AUTHOR=Zhang Youzheng , Jiang Pengcheng , Guo Yaolin , Wu Ming , Shao Xuexin , Xu Hengtao , Wu Tonggui , Yuan Wenwen , Li Niu 

TITLE=Nitrogen and phosphorus additions alter soil N transformations in a Metasequoia glyptostroboides plantation

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1448356

DOI=10.3389/fpls.2024.1448356

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Nitrogen (N) and phosphorus (P) enrichment due to anthropogenic activities can significantly affect soil N transformations in forest ecosystems. However, the effects of N and P additions on nitrification and denitrification processes in <italic>Metasequoia glyptostroboides</italic> plantations, and economically important forest type in China, remain poorly understood.</p></sec><sec><title>Methods</title><p>This study investigated the responses of soil nitrification and denitrification rates, as well as the abundances of nitrifiers and denitrifiers, to different levels of N and P additions in a 6-year nutrient addition experiment in a <italic>M. glyptostroboides</italic> plantation.</p></sec><sec><title>Results</title><p>Stepwise multiple regression analysis was used to identify the main predictors of nitrification and denitrification rates. The results showed that moderate N addition (N2 treatment, 2.4 mol·m<sup>-2</sup>) stimulated nitrification rates and abundances of ammonia-oxidizing archaea (AOA) and bacteria (AOB), while excessive N and P additions inhibited denitrification rates and reduced the abundance of <italic>nirS</italic>-type denitrifiers. AOB abundance was the main predictor of nitrification rates under N additions, whereas microbial biomass carbon and nirS gene abundance were the key factors controlling denitrification rates. Under P additions, tree growth parameters (diameter at breast height and crown base height) and AOB abundance were the primary predictors of nitrification and denitrification rates.</p></sec><sec><title>Discussion</title><p>Our study reveals complex interactions among nutrient inputs, plant growth, soil properties, and microbial communities in regulating soil N transformations in plantation forests. This study also offers valuable insights for formulating effective nutrient management strategies to enhance the growth and health of <italic>M. glyptostroboides</italic> plantations under scenarios of increasing elevated nutrient deposition.</p></sec>