In China and in the Mediterranean Basin, human carelessness is a major cause of wildfires.
In Australian bushfires, spot fires are known to occur as far as 20 kilometres (12 mi) from the fire front.
Fire helps to return nutrients from plant matter back to soil, the heat from fire is necessary to the germination of certain types of seeds, and the snags (dead trees) and early successional forests created by high-severity fire create habitat conditions that are beneficial to wildlife.
Although some ecosystems rely on naturally occurring fires to regulate growth, some ecosystems suffer from too much fire, such as the chaparral in southern California and lower elevation deserts in the American Southwest.
As the front approaches, the fire heats both the surrounding air and woody material through convection and thermal radiation.
First, wood is dried as water is vaporized at a temperature of 100 °C (212 °F).