(i) Alexander von Humboldt studied the relationship shown in the graph above. He observed that species richness increased within an explored area but only upto a limit.
(ii) (a) Value of Z lies between 0.1 -0.2, when area is small to normal.
(b) Value of Z lies between 0.0-1.2, when area is very large. Z is slope of the line which is regression coefficient.
(iii) Slope of the line ‘B’ will becomes steeper when area is very large like continents.