Gradient of Biodiversity:-

Biodiversity change with change in laltitude and altitude

1. Altitudnal gradient:- On moving from low altitude to high altitude [plain to mountain ) biodiversity decreases.
2. Latitudnal gradient:- On moving from low latlitude to high latitude (equator to pole) Biodiversity decreases with very few exception.

Tropical area have more species diversity with respect to temperate and polar area.

Columbia located near equator and it has 1400 species of bird,

New York located at 41^°N, it has 105 species of bird.

Greenland located at 71^°N has 56 species of bird

But India has more than 1200 species of bird. A forest of tropical area have more than 10 times species of vascular plant with respect to forest of temperate area.   

(c) Species Area relationship:-

Great German Alexander von Humboldt observed within a region species diversity increases with increase in explore  area but upto a limit. Actually the relationship between richness and explore area for diverse variety of taxa is termed out to be rectangular hyperbola graph. Bt on a logarithm  scale it become straight line.

Where is species richness

A is explore Area

C = Y intercept

Z = Scope of line

Usually value of z values from 0.1 to 0.2 but it may vary from 0.6 to 1.2

For e.g.:- Z value for fruit eating birds and mammals is 1.15