Plant diversity of the Las Pinas-Parañaque critical habitat and ecotourism area, Metro Manila, Philippines (research note)

This study was conducted to highlight the diversity of true, associated, and beach type mangrove and other tree species in the Las Pinas-Paranaque Critical Habitat and Ecotourism Area (LPPCHEA). Information on the distribution and abundance of mangrove and other tree species present in the area is a requisite for its sustainable management. Sampling of mangrove and other tree species was conducted from September to December 2008. A total of 75 plots were randomly established in Long Island (48 plots) and Freedom Island (27 plots). Transect line plot technique was used to assess the tree species. Tree parameters were analyzed through the use of environmental indicators such as relative density, Shannon Diversity Index, and Shannon Equitability Index. A total of 8 true and associated mangrove species and 3 beach type species were identified within the critical habitat. These included Avicennia marina (Forsk.) Vierh, Lumnitzera racemosa Wild. 1803, Sonneratia alba J. Smith, Rhizophora spp., Bruguiera sexangula (Lour.) Poiret 1816, Thespesia populnea (L.) Sol. Ex Correa, Morinda citrifolia L., Excoecaria agallocha Linn. 1759, Acacia farnesiana (L.) Willd, Premna odorata Blanco, and Terminalia catappa L. for beach type species. In terms of density A. marina and Rhizophora spp. had the highest relative density for mature true and associated mangrove and beach type species (58.25% and 18.85%, respectively), while seedlings of A. marina were the highest at LPPCHEA (95.13%), followed by L. racemosaa (1.20%). In the case of saplings, Leucaena leucocephala (Lam.) de Wit had the highest in number at Freedom Island, while A. marina saplings occupied the highest density at Long Island. The computed Shannon Diversity Index H for mature true and associated mangrove and beach type mangrove and other forest tree species was found at 0.602, 0.126 for seedlings, and 0.790 for saplings. Thus, mature forest trees and saplings found in LPPCHEA had more diverse distribution than seedlings. However, in the case of species EH is observed below 0.5. This is true in mature, seedlings, and saplings of true, associated, and beach type mangrove species and other forest tree species. Their values were computed on 0.195, 0.044, and 0.264, respectively.