Leopold observes that even when one species of plant or animal pest is conquered by nature, another springs up. He traces the history of various pests like the English sparrow, the starling, and cheat grass. Cheat grass has replaced the native grasses that were unable to recover after the overgrazing of the natural grassland.
The ecosystem of Oregon is delicately balanced, and disturbances wrought by agriculture have led to the proliferation of this invasive species. Leopold blames this entirely on thoughtless and greedy human interventions in the landscape.
It is difficult for cows to eat the prickly cheat grass, and it is difficult to protect hills that are covered in it from fire. As a result, fires in the areas covered by the grass end up destroying the native plants, which leaves less for deer and birds to eat, especially in the wintertime. Cheat also grows in hayfields and lowers the quality of hay, and prevents pine seedlings from growing. However, Leopold has observed that “cheat-afflicted regions” manage to find uses for it. It reduces erosion, and sheep find it edible. Leopold has noticed that society as a whole has “no sense of pride in the husbandry of wild plants and animals,” and “no shame” in caring for a sick landscape.
For everything bad about cheat grass, it also has positive qualities. The landscape has managed to shift around and accommodate it, as nature usually does. Leopold wishes the general population felt more responsibility for the landscape, and felt as though they contributed to its health and wellbeing.