城市绿地不同植被类型土壤温室气体通量及影响因素

Greenhouse Gas Fluxes and Influencing Factors in Soils of Different Vegetation Types in Urban Green Spaces

以呼和浩特树木园3种不同植被类型城市绿地(杨树人工林、灌木林、草地)为供试样地,运用PS-3000超便携式土壤温室气体测量系统测定了土壤CO_(2)和CH_(4)通量,并同步测定环境水热因子、土壤理化性质和微生物数量等指标,研究了3种类型城市绿地土壤温室气体通量变化特征及其对环境因子的响应,以期为估算大气温室气体体积分数及缓解城市热岛效应提供参考依据。结果表明:①3类样地土壤均表现为对CO_(2)的排放和CH_(4)的吸收,年均通量由大到小表现为杨树人工林(CO_(2)164.80 mg·m^(-2)·h^(-1)、CH_(4)-45.40μg·m^(-2)·h^(-1))、草地(CO_(2)138.59 mg·m^(-2)·h^(-1)、CH_(4)-39.24μg·m^(-2)·h^(-1))、灌木林(CO_(2)114.99 mg·m^(-2)·h^(-1)、CH_(4)-38.62μg·m^(-2)·h^(-1));②3类样地土壤CO_(2)通量与各土层土壤、地表、大气温度、土壤碳氮质量分数和表层土壤细菌、放线菌数量及微生物生物量碳、氮质量分数均呈显著正相关,CH_(4)通量则与之呈显著负相关,而与大气、地表湿度和土壤真菌数量均未达到显著水平;③冗余分析表明,土壤碳氮质量分数(0<h≤20 cm)是引起土壤CO_(2)和CH_(4)通量差异的显著性解释因子,分别解释了72.00%、20.30%和8.60%;④3类样地CO_(2)和CH_(4)季节通量均表现为夏秋季大于冬春季,百年尺度上,全球增温潜势(以CO_(2)当量计)由大到小表现为杨树人工林(1412.91 g·m^(-2))、草地(1187.92 g·m^(-2))、灌木林(984.18 g·m^(-2)),其中CO_(2)排放带来的增温效应占全球增温潜势(G WP)的99.3%。

The study was conducted in the tree garden of Hohhot,with three different vegetation types of urban green spaces(poplar plantation,shrub forest,and grassland)as the study sites.The researchers used an ultra-portable soil greenhouse gas measurement system(PS-3000)to measure the soil CO_(2) and CH_(4) fluxes,and simultaneously monitored the environmental water and heat factors,soil physicochemical properties,and microbial quantities.The objectives were to investigate the characteristics of soil greenhouse gas fluxes in these three urban green spaces and their responses to environmental factors,in order to provide references for estimating atmospheric greenhouse gas concentrations and mitigating urban heat island effects.The results showed that all three sites exhibited soil CO_(2) emissions and CH_(4) uptake,with the annual mean fluxes decreasing in the order of poplar plantation(164.80 mg·m^(-2)·h^(-1)of CO_(2),-45.40μg·m^(-2)·h^(-1)of CH_(4)),grassland(138.59 mg·m^(-2)·h^(-1)of CO_(2),-39.24μg·m^(-2)·h^(-1)of CH_(4)),and shrub forest(114.99 mg·m^(-2)·h^(-1)of CO_(2),-38.62μg·m^(-2)·h^(-1)of CH_(4)).The soil CO_(2) flux was significantly positively correlated with soil,surface,and atmospheric temperatures,soil carbon and nitrogen contents,and the number of surface soil bacteria,actinomycetes,and microbial biomass carbon and nitrogen.The CH_(4) flux showed significant negative correlations with these factors,but no significant relationships with atmospheric,surface humidity and soil fungal count.Redundancy analysis revealed that soil carbon and nitrogen contents(0<h≤20 cm)were the significant explanatory factors for the differences in soil CO_(2) and CH_(4) fluxes,accounting for 72.00%,20.30%,and 8.60%of the variations,respectively.The seasonal fluxes of CO_(2) and CH_(4) were higher in summer and autumn than in winter and spring.On a 100-year scale,the global warming potentials(Expressed in CO_(2)-equivalent units)decreased in the order of poplar plantation(1412.91 g·m^(-2)),grassland(1187.92 g·m^(-2)),and shrub forest(984.18 g·m^(-2)),with CO_(2) emissions contributing 99.3%to the total G WP.