Rhodieleen Anne de la Cruz, Marianne Ganzon, Romeo Belonio III (January 19, 2002)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
The community structure of two pioneering mangrove communities in Baguingin, Tigbauan, Iloilo a regenerating site (Site 1) and a newly colonized site (Site 2) was compared in terms of c) basal area, a) diversity, b) relative frequency, d) relative density, and el relative dominance of species using the Transect Line Plots Method. The number of trees, saplings and seedlings per species were counted in four 100m², 50m² and 4m quadrats, respectively, established along the transect in site i, and in two sets of same sized quadrats in site 2. The girth of mangrove trees at breast height (DBH) in the 100m quadrats were also measured to compute for basal area as estimate of aboveground biomass of the plants. Physico-chemical conditions of the study sites were described in terms of: a) soil salinity, b) soil pH, c) soil temperature, and el soil particle size composition.
Five mangrove species were observed in the regenerating mangrove community, namely: Sonneratia alba, Avicennia marina, Excoecaria agallocha, Lumnitzera racemosa and Bruguiera cylindrica. Three mangrove species were found in the newly colonized mangrove site, namely: Avicennia marina, Excocaria agallocha and Lumnitzera racemosa. Species diversity was low in both sites, but was slightly higher in site 1 (H= 0.3918) than in site 2 (R -0.3436). The total number of trees and saplings (123/400m² and 380/400m, respectively) were higher in site 1 than in site 2 (50/400m² and 144/400m², respectively). The number of seedlings however was threefolds higher in site 2 (17,350/400m²) than in site 1 (6,350/400m²). Total basal area was higher in site 1 (303.93cm² 100m²) compared with site 2 (107.63cm² 100m²). and saplings, as well as The of trees, seedlings the relative frequency and dominance were highest for Avecennia marina in site 1. In site 2, the number of trees and saplings were highest for Lumnitzera racemosa but the number of seedlings as well as the relative dominance and frequency were highest for Avecennia marina. Physico-chemical conditions in the two sites did not vary widely. Soil temperature ranged from 28-31 °C, soil pH from 6-9 units, and soil salinity from was 2-10 ppt. Soil 528-628 coarse sand, 228-338 fine sand and 14%-16% and clay.