Warming climate impacts on elevational shifts in expansive native synanthropic plants along the roads: Examples of four species

Roads are known to support the dispersal of plant species, especially along elevational gradients. We compared the elevational distributions of four expansive native synanthropic plant species along roadsides in the Orlické hory Mountains (Czech Republic) over a 40-year period. Two species (Anthriscus sylvestris and Chaerophyllum aromaticum) have distribution optima in lowlands and foothills, whereas the other two psychrophilic species (Anthriscus nitidus and Chaerophyllum hirsutum) have distribution optima at relatively high elevations. We found that the average elevation of these species, except for Anthriscus sylvestris, rose by 23–74 m. The maximum occurrence elevation of all the species rose by 98–248 m, except for Chaerophyllum hirsutum, which was limited by the maximum elevation of the studied area. On the other hand, the presence of psychrophilic Anthriscus nitidus and Chaerophyllum hirsutum in lower elevations stagnated or even decreased. This shift cannot be attributed only to changes in traffic frequency and appears to be consistent with changes associated with a warming climate.

Our results suggest that climate change may in some cases influence the spread of synanthropic expansive plants, and that roadsides of mountain roads may serve as early detection sites for shifts in species distributions, which can be attributed to changes in climate.