SINGLE STRATUM, HUMUSLESS STREET TREE SUBSTRATES

Growth of Gleditsia triacanthos ‘Skyline’ and of an underplanting of eight different shrubs and nineteen different perennials was tested in a small planting strip prone to heat and in four different substrates.
It was tested if trees developed better in three mineral humusless substrates (course height 90 cm) than in the classical two-layer formations consisting of humus rich topsoil and sandy subsoil.
All substrates were analysed before planting in November 1997 and fertilized to a standardized level.
After good initial development, the growth in height of the trees and in width of their canopy has stagnated since the year 2000. Values for vitality declined.
After 2000, not a single tree achieved the evaluation factor 7 (good growth) or 9 (vigorous growth), irrespective of the different substrates.
All nine shrub varieties showed significantly better evaluation factors.
In this case between 77.8% (plot 1) and 40.5% (plot 4) of all shrubs got the evaluation factor 9. The comparison of vitality evaluation factors showed that perennials react in a more differentiated way to the different substrates than do shrubs.

International Conference on Urban Horticulture

P. Schönfeld

Gleditsia triacanthos ‘Skyline’, growth, perennials, shrubs, nutrient

https://doi.org/10.17660/ActaHortic.2004.643.17