Dig away the ground around approximately 25 percent of the above-ground roots with a small shovel. Select roots that are approximately 1 foot in diameter or less as these will provide fewer nutrients to the tree than the larger roots. Continue to dig until the surfaces of the selected roots are uncovered.
Cut the root at the point where it pokes out of the soil with a sharp hand saw, taking care that you do not cause damage to any surrounding roots or vegetation.
Recover the root with the soil that was previously removed. This will ensure that the newly severed roots do not become susceptible to fungal or bacterial infections.
Water the tree. Provide the tree with a healthy drink of water to replenish the recently compromised root system.
Cover the area under the tree with a 2-inch layer of wood mulch. The decomposing mulch will offer nutrients to the tree's roots while protecting the ground from any erosion, which will also expose roots that would otherwise remain underground.