Depth-driven responses of microbial residual carbon to nitrogen addition approaches in a tropical forest: Canopy addition versus understory addition

Luhui Kuang; Zhijian Mou; Yue Li; Xiaofei Lu; Yuanwen Kuang; Jun Wang; Faming Wang; Xi'an Cai; Wei Zhang; Shenglei Fu; Dafeng Hui; Hans Lambers; Jordi Sardans; Josep Peñuelas; Hai Ren; Zhanfeng Liu

doi:10.1016/j.jenvman.2023.118009

Depth-driven responses of microbial residual carbon to nitrogen addition approaches in a tropical forest: Canopy addition versus understory addition

J Environ Manage. 2023 Aug 15:340:118009. doi: 10.1016/j.jenvman.2023.118009. Epub 2023 Apr 25.

Authors

Luhui Kuang¹, Zhijian Mou², Yue Li¹, Xiaofei Lu³, Yuanwen Kuang¹, Jun Wang¹, Faming Wang¹, Xi'an Cai¹, Wei Zhang¹, Shenglei Fu⁴, Dafeng Hui⁵, Hans Lambers⁶, Jordi Sardans⁷, Josep Peñuelas⁷, Hai Ren¹, Zhanfeng Liu⁸

Affiliations

¹ Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems & CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; South China National Botanical Garden, Guangzhou, 510650, China; Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Guangzhou, 510650, China.
² Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems & CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; South China National Botanical Garden, Guangzhou, 510650, China; Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Guangzhou, 510650, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
³ School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing, 210044, China.
⁴ College of Environment and Planning, Henan University, Kaifeng, 475004, China.
⁵ Department of Biological Sciences, Tennessee State University, Nashville, TN, 37209, USA.
⁶ School of Biological Sciences, University of Western Australia, Perth, WA, 6009, Australia.
⁷ CSIC, Global Ecology Unit CREAF-CSIC-UAB, Cerdanyola del Valles, 08193, Catalonia, Spain; CREAF, Cerdanyola del Valles, 08193, Catalonia, Spain.
⁸ Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems & CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; South China National Botanical Garden, Guangzhou, 510650, China; Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Guangzhou, 510650, China. Electronic address: [email protected].

PMID: 37105101
DOI: 10.1016/j.jenvman.2023.118009

Abstract

Canopies play an important role in nitrogen (N) redistribution in forest ecosystems, and ignoring the canopy's role might bias estimates of the ecological consequences of anthropogenic atmospheric N deposition. We investigated the effects of the approach of N addition (Canopy addition vs. Understory addition) and level of N addition (25 kg N ha^-1yr^-1 vs. 50 kg N ha^-1yr^-1) on microbial residual carbon (MRC) accumulation in topsoil and subsoil. We found that the response of MRC to both approach and level of N addition varied greatly with soil depth in a tropical forest over eight years of continuous N addition. Specifically, N addition enhanced the accumulation of fungal and total MRC and their contribution to soil organic C (SOC) pools in the topsoil, whereas it decreased the contribution of fungal and total MRC to SOC in the subsoil. The contrasting effects of N addition on MRC contribution at varying soil depths were associated with the distinct response of microbial residues production. Understory N addition showed overall greater effects on MRC accumulation than canopy N addition did. Our results suggest that the canopy plays an important role in buffering the impacts of anthropogenic atmospheric N deposition on soil C cycling in tropical forests. The depth-dependent response of microbial residues to N addition also highlights the urgent need for further studies of different response mechanisms at different soil depths.

Keywords: Canopy nitrogen addition; Microbial residual carbon; Nitrogen addition; Soil depth; Tropical forest; Understory nitrogen addition.

MeSH terms

Carbon
Ecosystem*
Forests
Nitrogen* / analysis
Soil / chemistry
Trees

Substances

Nitrogen
Carbon
Soil