Climate change, nutrient pollution, land conversion, overexploitation, and invasive species and diseases – the ‘big five’ global drivers of ecosystem change – are altering biodiversity in the Arctic. Changes in biodiversity have implications for local people since they depend on biodiversity for their traditional activities. Remote Arctic areas lack scientific records of biodiversity status and trends. Indigenous knowledge (IK) can help fill in these information gaps. More importantly, IK is essential to establish policies and practices for biodiversity conservation and sustainable use of biological diversity. This study presents indigenous people’s perceptions of changes and trends in biodiversity in Arctic Yakutia in Northeastern Siberia, Russia. The results document the perception of indigenous people on biodiversity changes at the study sites: new species of plants and animals have expanded their ranges to the north, and the abundance of native species as well as the phenology of plants have changed. IK relates these trends to different global change drivers, assumes that the changes are both naturally and anthropogenically driven, and reflects resulting alterations in species interactions in the forest tundra and tundra ecosystems.