German naturalist and geologist Alexandar von Humboldt noted that within the region a large number of extinct species with continuous growth are possible, but only reaching a limit.

In the logarithmic scale, the relationship is a straight line defined by the equation.

Log S = Log C + Z Log A

S – Species richness

A – Area

Z – Slope of the line

Y – Y- intercept

The Z value lies in the range of 0.1 to 0.2 regardless of whether there are taxonomic groups or regions and this process is known as species relationship area.