Meta分析模拟氮沉降对我国北方草地氧化亚氮排放速率的影响

Effect of Nitrogen Deposition on Grasslands Nitrous Oxide Emission Rates by Meta-Analysis Method

氧化亚氮(N_2O)是三大温室气体之一,氮沉降显著提高土壤氮素供给水平,可能会大幅增加草地生态系统N_(2)O排放速率。北方草地是我国重要的生态安全屏障和畜牧业基地,但目前有关氮沉降对我国北方草地生态系统N_(2)O排放速率的影响强度及主要调控因素尚不清楚。本研究采用Meta方法,通过对中国北方草地已开展的32个实验结果进行综合分析。结果发现:模拟氮沉降对中国草地生态系统N_(2)O排放的平均效应值为0.82±0.11(95%置信区间0.61~1.02),氮沉降极显著地增加了我国草地N_(2)O排放速率(P<0.001)。不同氮素类型对平均效应值存在显著性影响,顺序依次为硫酸铵、尿素、硝酸钠、硝酸铵、家畜尿液。施用氮素剂量、土壤有机碳含量、气温和海拔对平均效应值均具有显著性影响,氮素剂量和土壤有机质含量可以解释效应值变异的47.31%和45.27%。氮沉降的平均效应值与氮素剂量和气温之间存在极显著正相关关系,而与土壤有机碳和海拔间存在极显著负相关关系。通过对退化草地的恢复治理、提高土壤有机碳含量可大幅降低氮沉降对我国草地生态系统N_2O排放的激发效应。

The increase of greenhouse gas concentrations has become a critical situation in global warming.Nitrous oxide(N2O)is one of the three primary greenhouse gases.Nitrogen deposition changes the characteristics of soil microbial communities and affects the N_(2)O emission rate.Northern grassland plays a vital role in ecological security barriers and animal husbandry in China.However,the effect of nitrogen deposition on N_(2)O emission rates and its regulatory factors are still unclear.In this study,32 grasslands’experimental results were analyzed using Meta-analysis method.The results indicate that the average effect size was approximately 0.82±0.11(95%confidence interval 0.61~1.0)for simulated nitrogen deposition on N_(2)O emission rates(P<0.001).Different nitrogen types significantly affected the average effect size,with a high-to-low order high of ammonium sulfate,urea,sodium nitrate,ammonium nitrate,and livestock urine.Nitrogen dosage,soil organic carbon,air temperature,and altitude had significant effects on the average effect size.Furthermore,the effect size variation of 47.31%and 45.27%could be explained by nitrogen dosage and soil organic matter content,respectively.There was a significant positive correlation between effect size,nitrogen dosage,and air temperature.Furthermore,a significant negative correlation was revealed between the average effect size,soil organic carbon,and altitude.In addition,the grasslands nitrogen deposition effect on N_(2)O emission may be significantly reduced by increasing soil organic carbon content through grassland adaptive management measures.