What is the role of succession and how does this maintain ecosystems?

Succession is the term given to describe the changes that take place within an ecosystem. Barren land such as bare rock can be formed by the eruption of a volcano or a glacier retreating. The first stage of succession is the colonisation of a pioneer species. Pioneer species tend to have adaptations such as: (1) a tolerance to extreme conditions (2) The ability to fix nitrogen from the air (3) Ability to photosynthesis light. (4) Can easily disperse seeds across vast distances (5) Rapid germination of seeds. Succession can take form of primary or secondary succession. Primary succession occurs as a result of an opening of a habitat, for example, a lava flow, an area left from retreated glacier, or abandoned strip mine. In contrast, secondary succession is a response to a disturbance, for example, forest fire, tsunami, flood, or an abandoned field. At each stage of succession a certain type of species can be identified which will change the environment making it less hostile. There are few if any new species replacing those which have already been established. Pioneer species change the abiotic environment by dying and releasing nutrients such as nitrates for production of amino acids and proteins for the organisms that follow. Mosses are typically the next stage of succession, followed by ferns. The growth of mosses and grass provides habitats for insects and animals Within a climax community there is often a dominant animal and plants species. During succession there are a number of common features such as: (1) Environment becomes less hostile – soil forms, nutrients are more plentiful, plants provide shelter from wind (2) Greater number of habitats (3) biodiversity increases – habitats become occupied by species. This is shown in the early stages of succession. At mid succession biodiversity is at its peak. More complex food webs due to high species diversity and therefore increased biomass - this also takes place at mid succession. In a climax community however, the dominant species can outcompete many other species and so biodiversity decreases. A climax community consists of animals and plants which have established equilibrium. All of the above factors reduce hostility; this increases the probability of a biodiverse ecosystem whereby a variety of nutrients minerals are made available-hence maintaining and progressing the ecosystem.