The Lorax confronts the Once-Ler, who has been cutting down Truffula trees to manufacture Thneeds. The two witness the cutting down of the last Truffula tree, marking an end to the viability of the Once-Ler's business. The lack of trees also adversely affects the environment, as is evident by the coughing of the residents of ThneedVille and the migration of all the wildlife.
Hoggish Greedly is clear cutting a forest, which loosens the soil as there are no roots to hold the soil in place. The Planeteers take advantage of this and show Hoggish Greedly the effects of water erosion on loose dirt.