self-perpetuating

self-per·pet·u·at·ing

     Fire

When the wood reaches about 300 degrees Fahrenheit (150 degrees Celsius), the heat decomposes some of the cellulose material that makes up the wood. 
[...]
The actual burning of wood then happens in two separate reactions:

• When the volatile gases are hot enough (about 500 degrees F (260 degrees C) for wood), the compound molecules break apart, and the atoms recombine with the oxygen to form water, carbon dioxide and other products. In other words, they burn.
• The carbon in the char combines with oxygen as well, and this is a much slower reaction. That is why charcoal in a BBQ can stay hot for a long time. (Harris)

     Plants

     System

• http://gear61sblog.blogspot.com/2010/11/self-perpetuating-nature-of.html

Reference

Harris, Tom. "How Fire Works." HowStuffWorks.com. HowStuffWorks, LLC. Web. 22 May. 2013. <http://science.howstuffworks.com/environmental/earth/geophysics/fire1.htm/printable>.