Microbially mediated nitrification improves modeled temperate forest responses to declining nitrogen deposition

Journal Article · Tue Nov 04 00:00:00 EST 2025 · Applied Soil Ecology

DOI:https://doi.org/10.1016/j.apsoil.2025.106585· OSTI ID:3001777

Ridgeway, Joanna R. ^[1]; Sulman, Benjamin N. ^[2]; Weber, S. E. ^[3]; Juice, S. M. ^[3]; Brzostek, Edward R. ^[3]

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1. West Virginia Univ., Morgantown, WV (United States); Dartmouth College, Hanover, NH (United States)
2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
3. West Virginia Univ., Morgantown, WV (United States)

As nitrogen deposition declines across the US, uncertainty remains in whether temperate forests will continue to sequester carbon. This uncertainty is amplified by ecosystem models that inaccurately capture the microbial mechanisms that drive soil carbon sequestration and nitrogen loss. Further, even soil process models that represent decomposer microbes and better capture soil carbon retention under nitrogen deposition broadly underrepresent microbial nitrogen transformations. To address this limitation, we leveraged three decades of biogeochemical cycling data from a whole-watershed nitrogen fertilization experiment to incorporate microbially-driven nitrification in the FUN-CORPSE (Fixation and Uptake of Nitrogen-Carbon, Organisms, Rhizosphere, and Protection in the Soil Environment) model. Our objectives include: 1) Reproducing key ecosystem responses to fertilization, 2) Integrating microbially-explicit nitrification in FUN-CORPSE, and 3) Assessing modeled soil C and N under projected N deposition shifts. FUN-CORPSE accurately represented soil C and streamwater N losses under ambient N deposition and captured how fertilization induced a 25 % decline in plant C cost of N acquisition, reducing decomposition and increasing soil C. Furthermore, with microbially-explicit nitrification, FUN-CORPSE captured the 100 % increase in nitrification rates and the 50 % increase in streamwater nitrate loss under N fertilization. Specifically, incorporating microbial nitrification improved modeled streamwater N leaching from R² = 0.01 to R² = 0.57. Under declining N deposition, FUN-CORPSE simulates that N losses recover more quickly than soil C pools. However, the predicted return of soil C to pre-fertilized levels suggests that additional C sequestered due to N deposition may be vulnerable to loss over the next century.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Office of Workforce Development for Teachers & Scientists (WDTS)
• Grant/Contract Number: AC05-00OR22725; SC0014664
• OSTI ID: 3001777
• Journal Information: Applied Soil Ecology, Journal Name: Applied Soil Ecology Vol. 217; ISSN 0929-1393
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

Microbial nitrification model
Nitrification
Nitrogen deposition
Plant-microbe interactions model