Comparative assessment of the mangrove structure of Nagsaulay, San Juan, Batangas in 2011 and 2017

Abstract

he mangrove ecosystem, despite being one of the most productive ecosystems in the biosphere, continues to be depleted mainly due to different human activities. Thus, regular monitoring is critical in order to reduce the impacts of the rapid decline of the mangrove forests. This study intends to assess the present status of the mangroves in Nagsaulay, San Juan, Batangas by comparing this with an earlier study of the site in 2011. In a 3,700 m2 cumulative area of the three belt transects, six true mangrove species—Rhizophora apiculata, Rhizophora mucronata, Rhizophora stylosa, Ceriops decandra, Avicennia marina, and Sonneratia alba—were identified. While the species currently thriving in the community are still the same as in 2011, a shift in species composition was observed in 2017, wherein the species with the highest importance value changed from R. apiculata to A. marina. Such shift is correlated with the difference in freshwater inputs in 2011 and 2017 and A. marina being euryhaline. Scatter plot diagram showed inconspicuous zonation patterns, with the transects being dominated mostly by A. marina. As a consequence, diversity index was lower in 2017. In the same setting, productivity was lower in 2017 due to smaller leaf area index.