Assessing the conservation status of mammals in human-modified landscapes of Sumatra

Tropical biodiversity is under significant threat due to habitat loss, fragmentation, and anthropogenic pressures, particularly in Southeast Asia. While these challenges are complex, it is essential to take action to prevent further biodiversity loss and promote recovery by identifying knowledge gaps in biodiversity studies and addressing these issues through site-specific approaches. In this thesis I provide insights into mammal research in Indonesia and examine the conservation status of medium-large terrestrial mammals in the human-modified landscapes of Sumatra, with the aim to explore strategies to enhance their protection. In Chapter 2, I reviewed 20 years of peer-reviewed English and Bahasa Indonesia literature to reveal knowledge gaps in mammal population and diversity studies in Indonesia. A key finding was the need for robust surveys and scientifically grounded analyses to estimate mammal populations accurately and implement long-term monitoring to assess their status. Three subsequent empirical chapters contribute to addressing these needs. In Chapter 3, in collaboration with multiple stakeholders and leveraging by-catch data from Sumatran tiger research, I updated the occupancy probabilities for the Asian tapir and used the data to predict critical areas or important habitats for the species across Sumatra. Subsequently, I conducted a camera trapping study from October 2021 to January 2023 (survey year 2022) in the Kampar peninsula, a peat swamp landscape encompassing restored forest in the central landscape and Acacia plantation forests on its periphery. In Chapter 4, I focused on the implementation of nature-based solutions (NbS) by the largest land manager in the landscape and assessed the impact on mammal assemblages across four habitat classes: core forest, linear forest remnants, mature Acacia, and young Acacia. I compared species richness in the current landscape configuration with four hypothetical landscape scenarios. The results indicate that the current landscape configuration supports critical areas for mammal groups, highlighting the need to safeguard linear forest remnants and adopt sustainable practices in Acacia plantations that consider mammal conservation. Furthermore, using baseline data from camera trap studies conducted in 2015, 2020 and 2022 within Ecosystem Restoration Concessions (or restored forests) managed by private entities in the central landscape, I compared population statuses through occupancy estimates for both the mammal community and specific species. The 2022 estimates were higher than those of 2015, with variations observed across species. While fluctuations in occupancy estimates were anticipated across the survey periods, I identified signs of a critical decline in the bearded pig, a species previously common with high occupancy estimates in 2015 and 2020 but with no records in 2022. This decline coincided with outbreaks of African Swine Fever, which have significantly impacted both wild and domestic pigs across Southeast Asia, including Indonesia. I recommend the establishment of long-term wildlife monitoring programmes and timely conservation interventions to address emerging threats effectively. Furthermore, I emphasise the importance of fostering this forested area and advocating for its recognition as an Other Effective Area-Based Conservation Measures (OECMs). Such recognition would complement formal protected areas by contributing to forest protection and biodiversity conservation at both national and global levels.