Evaluating the mechanisms of the impacts of key factors on soil soluble organic nitrogen concentrations in subtropical mountain ecosystems

Shihe Xing; Biqing Zhou; Liming Zhang; Yanling Mao; Fan Wang; Chengrong Chen

doi:10.1016/j.scitotenv.2018.10.097

Evaluating the mechanisms of the impacts of key factors on soil soluble organic nitrogen concentrations in subtropical mountain ecosystems

Sci Total Environ. 2019 Feb 15;651(Pt 2):2187-2196. doi: 10.1016/j.scitotenv.2018.10.097. Epub 2018 Oct 9.

Authors

Shihe Xing¹, Biqing Zhou², Liming Zhang², Yanling Mao², Fan Wang³, Chengrong Chen⁴

Affiliations

¹ College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian Province, China; Key Research Laboratory on Soil Ecosystem Health and Regulation in Fujian Provincial University, Fuzhou 350002, Fujian Province, China; Australian Rivers Institute and the School of Environment and Nature Science, Griffith University, Nathan 4111, Queensland, Australia. Electronic address: fafuxsh@126.com.
² College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian Province, China; Key Research Laboratory on Soil Ecosystem Health and Regulation in Fujian Provincial University, Fuzhou 350002, Fujian Province, China.
³ Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou 51027, Guangdong Province, China.
⁴ Australian Rivers Institute and the School of Environment and Nature Science, Griffith University, Nathan 4111, Queensland, Australia.

PMID: 30326451
DOI: 10.1016/j.scitotenv.2018.10.097

Abstract

Soil soluble organic nitrogen (SON) concentrations in terrestrial ecosystems were influenced differently and substantially by both biotic and abiotic factors. This study aimed to ascertain the mechanisms of the impact of the key factors on the SON concentrations of subtropical mountain ecosystems in southeastern China using an integrative approach, which combined a field plot survey, gray relational analysis and structure equation modeling. The results showed that the soil organic matter, clay content, protease activity and bacterial biomass were the key factors controlling the dynamics of the SON concentrations in subtropical mountain ecosystems. Protease activity, by catalyzing the degradation of complex organic nitrogen to SON, had the highest direct influence on the SON concentrations among all of the impact factors with direct impact effect of 0.44. Organic matter, which serves as a primary source of SON and can increase soil protease activity and bacterial biomass, contributed the most significantly to the SON concentrations in both direct and indirect pathways with total impact effects of 0.87. Clay, by adsorbing SON and affecting organic matter accumulation and protease activity, also had important direct or indirect influences on the SON concentrations with total impact effects of 0.48. The impact of the bacterial biomass on the SON concentrations was likely to be concealed by accompanying nitrogen-degrading enzyme activity with total impact effects of 0.22. Thus, the organic matter, clay content and protease activity exerted greater total impact effects on the SON concentrations compared with the bacterial biomass. Protease activity and organic matter had a greater positive direct impact on the SON concentrations compared with the bacterial biomass and clay content, while organic matter also had greater positive indirect impacts on the SON concentrations than did the clay content. This study's results could help to elucidate the differential mechanism of SON dynamics among various terrestrial ecosystems.

Keywords: Gray relational analysis; Key factor; Soluble organic nitrogen; Structure equation modeling; Subtropical mountain ecosystem.

MeSH terms

Camellia sinensis* / growth & development
China
Ecosystem
Eriobotrya* / growth & development
Forestry*
Nitrogen / analysis*
Soil / chemistry*
Soil Microbiology*

Substances

Soil
Nitrogen