The vast majority of the trees and shrubs used in Ohio landscapes evolved in ecosystems with soils topped by an organic layer. Think forest and grassland soils. Aged hardwood bark mulch serves as a stand-in for leaf litter found beneath trees in forests. However, if a little is good, more is not better.
Mulch piled around tree trunks to stratospheric heights has been called many things (some not printable) such as pyramid mulch and mountain mulch. My personal favorites are mulch volcanoes (or volcano mulch) for stratovolcano-like creations and mulch mounds for those that resemble shield volcanoes.
Sometimes we run across bizarre things in Ohio landscapes that simply defy explanation. Such was the case yesterday when I came across "tree moats" (sometimes called "mulch moats") in a park near my home in the southwest part of the state. I've encountered this bizarre practice before and fail to fathom the logic behind this ludicrous practice.