The following graph shows the species area relationship

The following graph shows the species area relationship. Answer the following questions as directed.
(i) Name the naturalist who studied the kind of relationship shown in the graph. Write the observations made by him.
(ii) Write the situations as discovered by the ecologists when the value of Z (slope of the line) lies between (a) 0.1 and 0.2 (b) 0.6 and 1.2. What does Z stand for?
(iii) When would the slope of the line B’ become steeper?

(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.