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Undergraduate Special Problem

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    Mangrove community structure survey in Iloilo River
    Bayate, Bryna Kimberly L. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2004-04)
    Mangroves are highly productive forests growing along tropical tidal mudflats and shallow water coastal areas where water is generally brackish. The structure of the mangrove stand in the Iloilo River was studied using the transect line plot method with 55 plots established in the 3 out of 4 stations of the river. Community Structure is described in terms of the following parameters: basal area, stems per hectare, relative density, relative frequency, relative dominance and importance value of the species and the Shannon Index of Diversity. Variations in these parameters are correlated with certain physico-chemical factors- soil and water temperature, soil and water pH, and water salinity.Nineteen(19) true mangrove species were found in the area belonging to 10 families. These include Mysinaceae family represented by Aegiceras corniculatum ; Avicenniaceae family represented by Avicennia alba, Avicennia marina, Avicennia officinalis and Avicennia rumphiana; Euphorbiaceae family represented by Excoecaria agallocha; Sterculiaceae family represented by Heritiera littoralis; Combretaceae family represented by Lumnitzera racemosa; Palmae family represented by Nypa fruticans; Rhizophoraceae family represented by Bruguiera cylindrica Rhizophora apiculata, Rhizophora mucronata, and Rhizophora stylosa; Sonneratiaceae family represented by Sonneratia alba, Sonneratia caseolaris, and Sonneratia ovata.Ruciaceae family represented by Scyphiphora hydrophyllacea and Meliaceae family represented by Xylocarpus granatum, and Xylocarpus meckongensis. Avicennia officinalis has the highest total basal area of 650.69m2/ha, Avicennia alba, Aegiceras corniculatum, Avicennia marina, Avicennia officinalis, Avicennia rumphiana, Exoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora mucronata, Rhizophora stylosa, Sonneratia alba and Xylocarpus moluccensis have equal relative frequency of 0.074. Avicennia marina obtained the highest stems per hectare with a value of 38933.33, relative density of 0.405 relative dominance of 0.332 and importance value of 0.913. The index of diversity is 1.010, indicating that the area is diverse.
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    Density of mangrove trees in selected municipalities in the Province of Antique, Panay Island, Philippines
    Arelis, Ian Jerwin C. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2006-03)
    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.