The basic images grow out of ecological studies of the relationships of organisms to each other in physical space. (religion-online.org)
Here, the evidence is clear but weak, being rooted in ecological studies whose results have not been confirmed through more rigorous methods. (sciencedaily.com)
As he produces evidence from ecological studies, and his own walks, of the damage the cattle are doing to the land, he also looks at the other side of the argument. (newscientist.com)