Soil amendments for plantings of urban trees

The effect of different admixtures of gravel to soil on freshly planted urb an trees (Acer platanoides L., Tilia europaea L., T. x euchlora K. Koch, Ti lia x europaea L. var. pallida and Platanus x acerifolia (Ait.) Willd.) was investigated. Expanded clay proved to be most favourable for Tilia. It imp roved soil water regime and aeration. Lava rock was deleterious for Tilia b ut not for Acer. The effect on trees was not much different in the case of Vertical gradients of the admixture compared to homogeneous mixtures. A hor izontal gradient with river gravel resulted in a slight stimulation of root development in all species examined in the third year after planting. (C) 1998 Elsevier Science B.V. All rights reserved.