The answer is yes, and no. There is a war going on under our feet when we enjoy our quiet landscapes on a summer day.  Every square foot of soil can only support a limited amount of green leafy plant growth.  We sometimes must make the choice which green leafy growth will survive or our plants will decide for us and we may not like their choice.  When it comes to trees and turf it is always a good idea to try to separate the two root zones for maximum health of each species.  When you water the lawn the grass is usually the winner over the tree roots because it is “faster to the draw”.  Trees need long drinks of water for 18 to 24 hours and we usually only water our lawns for too short a time, too frequently.  By doing this we drive life giving oxygen out of the soil and everyone suffers because both tree and grass roots come closer and closer to the surface and so become less and less drought tolerant. (ref: Watering Abstract, Mulching Abstract)