FIRE EFFECTS GUIDE - National Wildfire Coordinating Group

1. General Need for Improved Management. "Prescribed fire should not be a
substitute for good range management. A problem rooted in inappropriate range
management practices may not be corrected by vegetation treatment. In these
instances management should be altered prior to application of prescribed fire. If
livestock have premature access to the burn, the full benefits of the prescribed fire
may not be realized and negative impacts may occur unless management of the
livestock is included in the plan" (Bunting et al. 1987). "Followup management is
the most important aspect of a controlled burn and must be provided for in the
overall management plan" (Smith 1981). "Grazing management following burning
may significantly affect the degree of change in forage species productivity and
possibly the composition of the postburn vegetation" (Smith et al. 1985). The need
for management of livestock use on a burned area is most critical the first growing
season after fire, particularly in plant communities of arid and semiarid regions
(Trlica 1977). Livestock use must be managed on the sites of both prescribed fires
and wildfires.
Fire results in changes of animal behavior including grazing pattern, preferences,
utilization rates, forage consumption, and frequency of grazing use. Wild and
domestic animals are attracted to recently burned areas resulting in greater
utilization of the burned area than surrounding vegetation (Pase and Granfelt 1971;
Bunting et al. 1987). Cattle, horses, and sheep usually have the greatest impact.
Grazing animals frequently concentrate on a burn because the herbage or browse
is more accessible, palatable, and nutritious (Wright and Bailey 1982). Plant
growing points may also be exposed, increasing the likelihood of damage from a
foraging animal. Carbohydrate reserves of sprouting plants are usually depleted
because of energy required to regenerate after a fire. Repeated use of these plants
can cause considerably reduced vigor, and sometimes death of key forage or
browse species. (See VI.B.4.b. (1) and (2), this Guide, for a more detailed
discussion of carbohydrate reserves.)
Grazing in forested areas can help forest regeneration if competing plant species
are grazed, or hinder regeneration if tree seedlings or sprouts are eaten or
trampled. Extensive damage to young conifers from trampling has occurred in
clearcut areas that were seeded to grasses (McLean and Clark in Urness 1985),
and has been observed in burned clearcuts where postfire growth of grasses and
sedges attracted livestock (Zimmerman 1990). The presence of larger diameter
logging slash can discourage livestock and big game use.
2. Rest and Deferment.
a. Prefire. Prefire rest from grazing is required on many range sites to allow the
accumulation of enough fine fuel to carry the fire. This is important in shrub/grass
and pinyon-juniper types as well as in forested areas, particularly aspen
ecosystems where grass and shrub litter may be the main carrier fuels (Jones and
DeByle 1985). Allowing grazing, sometimes even for a short period of time during
the year before the fire, can remove enough fuel to limit fire spread. A patchy fire
may occur, or the fire may not be able to carry at all, and in both cases fire
treatment objectives are not met. Prefire rest may also be required to restore levels