Impact of the mountain pine beetle outbreak on the carbon and water balances of lodgepole pine stands in the BC interior

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Management responses to mountain pine beetle (MPB)-affected lodgepole pine stands vary from complete removal of the pine canopy and secondary structure (saplings, seedlings, shrubs and herbaceous plants) to selective removal of MPB-affected trees with varying degrees of secondary structure retention, to completely non-invasive strategies, i.e., allowing secondary structure to grow undisturbed in a dead stand. The appropriate management response must balance the potential future economic viability of components of the secondary structure with the need to preserve habitat, ecosystem biodiversity and to minimize disturbance to the carbon and water balances of the stand and surrounding ecosystems. The current bias towards clearcut harvesting in mixed-species stands in the BC Interior reflects the realities of market demand for certain types of wood and paper products. However, the presence of significant secondary structure in many of the affected pine stands could provide opportunities for mid-term (15-30 years) timber harvest, provide habitat for wildlife and reduce run-off to rivers and streams if preserved during salvage-logging operations. By studying changes to stand-level biomass accumulation, evapotranspiration, and microclimate of the residual forest ecosystems in salvage-logged and non-salvage-logged stands, we will determine the relative health and resiliency of MPB-affected forest ecosystems, with the aim of recommending the best management response or combination of responses to the MPB outbreak. The use of remote sensing instruments and vegetation models calibrated against field measurements of ecosystem photosynthesis and decomposition will allow the results of the study to be scaled from stand level to the landscape.