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CO 2 ‐ENRICHMENT AND NUTRIENT AVAILABILITY ALTER ECTOMYCORRHIZAL FUNGAL COMMUNITIES
Author(s) -
Parrent Jeri Lynn,
Morris William F.,
Vilgalys Rytas
Publication year - 2006
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2006)87[2278:canaae]2.0.co;2
Subject(s) - species richness , nutrient , biology , ecology , relative species abundance , guild , community structure , ecosystem , nutrient cycle , species diversity , botany , abundance (ecology) , habitat
Ectomycorrhizal fungi (EMF), a phylogenetically and physiologically diverse guild, form symbiotic associations with many trees and greatly enhance their uptake of nutrients and water. Elevated CO 2 , which increases plant carbon supply and demand for mineral nutrients, may change the composition of the EMF community, possibly altering nutrient uptake and ultimately forest productivity. To assess CO 2 effects on EMF communities, we sampled mycorrhizae from the FACTS‐I (Forest–Atmosphere Carbon Transfer and Storage) research site in Duke Forest, Orange County, North Carolina, USA, where Pinus taeda forest plots are maintained at either ambient or elevated CO 2 (200 ppm above ambient) concentrations. Mycorrhizae were identified by DNA sequence similarity of the internal transcribed spacer ribosomal RNA gene region. EMF richness was very high; 72 distinct phylotypes were detected from 411 mycorrhizal samples. Overall EMF richness and diversity were not affected by elevated CO 2 , but increased CO 2 concentrations altered the relative abundances of particular EMF taxa colonizing fine roots, increased prevalence of unique EMF species, and led to greater EMF community dissimilarity among individual study plots. Natural variation among plots in mean potential net nitrogen (N) mineralization rates was a key determinant of EMF community structure; increasing net N mineralization rate was negatively correlated with EMF richness and had differential effects on the abundance of particular EMF taxa. Our results predict that, at CO 2 concentrations comparable to that predicted for the year 2050, EMF community composition and structure will change, but diversity will be maintained. In contrast, high soil N concentrations can negatively affect EMF diversity; this underscores the importance of considering CO 2 effects on forest ecosystems in the context of background soil chemical parameters and other environmental perturbations such as acid deposition or fertilizer runoff.