Aspen grow throughout the Rocky Mountain region and thrive in light, well-drained mountain soils. Most urban soils aren't appropriate for aspens and even with the best care, few survive more than 25 years in a landscaped setting. The trees are not difficult to cut down, but completely removing the roots is a challenge because aspens spread through hundreds of underground suckers. Cut aspens when they show signs of decline, including a thinning crown and deadwood. Cutting them down will allow new trees to grow in their stead.
Cut the aspen tree as close to the ground as possible. Dig a trench around the base of the tree, 3 feet from the trunk and 15 inches deep.
Place the shovel under the rootball and place your weight on the shovel handle to slowly rock the rootball back and forth, dislodging it. An aspen tree has hundreds of shoots coming out of it, so you won't entirely dislodge it just by using the shovel.
Lift the trunk out of the soil as much as you can, turning it over to expose the roots. Cut through the roots with your shovel or hand pruning shears until you can lift the trunk out of the ground. Aspen trunks are usually less than 12 inches in diameter, so they aren't heavy.
Spray the freshly cut trunk and shoots with tricopyr according to package directions.
Cut emerging sprouts with hand pruning shears and spray again with triclopyr. Cutting them opens the vascular system of the tree, allowing the chemicals to work more effectively. Continue this process until the tree completely dies.