Floristic Survey of the Mangrove Vegetation in Barangay Nagsaulay, San Juan, Batangas

Abstract

Mangroves, despite being the most fertile, essential, and productive coastal ecosystems in the world, have become threatened due to increasing developmental activities. Philippine mangroves have declined by more than 50% due to conversion to fish ponds, reclamation for various developments and overexploitation. This rapid degradation has alarmed many to conduct reforestation. However, mangrove forests in the Philippines, particularly in Brgy. Nagsaulay, San Juan, Batangas, lack information that can be used as reference for rehabilitation projects and for its sustainable use. To augment this inadequacy, a survey of mangrove vegetation in the barangay was undertaken. The belt transect method was used to identify and analyze the mangrove vegetation. Population studies were also conducted. The location of the mangroves were obtained using scatterplot analysis. Species richness and diversity were determined using the Simpson’s Index, Shannon and Weiner’s Index, Margalef s Index, and Menhinick’s Index. Productivity of the mangrove vegetation was determined using the light meter method. Associated fauna and prevailing environmental conditions during the time of sampling were also noted. Results show that a total of six (6) species were found in the study site, namely, Rhizophora apiculata Bl., Rhizophora mucronata Lamk., Rhizophora stylosa Griff., Ceriops decandra (Griff.) Ding Hou, Avicennia marina (Forssk.) Vierh. and Sonneratia alba J.E. Sm. Vegetation analysis revealed that Avicennia marina v/as found to be the most dense species while Rhizophora apiculata was found to be the most dominant, most frequent and the most important species. Species richness and evenness of the area yielded low values. The computed net canopy photosynthesis of the mangrove ecosystem yielded a very high value of 9.5589 g C m’2 day'1 or 3,488.9939 g C m'2 yr’1. Abiotic factors such as climate, sediment, and water quality present during time of study, were suitable for the growth and development of mangroves.