Why must controlled fires be set in some ecosystems?

Because fires are not all bad.

Explanation:

They may destroy, but when they are done, there is more space for other plants to grow where the big tall trees would have taken up all the sunlight. Other times, some trees have pinecones that only open when exposed to extreme heat and the fire provides space for the seeds to grow and helps them open.

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•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation: