The land ethic simply enlarges the boundaries of the community to include soils, waters, plants, and animals, or collectively: the land.
This sounds simple: do we not already sing our love for and obligation to the land of the free and the home of the brave? Yes, but just what and whom do we love? Certainly not the soil, which we are sending helter-skelter downriver. Certainly not the waters, which we assume have no function except to turn turbines, float barges, and carry off sewage. Certainly not the plants, of which we exterminate whole communities without batting an eye. Certainly not the animals, of which we have already extirpated many of the largest and most beautiful species. A land ethic of course cannot prevent the alteration, management, and use of these ‘resources,’ but it does affirm their right to continued existence, and, at least in spots, their continued existence in a natural state.
Leopold, Aldo: A Sand County Almanac, and Sketches Here and There, 1948, Oxford University Press, New York, 1987, pg. 204.