"Understanding the interactions between climate, forest management and the effects of insect outbreaks on the boreal forest"

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Climate change and large scale modifications to ecosystem structure due to forest harvesting are influencing natural disturbances such as insect outbreaks. My research program will evaluate the interaction between climate and forest management on past and current insect outbreaks. The spruce budworm (SBW) will receive a particular focus as a new outbreak is beginning in eastern Canada. In the short-term, I will evaluate the silvicultural hypothesis that forest management can reduce (or conversely amplify) the effects of SBW outbreaks by modifying tree species composition. This is a specific case of the general theory of the role of tree diversity in minimising the effects of insect herbivory. Current research also suggests that the effects of insect outbreaks are not only influenced by modifications of stand composition but also by modifications to landscape patterns of openings, young forest and mature forest and by the climate change influenced interactions between forests and outbreaking insects. Specifically, (1) I will evaluate the protective effects of mixed species stands when they are composed of phylogenetically distant trees versus whether there is greater vulnerability due to associational susceptibility or 'spill-over' from more preferred hosts to less preferred hosts such as black spruce. As a second specific objective, (2) I will evaluate the effect of forest management legacies in terms of host configuration on the development of the current and most recent past spruce budworm outbreak. Climatically, the current outbreak is mainly occurring north of where its major impacts have been observed over the last two centuries. Another short term objective (3) will thus be to evaluate how stands with similar compositions but at different geographic locations (i.e. a latitudinal and thus climatic gradient) respond to the SBW. Currently there is evidence that a number of outbreaking insect species have increased their ranges and the severity of forest damage that they've caused in recent times but these may be compensated by reductions in damage by other insect pests. Thus finally (4), I ask whether climate and forestry have amplified outbreaks of major forest insect pests across North America?