam were secured from the Forest Protection and Management Board of Mui Ca Mau National Park. All these baseline data were subjected to statistical analysis. Results show at least 10 mangrove plant species are present in the Park and about 95 percent of which consists of Rhizophora apiculata, Avicennia alba, and A. officinalis. At 79.24 percent similarity coeficients, three distinct zones emerged out of 8 patches. These are: Southeastern Coast Zone dominated by R. apiculata and A. alba; Western Coast Zone dominated by A. alba and A. officinalis; and Inland Zone with R. apiculata, A. alba, Bruguiera parviflora as the dominant species. The floristic abundance at Ca Mau National Park is largely determined by the pH of dry soil, percentage sand and compaction of the soil. There were 8 dominant animal species found in the Park. Their presence is favored by the combination of 4 physical variables, namely, soil compaction, organic matter, total nitrogen, and tidal inundated times, and by the abundance of Bruguiera sexangula and R. apiculata mangrove species. Government policies on protected areas may have contributed to the stability of the National Park in at least two areas. The first one is on the strict enforcement of the law prohibiting poaching inside the park. Second, the establishment of the Buffer Zone prevented the influx of poor farmers to the Protected Zone. The implications of these findings to the environmental management of the Park have been discussed.