Enhanced soil potential NO emissions by land-use change are linked to AOB-amoA and nirK gene abundances and denitrifying enzyme activity in subtropics.

Sci Total Environ

State Key Laboratory of Subtropical Silviculture, College of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; Department of Renewable Resources, University of Alberta, Edmonton T6G 2E3, Canada.

Published: December 2022

AI Article Synopsis

  • Converting natural forests to intensively managed tea plantations in subtropical China increases soil nitrous oxide (NO) emissions by altering nitrogen cycling processes.
  • The study found significant increases in denitrifying enzyme activity (52%) and the abundance of specific nitrifying and denitrifying genes (38%) after forest conversion.
  • These changes led to higher soil inorganic nitrogen levels, affecting the abundance of nitrogen-related microorganisms and their contribution to NO emissions.

Article Abstract

Conversion of forestland to intensively managed agricultural land occurs worldwide and can increase soil nitrous oxide (NO) emissions by altering the transformation processes of nitrogen (N) cycling related microbes and environmental conditions. However, little research has been conducted to assess the relationships between nitrifying and denitrifying functional genes and enzyme activities, the altered soil environment and NO emissions under forest conversion in subtropical China. Here, we investigated the long-term (two decades) effect of converting natural forests to intensively managed tea (Camellia sinensis L.) plantations on soil potential NO emissions, inorganic N concentrations, functional gene abundances of nitrifying and denitrifying bacteria, as well as nitrifying and denitrifying enzyme activities in subtropical China. The conversion significantly increased soil potential NO emissions, which were regulated directly by increased denitrifying enzyme activity (52 %) and nirS + nirK gene abundance (38 %) as shown by structural equation modeling, and indirectly by AOB-amoA gene abundance and inorganic N concentration. Our results indicate that converting natural forests to tea plantations directly increases soil inorganic N concentration, resulting in increases in the abundance of soil nitrifying and denitrifying microorganisms and the associated NO emissions. These findings are crucial for disentangling the factors that directly and indirectly affect soil potential NO emissions respond to the conversion of forest to tea plantation.

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Source
http://dx.doi.org/10.1016/j.scitotenv.2022.158032DOI Listing

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