When I built my home in Austin 8 years ago, I noticed when the trees were planted, HEAPS of mulch was used around the trees. I added more mulch in the second year, since I saw all the neighbors doing the same thing. In the third year I decided not to add mulch and just let the grass grow up to the trunks and prefer this for 'looks'. What i've noticed is several of my neighbors are still doing the 'mulch thing', and their trees are smaller even though they were in their homes at least a year before myself. A few of their trees have also died. Most of the trees are either Crape Myrtle or Live Oak. My question, WHY the heaps of mulch after trees have been established?TIA