Abstract:
Structure of the tree communities and their association with edaphic factors were investigated in the limestone forest of Brgy. Tadao, Pasuquin, Ilocos Norte. Tree diversity assessment was performed in 20m by 20m quadrats and habitat variables were collected in each quarter of the quadrat. A total of 226 trees belonging to 56 species (=10 cm) among 30 families were recorded within four sampling sites of the limestone forest. Moraceae had the maximum number of species (5 species) followed by Calophyllaceae, Fabaceae, Lamiaceae, Myrtaceae and Sapindaceae (4 species each). Diversity of tree species in the four sampling sites calculated using Shannon-Wiener index (H’) showed that the highest diversity was in Site 3 (3.096) and the lowest diversity was in Site 2 (2.081). The Simpson’s Indices varied from 0.8240 to 0.9463. The most important species is Podocarpus costalis (IV = 25.26) followed by Syzygium ilocanum (IV = 19.69) and Chionanthus sp. (IV = 17.14). The ten most important species were analyzed using Canonical Correspondence Analysis to determine the association between the edaphic variables and the tree species. It appears that the distribution of tree species was determined by water holding capacity, soil pH and organic matter content.
