What process happens after an entire ecosystem is destroyed

The answer is: Ecological Succession

STEPS: 
1.) Bare rock (there is no grass at this point).

2.) Lichens (lichens begin to appear).

3.) Small Plants & Lichens (small plants begin to grow & the lichens are spreading).

4.) Grasses (grass starts to grow in certain spots).

5.) Shrubs & Grasses (the grass has covered, at least the majority, of the ground and shrubs begin to appear).

6.) Trees (the shrubs have grown into trees that are tall enough to provide shade)

7.) Animals (the animals return or new animals appear).

He used pea plants to study the patterns of heredity.