Question

What is ecological succession? How is hydrarch different from xerarch succession?

Answer 1

The process by which the structure of the biological community evolves over time is called ecological succession. The time scale can be of some decades to millions of years. The ecological succession is considered to be the advanced theory used in ecology.

Complete answer:
The ecological succession is the process by which the biological community evolves over time. The ecological succession is usually known to proceed in two steps called primary succession and secondary succession.
The primary succession occurs in essentially the lifeless areas. The region in which the soil is incapable of sustaining life requires primary succession. Whereas secondary succession occurs in areas in which the previously occurring life forms have been removed or demolished. The succession of species over time is sequential and not random. At every stage certain species evolve and cause ecological breakdown of substrates causing the availability of raw nutrients for growth of complex organisms.
Initially a small number of species inhabits the community and makes it suitable for their survival. After some pace of time, when the other species try to take hold into the environment, some of the ecological changes take place in the environment. Thus, this process continues till the ecological community reaches a climax condition in which equilibrium is obtained and no more succession can take place. The last tier of the succession is called the climax community.
Hydrarch succession takes place in the wetter conditions. It is the plant succession which usually starts on relatively shallow water bodies such ponds and lakes and culminates into mature forest. In contrast, the search succession takes place on bare ground or huge rocks and culminates into a climax mature forest. The lichens and mosses usually called pioneer species cause the weathering of rocks and bare ground which transform it by trapping the dust molecules and forming a thin layer of soil for growth of small plants.

Note: The pioneer species are the species that start their life on any surface; these species are the starting point of the ecological succession in any area. After pioneer species, many other species are involved in this process and at last cause the establishment of climax community and thus, equilibrium is reached.