Download or read book Comparing Arbuscular and Ectomycorrhizal Fungal Communities in Seven North American Forests and Their Response to Nitrogen Fertilization written by Jennifer Lyn Lansing and published by . This book was released on 2003 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mycorrhizal fungi are found extensively in forest soils and play a crucial role in carbon and nitrogen cycling between plant and soil. However, little is known about how mycorrhizal communities differ between forest systems or what role they play in below ground carbon dynamics. This study addresses the basic ecological questions of how ECM and AM vary between gymnosperm and angiosperm host taxa in undisturbed forest ecosystems which vary in climate and soil characteristics. I use a manipulative N fertilization experiment to study the mycorrhizae between forest sites and their role in ecosystem cycling. AM and ECM percent colonized root length and colonized root length per minirhizotron frame differed between sites and between years. The extramatrical hyphae of all four major AM genera were present at all sites whereas spores, in low abundance, were mainly Glomus spp. Richness of ECM morphotypes was similar between sites at a variety of scales. Functional groups based on ECM morphological characters differed between sites and some fertilization effects were found. Site location was the most influential factor in determining mycorrhizal abundance, composition, and overall role in carbon and nitrogen cycling. At the P. edulis site, I intensively studied the abundance, diversity, composition, and spatial distribution of ECM using morphotyping and RFLP analysis. Years differed in ECM abundance and composition. ECM types differed in frequency across the landscape, abundance at any individual tree, and spatial aggregation. Each P. edulis tree was similar in ECM tip abundance, richness, and number of dominant ECM types. At all scales a few ECM types were dominant however there was temporal and tree to tree variability in which ECM were dominant. The individual tree is the most important sampling unit when assessing P. edulis ECM diversity and composition. Also at the P. edulis site, using RFLP analysis to identify ECM types and 14C to estimate age I found a differential response in the 14C signature of RFLP types to N fertilization indicating that N fertilization does not affect all ECM fungi similarly and functional differences in ECM fungi exist.