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

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

Project Summary: Current global climate change models predict increases in the frequency and intensity of drought in the southwestern U.S. In pinyon-juniper woodlands, we hypothesize that drought stress leads to increased competition between pinyon and juniper, greater dependence of pinyon on facilitative nurse plants, and changes in pinyon ectomycorrhizal (EM) fungal abundance and community structure. Because EM fungi can alleviate environmental stress by increasing water and nutrient 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 and growth, as well as their EM fungi. We will use a combination of field experiments, greenhouse studies, 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-juniper woodlands, 2) provide data on plant responses and EM fungal community shifts in response to competition 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 is necessary to allow comparisons of ecological data on fungi from different locations to begin to understand the factors that affect their abundance and distribution.