Trees need roots...roots need earth. If the ground is washed or carved from the roots the tree will eventually topple. There are forces that can seek to excavate the soil from our spiritual root system. We need to tend the soil at the base of our growth and not just take pride in the height of our trunk or the breadth of our branches. (see picture) When the folks cut this country road through a hillside they set forces of erosion in place that eventually throw trees into the very road they cleared for travel.
Colossians 2:7 Let your roots grow down into him, and let your lives be built on him. Then your faith will grow strong in the truth you were taught, and you will overflow with thankfulness.