What are the motifs in The Everglades: River of Grass by Marjory Stoneman Douglas?

A recurring idea in the book is the importance of the environment and conservation efforts. Man's tampering with the environment led to the changing of the balance of the ecosystems which changed the environmental conditions for the animal and plant life. This also brought about changes in the ecosystem in the area which affected the economy. It wasn't until the late 1970s that people became concerned with the protection of the Everglades and began to study the ecosystem of the Everglades and the damage that had been done to it.