Answer is chronosequencing.
When a forest is partially burned, the land of the forest undergoes a series of changes. Some pioneer plants such as mosses will quickly take hold, gradually changing the landscape. This changes the soil composition such that a new set of plants will grow there. This in turn creates yet another set of conditions that eventually allows for the return of the forest. Ecologists by studying regrowth in the forest where original forests that had been burned at different times, an approach called chronosequencing.
