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A Study of the Relationship Between Site Conditions and Urban Tree Growth

A study of 105 urban London plane (Platanus acerifolia) was undertaken between May 1990 and May 1992. One third of the 25 year old trees were in compacted gravel, one third in a paved area and one third in turf. Significant differences in tree condition were found between the three sites, as well as significant differences in soil dry bulk density, aeration (measured using steel rods), soil moisture tension and foliar essential element concentrations. Regression analysis was used to explore these relationships; spring soil aeration, summer soil moisture stress, and foliar nitrogen and potassium concentrations were found to have most influence on tree performance. Leaf colour and shoot extension were found to be the most sensitive measures of tree condition. Practical advice is given on the implications of the study on the assessment and monitoring of urban trees.