What are the effects of different soil types on the fitness and survival of two Juniperus virginiana varieties?

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Samia Hamati and David Ward, Biological Sciences, Kent State University, Kent, OH

Background/Question/Methods
Eastern redcedar Juniperus virginiana is a widespread conifer that is encroaching into new habitats and states in the U.S. A number of varieties of J. virginiana have been identified, which may affect their abilities to encroach, particularly with regard to potential effects on their ecophysiology. There are two dominant varieties of J. virginiana: J. virginiana var. virginiana, found in eastern North America, and J. virginiana var. silicicola, found in the south-eastern states. Populations found in different geographic areas and environments may be faced with different biotic and abiotic pressures, driving the evolution of these populations in different directions through natural selection. J. virginiana is known to tolerate a wide range of soil conditions. Typically, J. virginiana var. virginiana is found in limestone habitats, whereas J. virginiana var. silicicola usually occurs on sandy acidic soils. We are interested in studying the ecological and ecophysiological differences between the two J. virginiana varieties and to understand whether the differences in traits are caused by natural selection and local adaptation to a specific soil type. We conducted a common-garden experiment in two sites in Ohio (Sandusky and Madison) having different soil types (limestone and acidic sands). We tested the effects of the two soil types and intraspecific competition on the fitness and survival of J. virginiana seedlings. We measured seedling survival and growth rates. In addition, we recorded photosynthetic rate and water potential as an estimate of the plants’ overall performance.

Results/Conclusions
Preliminary analyses suggest that there was no effect of intraspecific competition on J. virginiana’s growth rate, plant water stress, and photosynthetic rate for the two varieties across our sites. However, J. virginiana var. virginiana and J. virginiana var. silicicola seedlings growing in the sandy acidic soil had higher survival rate and fitness than J. virginiana seedlings growing in the limestone soil. Future efforts will determine how the ecological, physiological, and morphological differences between the two main varieties of J. virginiana affect the encroachment of this species into new habitats and environments.