Density of mangrove trees in selected municipalities in the Province of Antique, Panay Island, Philippines

Abstract

Mangroves line one quarter of the world’s tropical coastlines, and approximately 117 countries and territories have mangrove resources within their borders. Although over recent years mangrove deforestation has occurred at a phenomenal rate worldwide, constant assessment in the Philippines has been made to monitor its current status. To characterize the density of mangrove trees better in Panay Island, surveys were undertaken within the coastal and riverine estuaries in the 11 municipalities of the province of Antique. Detailed records were taken by transect and ocular surveys along 40 barangays with 75 transects and 223 plots established. The mangroves of Antique were composed of 31 species of true mangroves belonging to 14 families and a total of 16 generas. Considerable values in terms of relative density and stems per hectare were found with Nypa fruticans as the highest, with a relative density of 70.372% trees per hectare and an average stem density of 4,457.249 stems/ha. Other significant species included Sonneratia alba (4.534%; 625 stems/ha), Avicennia marina (4.524%; 1,525 stems/ha), and Rhizophora apiculata (4.232%; 50 stems/ha). Close examination of the data suggested the variability of distribution patterns and density to be attributable to the differing responses of individual species to the environmental factors and other human activities. It was also concluded that habitat classification and topography could directly affect mangrove distribution and also capable of altering basic zonation patterns.