Climatic niche and potential climate-driven range shifts of cushion plants in mountain regions worldwide

Cushion plants are key ecosystem engineers in alpine environments and a classical example of functional convergence across mountain systems worldwide. As cold-adapted species, they are expected to be highly sensitive to ongoing climate change. However, a comprehensive global assessment of their realized climatic niches and potential future range dynamics has been lacking. Here, we used a worldwide dataset of cushion plant occurrences to analyse realized climatic niches in different parts of the world, identify the key environmental factors determining cushion species distributions, and assess how climatically suitable areas may shift under future climate change.
Our analysis focused on five mountain regions representing major biodiversity hotspots for cushion plant species, the Andes, the European Alps and Pyrenees, the Himalaya, New Zealand and Tasmania, and the North American Cordillera and included 24,237 records representing 188 species. Using bioclimatic variables from CHELSA 2.1 for present (1981 - 2010) and future (2071 - 2100) climates, complemented with soil pH and topographic data, we quantified realized climatic niches via PCA and evaluated niche equivalency and similarity among regions. Additionally, we developed ensemble species distribution models using pseudo-absences sampled with a target-group background approach to infer key environmental drivers and project climate-driven shifts in suitable habitat.
Preliminary results reveal that cushion plants occupy markedly different climatic spaces across mountain regions, with the strongest niche similarity between species of the Himalaya and the North American Cordillera. We will further present results from SDMs, including projected changes in climatically suitable areas under future scenarios, providing new insights into the vulnerability and potential redistribution of cushion plant species under global warming.