Diversity loss and light limitation threaten the sustainability of ecosystem productivity gains under nitrogen enrichment

被引：0

作者：

Zhang, Wenshuo ^{[1
,2
]}

Li, Tingting ^{[1
,2
]}

Li, Jiawen ^{[3
]}

Zhang, Ruiyang ^{[1
]}

Xu, Li ^{[1
]}

Wang, Jinsong ^{[1
]}

Hu, Jian ^{[4
]}

Niu, Shuli ^{[1
,2
]}

Tian, Dashuan ^{[1
,2
]}

机构：

[1] Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing

[2] College of Resources and Environment, University of Chinese Academy of Sciences, Beijing

[3] College of Life Sciences, China West Normal University, Nanchong

[4] Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, Southwest Minzu University, Chengdu

来源：

Science of the Total Environment | 2025年 / 958卷

基金：

中国国家自然科学基金;

关键词：

Alpine grassland; Biodiversity loss; Biomass-specific GEP; Gross ecosystem productivity; Light competition; Long-term experiment; Nitrogen deposition;

D O I：

10.1016/j.scitotenv.2024.177960

中图分类号：

学科分类号：

摘要：

Plant photosynthesis significantly regulates atmospheric CO₂ but is often limited by nitrogen (N) availability. While N deposition could alleviate this limitation and enhance gross ecosystem productivity (GEP), its long-term effects are uncertain due to potential negative impacts like biodiversity loss and soil acidification. Yet, many long-term N addition experiments emphasize community biomass over gross GEP. Here, we conducted a six-year N addition experiment in an alpine meadow, frequently monitoring GEP, community structure, aboveground net primary productivity (ANPP)and plant traits. We found that N addition significantly enhanced GEP in the first three years, but during 4–6 years this effect disappeared. We further disentangled the mechanisms affecting GEP into biomass-based and non-biomass-based processes. The latter is expressed as biomass-specific GEP, defined as GEP per unit biomass. Differing with GEP, biomass-specific GEP provides a metric of carbon assimilation efficiency normalized to biomass. Unlike previous studies, we found that it was not ANPP, but specific GEP that determined the loss of the short-term N effect. ANPP showed a consistent increase under N addition, whereas specific GEP decreased in the last three years. This specific GEP reduction was primarily regulated by biodiversity loss and increased light limitation under N addition. Overall, our findings suggest that short-term benefits of N deposition on GEP are not sustained in long term, highlighting the need to explore the non-biomass-based mechanisms to better predict ecosystem responses to prolonged N enrichment. © 2024 Elsevier B.V.

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