Tree Composition, Diversity, and Stand Structure of Mid-montane Forest in Sipit Watershed, Mount Makiling Forest Reserve ASEAN Heritage Park, Philippines

Abstract

This study aimed to establish benchmark data and assess diversity, stand structure, and identify species and habitats that need immediate protection and conservation and monitor ecosystems dynamics through time. A 2-ha long-term ecological research (LTER) plot was established in the mid-montane forest in Sipit Watershed of Mount Makiling Forest Reserve ASEAN Heritage Park (MMFR AHP). Fifty 20 m x 20 m subplots were established from the said 2-ha LTER plot and oriented 100 m north and 200 m east. Trees with diameter at breast height (DBH) of ≥ 10 cm were measured in fifty 20 m x 20 m plots. A total of 1,055 tree individuals belonging to 73 species among 49 genera and 33 families were inventoried. The importance value index (IVI) shows dominant species – namely, Antidesma pleuricum Tul. (40.40), Neolitsea vidalii Merr. (34.14), Palaquium philippense C.B.Rob. (27.77), Micromelum minutum (G.Forst) Wight & Arn. (27.50), and Syzygium barnesii (Merr.) Merr. (16.16). Further, the inventory recorded a total of 11 threatened species thriving in the area and several species suspected to be unique in the area or can only be found abundant therein. The study reveals that the population of P. philippense was maintained intact and preserved within the Sipit Watershed for about a hundred years. Findings also reveal a very high diversity at 3.32 Shannon diversity index with an evenness of 0.28 and relatively high endemism, where 44% (32 species) of the 73 species are endemic. The study is very significant in long-term vegetation dynamics for sustainable management and conservation of protected areas like MMFR AHP, as well as for future research and studies for biodiversity conservation, climate change, and protection of other mountain ecosystems.