Wood-biological investigations on the influence of deicing salt on roadside trees in Hamburg

Summary From the urban area of Hamburg, 341 roadside trees of the generaAcer, Aesculus, Betula, Fraxinus, Platanus, Quercus, Robinia, Sorbus andTilia have been investigated concerning their sensitivity to deicing salt. The methods used were tree-ring analysis, histometrical studies, and X-ray microanalysis. Since the middle of the Sixties the radial growth of most tress decreased more than 50% on all sites with a high salt content in the soil, leading to a reduction of the water-conducting area in the stems. The necrosis of the leaves is presumably a result of this situation. All maples, horsechestnuts, and limes growing along roads affected by deicing salt showed a highly decreased vitality. Only oak and black locust do not exhibit any saltinfluenced growth responses. For the recovery of the injured trees as well as for safeguarding the more tolerant tree species a further salt transport to the roots must be prevented, and the amount of salt already accumulated must be removed from the soil-tree-soil cycle.