What is point diversity, alpha diversity, gamma diversity, and episilon diversity?Give easy examples for each?

These are four levels of diversity given by Whittaker.

Point diversity - It refres to diversity on the smallest scale such as the diversity of microhabitat or sample taken from within a homogenous habitat. For example - A leaf or a flower.

Alpha diversity refers to the variety of organisms occurring in a particular habitat. Example - A single plant.

Gamma diversity - This refers to diversity of a larger unit such as a landscape or island. It can also be defined as overall diversity of a group of areas of alpha diversity. Example - A group of plants occurring together.

Epsilon diversity applies to large biogeographic areas. It includes diversity of a group of areas of gamma diversity. Example - The forest within which the plants are located.