Inorganic Nitrogen Addition Affects Soil Respiration and Belowground Organic Carbon Fraction for a Pinus tabuliformis Forest
Inorganic Nitrogen Addition Affects Soil Respiration and Belowground Organic Carbon Fraction for a Pinus tabuliformis Forest
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DOI：
10.3390/f10050369
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发表时间：
2019-04
期刊：
影响因子：
2.9
通讯作者：
Huan-shi Zhang;Yanhong Liu;Zhiyong Zhou;Y. Zhang
中科院分区：
文献类型：
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作者：
Huan-shi Zhang;Yanhong Liu;Zhiyong Zhou;Y. Zhang
森林生态系统从大气中固碳的能力很大程度上取决于土壤有机质与氮的相互作用，因此，在未来全球变化的情景下，这一过程将受到氮沉降的极大影响。为了阐明这种相互作用，当前的研究探讨了不同氮沉降水平下土壤碳含量和土壤呼吸的变化。在中国北方油松林的 20 个 100 m2 样地中分别添加浓度为 0、50、100、200 和 400 kg N ha−1year−1 的 NH4NO3。施氮两年后分析土壤样品的养分含量和生物物理特性，并在研究期间每月测量土壤呼吸速率。季节变化和氮添加显着影响土壤呼吸速率。平均而言，氮添加显着降低了年土壤呼吸速率23.74%。与对照地块相比，氮处理地块的细根生物量平均显着降低了 43.55%。但秋季和冬季土壤呼吸率占年累积土壤呼吸率的平均比例分别由23.57%和11.04%大幅上升至25.90%和12.18%。对照区土壤微生物生物量碳含量为342.39 mg kg−1，比施氮处理区平均值高23.50%。添加氮后，土壤溶解性有机碳平均减少 22.60%。细根生物量与年累积土壤呼吸速率、土壤微生物生物量碳含量和土壤溶解性有机碳含量之间存在显着相关性。这表明氮添加影响土壤有机碳转化和碳排放，主要是通过抑制细根产生。
The capability of forest ecosystems to sequester carbon from the atmosphere largely depends on the interaction of soil organic matter and nitrogen, and thus, this process will be greatly influenced by nitrogen deposition under the future scenario of global change. To clarify this interaction, the current study explored the variations in soil carbon fraction and soil respiration with different levels of nitrogen deposition. NH4NO3 was added at concentrations of 0, 50, 100, 200, and 400 kg N ha−1 year−1 separately on twenty 100 m2 plots in a Pinus tabuliformis Carr forest in northern China. Soil samples were analyzed for their nutrient content and biophysical properties two years after nitrogen application, and the soil respiration rate was measured every month during the study period. Seasonal variation and nitrogen addition significantly affected soil respiration rate. On average, nitrogen addition significantly reduced the annual soil respiration rate by 23.74%. Fine root biomass significantly decreased by an average of 43.55% in nitrogen treatment plots compared to the control plot. However, the average proportions of autumn and winter soil respiration rates out of the annual cumulative soil respiration rate greatly increased from 23.57% and 11.04% to 25.90% and 12.18%, respectively. The soil microbial biomass carbon content in the control plot was 342.39 mg kg−1, 23.50% higher than the average value in nitrogen treatment plots. The soil dissolved organic carbon was reduced by 22.60%, on average, following nitrogen addition. Significant correlations were detected between fine root biomass and the annual cumulative soil respiration rate, soil microbial biomass carbon content, and soil dissolved organic carbon content. This demonstrates that nitrogen addition affects soil organic carbon transformation and carbon emission, mainly by depressing fine root production.