季节增温对内蒙古半干旱草地土壤化学计量特征的影响

Effects of seasonal warming on soil stoichiometry in semiarid grassland of Inner Mongolia

通过在内蒙古草地开展模拟全球气候变化的试验,测定分析土壤0-10、10-20 cm总有机碳(SOC)、总氮(TN)、总磷(TP)、铵态氮(NH4_(+)^(-)N)、硝态氮(NO_(3)^(-)-N)、有效磷(AP)的含量及生态化学计量特征,探究非生长季增温和生长季增温对我国北方温带草原生态系统土壤养分含量及生态化学计量比的影响。结果表明:1)非生长季增温和生长季增温改变了内蒙古草地土壤的养分含量及生态化学计量比,且对部分指标存在交互作用。非生长季增温对土壤养分含量的影响主要集中在0-10 cm土层,非生长季增温显著提高了0-10 cm土壤总有机碳含量(P<0.05)和10-20 cm土壤总磷含量(P<0.05),显著降低了0-10 cm土壤硝态氮含量(P<0.05)。而生长季增温显著提高了0-20 cm土壤铵态氮含量(P<0.05),显著降低了0-10 cm土壤硝态氮含量和10-20 cm土壤总有机碳含量(P<0.05)。此外,非生长季增温与生长季增温对0-10 cm土壤总有机碳、总磷和铵态氮含量存在显著交互影响(P<0.05)。2)非生长季增温显著降低了10-20 cm土层土壤中的N꞉P(P<0.05)。而生长季增温对C、N、P之间的化学计量比无显著影响(P>0.05)。此外,非生长季增温与生长季增温对0-10 cm土壤C꞉N、C꞉P、N꞉P和10-20 cm土壤C꞉N存在显著交互影响(P<0.05)。研究结果表明,非生长季气候变暖对我国北方典型草地土壤化学计量特征的影响跟生长季气候变暖同样重要,不同季节气候变暖之间存在交互作用,在未来全球变化研究中,应重点关注气候变暖的季节差异。

In this study,the effects of non-growing-season and growing-season warming on the soil nutrient content and ecological stoichiometric ratio of a northern temperate steppe ecosystem in China were determined through a warming experiment in Inner Mongolia.The ecological stoichiometric characteristics of soil in the 0-10 and 10-20 cm layers,including the contents of soil total organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),ammonium nitrogen(NH_(4)^(+)-N),nitrate nitrogen(NO_(3)^(−)-N),and available phosphorus(AP),were analyzed in this experiment.The results showed that:1)non-growing-season and growing-season temperature increases changed the nutrient contents and ecological stoichiometric ratio of the grassland soil in Inner Mongolia,and interaction effects were found for some indices.The effects of non-growing-season warming on soil nutrient content were mainly concentrated in the 0-10 cm soil layer.Non-growing-season warming significantly increased the total organic carbon content of the 0-10 cm soil(P<0.05)and total phosphorus content of the 10-20 cm soil(P<0.05).The nitrate nitrogen content in the 0-10 cm soil was significantly decreased(P<0.05).The increased temperature during the growing season significantly increased the ammonium nitrogen content in the 0-20 cm soil(P<0.05),and significantly decreased the nitrate nitrogen content in the 0-10 cm soil and the total organic carbon content in the 10-20 cm soil(P<0.05).In addition,non-growing-season and growing-season warming interactively affected the contents of total organic carbon,total phosphorus,and ammonium nitrogen in the 0-10 cm soil(P<0.05).2)Non-growin-season warming significantly reduced the N꞉P in the 10-20 cm soil layer soil(P<0.05).However,growing season warming had no significant effect on the stoichiometric ratio between C,N,and P(P>0.05).In addition,non-growing-season and growing-season warming interactively affected C꞉N,C꞉P,and N꞉P in the 0-10 cm soil and C꞉N in the 10-20 cm soil(P<0.05).The results of this study indicated that non-growing-season climate warming is as important as growing-season climate warming affects the stoichiometric characteristics of the soil of typical grasslands in northern China,and interactions occur between different seasons of climate warming on soil stoichiometry.Therefore,seasonal differences in climate warming should receive more attention in future global change studies.