DOI: 10.5061/dryad.3r2280gw1
title: Data from: Forest nitrogen dynamics in response to increasing nitrogen deposition: comparing above-canopy and soil fertilizations in a mature beech forest

description: Nitrogen (N) fertilization experiments provide critical insights into how
 increasing N deposition alters the balance between N retention and
 saturation in forest ecosystems. However, most studies have considered
 soil N applications, overlooking tree canopy-atmosphere interactions,
 leading to an incomplete understanding of the fate of N in forests. We
 investigated ecosystem N dynamics four years after the establishment of a
 nitrogen manipulation experiment in a beech forest, involving Control
 (N0), 30 kg N ha^-1^ y^-1^, distributed to soil (N30) and above tree
 canopies (N30A), and 60 kg N ha^-1^ y^-1^ applied to the soil (N60). We
 assessed N concentration and δ15N across forest compartments (leaves, fine
 roots, ectomycorrhizal root tips, soil, and litter) and quantified
 microbial functional genes related to soil N processes. N concentrations
 were minimally affected by treatments, whereas δ15N increased along
 compartments, particularly in the N60, indicating enhanced soil N losses.
 Both N30 and N60 increased N concentrations and d15N values in
 ectomycorrhizal root tips and soil, suggesting enhanced fungal N
 immobilization but limited transfer to the host plants. In contrast, N30A
 led to 15N depletion in fine roots and litter, reflecting stronger plant
 reliance on ectomycorrhizal activity and potential alterations in litter
 quality, which may inhibit decomposition. Soil nitrifiers and denitrifiers
 were abundant, regardless of the treatments. Our findings highlight the
 need for future experiments to simulate realistic N deposition scenarios,
 including canopy interactions, to better understand ecosystem N dynamics
 and forest responses under global change.
description: # Data from: Forest nitrogen dynamics in response to increasing nitrogen
 deposition: comparing above-canopy and soil fertilizations in a mature
 beech forest Dataset DOI:
 [10.5061/dryad.3r2280gw1](https://doi.org/10.5061/dryad.3r2280gw1) ##
 Description of the data and file structure This dataset contains
 measurements related to an experimental study simulating an increase in
 nitrogen deposition in forest ecosystems via nitrogen fertilization. It
 includes information on different nitrogen treatments, forest compartments
 considered, and measurements carried out. * Nitrogen treatments were
 applied either through **above-canopy** or **soil fertilizations**,
 depending on the applied dose. * Each treatment was replicated in **three
 plots**. * Sampling included different forest compartments to assess
 responses in ecosystem nitrogen dynamics. Replicates were n=3 for all
 forest compartments, except for leaf litter and seeds (see Materials and
 Methods in Teglia et al. 2025 for more details). ### Files and variables
 #### File: dataset_Teglia_et_al._2025.xls **Description:** This dataset
 includes nitrogen content (%) and δ¹⁵N (‰) measurements from tree and soil
 samples collected under four nitrogen fertilization treatments. Data are
 organized by treatment, plot, tree ID, and forest compartment.
 **Variables** * Forest compartments values: * soil: soil core (5 cm
 diameter and 10 cm depth) * leaves * Litter_of: partially undecomposed
 litter – OF * Litter_oh: decomposed litter – OH * fineRoots: fine roots *
 ERT: ectomycorrhizal root tips * seeds * Nitrogen content in the sample.
 Unit: % * Stable nitrogen isotope composition (δ¹⁵N). Unit: ‰ #### File:
 Functional_genes_Teglia_et_al._2025.xls **Description:** This dataset
 includes data from functional genes quantification in soil samples
 collected under four nitrogen fertilization treatments. Data are organized
 by treatment, plot, tree ID, and different functional genes quantified.
 ##### Functional genes quantified * Genes encoding the ammonia
 monooxygenase subunit A of bacteria amoA AOB and archaea (***amoA AOA***),
 and the nitrite oxidoreductase subunit B of bacteria (***nxrB**)*, which
 catalyze the oxidation of ammonia to nitrite and nitrite to nitrate,
 respectively. * Genes involved in denitrification, including those
 encoding nitrite reductases (bacterial ***nirS*** and bacterial and fungal
 ***nirK***), nitric oxide reductase (bacterial ***qnorB***), and nitrous
 oxide reductase (bacterial ***nosZ***). * Gene encoding dinitrogenase
 reductase involved in nitrogen fixation (bacterial ***nifH***)
 **Units**(please note that XX indicates a given functional gene): *
 XX_dna:  gene copies/ g dry soil used in DNA extraction =  copies/g dry
 soil  * XX_ds: genes copies/ ng DNA extrated = copies / ng DNA extracted *
 XX_norm : in this case number of gene copies was calculate as the ratio
 copies / g dry soil normalized  for DNA extraction yield as well = copies
 / g dry normalized to extraction yield. These are the variables that were
 used in all the analyses presented in the manuscript by Teglia et al.
 2025.