We would not expect a palm tree to grow in Chicago, or an upland oak tree to grow in a swamp. Urban environments, especially below ground, can be just as foreign to any tree and must be managed to provide the basic requirements needed for good root growth.
Up to 80% of urban tree problems originate below ground and threaten sustainability of the urban forest. Urban landscapes are very different than the natural landscapes where trees evolved, and often lack some of the basic components of the natural environment essential for good root growth and healthy trees. By understanding the soil resources that need to be made available in urban landscapes for good root growth, we can manage the urban soil environment for healthy, long-lived trees. Urban tree root structure is not the same as trees in the forest. Urban tree root systems are altered by the production and planting procedures, and by restrictions and disturbances throughout their life-span. Understanding how these affect tree health and stability is important for tree longevity and sustainability. The half of the tree below ground is challenging to study, and is often overlooked. This long-standing Morton Arboretum program has been a major contributor to what we know about the urban Landscape Below Ground.
The Morton Arboretum, TREE Fund, J. Frank Schmidt Family Charitable Foundation, Horticultural Research Institute