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

项目摘要：当前的全球气候变化模型预测美国西南部干旱的频率和强度将增加。在小松林地，我们假设干旱胁迫导致小松和杜松之间的竞争加剧，小松对促进性护理植物的依赖增加，以及小松外生菌根（EM）真菌丰度和群落结构的变化。由于EM真菌可以通过增加寄主植物对水分和养分的吸收来缓解环境胁迫，因此了解影响这些共生菌的因素非常重要。该项目的目标是研究竞争和促进如何影响小松的生存和生长，以及它们的EM真菌。我们将结合田间实验、温室研究和分子工具（RFLP分析和DNA测序）来鉴定EM真菌物种。我们的研究结果将1)量化松柏林地EM真菌的多样性和分布，2)提供植物响应和EM真菌群落在竞争和促进下的变化数据，3)有助于建立EM真菌序列库。由于这些真菌中的许多只能用分子工具来鉴定，后一个目标是必要的，以便对来自不同地点的真菌的生态数据进行比较，从而开始了解影响其丰度和分布的因素。

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.