ILLINOIS TREES: SELECTION, PLANTING, AND CARE 



33 



Fig. 31. — Excavation 

 within a few feet of 

 tree trunks destroys 

 roots and may result in 

 the eventual dying of 

 branches or death of in- 

 jured trees. 



.-^~; 



Fig. 32.— Retaining 

 walls to maintain soil 

 around trees may pre- 

 vent root injury where 

 extensive excavation or 

 erosion occurs. 



tical, you can help the affected trees recover by supplying addi- 

 tional nutrients and water until their fibrous roots overcome the 

 effect of excavation, and by doing some corrective pruning to 

 reduce the amount of top growth that must be supported by the 

 injured root system. Professional arborists are familiar with the 

 practices required to prevent or overcome such injury, including 

 the subsequent fertilizing and watering needed during the recov- 

 ery period, which may be 2 years or more. 



Raising the grade around trees by adding soil can be as in- 

 jurious to roots as lowering the grade. Roots buried under an 

 extra foot or more of soil may suffocate and die because of an 

 overabundance of water and inadequate air. Deep soil fills may 

 cause root injury resulting from compaction of soil around the 

 roots. Pavement placed on the fill soil will reduce the amount of 

 air and water available to the roots (Fig. 33). Even covering 

 roots and trunk bases with soil or paving during construction 



