Zou et al. (2025) Nitrogen limitation reduces CO₂ emissions from land use change primarily by decreasing CO₂ and climate interactions

Identification

• Journal: Agricultural and Forest Meteorology
• Year: 2025
• Date: 2025-11-24
• Authors: Xinyu Zou, Ying‐Ping Wang, Yuanyuan Huang
• DOI: 10.1016/j.agrformet.2025.110940

Research Groups

• Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
• CSIRO Environment, Clayton South, VIC, Australia

Short Summary

This study quantifies the impact of nitrogen (N) limitation on direct and indirect CO₂ emissions from land-use change using the CABLE model, revealing that N limitation significantly reduces total emissions primarily by weakening interactions between land-use change and atmospheric CO₂ and climate.

Objective

• To quantify the impact of N limitation on direct and indirect CO₂ emissions from land-use change over two historical periods: 1701–1959 and 1960–2020.
• To determine how N limitation affects direct and indirect CO₂ emissions from primary forests, secondary forests, or non-forests over these two periods.
• To identify the dominant mechanisms by which N limitation influences CO₂ emissions from land-use change.

Study Configuration

• Spatial Scale: Global, with input data at 0.25° by 0.25° and 0.5° by 0.5°, re-gridded to 1.875° by 1.25° for CABLE simulations.
• Temporal Scale: Simulations from 850 to 2020, with analysis focused on two periods: 1701–1959 and 1960–2020.

Methodology and Data

• Models used: Australian Community Atmosphere Biosphere Land Exchange model (CABLE) version 2.0, configured with carbon cycle only (CABLE-C) and with coupled carbon and nitrogen cycles (CABLE-CN).
• Data sources:
  • Land-use change: LUH2-GCB2021 (Chini et al., 2021; Hurtt et al., 2020).
  • Meteorological forcings: CRU-JRA66 (version 10).
  • Nitrogen deposition: Lamarque et al. (2013) (RCP8.5 for future years).
  • Nitrogen fixation: Peng et al. (2020) for non-cropland.
  • Atmospheric CO₂ concentration: TRENDY models for GCB2021 (Friedlingstein et al., 2020).
  • Benchmarking data: International Land Model Benchmarking (ILAMB) system, FLUXCOM (GPP, ER), Xu et al. (2021) (Biomass), Harmonized World Soil Database (HWSD) (Csoil).
  • Comparison data: Global Carbon Budget 2023 (GCB2023) from 20 dynamic global vegetation models (DGVMs) and three bookkeeping approaches.

Main Results

• CABLE-CN simulations showed good agreement with benchmark data for global gross primary production (GPP), soil respiration, plant biomass, and soil carbon, with Pearson correlation coefficients ranging from 0.6 to 0.9.
• From 1960 to 2020, cumulative CO₂ emissions from land-use change were estimated at 119 Pg C without N limitation and 73 Pg C with N limitation, compared to 100 ± 35 Pg C from DGVMs and 87 ± 24 Pg C from bookkeeping approaches in GCB2023.
• Nitrogen limitation reduced global direct CO₂ emissions from land-use change by 0.12 Pg C yr⁻¹ during 1701–1959 and by 0.4 Pg C yr⁻¹ during 1960–2020.
• Nitrogen limitation reduced global indirect CO₂ emissions by 0.24 Pg C yr⁻¹ during 1701–1959 and by 0.4 Pg C yr⁻¹ during 1960–2020.
• Overall, N limitation reduced total CO₂ emissions from land-use change by 79 Pg C (28%) from 1701 to 2020.
• The strongest effect of N limitation was on the interaction between land-use change and atmospheric CO₂, which was the largest component of indirect emissions.
• The primary mechanism for emission reduction was N limitation reducing soil carbon inherited from lands converted to secondary forests (>75% of total reduction), with reduced regrowth of secondary forests contributing less than 25%.
• N limitation generally reduced direct emissions by lowering donor carbon pool sizes and reduced indirect emissions by weakening the lost carbon sink and lowering emissions arising from interactions of land-use change with CO₂ and climate.

Contributions

• This study is the first to partition and quantify the effects of N limitation on both direct and indirect CO₂ emissions from land-use change.
• It provides a detailed mechanistic understanding of how N limitation influences these emissions, highlighting the dominant role of soil carbon and interactions with atmospheric CO₂.
• The findings challenge previous studies suggesting N limitation increases CO₂ emissions from land-use change, instead showing a net reduction.
• It underscores the critical importance of incorporating N limitation into carbon cycle assessments for improving model accuracy, understanding emission drivers, and informing climate policy, especially given increasing atmospheric CO₂ concentrations.
• The research suggests that models omitting N limitation may overestimate CO₂ emissions from land-use change and the potential for land-based carbon mitigation.

Funding

• National Key Research and Development Program of China (2023YFB3907402)
• Strategic Priority Research Program of the Chinese Academy of Sciences (Category B, Geographic Intelligence, no. XDB0740300)
• Postdoctoral Fellowship Program of China Postdoctoral Science Foundation (GZC20241691)
• Australian Tesstrail Ecosystem Research Network’s next-generation BGC project (partial support for Y.-P. Wang)

Citation

@article{Zou2025Nitrogen,
  author = {Zou, Xinyu and Wang, Ying‐Ping and Huang, Yuanyuan},
  title = {Nitrogen limitation reduces CO₂ emissions from land use change primarily by decreasing CO₂ and climate interactions},
  journal = {Agricultural and Forest Meteorology},
  year = {2025},
  doi = {10.1016/j.agrformet.2025.110940},
  url = {https://doi.org/10.1016/j.agrformet.2025.110940}
}