Intense forest fires can burn all of the vegetation in an area. many burn sites are allowed to regenerate naturally and within 20 years support healthy forests. this is an example of:

1)

competitive exclusion principle
2)

secondary succession
3)

law of conservation of matter
4)

primary succession
5)

exponential growth rates

2)  secondary succession

Explanation:

Ecological succession is the change in the biotic community of the ecosystem due to the changes occurring in the abiotic components such as water, soil, atmosphere and others. These changes occur with respect to time until the ecosystem attains the stability.

A secondary succession can be define as the changes which occur after a catastrophic event or ecological disturbance. Such changes brings stability with the help of precursors of previously existing species at the same place.

According to the given situation, secondary succession could have occurred this is because of the fact that the forests fire can burn the vegetation in an area. The burn sites will regrow into a healthy forests because of some of the precursors of previously existing plant species like seeds, stem, roots and others which will help in regrowth of new plants.