DISSERTATION RESEARCH: Do Common Mycorrhizal Networks Limit Plant Competition and Species Exclusion in Temperate Forests?

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AbstractDISSERTATION RESEARCH: Do Common Mycorrhizal Networks Limit Plant Competition and Species Exclusion in Temperate Forests?SchmitzDEB-0309225In nature, networks of mycorrhizal fungi encompass and connect the roots of neighbor plants, often including multiple species over several square meters. Greenhouse experiments show that carbon and nitrogen acquired by seedlings move directionally into neighbors via these common mycorrhizal networks (CMN) when neighbors are shaded or have low N concentration. It has been hypothesized that CMN limit competition, particularly between overstory and recruiting tree populations, and have indirect effects on forest community structure. This research will 1) demonstrate the importance of CMN for the growth and survival of three tree seedling species growing in a temperate forest, 2) evaluate the influence of CMN on the hierarchy of seedling species performance, 3) quantify mycorrhizal host-specificity and the frequency of interspecific CMN in the field, and 4) clarify the rules that govern the distribution of soil N to multiple hosts by CMN. An additional study will demonstrate, for the first time, carbon flow between overstory trees and seedlings using13-C isotope analysis. This study will aid in interpretation of CMN effects on seedling performance, and stand as a major contribution to our understanding of mycorrhizal functioning, plant competition, and succession in forest ecosystems.