Question

A species-area curve is drawn by plotting the number of species against the area. How is it that when a very large area is considered the slope is steeper than that for smaller areas?

Answer 1

Larger  areas tend to contain larger numbers of species,& empirically,the relative numbers seem to follow systematic mathematical relationships.The species-area relationship is usually constructed for single type of organism,such as all vascular plants or all species of specific trophic level within a particular site.