DOI: 10.5061/dryad.x3ffbg7xm
title: Factors influencing fine root decomposition rate in response to nitrogen addition vary across root characteristics

description: Nitrogen (N) deposition strongly affects litter decomposition and nutrient
 release , thereby reshaping carbon cycling in terrestrial ecosystems.
 Although most studies have focused on above-ground litter, the effects of
 N addition on fine root decomposition and their underlying drivers,
 particularly across different root characteristics, remain poorly
 understood. We synthesized a meta-analysis of 144 observations from 30
 studies to quantify the response of fine root decomposition rates to N
 addition and to identify the key factors that regulate these responses
 across root characteristics. On average, N addition reduced fine root
 decomposition rates and mass loss by 8.52% and 6.24%, respectively.
 Negative responses to N addition were most pronounced in roots ≤2 mm in
 diameter and in first- and second-order roots. Soil microbial biomass N
 and clay content were the dominant drivers of these responses in roots ≤2
 mm. Within different root characteristics, soil microbial biomass N and
 soil N content were the most important factors regulating the response of
 decomposition rates to N addition for roots ≤1 mm, while N addition amount
 was the key determinant for third- to fifth-order roots. These results
 suggest that the controls on fine root decomposition under N addition vary
 with root characteristics. This highlights the need to incorporate root
 variability into ecosystem models to improve predictions of below-ground
 carbon cycling under future climate change.
description: # Factors influencing fine root decomposition rate in response to nitrogen
 addition vary across root characteristics Dataset DOI:
 [10.5061/dryad.x3ffbg7xm](10.5061/dryad.x3ffbg7xm) ## Description of the
 data and file structure 144 observations on the responses of fine root
 decomposition rate to nitrogen addition from 30 peer-reviewed publications
 at the global scale were collected. ### Files and variables #### File:
 Fine_root_decomposition_Wang_et_al.FE.csv **Description:** NA indicates
 not available; Null indicates not applicable. ##### Variables * Lon:
 Longitude of site in decimal degrees. * Lat: latitude of site in decimal
 degrees. * MAT: Mean annual temperature in degrees ℃ * MAP: Mean annual
 precipitation in mm * Ecosystem_type: Ecosystem types of plants include
 forest, grassland, and wetland * Climatic_zone: Climatic zones of plants 
 include Subtropical, tropical and temperate * MYC: Mycorrhizal types
 include ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) *
 Leaf_form: Leaf forms of plants include conifer and broadleaf *
 Leaf_phenology: leaf phenology of plants includes evergreen and deciduous.
 * Growth_form: Growth forms of plants  include trees, shrubs, and herbs *
 Initial_C (g·kg-1): Initial carbon content of fine root litter * Initial_N
 (g·kg-1): Initial nitrogen content of fine root litter * Initial_P
 (g·kg-1): Initial phosphorus content of fine root litter * Initial_lignin
 (g·kg-1): Initial lignin content of fine root litter * Initial_cellulose
 (g·kg-1): Initial cellulose content of fine root litter * Buried_depth
 (cm): Buried depth of fine roots * Mesh_size (mm): Mesh size of fine root
 litterbags * Duration(year): fine root decomposition durationRoot_order
 Root_diameter(mm) * Root_order: R1–R2, the first two orders; R3–R4, the
 third to fourth order; R5–R6, the fifth to sixth order; R1–R3, the first
 three orders; R4–R5, the fourth to fifth order * Root_diameter: &lt;2 mm,
 diameter less than 2 mm * N_form:  Forms of nitrogen addition, including
 inorganic (i.e., NH4Cl, NaNO3, NH4NO3) and organic nitrogen(i.e., urea) *
 N_amount (kg·ha-1·yr-1): amount of nitrogen addition, including  ≤ 50
 kg·ha-1·yr-1, 50-150 kg·ha-1·yr-1, and &gt; 150 kg·ha-1·yr-1 * K:
 mt/m0=e^(-kt), where mt is the residual mass of fine root at time t
 (year), m0 is the fine root mass at the beginning of the experiment, and k
 is the decomposition coefficient. * Kc: Kc represents the mean k values
 of the control group * Kt: Kt represents the mean k values of the
 treatment group * SDc: SDc represents the standard deviation of the
 control group * SDt: SDt represents the standard deviation of the
 treatment group * Nc: Nc represents the sample sizes of the control groups
 * Nt: Nt represents the sample sizes of the treatment groups *
 Control_mass_remaining (%): Control mass remaining represents the mass
 remaining rate  of fine root in the control group *
 Treatment_mass_remaining (%): Treatment mass remaining represents the mass
 remaining rate  of fine root decomposition in the treatment group *
 Control_C_remaining (%): Control C remaining represents carbon remaining
 rate  of fine root in the control group * Treatment_C_remaining (%):
 Treatment C remaining represents carbon remaining rate  of fine root in
 the treatment group * Control_N_remaining(%): Control N remaining 
 represents nitrogen remaining rate  of fine root in the control group *
 Treatment_N_remaining (%): Treatment N remaining represents nitrogen
 remaining rate of fine root in the treatment group * Control_P_remaining
 (%): Control P remaining represents phosphorus remaining rate of fine
 root in the control group * Treatment_P_remaining (%): Treatment P
 remaining represents phosphorus remaining rate  of fine root in the
 treatment group * pH: pH represents soil pH * SOC(g·kg-1): SOC represents
 soil organic carbon * Soil_N(g·kg-1): Soil_N represents soil nitrogen *
 Sand(%): Sand represents the sand content of soil * Clay(%): Clay
 represents the clay content of soil * BBC(g·m-2): BBC respresents
 bacterial biomass carbon * F:B_biomass: F:B_biomass respresents soil 
 fungi to bacteria biomass ratio * MBC(g·m-2): MBC respresents soil
 microbial biomass carbon * FBC(g·m-2): FBC respresents soil fungal biomass
 carbon * MBN(g·m-2): MBN respresents soil microbial biomass nitrogen