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Because outbreaks
usually develop in mature to over mature forests, especially in lodgepole
pine, large reserves of these forests pose a constant hazard in areas climatically
favorable for the mountain pine beetle (MPB). Thus, "storing" mature/over
mature trees on the stump should be discouraged, or at least the risk of
such should be realized. In addition, management plans for reserved
areas, such as parks and wildernesses, should consider the need for protection
against destructive outbreaks. The economic impact of tree mortality is
largely dependent on the effects of epidemics on allowable cut, regeneration
of affected areas, and increased fire.
Management must focus on forests and not MPB. Management should alter
stand conditions that favor buildup of beetle populations. However,
alternative strategies for reducing losses from MPB must emphasize biologically
sound silviculture that includes concern for other resource values.
Basically, there are two approaches to reducing losses from MPB in pine
forests: (1) long-term (preventive) forest management, and (2) direct control.
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The strategy
of preventive management is to keep beetle populations below injurious levels
by limiting the beetles' food supply through forestry practices designed
to maintain or increase tree/stand resistance. Preventive management
addresses the basic cause of epidemics, which is stand susceptibility, and
is considered the most satisfactory long-term solution. It includes
a combination of hazard rating, priority setting, and silvicultural manipulations.
protection costs. Situations where MPB instead of forest managers
set priorities and dictate management options should be avoided. In contrast,
suppression of MPB populations, that is killing them by various methods
of direct control; treats only one symptom of the problem (too many beetles).
Effects are usually, therefore, only temporary. When proper1y used,
direct control might be effective both in reducing the rate of the spread
and intensification of infestations; but should be considered only a "holding
action" until susceptible stands can be altered silviculturally.
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