Forest ecosystems throughout the world have evolved over millions of years with fire as a common disturbance process. Fires caused by lightning have been an evolutionary factor since plants first arrived on land.
Lightning is still the most common source of fire in many terrestrial ecosystems.
Since the recent evolution of humans and their acquisition of fire as a tool, they too have become a common source of fire. Past human uses of fire for manipulating vegetation, however, was highly variable from one place and time to another. In many remote mountain areas, and before the 20 th century, other biotic and physical features of the landscape were probably more important than people in controlling fire patterns. These factors include vegetation, topography, and climate. Many species of plants in fire-prone habitats have evolved special adaptations and survival strategies that help them persist and thrive with fire.