不同载畜率下荒漠草原N_(2)O通量的研究

Study of N_(2)O Fluxes in Desert Grassland with Different Stocking Rates

气候变化是目前人类面临的重要环境问题,N_(2)O是重要的温室气体之一。为探究不同载畜率对短花针茅荒漠草原N_(2)O通量的影响,于2019年6~9月,在内蒙古四子王旗短花针茅荒漠草原长期放牧平台(2004年开始),设置不放牧(CK)、轻度放牧(LG)、中度放牧(MG)和重度放牧(HG)4个载畜率水平载畜率分别为0、0.91、1.82、2.71羊单位/(hm^(2)·半年),测定土壤温度、土壤含水量、土壤pH值、土壤紧实度及N_(2)O通量。结果表明:不同载畜率处理下N_(2)O通量的月动态不同;取样时间对土壤温度、土壤含水量和硝态氮含量影响显著(P<0.05);放牧显著降低土壤含水量(P<0.05),增加土壤紧实度(P<0.05),但放牧对土壤温度和pH值的影响不显著;LG处理下N_(2)O通量显著低于CK、MG和HG处理(P<0.05),MG和HG处理N_(2)O通量与CK差异不显著;N_(2)O通量与土壤含水量呈显著负相关(P<0.05),与土壤温度呈显著正相关(P<0.05),与土壤紧实度呈负相关。

Climate change is critical environmental issue confronting humanity nowadays,and N_(2)O is one of the important greenhouse gases.To investigate the effect of different stocking rates on N_(2)O fluxes in the short-flowered needlegrass desert grassland,this experiment was conducted from June to September in 2019 on a long-term grazing platform(initiated in 2004)in Siziwang Banner,Inner Mongolia.Four stocking rate levels were established:no grazing(CK),light grazing(LG,stocking rate of 0.91 sheep units/hm^(2)·half-year),moderate grazing(MG,stocking rate of 1.82 sheep units/hm^(2)·half-year),and heavy grazing(HG,stocking rage of 2.71 sheep units/hm^(2)·half-year).Soil temperature,soil moisture content,soil pH and soil compaction were measured.The results showed that the monthly dynamics of N_(2)O fluxes varied under different stocking rates.Sampling time significantly affected soil temperature,soil moisture content,and nitrate nitrogen content(P<0.05).Grazing significantly reduced soil moisture content(P<0.05)and increased soil compaction(P<0.05),but had no significant impact on soil temperature and pH values;N_(2)O fluxes under the LG treatment were significantly lower than those under the CK,MG and HG treatments(P<0.05),while the N_(2)O fluxes under MG and HG treatments did not differ significantly from CK;N_(2)O fluxes were significantly negatively correlated with soil moisture content(P<0.05),positively correlated with soil temperature(P<0.05),and negatively correlated with soil compaction.