Interaction of future climate change scenarios of elevated tropospheric ozone and altered rainfall on loblolly pine seedlings inoculated with ophiostomatoid fungi
Type of DegreeMaster's Thesis
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Southern Pine Decline is a cause of premature mortality of Pinus species in the Southeastern United States. While the pathogenicity of ophiostomatoid fungi have been observed both in the laboratory and the field, the driving mechanisms for success of fungal infection, as well as the bark-beetle vectors is less understood. The goal of this thesis is to provide insight into the role of future climatic conditions, specifically elevated tropospheric ozone and altered precipitation patterns, in the progression of the Southern Pine Decline on loblolly pine. Two scientific questions were address: (1) will predicted future concentrations of tropospheric ozone affect loblolly pine vigor and increase susceptibility to root infecting ophiostomatoid fungi?; and (2) will predicted future rainfall patterns affect loblolly pine vigor and increase susceptibility to root infecting ophiostomatoid fungi? The first question was addressed in 2013, utilizing open-top chambers, three ozone concentrations and stem inoculations of four families of loblolly pine. Two of the families used were selected for tolerance to root infecting ophiostomatoid fungi, while the others were more susceptible. The second question was addressed in 2014, utilizing capped open-top chambers, simulated rainfall treatments and stem inoculations of four families of loblolly pine. Two of the families used were selected for tolerance to root infecting ophiostomatoid fungi, while the others were more susceptible. Overall, changes in climatic conditions are anticipated to increase Southern Pine Decline severity and incidence. There was a strong link between tolerance to root infecting ophiostomatoid fungi and susceptibility to elevated ozone concentrations. There was no strong relationship between sensitivity to moisture stress and susceptibility to root infecting ophiostomatoid fungi. In the future, ozone and precipitation patterns may work in tandem, as well as with Southern Pine Decline, and therefore may play an even more important role in the productivity of loblolly pine.