Nitrogen deposition is linked to changes in mineral-associated organic carbon in forest soils in the United Kingdom
Across 26 UK forest sites, nitrogen deposition showed contrasting effects on soil carbon pools. Broadleaf forests gained MAOC, while conifers lost it, and POC remained largely unchanged. Results reveal that soil type, forest structure, and plant–soil interactions strongly mediate how nitrogen shapes microbial processes and the stability of particulate and mineral‑associated organic carbon.
Subject Tags
- Forest
Abstract
Nitrogen is vital for soil microbes, yet added inorganic N can alter soil organic carbon (SOC) decomposition in complex ways. To assess how N deposition shapes SOC stability, we examined particulate organic carbon (POC) and mineral‑associated organic carbon (MAOC) across a natural N deposition gradient in 26 UK forest sites. Broadleaf forests showed stable POC and microbial biomass but increases in MAOC, while conifer forests experienced declines in MAOC with no change in POC or microbial pools. Mineral soils held more POC and MAOC than organo‑mineral soils, and most inorganic N measures did not differ by soil type. Although climate effects were weak, all major soil C pools declined with increasing stand basal area. These findings show that the influence of N deposition on soil C and N cycling depends strongly on forest type, stand structure, and soil properties, which together shape microbial activity and the stability of POC and MAOC.
Citation
Willard, S. J., Vanguelova, E., & Waring, B. (2026). Nitrogen deposition is linked to changes in mineral-associated organic carbon in forest soils in the United Kingdom. Plant and Soil, 1-19.
TNC Authors
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Samuel Willard (CONTRACTOR)
Postdoc. Provide Food & Water
The Nature Conservancy
Email: samuel.willard@tnc.org