摘要
土壤碳激发效应是影响有机质转化的关键机制,全球气候变暖和大气氮沉降对其的影响关系到土壤碳库的稳定性。本研究基于已进行4年氮添加的高寒泥炭湿地土壤,在5℃、15℃条件下,将对照以及不同水平的氮添加土壤培养60 d,结合13C标记的葡萄糖来探究模拟增温和氮沉降的耦合作用对土壤碳激发效应的影响。结果表明,增温显著地增加土壤碳矿化速率(P<0.05),而氮添加无显著影响。增温显著提升激发效应强度,在对照样地,15℃处理中土壤碳激发效应比5℃处理平均增加37.5%。不同温度中的氮添加均使土壤激发效应强度由正向转变为负向,低氮、中氮、高氮相比于对照碳激发效应强度分别平均降低71.1%、90.8%、113.3%。不同氮水平在5℃处理对土壤碳激发效应的影响不显著,而15℃处理土壤碳激发效应的强度随着氮添加水平的增加而减弱。外源碳添加水平影响土壤碳激发效应强度,与高碳添加水平相比,低碳添加使土壤碳激发效应平均增加23.9%。这些结果表明,温度的增加使正向的土壤碳激发效应更易发生,即在气候变暖的情况下导致土壤有机碳矿化的加速,进而加速气候变暖;氮添加则会导致负向的土壤碳激发效应发生,缓冲气候变暖导致的土壤碳库不稳定性的增加。实验结果表明温度越高,氮添加使土壤碳激发效应的强度降低的越显著,即气候变暖增强的背景下,大气氮沉降的加剧有可能导致土壤碳激发效应强度的降低,部分抵消升温而导致的正向碳激发效应。在未来气候变暖和大气氮沉降的共同作用下,究竟土壤激发效应和土壤碳库将会如何响应仍需进一步的量化研究和模型预测。
Soil carbon priming effect is a key mechanism affecting organic matter conversion.The effects of global climate warming and atmospheric nitrogen deposition on the priming effect are related to the stability of the soil carbon pool.The alpine peat wetland soil that had been added with nitrogen for 4 years was cultivated at 5℃and 15℃for 60 days and the glucose labeled with 13C was used to study the coupling effect of nitrogen addition and temperature increment on soil carbon priming effect.The results showed that the increase in temperature significantly affected the soil carbon mineralization rate(P<0.05),while nitrogen addition had no significant effect on it.The temperature significantly increased the intensity of the soil priming effect.For the control plot,the soil priming effect in the 15℃treatment increased by an average of 37.5%compared to the 5℃treatment.The soil priming effect intensity was changed from positive to negative by N addition in different temperatures,and the average priming effect intensity of low nitrogen,medium nitrogen,and high nitrogen was decreased by 71.1%,90.8%,and 113.3%,respectively,compared to the control.The effect of nitrogen levels on soil priming effect was not significant in 5℃treatment,while the intensity of soil priming effect was negatively correlated with nitrogen addition level in 15℃treatment.The intensity of soil priming effect was affected by exogenous carbon addition level,and it was increased by 23.9%on average by high-level carbon compared with that by low-level carbon addition.These results indicated that increasing temperature led to the probability of soil priming effect to increase,that is,it led to the acceleration of soil organic carbon mineralization in the case of global warming,thus accelerating global warming.While,nitrogen addition would lead to an opposite result,which meant that the negative soil carbon priming effect occurs,buffering the increase of soil carbon pool instability caused by global warming.The experimental results also showed that the higher the temperature is,the more significantly the intensity of soil carbon priming effect would be reduced by nitrogen addition.Under the background of enhanced global warming,the intensification of atmospheric nitrogen deposition might lead to the reduction of the intensity of soil carbon priming effect,partially offsetting the positive carbon priming effect caused by the increased temperature.How the soil priming effect and the soil carbon pool will respond to the combined effects of global warming and atmospheric nitrogen deposition in the future still needs further quantitative research and model prediction.
作者
李赟
王春梅
高士杰
王鹏
邱景琮
商帅帅
LI Yun;WANG Chunmei;GAO Shijie;WANG Peng;QIU Jingcong;SHANG Shuaishuai(College of Environmental Science and Engineering,Beijing Forestry University,Beijing,100083,China;School of Ecology and Nature Conservation,Beijing Forestry University,Beijing,100083,China)
出处
《环境化学》
CAS
CSCD
北大核心
2021年第8期2430-2438,共9页
Environmental Chemistry
基金
国家自然科学基金(41373069,41971024)资助.
关键词
土壤碳激发效应
模拟增温
氮添加
同位素标记
soil carbon priming effect
simulated warming
nitrogen addition
isotope labeling
