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Fires create a heterogeneous mosaic of burn severity across the
landscape. If the fuel is composed predominantly of grasses, there will be a light ground fire which
may spread rapidly but not last for long. Woody plants may not catch fire so easily, but may produce a
hotter fire when they do burn.
In less intense fires in subalpine forests as well as in tropical alpine areas with giant rosette plants,
mortality is negatively correlated to plant height. Because of slow plant growth in the alpine zone,
repeated fires may greatly postpone or even prevent regeneration of burned populations of dwarf shrubs
or krummholz.
The effects of fire may persist for a very
long time, especially at higher altitudes. Even decades after a fire, burned areas may be distinct
from unburned ones in vegetation composition, percentage of bare ground and in soil conditions. Due to
slow recovery in the alpine environment, fire can have a substantial impact on soil erosion.
Tolerance of fire varies significantly between species. Areas which normally do not experience
any fire may be dominated by species which are not able to survive a fire or disperse into burned areas. Even
a single burn may lead to the local extinction of species under these circumstances.
Repeated fires favour fire-tolerant species. Various ecological features may help plants
to persist in areas which are regularly burnt. These include protective bark and buds, regrowth from
belowground organs and rapid establishment from viable seeds.
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