title: Effects of long-term free-air ozone fumigation on delta15N and total N in Fagus sylvatica and associated mycorrhizal fungi.
abstract: Patterns of nitrogen (N) isotope composition (delta(15)N) and total N contents were determined in leaves, fine roots, root-associated ectomycorrhizal fungi (ECM) of adult beech trees (FAGUS SYLVATICA), and soil material under ambient (1 x O(3)) and double ambient (2 x O(3)) atmospheric ozone concentrations over a period of two years. From fine root to leaf material delta(15)N decreased consecutively. Under enhanced ozone concentrations total N was reduced in fine roots and delta(15)N showed a decrease in roots and leaves. In the soil and in most types of mycorrhizae, delta(15)N and total N were not altered due to ozone fumigation. The number of vital ectomycorrhizal root tips increased and the mycorrhizal community structure changed in 2 x O(3). Simultaneously, the specific rate of inorganic N-uptake by the roots was reduced under the double ozone regime. From these results it is assumed that 2 x O(3) changes N-nutrition of the trees at the level of N-acquisition, as indicated by enhanced mycorrhizal root tip density, altered mycorrhizal species composition, and reduced specific N-uptake rates.
authors.affiliation: Institute of Forest Botany and Tree Physiology, Albert Ludwigs University, Georges-Köhler-Allee 053/054, 79110 Freiburg, Germany. kristine.haberer@ctp.uni-freiburg.de
authors.forename: K
authors.initials: K
authors.lastname: Haberer
authors.forename: T
authors.initials: T
authors.lastname: Grebenc
authors.forename: M
authors.initials: M
authors.lastname: Alexou
authors.forename: A
authors.initials: A
authors.lastname: Gessler
authors.forename: H
authors.initials: H
authors.lastname: Kraigher
authors.forename: H
authors.initials: H
authors.lastname: Rennenberg
mesh_terms: D000388:Air; D000641:Ammonia / Q000378:metabolism; D044822:Biodiversity; D029964:Fagus / Q000187:drug effects* / Q000378:metabolism* / Q000382:microbiology; D005651:Fumigation; D038821:Mycorrhizae / Q000187:drug effects*; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D012988:Soil Microbiology; D013997:Time Factors
chemical_list: D009566:Nitrates; D009587:Nitrogen Isotopes; D010126:Ozone; D000641:Ammonia; D009584:Nitrogen