which of the following best describes the changes that take place in an ecosystem during primary succession

The given question is incomplete, the complete question is:

Which of the following best describes the changes that take place in an ecosystem during primary succession?

Lichens and mosses grow slowly on newly formed land, followed by grasses, shrubs, and trees.

Shrubs and trees regrow quickly in areas that have been disturbed by a forest fire.

Organisms compete for resources, and those that are best fit to survive establish themselves as the dominant species.

Natural disasters cause many populations to migrate to a new location in order to survive

The correct answer is that the growth of lichens and mosses takes place gradually on the freshly formed land, and is succeeded by shrubs, grasses, and trees.

Explanation:

An array of changes that takes place within an ecosystem's biotic community with regard to modifications that occurs with time within the non-living constituents of an ecosystem until stability is attained within the ecosystem is termed as ecological succession. A succession, which takes place in a previous barren land where there is no existence of life is known as primary succession.  

For example, a gradual growth of mosses and lichens on a freshly formed land, succeeded by shrubs, grasses, and trees is an illustration of primary succession. The pioneer species like mosses and lichens possesses the tendency to grow on the land, that is, not inhabited previously by any other species of plant and further helps in the growth of novel species of plants.  

On the bare rocks, lichens discharge acids that assist in the process of rock withering as it reduces the compaction of the rocks. Further, the aggregation of soil takes place that facilitates the growth of mosses. Eventually, the mosses help in bettering the quality of the soil, which further helps in the growth of shrubs, grasses, and trees.  

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