Data from: Afforestation mitigates soil nitrogen limitation by enhancing mineralization and lowering denitrification in central China

Wang, Xueyu 1 ; Zhai, Deping2; Quan, Xin1; Liao, Chang 1 ; Men, Xiuxian1; Wang, Xianxian1; Cheng, Xiaoli 1

Research facility: Yunnan University

Published Mar 27, 2026 on Dryad. https://doi.org/10.5061/dryad.m37pvmdhc

Data files

Mar 27, 2026 version files 71.84 KB

README.md

8.70 KB
Soil_Nitrogen_Transformation_Data.xlsx

63.14 KB

Abstract

Afforestation has profoundly altered soil nitrogen (N) transformation, particularly the key processes governing soil organic N and inorganic N dynamics, which determine soil N availability. However, the divergences in soil N transformation and the main influencing factors following different afforestation types have not been systematically clarified. Here, we examined soil net N mineralization rate (NMR), net nitrification rate (NNR), and potential denitrification rate (PDR) at 144 paired sampling sites by comparing different afforestation types (initial land use types and tree species) in central China. Afforestation significantly enhanced soil NMR, but lowered NNR and PDR, respectively, compared to non-afforested lands. Soil NMR and PDR responses to afforestation from cropland were more sensitive than those from shrubland. Notably, broadleaf afforestation (i.e., Quercus variabilis) had a stronger effect on altering NMR compared to coniferous afforestation (i.e., Platycladus orientalis) from cropland. These variations in soil NMR and NNR responses were primarily attributed to soil properties [e.g., soil organic nitrogen (SON), soil organic carbon (SOC), C: N ratio] across both non-afforested and afforested lands, whereas the main influencing factor for PDR shifted from microbial traits in non-afforested lands to soil properties in afforested lands. Although higher SON contents promoted soil NMR in afforested lands, significantly higher microbial biomass N in the afforested lands compared to non-afforested lands suggested intensified microbial inorganic N assimilation, which consequently constrained NNR and PDR relative to non-afforested lands, further avoiding N loss and N limitation. Our findings emphasized that afforestation types divergently influenced soil net N transformation rates with overall impacts on alleviating possible soil N constraints, thereby providing a theoretical basis for the regulation of soil N cycling under future afforestation and forest management.

DOI: https://doi.org/10.5061/dryad.m37pvmdhc

Description of the data and file structure

Data Description

This dataset contains measurements of soil nitrogen transformation rates, soil physicochemical properties, and microbial characteristics collected from central China. The study aimed to assess how different afforestation types influence soil nitrogen (N) cycling processes, particularly those governing soil N availability.

Experimental Efforts:

Sample Collection: During October to November 2021, paired sampling surveys were conducted across four subbasins in central China. Non-afforested lands (i.e., cropland or shrubland) were paired with adjacent afforested lands dominated by coniferous trees (Platycladus orientalis, Pinus massoniana) and broad-leaved trees (Quercus variabilis).
Sample Preparation: Six afforestation types were established in each subbasin:
(1) afforestation with P. orientalis from cropland;
(2) afforestation with P. massoniana from cropland;
(3) afforestation with Q. variabilis from cropland;
(4) afforestation with P. orientalis from shrubland;
(5) afforestation with P. massoniana from shrubland;
(6) afforestation with Q. variabilis from shrubland.

Each type included three replicates, resulting in a total of 144 soil samples (4 subbasins × 6 afforestation types × 2 paired lands × 3 replicates).Radon Detection: Soil nitrogen transformation rates, physicochemical properties, microbial biomass, and enzyme activities were measured using standard ecological methods.
Data Analysis: Nitrogen transformation rates were calculated and analyzed to evaluate differences between afforested and non-afforested lands.

Parameters Measured:

Net N mineralization rate (NMR)
Net nitrification rate (NNR)
Potential denitrification rate (PDR)
Soil physicochemical properties (e.g., SOC, SON, C:N ratio)
Soil inorganic and organic nitrogen fractions (e.g., NH₄⁺–N, NO₃⁻–N, DON)
Microbial biomass (MBC, MBN, MBP)
Soil enzyme activities (BG, NAG, LAP, AP)

Applications:

The dataset supports studies on:

Soil nitrogen cycling under afforestation
Controls of N mineralization, nitrification, and denitrification
Interactions among soil properties, microbial traits, and enzyme activities
Ecological processes related to soil nutrient limitation and ecosystem functioning

Files and variables

File: Soil_Nitrogen_Transformation_Data.xlsx

Description:

Variables

File Description:This Excel file contains data collected from soil samples analyzed for nitrogen transformation rates and associated environmental variables across all sampling sites in central China.

Sheet 1: Soil Data

Variable Name	Description	Units	Abbreviation
Plot name	Unique identifier for each sampling plot	-	-
Afforestation Plot	4 subbasins	-	-
Afforestation types	Afforested or non-afforested lands
Initial land use types	Cropland or Shrubland	-	-
Afforestation Tree	Platycladus orientalis, Pinus massoniana and Quercus variabilis	-	-
Net N mineralization rate	Soil net nitrogen mineralization rate	mg·kg⁻¹·d⁻¹	NMR
Net nitrification rate	Soil net nitrification rate	mg·kg⁻¹·d⁻¹	NNR
Potential denitrification rate	Soil potential denitrification rate	μg·kg⁻¹·h⁻¹	PDR
Soil moisture	Soil moisture content	%	SM
Soil temperature	Soil temperature	°C	ST
pH	Soil pH value	-	pH
Bulk density	Soil bulk density	g·cm⁻³	BD
Soil organic carbon	Soil organic carbon content	g·kg⁻¹	SOC
Total nitrogen	Soil total nitrogen	g·kg⁻¹	TN
C:N ratio	Ratio of soil carbon to nitrogen	-	C:N
Dissolved organic nitrogen	Dissolved organic nitrogen	mg·kg⁻¹	DON
Ammonium nitrogen	Ammonium nitrogen	mg·kg⁻¹	NH₄⁺
Nitrate nitrogen	Nitrate nitrogen	mg·kg⁻¹	NO₃⁻
Total phosphorus	Soil total phosphorus	g·kg⁻¹	TP
β-1,4-glucosidase	Enzyme activity	nmol g ^-1 h ^-1	BG
N-acetylglucosaminidase	Enzyme activity	nmol g ^-1 h ^-1	NAG
Alkaline phosphatase	Enzyme activity	nmol g ^-1 h ^-1	AP
L-leucine aminopeptidase	Enzyme activity	nmol g ^-1 h ^-1	LAP
Microbial biomass carbon	Microbial biomass carbon	mg·kg⁻¹	MBC
Microbial biomass nitrogen	Microbial biomass nitrogen	mg·kg⁻¹	MBN
Microbial biomass phosphorus	Microbial biomass phosphorus	mg·kg⁻¹	MBP
Leaf carbon	Carbon content in leaves	g·kg⁻¹	LeafC
Leaf nitrogen	Nitrogen content in leaves	g·kg⁻¹	LeafN
Litter carbon	Carbon content in litter	g·kg⁻¹	LitterC
Litter nitrogen	Nitrogen content in litter	g·kg⁻¹	LitterN
Root carbon	Carbon content in roots	g·kg⁻¹	RootC
Root nitrogen	Nitrogen content in roots	g·kg⁻¹	RootN
Litter mass	Litter biomass or mass	g·m⁻²	Litter

Missing Values:

Missing data, if any, are indicated by blank cells.

Code/software

Software Requirements:

Microsoft Excel (Version 2010 or later) – To view and analyze the dataset
Optional: R, Python, or SPSS for statistical analysis