CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
University of Chinese Academy of Sciences, Beijing, China.
Glob Chang Biol. 2020 Sep;26(9):5277-5289. doi: 10.1111/gcb.15206. Epub 2020 Jul 1.
Microbial-derived nitrogen (N) is now recognized as an important source of soil organic N. However, the mechanisms that govern the production of microbial necromass N, its turnover, and stabilization in soil remain poorly understood. To assess the effects of elevated temperature on bacterial and fungal necromass N production, turnover, and stabilization, we incubated N-labeled bacterial and fungal necromass under optimum moisture conditions at 10°C, 15°C, and 25°C. We developed a new N tracing model to calculate the production and mineralization rates of necromass N. Our results showed that bacterial and fungal necromass N had similar mineralization rates, despite their contrasting chemistry. Most bacterial and fungal necromass N was recovered in the mineral-associated organic matter fraction through microbial anabolism, suggesting that mineral association plays an important role in stabilizing necromass N in soil, independently of necromass chemistry. Elevated temperature significantly increased the accumulation of necromass N in soil, due to the relatively higher microbial turnover and production of necromass N with increasing temperature than the increases in microbial necromass N mineralization. In conclusion, we found elevated temperature may increase the contribution of microbial necromass N to mineral-stabilized soil organic N.
微生物衍生的氮（N）现在被认为是土壤有机 N 的重要来源。然而，控制微生物残体 N 的产生、周转和在土壤中稳定的机制仍知之甚少。为了评估高温对细菌和真菌残体 N 产生、周转和稳定的影响，我们在最适水分条件下，将 10°C、15°C 和 25°C 下标记的 N 的细菌和真菌残体进行了孵育。我们开发了一种新的 N 示踪模型来计算残体 N 的产生和矿化速率。结果表明，尽管细菌和真菌残体 N 的化学性质不同，但它们的矿化速率相似。大多数细菌和真菌残体 N 通过微生物同化作用被回收在矿物相关的有机物质部分中，这表明矿物结合在稳定土壤中残体 N 方面起着重要作用，而与残体 N 的化学性质无关。由于微生物对残体 N 的周转和产生随着温度的升高而高于微生物残体 N 的矿化增加，因此高温显著增加了土壤中残体 N 的积累。总之，我们发现高温可能会增加微生物残体 N 对矿物稳定的土壤有机 N 的贡献。
