PhD defense Danny Dwi Saputra

This thesis explores the potential of agroforestry to support soil recovery from natural and human-induced disturbances while maintaining multifunctionality. Diverse tree species within the cacao-based complex agroforestry were found to enhance root density and soil organic carbon (SOC), ultimately improving soil quality post-deforestation. A process-based model is used to evaluate the performance of cacao-based land-use systems under various scenarios, highlighting their carbon sequestration capabilities and resilience in water-scarce conditions. Furthermore, the impact of volcanic ash deposition on topsoil properties and recovery was examined, emphasizing the advantages of diverse tree species in coffee-based agroforestry. This informs the proposal of a dynamic soil structure-functions model concept for the post-volcanic eruption soil recovery context. The research underscores the roles of surface litter and roots in facilitating SOC recovery and functionality while emphasizing the importance of suitable tree species selection for cacao and coffee-based agroforestry, which are crucial for combating land degradation and promoting sustainable land use practices.