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| Lodgepole pine trees today still show
scars from the 1988 fires in Yellowstone. |
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The 1988 fires in Yellowstone National Park burned approximately
one-third of the park (Baskin 1999), approximately 250,000
hectares in the park and the surrounding lands (Turner et
al. 1994). Many people saw this as a disastrous wave
of destruction. However,
by the first spring after the fires, new grasses had already
grown half as tall as an elk in certain areas.
Burned meadows displayed a colorful array of wildflowers,
including yellow arnica, mountain hollyhock, and blue lupine
(Robbins 1998). People began to see that fire did not simply kill; it encouraged
new growth.
Wildfire creates a patchwork of affected areas.
Each level of burning can be assigned a burn class: unburned, light surface burn, severe surface
burn, and crown fire.
Larger burns (larger areas that have been burned)
are less likely than smaller burns to be dominated by a
single burn class. Those areas that were not burned may serve as a source of renewal
(Turner et al. 1994).
Many trees house their seeds in their canopy as well as
in the soil. High
severity fires will most likely burn a significant portion
of an area’s seedbank in the soil and the canopy.
In a lightly burned area, plants can often resprout
from surviving roots and rhizomes. In a severely burned area, plants depend
on surrounding or nearby plants as a seed source to initiate
new growth. As
much burning occurs in patches, with a combination of all
burn classes, there is usually an unburned or lightly burned
area close to a severely burned area which can serve as
the seed source for the severely burned area.
Plants will most likely resprout faster in smaller
burn areas. If less area is burned, any burned plants
will be closer to a seed source than plants in the heart
of a large, severely burned area.
Thus for larger burn areas, opportunistic or invader
species may be able to move into the area and establish
themselves before the burned plants have time to resprout
(Turner et al. 1994).
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