Floristic Composition, Diversity, and Ecology for Conservation of Lower Agno Watershed Forest Reserve, Mountain Province, Philippines

The paper shows the floristic species composition, structure, and diversity, including the ecological importance of the portion of Lower Agno Watershed Forest Reserve. Through quadrat and transect surveys, this study assessed six forest ecosystems, three grassland ecosystems, and five riparian sites. There were 41 tree species, 91 understorey species, 87 ground cover species, and 69 riparian species. Dominant species include Pinus kesiya Royle ex. Gordon, Chromolaena odorata (L.) King, Miscanthus sp., Wikstroemia ovata C.A. Mey ex Meisn, Ayapana triplinervis (Vahl) R.M. King & H. Rob, Leucaena leucocephala (Lam.) de Wit, Saccharum spontaneum L., and Lantana camara L. Forest ecosystems had secondary growth trees with a mean diameter ranging from 17 to 43 cm and mean height of 10 to 18 m. Results showed that the area was moderately diverse, with H' ranging from 2.26 to 2.90 and having a similarity index ranging from 0 to 50%. The site was ecologically important, home to 47 natives, nine endemic, nine internationally threatened, and four nationally threatened species. Regarding soil and plant nutrients, the values obtained were within the normal range for N, P, and K except for Alnus japonica (Thunb.) Steud. which acted as an accumulator with very high Cu content (53 ppm), making it an essential species in rehabilitating areas dominated by highly mineralized soil. Results could serve as baseline information vital in devising conservation and protection strategies to manage better and preserve the site.

Keywords: riparian ecosystem, forest ecosystem, grassland ecosystem, flora, diversity, plant similarity index