The role fire plays varies with the characteristics under which that ecosystem evolved. A second concept of fire ecology is called the fire regime. These conditions determine the frequency and intensity of fires, and the amount of fuel consumed and fire size. The frequency of wildfires depends on ignition sources and weather conditions which may help a fire spread. The intensity depends on the quantity of fuel available and how easily it will burn.
Trees actually record fire history.
Each year a tree adds a layer of cells, increasing the width of its trunk. When a fire passes through a forest, some trees are only scorched resulting in a layer of charcoal which is eventual enveloped by a layer of new growth. These fire scars provide a record that scientists can use to determine when a fire occurred.