Successions can be of various sizes. They can go slowly, for thousands of years, and maybe quickly – in several days. The duration of the succession depends on the composition of the community.
With the primary succession, the formation of a climax ecosystem takes hundreds and thousands of years.
The need to break down the parent rock is the main reason for the slow pace of primary successions.
With the secondary succession, the change of serial communities occurs much faster. Since a sufficient amount of nutrients and developed soil remain after the initial community, the initial stages in this case are short-lived.
- in Europe at the end of the Pliocene (3 million years ago) the ice age began. The glacier destroyed all life under its cover. He tore off and smoothed the soil cover, crumbled rocks. With its retreat and the warming of the climate, vast expanses of bare, lifeless land were exposed. Gradually, it was inhabited by various plants and animals. Of course, these changes took place very slowly. Where the glacier destroyed the rainforests, their restoration continues to this day. These areas have not yet reached a steady state. So they did not have enough millions of years to complete the succession.
- The changes that led the broad-leaved forests of the Miocene (20 million years ago) to the present northern Central Asian deserts also proceeded slowly.
The current state of the flora and fauna of the Central Karakum desert developed very slowly. It began from the moment when the ancient Aral-Caspian Sea exposed, retreating, a huge area of its bottom.
- Successions after a forest fire pass much faster, when in a certain sequence one biocenosis changes to another, which finally leads to the restoration of a stable community.
- Fouling of exposed cliffs occurs relatively quickly: sections of rock as a result of erosion or landslide.
- The fastest successions are observed in a temporary reservoir or during a change of communities in a decaying animal corpse, in a rotting tree trunk, in an infusion of hay.
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