Alexander Von Humboldt observed the species area relationship. He observed that when the area explored increases, the species richness increases but till a certain limit. That is represented by the rectangular hyperbola which represents the equation S = CA^Z where S is the species richness, A is the area, C is a constant and Z is the regression constant. The straight line represents the logarithmic form of the same equation which is logS = logC + ZlogA.