LAUSR

Mountain ecosystems are exposed to multiple anthropogenic pressures that are reshaping the distribution of plant populations. Range dynamics of mountain plants exhibit large variability with species expanding, shifting, or shrinking their elevational range. Using a dataset of more than 1 million records of common and red-listed native and alien plants, we could reconstruct range dynamics of 1,479 species of the European Alps over the last 30 y. Red-listed species were not able to track climate warming at the leading edge of their distribution, and further experienced a strong erosion of rear margins, resulting in an overall rapid range contraction. Common natives also contracted their range, albeit less drastically, through faster upslope shift at the rear than at the leading edge. By contrast, aliens quickly expanded upslope by moving their leading edge at macroclimate change speed, while keeping their rear margins almost still. Most red-listed natives and the large majority of aliens were warm-adapted, but only aliens showed high competitive abilities to thrive under high-resource and disturbed environments. Rapid upward shifts of the rear edge of natives were probably driven by multiple environmental pressures including climate change as well as land-use change and intensification. The high environmental pressure that populations encounter in the lowlands might constrain the ability of expanding species to shift their range into more natural areas at higher elevations. As red-listed natives and aliens mostly co-occurred in the lowlands, where human pressures are at their highest, conservation should prioritize low-elevation areas of the European Alps.