ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Windrow, Slash Pile, and Jackpot Burns
Burning windrows and slash piles often results in large areas between piles where
the vegetation is unaffected by fire. Because of this, small mammal populations in
these unburned areas remain essentially unchanqed. Jackpot burning (the burning of
slash concentrations), is similar to burning piled slash in that large areas are left
unburned. However, jackpot burning has the additional benefit to chipmunks, golden-
mantled ground squirrels and shrews of leaving residue in the unburned areas. Since
there is less soil disturbance with jackpot burning, this treatment may be used to
discourage pocket gopher populations which tend to increase with scarification
(Barnes 1974, Volland 1974). Columbian around squirrels and pocket gophers are
attracted to forest openings and do not seem to be significantly affected by the
presence or absence of slash. Voles, shrews, and deer mice increase in response to
increasing herbaceous and seed-producing ground cover.
When slash is piled several months before being burned, it provides a home for
small mammals (Tevis 1956d). When these slash piles are burned, more animals may be
killed than in a broadcast or jackpot burn.
Slash burning has been used in attempts to control some small mammal populations
(Tevis 1957d, Motobu 1978, Fala 1975). However, the potential reproductive rate of
small mammals is so great that fire-induced mortality only has a short-term effect on
population levels (Tevis 1956a).
MECHANICAL REMOVAL OF RESIDUES
Little has been published on the effects mechanical slash removal has on small
mammal populations. The literature suggests that many species of small mammals will
continue to inhabit areas where residues of 3 inches diameter and larger are removed
mechanically if the mat of ground vegetation is not a1 tered appreciably. The
exceptions to this prediction are shrews, chipmunks, and go1 den-mantled ground
squirrels, which may become less numerous with removal of large woody materials. Red-
backed vole populations may be suppressed by the removal of the forest canopy, and the
removal of large woody residues further reduces their habitat (Gashwiler 1959, 1970,
Tevis 1956c, Gunderson '1959). Voles of the genus Microkus will flourish because of
the retention of ground cover. Deer mice will increase, as will pocket gophers and
Columbian ground squirrels. The presence of rabbits, hares, and porcupines wil l depend
on the availability of brush or young trees for cover and food.
LEAVING RESIDUES
Leaving residues can be disadvantageous in view of fire and insect hazard, and
hampered big game movements. Yet leaving residues can provide ideal habitat for small
mammals. Removal of the overstory releases the growth of herbs, grasses, and shrubs,
but protection from predators is still provided by the slash. Where residues are not
removed, the numbers of most small mammal species already present could be expected to
increase with the exception of the red-backed voles, which are generally associated
with forest communities. Porcupines probably would be restricted unless, or until,
there are saplings or brush for food.
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