Growth Of Lodgepole Pine Stands And Its Relation To Mountain Pine Beetle Susceptibility

Periodic diameter and basal area growth were determined for partially cut stands of lodgepole pine at five locations over approximately 10 year periods. After cutting, average diameters in the partially cut plots generally increased by 0.8 inches or more, while average diameter in the uncut controls increased by 0.6 inches or less. Diameter growth in the partially cut plots was generally significantly greater than diameter growth in the controls. Individual tree growth is discussed in relation to potential susceptibility to mountain pine beetle infestation. Basal area decreased in three of the four GSL (growing stock level) 40 stands because of windthrow. Basal area generally increased >1.0 ft 2 / acre/year in partially cut plots except in the GSL 40 stands with substantial windthrow and one GSL 100 with an Armillaria infection pocket. Basal area increases in the control plots ranged from 0.2 to 1.1 ft 2 /acre/year, although the one control with a BA growth rate of 1.1 ft 2 /acre/year had a relatively low initial BA. Data from the stands are employed in the susceptibility rating methods of Amman et al.(1977), Shore and Safranyik (1992),and Anhold et al. (1996 to determine stand susceptibility and the results discussed in terms of general applicability of these methods to partially cut stands. Basal area growth is used to estimate the length of time required for various stand densities to reach specific susceptibility thresholds for mountain pine beetle infestation. Several of the GSL 40 stands are not projected to reach the susceptibility thresholds in 100 years because of windthrow. Barring mortality 1%,GSL 80 stands are estimated to reach the basal area threshold of 120 ft 2 per acre in

Ten-year diameter and basal area growth were determined for partially cut stands at 4 locations. Average diameters in the partially cut plots generally increased by 1 inch or more, while average diameter in the uncut controls increased by 0.9 inches or less. Individual tree growth is discussed in relation to potential susceptibility to mountain pine beetle infestation. Basal area increases ranged from 0.9 to 1.9 ft2/acre/ yr in partially cut plots, while basal area increases in the control plots ranged from 0.4 to 1.4 ft2/acre/yr. Endemic mountain pine beetle infestations and snow breakage accounted for most of the mortality on the plots, which decreased the residual basal area and basal area growth. Increases in basal area are used to estimate the length of time required for various stand densities to reach the susceptibility thresholds for mountain pine beetle infestation. Stand marking may influence future susceptibility to beetle infestations.

Tree losses resulting from infestation by the mountain pine beetle (Dendroctonus ponderosae Hopkins) were measured in two stands of lodgepole pine (Pinus contorta Dougl.) where the beetle population had previously been epidemic. Measurement data showed that larger diameter trees were infested and killed first. Tree losses ranged from 1 percent of trees 4 inches (d.b.h.) to 87 percent of those 16 inches and greater d.b.h. Numbers of adult beetle emergence holes averaged 1.3 per square foot of bark area in trees 7 inches d.b.h. and 62 in trees 28 inches and greater d.b.h. The observations indicate that large infestations of mountain pine beetle depend on the presence of large diameter trees within a stand of lodgepole pine, thus implying that beetle population growth is food-limited.

"This book presents a synthesis of published information on mountain pine beetle (Dendroctonus ponderosae Hopkins [Coleoptera: Scolytidae]) biology and management with an emphasis on lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forests of western Canada. Intended as a reference for researchers as well as forest managers, the book covers three main subject areas: mountain pine beetle biology, management, and socioeconomic concerns. The chapters on biology cover taxonomy, life history and habits, distribution, insect-host tree interactions, development and survival, epidemiology, and outbreak history. The management section covers management strategy, survey and detection, proactive and preventive management, and decision support tools. The chapters on socioeconomic aspects include an economic examination of management programs and the utilization of post-beetle salvage timber in solid wood, panelboard, pulp and paper products."--Publisher's description.

We used a simulation model and two management scenarios to investigate possible effects of a severe mountain pine beetle (Dendroctonus ponderosae Hopkins) epidemic in Alberta, Canada. Our simulated outbreak was based on the current epidemic in British Columbia, which may kill close to 80% of the province's pine volume. Our two management scenarios were conventional harvest and a pine-reduction strategy modeled on a component of Alberta's Mountain Pine Beetle Management Strategy. The pine strategy seeks to reduce the number of susceptible pine stands by 75% over the next 20 years through targeted harvesting by the forest industry. Our simulations showed that the pine strategy could not be effectively implemented, even if the beetle outbreak was delayed for 20 years. Even though we increased mill capacity by 20% and directed all harvesting to high volume pine stands during the pine strategy's surge cut, the amount of highly susceptible pine was reduced by only 43%. Additional pine volume remained within mixed stands that were not targeted by the pine strategy. When the outbreak occurred in each scenario, sufficient pine remained on the landscape for the beetle to cause the timber supply to collapse. Alternative management approaches and avenues for future research are discussed.

Over the past 15 years, selective cutting prescriptions have been applied by forest operations in southeastern British Columbia as part of a strategy to reduce landscape-level susceptibility to damage from mountain pine beetle outbreaks. The prescriptions have been applied in stands where maintenance of some mature forest cover is needed to meet management objectives for viewscapes, recreation and habitat or to hold some pine volume during periods of rising beetle activity until it is required or available for harvest. In this study, we examined 10 of these sites 5 to 14 years after harvest, and determined current stand composition and structure from direct sampling and pre- and post-treatment stand characteristics from stand reconstruction. We then related these characteristics to original treatment specifications; the volume removed during harvest and remaining on site after treatment; subsequent losses to wind, snow or bark beetle damage; current stocking status; radial growth rates of residual overstorey trees; and the nature of fuel complexes created and effects of treatment on potential fire behaviour.