Floral composition and diversity of ultramafic forests in Homonhon Island, Eastern Samar, Philippines

Abstract

The Philippines has suffered tremendous deforestation due to rampant anthropogenic impacts such as mining. In particular, the forests of Homonhon Island are threatened by mining activities. In this study, we assessed its ultramafic vegetation's floristic composition and diversity to initiate its conservation efforts on Homonhon Island. In five sampling areas on the island, we have documented 181 species in 148 genera and 83 families, with 176 native species. Twenty-two species are classified as threatened based on the International Union for Conservation of Nature. On the other hand, in DENR-DAO 2017-11, 38 species are classified as threatened. Homonhon Island exhibits a very high species diversity overall, and the forests in Barangay Bitaugan revealed the highest species diversity among the sampled areas. Alstonia macrophylla and Terminalia surigaensis chiefly dominates the island's forests. Despite being threatened by mining, Homonhon Island's ultramafic forests exhibit a diverse floristic composition worthy of protection. It serves as a sanctuary for many of the Philippines' highly threatened species. Its local government agencies should implement strict protection and management policies to prevent further disturbance to its flora. We can anticipate this study to be used in the restoration, rehabilitation, and conservation of the remaining forests on the island.