WHY IS THE WORLD GREEN?
This is a classic question in ecology. The classic answer is that there is an odd number of trophic levels. In a system with one trophic level--plants as producers--the world is green. In a system with two trophic levels, primary consumers eat plants and the world is brown. Add a secondary consumer to eat the primary ones and it's green again. This summer, grasshoppers irrupted in Mulkey meadow and suddenly it wasn't green anymore...