The roadside effect: visual proof

Garden angelica (Angelica archangelica) in a roadside in northern Norway, profiting from the wet conditions caused by the roadside ditch.

Mountain roadsides, the most fascinating places on earth. That is, if you believe a PhD-student who has been studying them for more than 5 years now.

Alpine species like the pincushion plant (Diapensia lapponica) and the alpine bearberry (Arctostaphylos alpinus) enjoy a roadside ‘rock garden’.

We returned safely from our fieldwork season in the northern Scandes, with suitcases full of data proving the fascinating role of mountain roads in plant species distributions. Whether they are non-native species advancing in cohorts from the valley, or alpine species exploring the rocky conditions, countless species seem to profit from this peculiar ecosystem.

Yellow mountain saxifrage (Saxifraga aizoides), a plant typical for rocky alpine environments, thriving in between the roadside gravel.

This pattern is strikingly visible with the naked eye already: next time in the mountains just look at the roadside and admire the differences with the natural vegetation next to it. But we aim for more than visual proof only, of course.

We have never been more ambitious in trying to get to the ‘why’ behind it: why is this plant exactly here, and not a few meters further away from the road? What is it that attracts alpine species in roadsides below the treeline? Why is it that fireweed is so extremely common in roadsides, and plays only a minor role in the natural vegetation

Fireweed (Epilobium angustifolium), the most common roadside forb in the Scandinavian subarctic.

Now we dive into the lab and the data, aiming to answer all questions that popped up. Most important one of all: what has happened in the 5 year period since our first survey in exactly the same plots?

A tip of the veil? A lot!

The pincushion plant (Diapensia lapponica) within one of our study plots, bordered by the yellow measurement tape.