The responses of soil nitrogen transformation to nitrogen addition are mainly related to the changes in functional gene relative abundance in artificial Pinus tabulaeformis forests

Jingjing Li; Guoliang Wang; Benshuai Yan; Guobin Liu

doi:10.1016/j.scitotenv.2020.137679

The responses of soil nitrogen transformation to nitrogen addition are mainly related to the changes in functional gene relative abundance in artificial Pinus tabulaeformis forests

Sci Total Environ. 2020 Jun 25:723:137679. doi: 10.1016/j.scitotenv.2020.137679. Epub 2020 Mar 5.

Authors

Jingjing Li¹, Guoliang Wang², Benshuai Yan³, Guobin Liu⁴

Affiliations

¹ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi Province, China.
² State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi Province, China; Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling 712100, Shaanxi, China. Electronic address: glwang@nwsuaf.edu.cn.
³ Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling 712100, Shaanxi, China.
⁴ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi Province, China; Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling 712100, Shaanxi, China. Electronic address: gbliu@ms.iswc.ac.cn.

PMID: 32213396
DOI: 10.1016/j.scitotenv.2020.137679

Abstract

The increase of soil nitrogen (N) availability may alter soil microbial community composition and the natural N cycle in forest ecosystems. However, the responses of soil microbial nitrogen functional genes (NFGs) to N addition and their consequent effect on the N-cycle processes are poorly understood. In this study, soil samples were collected from an artificial Pinus tabulaeformis forest located in Loess Plateau (China) to which N at four different concentrations was added (0 [N0], 3 [N3], 6 [N6], and 9 [N9] g N m^-2 y^-1) for 4 years. We quantified the relative abundance of NFGs using functional gene microarray GeoChip 5.0 and determined net N transformation and N₂O emission rates in a 14-day incubation experiment. The results showed that N3 and N6 treatments did not significantly affect the total relative abundance and diversity of NFGs assemblage but significantly increased the relative abundance of specific genes for the NH₃ cycle (ureC, nirA, and nrfA), and nitrification (amoA) and denitrification (norB). These positive effects were related to the increase in soil organic C, NO₃^--N, and microbial biomass C (MBC). N9 treatment significantly decreased the relative abundance of all NFGs, and this negative impact was correlated with reduced dissolved organic C and MBC. Moreover, N addition significantly changed net N nitrification, mineralization, and N₂O emission rates, and NFGs explained the higher variances in the N transformation processes than soil properties. Specifically, ammonia-oxidizing archaea (amoA-AOB) and MBC were the key factors related to net N nitrification; ureC, nirK, and MBC were the key factors related to net N mineralization; and narG and nirS were the key factors related to N₂O emission. Our results show that global N deposition may mainly influence N transformation processes by regulating the corresponding NFG relative abundance, thereby affecting the N cycle in forest soils.

Keywords: N(2)O emission; Net N transformation; Nitrogen addition; Nitrogen functional genes; Temperate forest soil.

MeSH terms

Archaea
China
Ecosystem
Forests
Nitrification
Nitrogen / analysis
Pinus*
Soil Microbiology
Soil*

Substances

Soil
Nitrogen