title: Girdling affects ectomycorrhizal fungal (EMF) diversity and reveals functional differences in EMF community composition in a beech forest.
abstract: The relationships between plant carbon resources, soil carbon and nitrogen content, and ectomycorrhizal fungal (EMF) diversity in a monospecific, old-growth beech (Fagus sylvatica) forest were investigated by manipulating carbon flux by girdling. We hypothesized that disruption of the carbon supply would not affect diversity and EMF species numbers if EM fungi can be supplied by plant internal carbohydrate resources or would result in selective disappearance of EMF taxa because of differences in carbon demand of different fungi. Tree carbohydrate status, root demography, EMF colonization, and EMF taxon abundance were measured repeatedly during 1 year after girdling. Girdling did not affect root colonization but decreased EMF species richness of an estimated 79 to 90 taxa to about 40 taxa. Cenococcum geophilum, Lactarius blennius, and Tomentella lapida were dominant, colonizing about 70% of the root tips, and remained unaffected by girdling. Mainly cryptic EMF species disappeared. Therefore, the Shannon-Wiener index (H') decreased but evenness was unaffected. H' was positively correlated with glucose, fructose, and starch concentrations of fine roots and also with the ratio of dissolved organic carbon to dissolved organic nitrogen (DOC/DON), suggesting that both H' and DOC/DON were governed by changes in belowground carbon allocation. Our results suggest that beech maintains numerous rare EMF species by recent photosynthate. These EM fungi may constitute biological insurance for adaptation to changing environmental conditions. The preservation of taxa previously not known to colonize beech may, thus, form an important reservoir for future forest development.
authors.affiliation: Abteilung Forstbotanik und Baumphysiologie, Büsgen-Institut, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
authors.forename: Rodica
authors.initials: R
authors.lastname: Pena
authors.forename: Christine
authors.initials: C
authors.lastname: Offermann
authors.forename: Judy
authors.initials: J
authors.lastname: Simon
authors.forename: Pascale Sarah
authors.initials: PS
authors.lastname: Naumann
authors.forename: Arthur
authors.initials: A
authors.lastname: Gessler
authors.forename: Jutta
authors.initials: J
authors.lastname: Holst
authors.forename: Michael
authors.initials: M
authors.lastname: Dannenmann
authors.forename: Helmut
authors.initials: H
authors.lastname: Mayer
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kögel-Knabner
authors.forename: Heinz
authors.initials: H
authors.lastname: Rennenberg
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
mesh_terms: D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D029964:Fagus / Q000382:microbiology*; D005658:Fungi / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D017422:Sequence Analysis, DNA; D014197:Trees
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D002244:Carbon