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

摘要论文研究：温带森林中常见的菌根网络是否限制了植物竞争和物种排斥？在自然界中，菌根真菌网络包围并连接邻近植物的根，通常包括几平方米内的多个物种。温室试验表明，当邻居被遮蔽或氮浓度较低时，幼苗获得的碳和氮通过这些共同的菌根网络（CMN）定向转移到邻居中。有假设认为，CMN限制了竞争，特别是在林下种群和新生种群之间的竞争，并对森林群落结构有间接影响。本研究将1)论证CMN对三种温带森林树种幼苗生长和存活的重要性；2)评估CMN对幼苗物种表现层次的影响；3)量化田间菌根寄主特异性和种间CMN发生频率；4)阐明CMN对土壤N向多个寄主分配的规律。另一项研究将首次利用13- c同位素分析证明上层树木和幼苗之间的碳流。该研究将有助于解释CMN对幼苗性能的影响，并为我们理解森林生态系统中菌根功能、植物竞争和演替做出重大贡献。

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.