| 气候变暖对冻结期黑土碳氮循环关键过程及指标的影响 |
| 摘要点击 2217 全文点击 643 投稿时间：2020-07-21 修订日期：2020-10-11 |
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| 中文关键词 气候变暖 冻结期 黑土 碳循环 氮循环 |
| 英文关键词 climate change freezing period black soil carbon cycle nitrogen cycle |
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| 中文摘要 |
| 冬季土壤碳氮循环是全球生物地球化学循环的重要组成部分，对气候变暖的响应极为敏感.为更好地了解气候变暖对冻结期黑土碳氮动态的影响，本试验采用红外辐射仪模拟土壤增温，并进行了两种不同水平的增温研究（W1和W2）.结果表明，在冻结期（2019年11月至翌年1月），与对照处理（C）相比，模拟增温使表层土壤温度（0 cm土壤温度）分别上升1.54℃（W1）和4.10℃（W2），并显著增加了土壤含水量，这很可能是由于积雪融化造成的.两种增温水平均降低了积雪覆盖厚度、土壤冻结深度、土壤有机碳（SOC）含量及活性有机碳（LC）含量.而冻结期增温对黑土氮循环关键过程及指标的影响则相对更复杂，随着增温幅度的提升，硝态氮（NO3--N）含量显著降低、全氮（TN）含量及净氮硝化速率明显增加，而铵态氮（NH4+-N）、总无机氮（TIN）含量及净氮矿化速率则显著地呈现出先增加后降低的趋势.气候变暖将给冻结期黑土带来更为温暖湿润的环境，并且由此引起的土壤碳氮含量及转化过程的变化将会对随后生长季植物和微生物群落的结构组成、生产力及碳氮循环等过程产生深远的影响.这为研究冻结期东北黑土碳氮循环机制提供了一定的科学依据. |
| 英文摘要 |
| As an critical part of the global biogeochemical cycle, the winter soil carbon and nitrogen cycles are extremely sensitive to climate warming. Furthermore, the black soil in northeast China is fertile and rich in organic matter and is a vital production base of commodity grains in China. For as long as half a year, the black soil is in a freezing-thawing state. Climate warming will change the snow cover thickness and soil freezing degree on the surface of the black soil in the winter and affect the freezing-thawing cycle frequency and timing of the soil, thus exerting a profound influence on the fixation, transformation, and release of soil carbon and nitrogen during the freezing period and throughout the year. To better understand the effects of climate warming on the black soil carbon and nitrogen dynamics during the freezing period, an experiment was conducted with two warming levels (W1 and W2) using an infrared radiometer to simulate soil warming. The warming increased the surface soil temperature (0 cm soil temperature) by 1.54℃ (W1) and 4.10℃ (W2), respectively, and significantly increased the soil moisture content compared with the control (C) during the freezing period, most likely because of the melting snow. The snow cover thickness, soil freezing depth, soil organic carbon (SOC), and labile organic carbon (LC) content were reduced by both warming treatments. However, the effect of the temperature increase during the freezing period on the key processes and indicators of the nitrogen cycle in black soil was relatively more complicated. With the increase in temperature, the content of nitrate nitrogen (NO3--N) decreased significantly, and the content of total nitrogen (TN) and net nitrogen nitrification rate increased significantly, while the ammonium nitrogen (NH4+-N), total inorganic nitrogen (TIN) content, and the net nitrogen mineralization rate exhibited a significant increase first and then decreased. In summary, climate warming will bring a warmer and more humid environment to the black soil during the freezing period, and the resulting changes in the soil carbon and nitrogen content and transformation processes will have a profound impact on the structure, productivity of the plants and microbial communities, and carbon and nitrogen cycles in the subsequent growing season. The results provide a scientific basis for studying the carbon and nitrogen cycle mechanisms of the northeast black soil during the freezing period. |
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