I think the trees try to keep a reserve of water around them, instead of letting it go back into the ground. Some anecdata - my family due to risk of falling de

I think the trees try to keep a reserve of water around them, instead of letting it go back into the ground. Some anecdata - my family due to risk of falling decided to cut down some trees. Mere days after that the sewage flooded the basement. The trees were apparently keeping a reserve of sewage water around their roots that got released once they were cut down, flooding the basement. Multiple trees could keep that water around releasing it once there is too much water, thus forming or preserving aquifer. Not to mention they reduce evaporation.