During the mid 1990s damage to vegetation was observed along heavily trafficked roads in Sweden to an extent that had not been seen earlier. The objective of this report is to present the current state of scientific knowledge as regards the effects of de-icing salt on vegetation. The de-icing salt will leave the road surface as runoff, splash or spray. Most of the salt is deposited within 10 m of the road edge, but damage to vegetation can occur far as 100 m from the road. The salt reaches the trees either by being deposited on the above ground parts or by being transported to the roots. Damage can occur regardless of the pathway. The conclusions from the literature review were formulated as the following research needs: (1) the relative importance of salt spray to soil salt at different exposure levels in inducing damage to vegetation; (2) the effects of different de-icing methods and possible remedies regarding the dispersion of de-icing salt to the surroundings; (3) the relation between long-term accumulation of Na and Cl in vegetation and the short-term exposure to saline spray; and (4) the importance of de-icing salt exposure in combination with other stress factors influencing roadside vegetation. (A)
Abstract