Tropical mountain forest frontier landscapes are increasingly target of protected areas (PAs) implementation, in many cases to secure the supply of globally demanded ecosystem services (ES). However, whether PAs manage to achieve their objectives is not always clear, nor are the implications of PA establishment for the supply of ES relevant for local populations. To address these knowledge gaps, we assess the year-to-year supply of six stakeholder-relevant ES across ES categories in two forest frontier, mountainous landscapes in the periphery of PAs in north-eastern Madagascar. As ES most relevant to local populations, we assess food crops production, flood control and bequest value. As globally-demanded ES, we evaluate export cash crops production, global climate regulation and existence value. Our results suggest that PA implementation managed to stem on-going losses of global climate regulation and existence value, but at the expense of also driving decreases in food crops production and bequest value supply to local populations. While our findings are encouraging for global conservation objectives, they also highlight the stark costs local populations might incur under PA establishment, and thus the need to assure that local livelihoods and well-being, including cultural dimensions, are not undermined by conservation interventions.
