氮素形态与温度对鲁西沙区林地土壤有机碳矿化的交互作用

Combined effects of nitrogen forms and temperature on soil organic carbon mineralization of forest in the sandy area of western Shandong Province,China

为探讨氮素形态与温度对土壤有机碳(SOC)矿化的交互作用,本研究以鲁西黄河故道沙区黑杨(Populus nigra)人工林为例,采用室内培养实验,研究不同氮素形态(硝态氮、铵态氮)及不同温度(10、20、30℃)对SOC矿化的单独及交互作用。结果表明:10℃时铵态氮的输入使SOC累积矿化量比对照(不输入氮)增加11.8%~21.3%,表明该区域SOC矿化受铵态氮限制;随温度升至20℃和30℃,铵态氮输入对SOC矿化的影响转为抑制作用。硝态氮输入在整个培养过程中抑制SOC矿化;培养结束时,硝态氮输入处理的SOC累积矿化量比对照降低4.1%~11.5%(10℃)、9.1%~29.3%(20℃)和8.6%~23.7%(30℃)。增温促进SOC矿化。增温和两类氮输入对SOC矿化的交互作用均为负效应,两因素对SOC矿化交互作用的实测值比理论值降低7.9%~21.9%(硝态氮)、16.1%~23.6%(铵态氮),因为两类氮输入有降低SOC矿化温度敏感性的趋势。研究表明,硝态氮、铵态氮对SOC矿化的影响存在差异,增温、氮输入对SOC矿化的交互作用显著小于两因素单独作用之和。

The continuous increase in atmospheric nitrogen(N)deposition and global warming caused has significantly changed the mineralization of soil organic carbon(SOC)in forest ecosystem.Most studies have focused on the single effects of N deposition and temperature on SOC mineralization,and the combined effect of N forms and temperature on SOC mineralization is still poorly understood.Soil samples were collected from an artificial Populus nigra forest in the sandy area of western Shandong Province,and the combined effect of N forms(nitrate and ammonium)and temperatures(10,20℃,and 30℃)on SOC mineralization was studied using an incubation experiment.The results showed that,compared to the control treatment,ammonium addition increased the cumulative SOC mineralization by 11.8%-21.3%at 10℃,indicating a N-limitation on the microbial decomposition of SOC.As the temperature increased to 20℃ and 30℃,the effect of ammonium nitrogen addition on SOC mineralization was negative.Nitrate addition reduced SOC mineralization during the entire incubation period.At the end of the incubation,the cumulative SOC mineralization after nitrate addition was reduced by 4.1%-11.5%(10℃),9.1%-29.3%(20℃),and 8.6%-23.7%(30℃),respectively compared to that of the control treatment.Increased temperature enhanced SOC mineralization.The combined effect of temperature and N addition on SOC mineralization was antagonistic.The measured values of such interactions on SOC mineralization were 7.9%-21.9%(nitrate addition)and 16.1%-23.6%(ammonium addition)lower than theoretical values due to the decreased tendency of the temperature sensitivity of SOC mineralization after N addition.In general,nitrate and ammonium addition produce different effects on SOC mineralization.The interactive effect of N addition and temperature on SOC mineralization may have been overestimated based on their single effects.