Established Street Trees, Soil Suction And Leaf Water Potential

D.A. Cameron and A.P.K. O'Malley

This paper presents research into the influence of street trees on soil moisture and subsequently on houses and pavements. Moisture changes occur due to environmental changes arising from the creation of urban areas. Moisture changes in the urban environment may cause surface and sub-soil movements. When exacerbated by tree-related desiccation, distortion of footings and pavements and cracking of houses and roads are more likely. With the trend towards smaller-sized blocks in urban areas, the problem has intensified and is a worldwide dilemma. In this research the influence of four species of established street trees on soil moisture (and soil suction) and surface movements was studied over a one year period. The sites were located in Salisbury, a well-established northern suburb of Adelaide. Generally the sites are moderately to highly reactive. The overall research objectives were to provide information on soil moisture changes and water use of different tree species. This information is urgently needed to assist firstly engineers, which requires a rational basis for selection of species of street trees.