Dissertation Research: Biotic Interactions and Mycorrhizal Dynamics in Drought-Stressed Pinyon Pine

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Project Summary:Current global climate change models predict increases in the frequency and intensity ofdrought in the southwestern U.S. In pinyon-juniper woodlands, we hypothesize that drought stressleads to increased competition between pinyon and juniper, greater dependence of pinyon onfacilitative nurse plants, and changes in pinyon ectomycorrhizal (EM) fungal abundance andcommunity structure. Because EM fungi can alleviate environmental stress by increasing water andnutrient uptake by the host plant, it is important to understand factors that affect these mutualists.The goal of this project is to examine how competition and facilitation affect pinyon survival andgrowth, as well as their EM fungi. We will use a combination of field experiments, greenhousestudies, and molecular tools (RFLP analysis and DNA sequencing) to identify EM fungal species.The results of our study will 1) quantify EM fungal diversity and distribution in pinyon-juniperwoodlands, 2) provide data on plant responses and EM fungal community shifts in response tocompetition and facilitation, and 3) contribute to the current library of EM fungal sequences.Because many of these fungi can only be identified with molecular tools, the latter objective isnecessary to allow comparisons of ecological data on fungi from different locations to begin tounderstand the factors that affect their abundance and distribution.