Nitrogen addition, not warming, enhances soil microbial necromass carbon accumulation in a desert steppe

doi:10.1093/jpe/rtag100

J Plant Ecol ›› Advance articles DOI:10.1093/jpe/rtag100

Nitrogen addition, not warming, enhances soil microbial necromass carbon accumulation in a desert steppe

Qian Wu^?, Xin Ju^?, Ai-Min Zhu, Xiao-Jia Zhang, Hai-Yan Ren^*, Guo-Dong Han^*

Key Laboratory of Grassland Resources of the Ministry of Education, College of Grassland Science, Inner Mongolia Agricultural University, Hohhot, China
Qian Wu and Xin Ju contributed equally to this work.
Authors for correspondence:
Guodong Han, Email:hanguodong@imau.edu.cn
Haiyan Ren, Email: renhy@imau.edu.cn

Received:2025-03-22 Revised:2026-03-13 Accepted:2026-04-02 Published:2026-06-10
Supported by:
This research was financially supported by the Basic Research Fund for Universities Directly Under Inner Mongolia Autonomous Region (BR230501), the National Natural Science Foundation of China (32301502, 32260301), Natural Science Foundation of Inner Mongolia Autonomous Region (2025YQ019).

氮添加促进荒漠草原土壤微生物残体碳积累

Abstract

Abstract: Soil microbial necromass carbon (MNC), a critical component of soil organic carbon (SOC), plays a vital role in the formation and stabilization of SOC. Climate warming and increased atmospheric nitrogen (N) deposition are key factors influencing carbon sequestration in grassland ecosystems. However, the impacts of warming and N deposition, as well as their interactions, on soil MNC in arid grasslands remain poorly understood. In this study, we investigated soil MNC, including fungal necromass carbon (FNC) and bacterial necromass carbon (BNC), following a continuous 16-year manipulation of warming and N addition in a desert steppe in Inner Mongolia, China. We also analyzed these parameters in conjunction with soil microbial diversity, plant coverage and soil properties. The results showed that N addition significantly increased soil MNC and FNC, as well as fungal diversity while not affecting BNC or bacterial diversity. Warming did not significantly affect MNC (including both FNC and BNC) or soil microbial diversity and there was no interactive effect between warming and N addition. Soil MNC, FNC, and BNC were found to be higher in the topsoil layer than in the subsoil layer, and FNC contributed more to SOC than BNC. Notably, the increase of soil MNC and FNC under N addition was mainly mediated by increased soil N content. This study clarifies the critical role of MNC in soil carbon storage and offers an empirically grounded basis for forecasting grassland carbon changes under future global change scenarios.

Key words: global change, desert steppe, fungal necromass carbon, bacterial necromass carbon, soil microbial diversity

摘要：
土壤微生物残体碳是土壤有机碳的重要组成部分，在有机碳的形成和稳定性维持过程中起着十分重要的作用。气候变暖以及大气氮沉降增加是影响草原生态系统碳固存的重要因素。然而，气候变暖和氮沉降增加及其交互作用对干旱区草原土壤微生物残体碳的影响目前仍不清楚。本研究基于内蒙古荒漠草原，对经过持续16年增温和氮添加处理后的草地土壤微生物残体碳（包括真菌残体碳和细菌残体碳）进行研究，同时，分析微生物残体碳与土壤微生物、植物群落盖度以及土壤基础理化性质之间的关系。研究结果表明，氮添加显著增加了土壤微生物残体碳和真菌残体碳，同时也提高了真菌多样性，但对细菌残体碳和细菌多样性没有影响。增温及其与氮添加的交互作用对微生物残体碳（真菌残体碳、细菌残体碳）及土壤微生物多样性均无显著影响。不同处理下，土壤微生物残体碳、真菌残体碳、细菌残体碳在表层土壤中的含量均高于下层土壤，且真菌残体碳对土壤有机碳的贡献大于细菌残体碳。氮添加主要通过增加土壤全氮含量来促进微生物残体碳和真菌残体碳的积累。本研究阐明了微生物残体碳在土壤碳储存中的关键作用，并为预测未来全球变化情景下草原碳含量的变化提供了依据。

关键词: 全球变化, 荒漠草原, 真菌残体碳, 细菌残体碳, 土壤微生物多样性

Qian Wu, Xin Ju, Ai-Min Zhu, Xiao-Jia Zhang, Hai-Yan Ren, Guo-Dong Han. Nitrogen addition, not warming, enhances soil microbial necromass carbon accumulation in a desert steppe[J]. J Plant Ecol, DOI: 10.1093/jpe/rtag100.

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