Abstract
Urbanisation increases the area of land covered by impervious surfaces such as rooftops, roads, driveways and parking areas, and urbanisation can impose dramatic changes on a catchment by altering its natural drainage characteristics. Increasing the amount of impervious surface within a catchment effectively seals off much of the underlying soil and prevents precipitation from infiltrating into the soil. These changes increase stresses on urban forests and ecosystems in the urban environment. Soil conditions are also altered as a result of compaction, leading to further decreased water availability, lack of rooting space and an increase in soil temperature, all affecting street tree health. It was hypothesised that street tree health may be improved by replacing conventional impervious concrete surfaces surrounding street tree planting pits with permeable interlocking concrete pavers (PICP). It was thought that the PICP would lead to an increase in soil moisture and aeration below the surface, thereby improving street tree health. This paper presents the initial results of a study comparing the moisture and temperature of soil beneath PICP with those of a conventional asphalt (AC) pavement. The study found that soil temperatures under AC pavements were higher than those under PICP pavements. Soil moisture was also found to be higher under the AC pavement compared with the PICP at the same depth.