Floral Diversity Assessment of Mangrove Ecosystems in Masinloc, Zambales

Abstract

The study was conducted to assess the floral diversity of the remaining mangrove stands in the four coastal barangays of Masinloc, Zambales including Brgy. Baloganon, Brgy. Inhobol, Brgy. San Lorenzo and Brgy. San Salvador. The factors that contributed to the present state of mangrove ecosystems were likewise evaluated.

Three 10 x 10 m quadrants were located in each study site. The species composition and the floral diversity of each mangrove ecosystem were analyzed and compared using the following indices: Sahnnon-Weiner Index of Diversity (SHDI), Shannon-Weiner Index of Eveness (SHEI) and Simpson's Index of Dominance.

Sixteen (16) key informants were interviewed using unstructured questionnaire to determine the perceived awareness of the community on mangrove importance, the factors that affect the condition of mangrove ecosystems and the rehabilitation practices and mangrove management initiatives implemented in the area.

Results showed that there were ten major mangrove species belonging to only five families of Rhizophoraceae, Sonneratiacea, Avicenniaceae, Palmae and Combretaceae. Four minor mangrove components and six mangrove associates were also identified. The most common species found in all study sites were Sonneratia alba, Avicennia marina, Rhizophora apiculata and R. mucronata.

S. alba was the most dominant species in Brgy. Baloganon and San Salvador having an importance value of (IV) of 192.86 and 165.02, respectively. A. marina dominated in Brgy. Inhobol (44.27) while R. apiculata recorded the highest IV (99.99) in San Lorenzo.

Among the sites studied, Brgy. Inhobol was the most diverse in terms of mangrove flora composition attaining an SHDI of 0.97, with the highest SHEI and the lowest dominance. Brgy. Baloganon was the least diverse with an SHDI of only 0.28, with the lowest SHEI and the highest dominance.

Generally, Masinloc possessed young mangrove vegetation as indicated by its high percentage of saplings (60.98%). Most of the mature species were within the diameter range of 4.1 – 20.0 cm. S. alba was the only species representing all diameter class and was one of the two species obtaining a dbh of more than 40cm. Mangrove ecosystems in Masinloc are still in their healthy state. Brgy. San Lorenzo (Panglit Island) had the highest percentage of healthy trees (97%) and the lowest percentage of unhealthy (0.62%) and dead trees (2.48%) This was attributed to the low population density of the island, its inaccessibility from human exploitation and proximity to the mountains.

Coastal dwellers, fisherfolks, resort and fishpond owners valued mangroves in terms of resource and regulatory functions particularly in protecting the shoreline, preventing erosion of their establishments, enriching stocks of marine animals, as firewood, as a raw materials for house, pgpen, bridge and fence construction and source of income from the sale of propagules.

Among the identified threats to mangrove ecosystems were the use of sayudsod in catching shrimps, crab harvesting by soil digging, water pollution, coastal development, squatting, continued fishpond development and lack of formal regulations.

Mangrove reforestation activities were found to be a collaborative effort between the government and the Jaime V. Ongpin Foundation, Inc. Currently, there are few and unclear policies with regards to mangrove management in Masinloc.

Of the four sites studied, Brgy. Inhobol should then be given utmost priority in conservation since it possessed the highest mangrove floral diversity. Other areas like San Lorenzo, Baloganon and San Salvador should likewise be protected through formal regulations and introduction of wise pattern of mangrove resource utilization.