Spatiotemporal Analysis of Mining-Induced Vegetation Loss in Homonhon Island Using Normalized Difference Vegetation Index: Possible Impacts on Biodiversity and Community

Abstract. Homonhon Island in Guiuan, Eastern Samar is a historically and ecologically important site that has been subject to mining operations since the 1980s. Being rich in nickel and chromite, there are currently five mineral production sharing agreements in the 104 km² island inhabited by almost 5,000 residents. It is reported to be home to the critically endangered and endemic Philippine cockatoo, plus 72 endemic and 15 threatened plant species based on recent surveys. The almost 50 years of mining in the island resulted in lack of clean water and electricity, dust and noise pollution, reduction of crop yield and fisheries, deforestation, and threat to biodiversity. These alarming effects not only threaten the existence of the island and its current residents, but also pose a serious risk to the future generations. The evolution of the landscape due to the rampant mining activities were analyzed using NDVI on a time series of Landsat images from 1973 to 2024. The results show that about 56% of the land area exhibited overall NDVI decline, implying vegetation degradation or loss. The spatial overlay of the NDVI change results, building polygons, and threatened species illustrates the possible effects of mining areas on humans and biodiversity. The existence of mining tenements in more than 80% of the entire island poses serious threats, necessitating effective and comprehensive action. Geospatial technologies can provide a reliable means of monitoring mining areas, from planning to rehabilitation, to ensure compliance and help mitigate adverse impacts.