REHABILITATION OF SEVERELY COMPACTED URBAN SOIL TO OPTIMIZE TREE ESTABLISHMENT AND GROWTH

Urban construction activities damage soil structure and reduce organic matter, reducing tree growth rates and canopy coverage. Soil rehabilitation protocols are therefore needed to improve soil and promote root development after planting. This study evaluates four protocols for soil rehabilitation by determining their effects on soil physical properties and the growth of five tree species. Rehabilitation plots were scraped and graded according to common construction practices. Following topsoil removal, subsoil was compacted to 2.0 g/cm³ mean bulk density. Treatments included: Undisturbed (no topsoil removal, compaction or amendments), Minimum Effort (topsoil surface application), Enhanced Topsoil (topsoil application and rototilling), and Profile Rebuilding (compost amendment, subsoiling, topsoil application and rototilling). The Profile Rebuilding treatment significantly lowered the bulk density. Ulmus japonica × wilsoniana ‘Morton’ (Accolade^® elm), Acer rubrum (red maple), Quercus bicolor (swamp white oak), Prunus spp. ‘First Lady’ (First Lady flowering cherry) and Quercus macrocarpa (bur oak) were each randomly planted in treatments. Our data indicate that soil rehabilitation can improve plant growth in the first season after planting. This study site will allow assessment of the effects of soil rehabilitation on the rhizosphere’s ability to provide desired ecosystem services over an extended period of time.