College of forestry, Gansu Agriculture University
为探究高寒湿地土壤碳氮组分对气候变暖和氮沉降的响应特征，以尕海湿地区沼泽草甸为研究对象，采用开顶箱增温（OTC）和外源氮素(NH4NO3)添加，用以模拟未来气候变暖及氮沉降实验，分别设置对照（CK）、增温（W）、施氮（N）和增温施氮（WN）4种处理。在实验进行一年半后对土壤碳氮组分含量进行了测定。结果显示: 1）开顶箱增温装置提高0～15 cm 土层平均温度0.53 ℃，显著降低了0～10 cm土层含水量（SMC）和pH，以及土壤全氮（TN）、微生物量氮（MBN）、铵态氮（NH4+-N）、有机碳（SOC）及可溶性有机碳（DOC）含量，却显著提高了硝态氮（NO3--N）含量。2）施氮显著降低了NH4+-N、SOC和10～20 cm土层微生物生物量碳（MBC）及DOC含量，但增加了土壤TN、MBN和NO3--N含量。3）增温施氮显著增加了土壤SMC、TN、NO3--N和MBC含量，显著降低了MBN、NH4+-N和DOC含量。4）相关分析显示，土壤水分与各理化因子均存在正相关性，土壤碳氮组分间均呈现正相关性。结果说明，模拟增温施氮缓解了尕海湿地植物生长的温度和氮的限制，促进了TN的积累，对土壤微生物量碳氮组分影响较大，导致土壤微生物碳氮组分及分布特征发生转换。
To examine the attributes of soil carbon and nitrogen fractions in alpine wetland soils under the influence of climate warming and nitrogen deposition, a study was conducted. Four treatments were established, namely control (CK), warming (W), nitrogen application (N), and warming nitrogen (WN). These treatments were designed to simulate potential future scenarios of climate warming and nitrogen deposition in a swamp meadow located in the Gahai Wetland Area. The soil carbon and nitrogen levels were quantified a year and a half following the completion of the experiment.. The results showed that: 1) The utilization of the open top box warming device resulted in a notable elevation of the mean temperature within the 0-15 cm soil layer by 0.53°C. Additionally, this intervention led to a significant decrease in the water content (SMC) and pH levels, as well as the concentrations of soil total nitrogen (TN), microbial nitrogen (MBN), ammonium nitrogen (NH4+-N), organic carbon (SOC), and soluble organic carbon (DOC) within the 0-10 cm soil layer. Conversely, there was an observed increase in the concentration of nitrate nitrogen (NO3--N)..2) Nitrogen application considerably lowered the contents of NH4+-N and SOC in all soil layers, as well as the contents of microbial biomass carbon (MBC) and DOC in soil layers 10-20 cm deep, but increased the contents of TN, MBN, and NO3--N. 3) The application of nitrogen through warming conditions resulted in a large rise in SMC, TN, NO3--N, and MBC content. Conversely, it led to a significant reduction in MBN, NH4+-N, and DOC.. 4) Correlation analysis showed that there was a positive correlation between soil moisture and all physicochemical factors, and soil carbon and nitrogen components were positively correlated.. The results indicated that the simulated warming application of nitrogen alleviated the temperature and nitrogen limitation of plant growth in the Gahai wetland, promoted the accumulation of TN, and had a greater impact on the soil microbiota carbon and nitrogen fractions, which led to the conversion of soil microbial carbon and nitrogen activities and distribution characteristics.