干湿交替和模拟氮沉降对巴音布鲁克高寒湿地土壤CO_2排放的影响

Effect of alternating wetting and drying and simulated nitrogen deposition on soil CO_2 emission in alpine wetlands of Bayinbulak

为探讨干湿交替和模拟氮沉降对高寒湿地土壤CO_2排放的规律,以新疆巴音布鲁克高寒湿地土壤为研究对象,通过室内模拟控制试验,研究水分变化下[100%、70%、50%、40%和25%WFPS(土壤充水孔隙度Water filling soil porosity)]氮添加N0(0 kg·hm^(-2)·a^(-1))、N10(10 kg·hm^(-2)·a^(-1))和N100(100 kg·hm^(-2)·a^(-1))处理对巴音布鲁克高寒湿地土壤CO_2排放的影响。研究结果表明:土壤CO_2排放速率及累积排放量随WFPS值及氮添加量的增大而增加。一个循环,土壤由干到湿的过程中,初期土壤CO_2排放速率最高,随后随着水分减少,土壤CO_2排放速率呈降低趋势;首次干湿循环土壤CO_2累积排放量最大。土壤TN、NO_3^--N、NH_4^+-N、SOC含量均随土壤水分和氮添加量的增加而增加,而土壤SON随土壤水分和氮添加量的增加而减少。水分与土壤CO_2排放速率呈极显著正相关,氮添加与CO_2排放亦呈正相关。除了土壤SON、SOC含量与土壤CO_2排放速率呈负相关关系外,土壤TN、NO_3^--N、NH_4^+-N与CO_2排放都呈现出正相关关系。

Effects of water changes and nitrogen deposition on the carbon cycle in alpine wetlands are the focus in the global change ecology.The primary objective of this study was to investigate the dynamics of soil CO2 emission in alpine wetland under the conditions of alternating dry-wet（soil water changing） and simulated nitrogen deposition（nitrogen addition）.Water changing treatments were 100%, 70%, 50%,40% and 25% of water filling soil porosity（WFPS）, and nitrogen addition treatments were 0 kg·hm^-2·a^-1（N0）, 10 kg·hm^-2·a^-1（N10）and 100 kg·hm^-2·a^-1（N100）. Changes of soil CO2 emissions under these treatments were measured in alpine wetland soils of Bayinbuluk using the indoor control experiments. Results showed that：The soil CO2 emission rates and cumulative emission increased with the increase of WFPS and nitrogen addition. In the soil process from wet to dry, soil CO2 emission rate decreased with the reduction of soil moisture content.The cumulative CO2 emission in the first process from wet to dry was significantly higher than the rest soil water changing process. The con-tents of soil total nitrogen（TN）, NO3---N, NH4-＋-N and soil organic carbon（SOC）increased with the increase of soil moisture content and nitrogen addition, while soil organic nitrogen（SON）reduced in the similar treatment changes of soil water treatments and nitrogen addition treatments. Significantly positive correlations between soil moisture content and the soil CO2 emission rates and between nitrogen addition and the soil CO2 emission rates were found in this study. The soil CO2 emission rate was significantly negative correlated with SON and SOC,while it was significantly positive correlated with TN, NO3---N and NH4-＋-N. These results provide a scientific basis for the further understanding of the changes of soil CO2 emission under the conditions of nitrogen deposition and extreme climate change in arid alpine wetlands.