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.
As opposed to the first, primary succession, secondary succession is a process started by an event that reduces an already established ecosystem to a smaller population of species, and as such secondary succession occurs on preexisting soil whereas primary succession usually occurs in a place lacking soil.