By Gary Allen Burns
Surface fires are the most common kind of forest fire. The flames burn near the ground, consuming the grass and brush on the surface, leaving the tree canopy untouched. The dry litter on the ground, of course, is more combustible than the green leaves.
Crown fires — fires in the crown canopy — are more dangerous. Hardwood trees are not as flammable as conifers, which can be explosive. In addition, the wind can carry burning needles, leaves and sparks great distances.
Ground fires result from spontaneous combustion of decaying humus or peat in wet bogs.
The humus or peat usually smolders, seldom flaming, and burns from the surface down, where it becomes hotter. The fire can kill the root system of the trees.
There may be little evidence of a fire except for dead standing trees.