Montane forests such as those on Mt. Pohen Bali have become increasingly important for conserving Indonesia’s biodiversity. The importance of the tropical montane forest for Indonesia is understandable, considering that much of its tropical lowland forest has been cleared for more than 30 years. However, scientific knowledge in this field is still limited, particularly in volcanic tropical montane forest. Mt. Pohen at Batukahu Nature Reserve is located in a high plateau at the center of Bali Island. Disturbance in this nature reserve mostly originated from anthropogenic activities. Fires, establishment of geothermal mining plant, and over extraction of forest products are some of the threats to this nature reserve. As a result, the trajectory of the ecosystem may have swift to an alternative state where alien invasive species are abundant and tree species decreasing as well as the declining of some native or naturalized species. This book presents research study on the effects and the ecological consequences of disturbances on plant at high-elevation forest. The study is significant in terms of generating useful baseline data for the management of montane ecosystems in this region.