title: Whole-tree seasonal nitrogen uptake and partitioning in adult Fagus sylvatica L. and Picea abies L. [Karst.] trees exposed to elevated ground-level ozone.
abstract: The effect of long-term exposure of twice-ambient O(3) (2 × O(3)) on whole-tree nitrogen (N) uptake and partitioning of adult beech and spruce was studied in a mixed forest stand, SE-Germany. N uptake as (15)N tracer and N pools were calculated using N concentrations and biomass of tree compartments. Whole-tree N uptake tended to be lower under 2 × O(3) in both species compared to trees under ambient O(3) (1 × O(3)). Internal partitioning in beech showed significantly higher allocation of new N to roots, with mycorrhizal root tips and fine roots together receiving about 17% of new N (2 × O(3)) versus 7% (1 × O(3)). Conversely, in spruce, N allocation to roots was decreased under 2 × O(3). These contrasting effects on belowground N partitioning and pool sizes, being largely consistent with the pattern of N concentrations, suggest enhanced N demand and consumption of stored N with higher relevance for tree-internal N cycling in beech than in spruce.
authors.affiliation: Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland. Electronic address: rosemarie.weigt@psi.ch.
authors.forename: R B
authors.initials: RB
authors.lastname: Weigt
authors.affiliation: Ecophysiology of Plants, Department Ecology and Ecosystem Management, Technische Universität München, 85354 Freising, Germany.
authors.forename: K H
authors.initials: KH
authors.lastname: Häberle
authors.affiliation: Forest Yield Science, Department Ecology and Ecosystem Management, Technische Universität München, 85354 Freising, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Rötzer
authors.affiliation: Ecophysiology of Plants, Department Ecology and Ecosystem Management, Technische Universität München, 85354 Freising, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Matyssek
mesh_terms: D028202:Abies; D000393:Air Pollutants / Q000378:metabolism* / Q000633:toxicity; D018533:Biomass; D029964:Fagus / Q000187:drug effects / Q000378:metabolism*; D005858:Germany; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D010126:Ozone / Q000633:toxicity*; D028222:Picea / Q000187:drug effects / Q000378:metabolism*; D028223:Pinus; D018517:Plant Roots / Q000737:chemistry; D012621:Seasons
chemical_list: D000393:Air Pollutants; D010126:Ozone; D009584:Nitrogen
keywords: European beech; Forest trees; Nitrogen partitioning; Norway spruce; Tropospheric ozone; Whole-tree budget