Ecology, Environment and Conservation Paper

THE FLORA OF THE LIMESTONE FOREST OF BALADINGAN, TICAO ISLAND, PHILIPPINES

Hilconida P. Calumpong

Abstract

About 110 ha of limestone forest in Baladingan, Ticao Island, Philippines were surveyed in 2010 using the transect plot method wherein 61 tree species in 32 families, six of which were previously listed, and an additional 10 non-tree species, were recorded. Twenty three species are endemic; half of which were reported endemic only to Ticao and only seven were encountered during this survey. Nine species in five families are introduced; 10 species in 7 families are endangered. Tree density ranged from 300 trees/ha to 2800 trees/ha with an average of 1771+364 trees/ha; highest density was in G2-forest contributed mostly by Rutaceae and Euphorbiaceae. In terms of tree size, biggest trees (DBH of 180 cm) were found in Antipolo. Stand BA for the 15 sites surveyed ranged from 15.62 m2/ha to 74.37 m2/ha with an average of 35.25+ 15.78 m2/ha with Plot 6 of limestone forest (LF) having the highest SBA of 74.37 m2/ha while Plot 7 of LF and Plot 2 of Sawang Forest having the lowest with 15.62 m2/ha. Seedlings and saplings of 54 species, 36 seedlings species and 44 saplings species, were seen with highest density observed in the Sawang forest (240/m2) contributed mostly by Diospyros maritima while highest density of sapling was found in Plot 3 of LF (57.5 +5.2 saplings/100m2) contributed mostly by Leucosyke capitellata and Diospyros ebenum. Based on the number of trees, Plot 1 of LF has the highest Diversity Index (H’=3.2073) and consequently, the lowest Index of Dominance (c=0.0572) while Plot 2 of G forest has the highest c (0.684) and consequently, the lowest H’ (0.7071). The limestone forest is the major source of water for the Monreal area and a source of construction materials and firewood for the residents. The major threat to the forest is fragmentation due to coconut plantation, agriculture, cattle grazing and human settlement. It is strongly recommended that the three remaining fragments of primary limestone forest be protected.