Biosphere Reserves are one of the main policy instruments for protecting areas of high ecological value. However, more information is needed about land use/cover changes within Biosphere Reserves, specifically considering dynamics in their core, buffer, and transition zones. This study aimed to analyse the dynamics of land use/cover change between 1961 and 2018 and assess future changes from 2018 to 2034 in part of the Araucarias Biosphere Reserve located in south-central Chile. Land use/cover maps were obtained through photointerpretation of aerial photography and satellite images. Land use/cover transitions, gains, losses, and net changes were then calculated for the periods 1961–1974, 1987–2002, and 2002–2018. Futures changes until 2034 were simulated using Markov chains and cellular automata. Results showed that between 1961 and 1987, 95% of the study area remained stable, with small changes associated with the succession of natural vegetation and the abandonment of areas dedicated to crops and livestock. However, between 1987 and 2018, an increased in anthropogenic activity contributed to two wildfire that affected large areas of old-growth forest in the core and buffer zones. The results indicate that the conservation of the core area of the biosphere reserve is threatened by the lack of territorial planning instruments to organise the activities carried out in the buffer and transition areas of the Biosphere Reserve. In the absence of new wildfires, most of the natural vegetation may recover through natural or assisted ecological restoration.