中亚热带2种天然林表层土壤N2O排放速率

运用静态箱-气相色谱法对中亚热带地区米槠天然林和阿丁枫天然林土壤N2O排放速率进行了1年（2012年1月—2013年1月）原位观测,分析了土壤温度及含水量对土壤N2O排放速率的影响,并探讨土壤无机N含量变化与土壤N2O排放速率的关系。结果表明,观测期间,2种天然林均表现为大气N2O排放源,米槠天然林和阿丁枫天然林平均土壤N2O排放速率分别为7.29μg·m^-2·h^-1、7.41μg·m^-2·h^-1;米槠天然林和阿丁枫天然林土壤N2O排放速率季节变化明显,最高排放速率均出现在夏季6月,分别为16.51μg·m^-2·h^-1、18.86μg·m^-2·h^-1;2个林分N2O排放速率最低值分别出现在2012年1月和2012年9月,分别为3.04μg·m^-2·h^-1和2.17μg·m^-2·h^-1。2种天然林土壤N2O排放速率均与土壤温度无显著相关性,与土壤含水量显著正相关（P〈0.05）;2种天然林土壤N2O排放速率与NH4＋含量均无显著相关性,米槠天然林和阿丁枫天然土壤N2O排放速率与NO3-含量分别呈显著负相关和显著正相关（P〈0.05）。研究结果表明,土壤含水量及NO3-含量的变化对中亚热带天然林土壤N2O排放速率有着重要的影响。

Soil N2 O Emission Rates of Two Natural Forests in Mid-subtropical China

We investigated in situ soil N2 O emission rates in two nature forests（Castanopsis carlesii and Altingia gracilipes） in Fujian,China,from January 2012 to January 2013,using static chamber and gas chromatography techniques.Effects of soil moisture and temperature on N2 O emission rates were analyzed,together with the relationship between soil NH4^＋,NO3^-contents and N2 O emission rates.The results showed that both forests were atmosphere N2 O emission sources,with the mean emission rates of 7.29 μg·m^-2·h^-1and 7.41 μg·m^-2·h^-1,respectively for the Castanopsis Carlesii and Altingia gracilipes.The N2 O emission rates showed a pronounced seasonal fluctuation,with minimum values in January and September,3.04 μg · m-2·h-1for the Castanopsis carlesii forest and2.17 μg·m^-2·h^-1for Altingia gracilipes forest;and with maximum values in June for both forests.For both forests,N2 O emission rates were significantly correlated with soil moisture（P〈 0.05）,but not with soil temperature.And N2 O emission rates of the Castanopsis Carlesii forest and the Altingia gracilipes forest were negatively and positively correlated with the NO3^-contents,respectively（P 〈0.05）;neither correlations between N2 O emission rates and the NH4＋contents were significant.These results showed that soil moisture and NO3-contents played an important role in the change of the N2 O emission rates for the natural forests in mid-subtropical China.