It is important to remember that we are all part of an essential, living breathing ecosystem, all part of the web of life. This web of life is made up of millions of different kinds of plants and animals, the interactions between them, and all the of different habitats that they live in.
The strands of the web are woven together so that if you remove even a single strand from the web, the whole web gets weaker, less able to do its job. When you change one part of the forest ecosystem by removing all the trees, all the other parts of the ecosystem will change too.
