Lundgren 
How Ecosystems Work [PDF ebook] 

This Title Explains What An Ecosystem Is And How The Plants And Animals Within An Ecosystem Rely On And Effect Its Existence. Different Types Of Ecosystems Are Described, As Well As The Food Webs Within Them. How Some Changes To An Ecosystem Can Be Good And How Some Harmful Changes Can Destroy Them. Teaches Students What An Important Role They Can Play In Keeping These Intricate Ecosystems Alive.