title: Decomposition of15N-labelled beech litter and fate of nitrogen derived from litter in a beech forest.
abstract: The decomposition and the fate of15N- labelled beech litter was monitored in a beech forest (Vosges mountains, France) over 3 years. Circular plots around beech trees were isolated from neighbouring tree roots by soil trenching. After removal of the litter layer,15N-labelled litter was distributed on the soil. Samples [labelled litter, soil (0-15 cm depths], fine roots, mycorrhizal root tips, leaves) were collected during the subsequent vegetation periods and analysed for total N and15N concentration. Mass loss of the15N-labelled litter was estimated using mass loss data from a litterbag experiment set up at the field site. An initial and rapid release of soluble N from the decomposing litter was balanced by the incorporation of exogenous N into the litter. Fungal N accounted for approximately 35% of the N incorporation. Over 2 years, litter N was continuously released and rates of N and mass loss were equivalent, while litter N was preferentially lost during the 3rd year. Released15N accumulated essentially at the soil surface.15N from the decomposing litter was rapidly (i.e. in 6 months) detected in roots and beech leaves and its level increased regularly and linearly over the course of the labelling experiment. After 3 years, about 2% of the original litter N had accumulated in the trees.15N budgets indicated that soluble N was the main source for soil microbial biomass. Nitrogen accumulated in storage compounds was the main source of leaf N, while soil organic N was the main source of mycorrhizal N. Use of15N-labelled beech litter as decomposing substrate allowed assessment of the fate of litter N in the soil and tree N pools in a beech forest on different time scales.
authors.affiliation: INRA, Centre de Nancy, Ecosystémes Forestiers, 54280 Champenoux, France e-mail: zeller@nancy.inra.fr Fax: +33-3-83394069, , , , , , FR.
authors.forename: B
authors.initials: B
authors.lastname: Zeller
authors.affiliation: INRA, Centre de Nancy, Ecosystémes Forestiers, 54280 Champenoux, France e-mail: zeller@nancy.inra.fr Fax: +33-3-83394069, , , , , , FR.
authors.forename: M
authors.initials: M
authors.lastname: Colin-Belgrand
authors.affiliation: INRA, Centre de Nancy, Ecosystémes Forestiers, 54280 Champenoux, France e-mail: zeller@nancy.inra.fr Fax: +33-3-83394069, , , , , , FR.
authors.forename: E
authors.initials: E
authors.lastname: Dambrine
authors.affiliation: INRA, Centre de Nancy, Ecosystémes Forestiers, 54280 Champenoux, France e-mail: zeller@nancy.inra.fr Fax: +33-3-83394069, , , , , , FR.
authors.forename: F
authors.initials: F
authors.lastname: Martin
authors.affiliation: CNRS-UPR 8481 CEFE, Bp 5051, F-34033 Montpellier, France, , , , , , FR.
authors.forename: P
authors.initials: P
authors.lastname: Bottner
keywords: Beech; Key words 15N; Litter decomposition; N mineralisation; N uptake