Climate change is associated with a higher extinction risk of a subshrub in anthropogenic landscapes

Abstract

1. In most ecosystems, the increasingly strong effects of climate change on biodiversity co-occur with other anthropogenic pressures, most importantly land-use change. However, many long-term demographic studies focus on populations monitored in protected areas, and our understanding of how climate change will affect population persistence under anthropogenic land use is still limited. 2. To fill this knowledge gap, we assessed the consequences of co-occurring land-use and climate change on vital rates and population dynamics of a fire-adapted Mediterranean carnivorous subshrub, the dewy pine (Drosophyllum lusitanicum). We used 7 years of individual data on 4753 plants monitored in three natural heathland sites that experience primarily fire as a disturbance, and five anthropogenic sites, where fires have been replaced by persistent disturbances from browsing or mechanical vegetation removal as a consequence of land-use change. All sites are projected to experience increasingly hotter summers and drier falls and winters. We used generalised additive models to model non-linear responses of survival, growth and reproduction to rainfall, temperature, size, density and time since fire in anthropogenic and natural dewy-pine populations. We then projected population dynamics under climate-change scenarios using an individual-based model. 3. Our findings reveal that vital rates respond differently to climate change in anthropogenic compared to natural habitats. While extinction risks did not change under climate change in natural habitats, future higher summer temperatures decreased survival and led to population declines and higher extinction probabilities in anthropogenic habitats. 4. Synthesis. Our results highlight the possible dramatic effects of climate change on populations largely confined to chronically disturbed, anthropogenic habitats and provide a foundation for devising relevant management strategies aiming towards the protection of species in human-disturbed habitats of the Mediterranean habitat. Overall, our findings emphasize the need for more long-term studies in managed landscapes.