Tree Species Diversity and Stand Structure in Selected Forest Patches of Marilog Forest Reserve, Southern Philippines

Tree species diversity and stand structure investigations were conducted in the forest patches of Barangay Baganihan (site 1) and Mt. Malambo in Barangay Datu Salumay (site 2), Marilog District, Southern Philippines. Thirty-three 20 × 20 m plots were established at 1,197-1,345 masl in the sites. A total of 900 individuals belonging to 33 families, 43 genera, and 65 species of trees were recorded. Analyses of data revealed that the two sites could be categorised as montane forests based on the forest structure and species composition. Palaquium philippense (Perr.) C.B. Rob., Syzygium tula (Merr.) Merr., and Astrocalyx calycina (S.Vidal) Merr. obtained the highest species importance value index in site 1, while Palaquium sp., P. philippense, and Lithocarpus caudatifolius (Merr.) Rehder in site 2. Shannon-Weiner indices (H’) in sites 1 and 2 are relatively low with H’ = 1.22 and H’ = 1.38, respectively. A total of eight threatened species were recorded, viz., A. calycina as endangered; Agathis philippinensis Warb., Becarianthus pulcherrimus (Merr.) Maxw., Camellia lanceolata (Blume) Seem., Dillenia megalantha Merr., P. philippense and Shorea contorta S.Vidal as vulnerable; and Cinnamomum mercadoi S.Vidal as other threatened species. A total of 14 endemic species of trees were also recorded in the study sites. The biodiversity in the two sites is under severe threat due to the different anthropogenic disturbances. A new population of A. calycina, a monotypic genus in the Philippines, was collected and the flowers were documented for the first time after a century. The present study is significant since it would help elucidate the patterns of tree species composition and diversity in the forest patches of Barangay Baganihan and Mt. Malambo in Barangay Datu Salumay. Further, this paper adds to the rich biological diversity in Mt. Malambo by supporting its great potential as an ecotourism site.