Ectomycorrhizal fungal communities in two North American oak forests respond to nitrogen addition

Abstract

Summary• How nitrogen (N) deposition impacts ectomycorrhizal (EM) fungal communities has been little studied in deciduous forests or across spatial scales. Here, it was tested whether N addition decreases species richness and shifts species composition across spatial scales in temperate deciduous oak forests.• Combined molecular (terminal restriction fragment length polymorphism (T-RFLP), sequencing) and morphological approaches were used to measure EM fungal operational taxon unit (OTU) richness, community structure and composition at the spatial scale of the root, soil core and forest during a 3-yr N fertilization experiment in Quercus-dominated forests near Chicago, IL, USA.• In N treatments, significantly lower OTU richness at the largest but not smaller spatial scales and a different community structure were detected. The effects of N appeared to be immediate, not cumulative. Ordination indicated the composition of EM fungal communities was determined by forest site and N fertilization.• The EM fungi responded to a N increase that was low compared with other fertilization studies, suggesting that moderate increases in N deposition can affect EM fungal communities at larger spatial scales in temperate deciduous ecosystems. While responses at large spatial scales indicate that environmental factors can drive changes in these communities, untangling the impacts of abiotic from biotic factors remain limited by detection issues.

Vegetation and Soil Environment Influence the Spatial Distribution of Root-Associated Fungi in a Mature Beech-Maple Forest

“…Soil water availability can affect mycorrhizae on beech (36,59), and this could be an important factor controlling fungi during early summer. A substantial body of evidence suggests that soil N can significantly alter and affect the distribution and community structure of ECM fungi (3,11,24,47,53). Although C and N were significantly correlated with fungal community structure in June and C was significantly correlated with root fungi in September, the correlations were not strong.…”

“…At the local scale, fungal distribution and richness might be influenced by differences in root growth and architecture (30,42), by the distance to the bole of the tree (11,42,49), or by the presence of neighboring trees (29, 64). Temporal changes in ECM communities could be associated with seasonal changes in plant physiology and phenology (3,8,17). …”

Variation in ectomycorrhizal fungal communities associated with Oreomunnea mexicana (Juglandaceae) in a Neotropical montane forest

“…Given that this genus is an important component of many EM fungal communities in the tropics (e.g., Peay et al 2010;Smith et al 2011;Tedersoo et al 2011) and appears to shift in community composition with changes in soil N availability (Lilleskov et al 2002;Avis et al 2003;Avis et al 2008), it was chosen to test hypotheses concerning phylogenetic diversity. To augment data on Russula distribution obtained from root tips, Russula fruiting bodies were collected every 2 weeks throughout the study period from January to July 2012 along four 50×4 m transects in each site.…”

Selection of Enzymes for Terminal Restriction Fragment Length Polymorphism Analysis of Fungal Internally Transcribed Spacer Sequences

“…The same was reported by Avis et al (2) and Dickie and FitzJohn (11), together with HpyCH4IV. However, the most-used enzymes in real fungal TRFLP profiling have been HinfI (3,10,13,19,26,27,29,38), HaeIII (3, 5, 6, 7, 10, 13, 27), AluI (6,7,29,38), TaqI (13,19,26,29,33), CfoI (29), HhaI and MspI (31), BsuRI (29), and Hsp92II (22), among others. While the outstanding performance of HpyCH4IV (an isoschizomer of MaeII) is in accordance with the present results, a comparison of Tables 2 and 5 shows that most of the other most-used enzymes cannot be considered optimal.…”

“…Terminal restriction fragment length polymorphism (TRFLP) profiling was originally developed as a means of genotyping mixed DNA samples (30) and is currently being employed in fungal community ecology studies (3,5,6,7,10,13,19,22,26,27,29,33,38), despite a number of technical and conceptual difficulties (11). Briefly, TRFLP profiling involves amplifying the DNA in pools of mixed genetic material with fluorescently labeled primers, digesting the products with restriction endonucleases, and sizing the labeled terminal fragments in a sequencer.…”