Most trees do not have a taproot; they tend to be more shallow-rooted than you might think. While some trees do have a taproot when they are saplings, after a few years the main root system changes to a widespread system with mainly horizontally growing surface roots and only a few vertical, deep anchoring roots.
Tree roots have to be shallow to stay within the loose, oxygenated soil near the surface. They are extensive, spreading to several times the width of the canopy. Damage to roots is a major cause of decline, death, or physical failure. Roots are injured or destroyed by soil compaction, soil removal, severed roots, fill soil over roots, flooding, or drought.
(Source: PNW ISA)