Roadside fertilizer?

Several Alaska researchers studied the vegetation along the Dalton Highway in moist-acidic tussock-tundra in 2006. The pH of the roadside that is annually covered in fine dust from the road, increased over time from 4 to 6. . The amount of grasses did, too as well as cloudberry, Rubus chamaemorus. The fine dust may be adding a bit of fertilizer to the roadsides. It is not surprising that grasses increase especially on disturbed sites, but cloudberries are a surprise. I wonder if berry yield also increases or if it is just vegetation.

Roadside vegetation