Abstract
Nitrogen (N) is a key nutrient regulating plant growth, forest productivity and ecosystem functioning in permafrost regions. Despite the critical role of succession in modifying soil N processes, how soil N dynamics respond to mid-successional Betula platyphylla forest development remains poorly understood. This study aimed to characterize soil N transformations across a 25- to 61-year stand-age gradient in permafrost forests of Northeast China. We determined soil inorganic nitrogen concentrations and net nitrogen mineralization (ammonization + nitrification) using in‑situ incubation experiments in 25-, 40- and 61-year-old mid-successional Betula platyphylla forests. Ammonium N increased significantly with stand age, whereas nitrate N concentration exhibited a decreasing trend. Generalized least‑squares (GLS‑AR1) modelling detected no significant main effect of stand age on soil inorganic N or net N mineralization rate (Rm). Mean Min-N remained stable across stands (8.39, 8.15 and 8.49 mg·kg⁻¹ for the 25-, 40-, and 61-year-old stands, respectively). Rm showed a numerical increase along the age gradient (0.11, 0.46, 0.67 mg·kg⁻¹·d⁻¹). Soil N dynamics were driven by significant stand‑age × soil‑depth and stand‑age × sample‑month interactions rather than stand age main effects. Inorganic‑N and mineralization rates were higher in topsoil (0–10 cm) than subsoil (10–20 cm). Ammonification dominated net N mineralization across all stands, contributing on average 3.88% (0–10 cm) and 4.18% (10–20 cm). Hierarchical partitioning analysis identified stand age as the primary driver of soil‑N variation, followed by sampling month, soil chemical properties and microbial biomass. Mid‑successional Betula platyphylla forest succession accelerates soil N turnover and modifies inorganic‑N composition without expanding total mineral‑N pools. These findings inform vegetation restoration and sustainable management of permafrost forest ecosystems.
Acknowledgements
We are grateful to Northeast Forestry University for the field sites, laboratory facilities and technical support that made this field investigation and sample analysis possible. Thanks are also extended to Shaoguan University for its support during manuscript preparation. We thank the staff who assisted with sampling and investigations from Mohe Forest Ecosystem National Positioning Observation and Research Station.
Funding
This research was funded by Basic and Applied Basic Research Foundation of Guangdong Province, grant number 2023A1515011736; the Science and Technology Planning Project of Shaoguan City, grant number 230324098035041; Scientific Research Startup Fund for Doctors at Shaoguan University, grant number 432/9900064703; Research Project of Shaoguan University, grant number SY2023KJ12.
Author information
Authors and Affiliations
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Supplementary Material 1 (download DOCX )
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Reprints and permissions
About this article
Cite this article
Wei, H., Chen, X. & Zhu, Y. Temporal soil nitrogen dynamics with stand age of Betula platyphylla forests in the permafrost region of Northeast China.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-74206-y
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-74206-y
Keywords
- Soil net nitrogen mineralization
- Inorganic nitrogen concentration
- Stand age
Betula platyphylla
- Permafrost region
Source: Ecology - nature.com
