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<p>The transfer of dissolved organic carbon (DOC) and nitrogen (DON) from litter to soil is a crucial yet poorly understood flux in forest biogeochemical cycles, particularly under anthropogenic nitrogen (N) deposition. This study investigated how decomposing litter influences the dynamics of soil soluble C and N and how N deposition regulates these processes in contrasting coniferous (CFF) and broad-leaved (BLF) forests. Using a column leaching experiment with treatments isolating litter and N addition effects, we quantified net changes in soil pools by subtracting the direct inputs from litter and added N. Results showed that litter presence did not simply supplement soil soluble C and N but instead induced a net decrease in native soil-derived DOC and total soluble N (TSN), primarily through stimulating microbial mineralization of soil organic matter (i.e., a priming effect). This priming effect was stronger in BLF than in CFF, consistent with its greater inputs of labile C. While N addition attenuated the litter-induced priming of soil C and N loss, it strongly enhanced nitrification across both forests, resulting in substantial nitrate accumulation. Critically, the influence of N addition on soil DOC was forest-specific: it increased the DOC pool in CFF, likely by promoting depolymerization, but decreased it in BLF, potentially through stimulating mineralization. These findings demonstrate that N deposition can reduce litter-driven priming losses but concurrently elevates the risk of nitrate leaching. We conclude that the trade-off between soil C retention and N loss risk is central to predicting the impacts of N deposition on forest biogeochemical cycling and ecosystem services.</p>

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Litter inputs and nitrogen addition drive contrasting net effects on soil soluble carbon and nitrogen in coniferous versus broad-leaved forests

  • 期刊论文

  • 发表日期：

    2026年1月20日

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  • Hongliang Ma,
  • Mengsi Wang,
  • Yunfeng Yin,
  • Ren Gao

摘要

The transfer of dissolved organic carbon (DOC) and nitrogen (DON) from litter to soil is a crucial yet poorly understood flux in forest biogeochemical cycles, particularly under anthropogenic nitrogen (N) deposition. This study investigated how decomposing litter influences the dynamics of soil soluble C and N and how N deposition regulates these processes in contrasting coniferous (CFF) and broad-leaved (BLF) forests. Using a column leaching experiment with treatments isolating litter and N addition effects, we quantified net changes in soil pools by subtracting the direct inputs from litter and added N. Results showed that litter presence did not simply supplement soil soluble C and N but instead induced a net decrease in native soil-derived DOC and total soluble N (TSN), primarily through stimulating microbial mineralization of soil organic matter (i.e., a priming effect). This priming effect was stronger in BLF than in CFF, consistent with its greater inputs of labile C. While N addition attenuated the litter-induced priming of soil C and N loss, it strongly enhanced nitrification across both forests, resulting in substantial nitrate accumulation. Critically, the influence of N addition on soil DOC was forest-specific: it increased the DOC pool in CFF, likely by promoting depolymerization, but decreased it in BLF, potentially through stimulating mineralization. These findings demonstrate that N deposition can reduce litter-driven priming losses but concurrently elevates the risk of nitrate leaching. We conclude that the trade-off between soil C retention and N loss risk is central to predicting the impacts of N deposition on forest biogeochemical cycling and ecosystem services.