Abstract ID: 3.12377 | Accepted as Talk | Talk/Oral | TBA | TBA

Mountain ecosystems are particularly vulnerable to climate change and experience temperature increases that are above the global average. The recent warming has already led to an upward shift in plant species’ elevational ranges, but these shifts are much slower than expected based on elevational temperature lapse rates. It is unclear, however, whether the lag times indicate the inability of species to track the changing climate, and hence an accumulating extinction debt and colonization credit, or whether they hide micro-scale adaptation, with species shifting to nearby cooler microhabitats that buffer them against warming. In this study, we analysed performance data from more than 7,000 individuals of 42 high-mountain plant species, combined with microclimatic measurements at 1 m spatial resolution. Using this data, we built population growth models, which we then projected onto 853 1 m-vegetation plots spanning a 1,700 m elevational gradient in an alpine landscape of the Austrian Alps. Comparing projected population growth rates with current species distributions, we found that species perform best on sites that are, on average, 1.3 °C cooler and 16 days less snow covered than at their current centre of occurrence. This discrepancy suggests that there has been very limited adaptation of species’ distributions to climatic changes of the past decades even when microclimatic variability of alpine terrain is appropriately accounted for. Therefore, even if temperature increase would cease immediately, we would see considerable species turn-over in the long run, with most sampling sites experiencing a potential species turnover of more than 50 % until the end of the century. Predicted lag times to local extinctions vary considerably among species and sites and can extend over several centuries. Our findings highlight that a strong disequilibrium between current climatic conditions and fine-scale distribution of species has emerged in this alpine model landscape over the last decades, even at a very fine spatial resolution. Microclimatic variation has hence hardly helped alpine species to cope with climate warming so far.