DOI: 10.5061/dryad.7wm37pw23
title: Data from: Patterns and drivers of atmospheric nitrogen deposition retention in global forests

description: Forests are the largest carbon sink in terrestrial ecosystems, and the
 impact of nitrogen (N) deposition on this carbon sink depends on the fate
 of external N inputs. However, the patterns and driving factors of N
 retention in different forest compartments remain elusive. In this study,
 we synthesized 408 observations from global forest 15N tracer experiments
 to reveal the variation and underlying mechanisms of 15N retention in
 plants and soils. The results showed that the average total ecosystem 15N
 retention in global forests was 63.04 ± 1.23%, with the soil pool being
 the main N sink (45.76 ± 1.29%). Plants absorbed 17.28 ± 0.83% of 15N,
 with more allocated to leaves (5.83 ± 0.63%) and roots (5.84 ± 0.44%). In
 subtropical and tropical forests, 15N was mainly absorbed by plants and
 mineral soils, while the organic soil layer in temperate forests retained
 more 15N. Additionally, forests retained more 15NH4+ than 15NO3−,
 primarily due to the stronger capacity of the organic soil layer to retain
 15NH4+. The mechanisms of 15N retention varied among ecosystem
 compartments, with total ecosystem 15N retention affected by N deposition.
 Plant 15N retention was influenced by vegetative and microbial nutrient
 demands, while soil 15N retention was regulated by climate factors and
 soil nutrient supply. Overall, this study emphasizes the importance of
 climate and nutrient supply and demand in regulating forest N retention
 and provides data to further explore the impacts of N deposition on forest
 carbon sequestration.
description: We searched the Web of Science Database for peer-reviewed papers
 prior to February 22, 2023, using “retention” and “N-15” as the keywords.
 The following criteria were applied to filter the peer-reviewed papers:
 (1) Selection of <sup>15</sup>N tracer experiments in forest
 ecosystems conducted in the field, excluding laboratory incubation or
 greenhouse experiments; (2) Selection of the absolute value of
 <sup>15</sup>N retention obtained from the
 <sup>15</sup>N tracer experiment, excluding the relative
 value; (3) Selection of <sup>15</sup>N tracer experiments
 including N addition treatments, excluding other treatments such as fire,
 phosphorus (P) addition, potassium addition, etc. Due to limited data on
 litter layers and understory vegetation components (i.e., shrubs, herbs,
 and grasses), the <sup>15</sup>N retention of litter layers
 was combined into organic soil <sup>15</sup>N retention.
 Within the entire forest ecosystem, the <sup>15</sup>N
 retention of understory vegetation was not consider, focusing instead on
 the <sup>15</sup>N allocation among different plant organs
 (i.e., leaves, branches, stems, roots). Ultimately, 408 observations were
 obtained from 56 peer-reviewed papers, totaling 62 sites and 92
 site-years. The study sites were distributed across North America (25
 sites), Europe (14 sites), Asia (14 sites), South America (3 sites),
 Oceania (4 sites), and Africa (2 sites), covering tropical forests (5
 sites), subtropical forests (10 sites), temperate forests (42 sites), and
 boreal forests (5 sites). Raw data for <sup>15</sup>N
 retention of different ecosystem compartments were obtained from tables,
 figures, results, or supplementary information in the peer-reviewed
 papers. When data were presented in figures, specific values were
 extracted using Getdata software 2.22 (GetData, Kogarah, NSW,
 AUS).
description: # Patterns and drivers of atmospheric nitrogen deposition retention in
 global forests We searched the Web of Science Database for peer-reviewed
 papers prior to February 22, 2023, using “retention” and “N-15” as the
 keywords. The following criteria were applied to filter the peer-reviewed
 papers: (1) Selection of 15N tracer experiments in forest ecosystems
 conducted in the field, excluding laboratory incubation or greenhouse
 experiments; (2) Selection of the absolute value of 15N retention obtained
 from the 15N tracer experiment, excluding the relative value; (3)
 Selection of 15N tracer experiments including N addition treatments,
 excluding other treatments such as fire, phosphorus (P) addition,
 potassium addition, etc. Due to limited data on litter layers and
 understory vegetation components (i.e., shrubs, herbs, and grasses), the
 15N retention of litter layers was combined into organic soil 15N
 retention. Within the entire forest ecosystem, the 15N retention of
 understory vegetation was not consider, focusing instead on the 15N
 allocation among different plant organs (i.e., leaves, branches, stems,
 roots). Ultimately, 408 observations were obtained from 56 peer-reviewed
 papers, totaling 62 sites and 92 site-years. The study sites were
 distributed across North America (25 sites), Europe (14 sites), Asia (14
 sites), South America (3 sites), Oceania (4 sites), and Africa (2 sites),
 covering tropical forests (5 sites), subtropical forests (10 sites),
 temperate forests (42 sites), and boreal forests (5 sites). Raw data for
 15N retention of different ecosystem compartments were obtained from
 tables, figures, results, or supplementary information in the
 peer-reviewed papers. When data were presented in figures, specific values
 were extracted using Getdata software 2.22 (GetData, Kogarah, NSW, AUS).
 Note: N_retention_data_v2 is based on N_retention_data_v1, with the
 addition of raw data. "XX" in the "forest_type" and
 "15N_tracer_type" sheets represents the 15N retention in
 different ecosystem compartments (i.e., plant, leaf, branch, stem, root,
 soil, organic soil, mineral soil, and total ecosystem). "XX_n"
 in the "forest_type" and "15N_tracer_type" sheets
 represents the sample size of "XX". "XX_mean" in the
 "forest_type" and "15N_tracer_type" sheets represents
 the mean value of "XX". "XX_se" in the
 "forest_type" and "15N_tracer_type" sheet represents
 the standard error of the mean value of "XX". "NA" in
 the "raw_data" sheet represents unavailable observed data.
 "MAT_CRU" and "MAP_CRU" columns of the
 "raw_data" sheet indicate that the missing values in the
 references are extracted from the CRU.