When considering classical mathematics, the Greeks must be a main focus of our attention. In fact, the primary reason for discussing earlier mathematics is to understand what the Greeks inherited and what they left to their posterity.
The organisms that engage in primary succession are known as pioneer species. Typical pioneer species include simple lichens, algae, and fungi. These simple organisms begin breaking down the resources in the environment and make it suitable for the later introduction of more complex species, such as vascular plants.
Primary ecological succession is the changing sequence of communities starting with the first biological occupation of a place where there were no living organisms previously. For example, the colonization and the following succession of communities on a bare rock is a case of primary ecological succession. Secondary ecological succession is the changing sequence of communities starting with the substitution of a community by a new one in a given place.