Effects of Long‐Term Free‐Air Ozone Fumigation on δ¹⁵N 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.

Effects of long-term ambient ozone exposure on biomass and wood traits in poplar treated with ethylenediurea (EDU)

“…Interestingly, a higher ECM colonization was observed in notprotected plants, which is a quite common response to O 3 in field experiments with trees (Haberer et al, 2007;Grebenc and Kraigher, 2007a). Decreased allocation of belowground carbon, in contrast, is expected to impair fine roots and root symbionts (Grebenc and Kraigher, 2007b).…”

Fine roots and ectomycorrhizas as indicators of environmental change

“…15 N measurements indicated a reduction of total nitrogen in fine roots from ozone treated adult trees (Haberer et al, 2007) while in seedlings Mg concentration was reduced under the same conditions (Ž eleznik et al, 2007). Opposite to the results from adult trees, in beech seedlings a significant reduction of number of vital ECM types and number of ECM root tips was observed (ibid).…”

Ozone Stress and Ectomycorrhizal Root–Shoot Signaling

“…In addition to ozone effects at the cellular and organ level, responses to the pollutant at the whole plant level, including plant-internal N-and C-cycling, are of special interest to estimate ozone toxicity in the long term. d (Högberg 1999;Hobbie et al 2005) and depleted in comparison to the source (Haberer et al 2007).…”