Short-term responses of soil nitrogen mineralization, nitrification and denitrification to prescribed burning in a suburban forest ecosystem of subtropical Australia

• Published in: The Science of the total environment 2018-11, Vol.642, p.879-886
• Main Authors: Zhang, Manyun, Wang, Weijin, Wang, Dianjie, Heenan, Marijke, Xu, Zhihong
• Format: Article
• Language: English
• Subjects: Forest soil; Functional gene abundances; N transformation; Prescribed burning
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.06.144

As an anthropogenic disturbance, prescribed burning may alter the biogeochemistries of nutrients, including nitrogen (N) cycling, in forest ecosystems. This study aimed to examine the changes in N mineralization, nitrification and denitrification rates following prescribed burning in a suburban forest located in subtropical Australia and assess the interactive relationships among soil properties, functional gene abundances and N transformation rates. After a prescribed burning event, soil pH value increased, but soil labile carbon and mineral N contents decreased. Net N mineralization rates, potential nitrification rates and ammonium-oxidizing archaea and bacteria (AOA and AOB) amoA gene abundances in the soils all increased after 3 months of the prescribed burning. However, the abundances of different functional genes related to denitrification changed differently after the prescribed burning. The net N mineralization rates could be best described by soil abiotic properties, rather than functional gene abundances. In contrast, potential denitrification rates were positively related to soil nirK gene abundances. Potential nitrification rates could be influenced by both soil chemical and microbial properties. The results revealed that the prescribed burning might increase N mineralization and nitrification rates in the forest soil. Nitrogen (N) transformation rates and functional gene abundances in forest soils altered substantially within the first 3 months after prescribed burning. Net N mineralization rates were best described by soil abiotic properties. In contrast, potential denitrification rates were positively related to soil nirK gene abundances. Potential nitrification rates could be influenced by both soil chemical and microbial properties. [Display omitted] •Soil pH value increased, but mineral N contents decreased after prescribed burning.•Nitrogen mineralization and potential nitrification increased after the burning.•Soil AOA amoA and AOB amoA gene abundances increased after prescribed burning.•Potential denitrification rates were mainly affected by functional gene abundances.