Habitat preferences, spatial distribution and current population status of endangered giant flower Amorphophallus titanum

Amorphophallus titanum is endemic to Sumatera and increasingly threatened in the wild by unsustainable harvesting, rapidly changing land cover, and global climate change. Management of this species requires better information on the habitat requirements, its population status and spatially explicit assessments of risk factors. Field surveys and historical records were used to characterize the distribution of A. titanum in Sumatera. Habitats were characterized using topography, soils, climate and land cover variables. An ensemble machine learning model using Random Forest and Artificial Neural Network techniques found that slope and distance to the nearest river are the two most important variables associated with the occurrence of A. titanum in Sumatera. The plant species associations of A. titanum are very diverse. Soil aeration and good drainage are key factors for the species, both in natural environments and in cultivation. Land cover change and climate change scenarios predicted significantly reduced suitable geographic distribution by 2070. Population hot spots were identified in Sumatera Utara (North Sumatera) and the Southern part of Aceh. Potential threats at occurrence points were evaluated using the Analytic Hierarchy Process (AHP) method. Human pressures, particularly harvesting and land conversion, are the main threats to the A. titanum populations. Most of the predicted suitable habitat areas of this species are located outside of conservation areas. Very few mature individuals were found in this study with local populations dominated by seedlings and juveniles. Based on the IUCN criteria, the conservation status of the endemic A. titanum in Sumatera is endangered with criteria EN A2cd+3 C, C2a(i).