华北平原杨树人工林5种植被类型土壤CO_2通量研究

Soil CO_2 Flux of Five Types of Vegetation in Poplar Plantation of Chinese North Plain Region

利用Licor-8100土壤CO2通量测定系统对华北平原地区5种不同密度和类型杨树人工林2009年10月份的土壤呼吸通量进行了观测、比较和分析。结果表明:(1)在短时间尺度上,它们的土壤呼吸通量有显著的差别,表现出明显的空间异质性。其大小顺序为:8 m行宽林间小藜、牛筋草地>2 m行宽林间苍耳地>8 m行宽林间水蓼、灰灰菜地>8 m行宽林间苍耳地>2 m宽林间裸地,其中平均值最大呼吸通量为3.23μmol/(m2.s),最小为1.87μmol/(m2.s)。(2)造成各植被类型和密度土壤呼吸差异的因素有土壤草根密度、与杨树的距离和地表空气流通性。(3)5种类型和密度的土壤呼吸通量的日变化过程并不一致,除8 m行宽林间小藜、牛筋草地和8 m行宽林间水蓼、灰灰菜地的呼吸通量与温度有较一致的规律,呈单峰型外,其余无明显的变化规律。(4)在较大时间尺度上,空气温度,土壤含水率和空气湿度有显著的相关关系;随着空气温度、土壤含水率和空气湿度的下降,土壤呼吸通量在一个月内呈逐渐的下降趋势。

Employing the Licor-8100,the soil CO2 flux of five types and density vegetation was observed in a poplar plantation in Chinese North Plain Region in 2009.The result showed that：（1） The soil CO2 flux of five types and density vegetation was significantly different at short time scale and indicated obvious spatial heterogeneity.The rate of released CO2 was the highest in 8 m wide woodland with Chenopodium serotinum L and Eleusine indica（L.） on it,the average value was 3.23 μmol/（m2·s） and the lowest was in 2 m wide woodland with nothing except a little litter on it,the average value was 1.87 μmol/（m2·s）.The sequence was： 8 m wide woodland with Chenopodium serotinum L and Eleusine indica（L.） on it 2 m wide woodland with Xanthium sibiricum Patrin on it 8 m wide woodland with Polygonum hydropiper Linnan and Chenopodium album Linn.on it 8 m wide woodland with Xanthium sibiricum Patrin on it 2 m wide woodland with nothing except a little litter on it.（2）The factors that made the rate of released CO2 flux different were the soil grass root density,the distance of observation location and the poplar and the flow rate of surface air.（3） Diurnal variation of soil CO2 flux was different in five types and density vegetation.Except for 8 m wide woodland with Chenopodium serotinum L and Eleusine indica（L.） on it and 8 m wide woodland with Polygonum hydropiper Linnan and Chenopodium album Linn.it,in which the changes of CO2 flux exhibited a single peak and showed relative consistency with the changes of temperature,there were no regular changes of CO2 flux in other vegetation types.（4）The soil respiration flux was significantly positively correlated with air temperature（Ta）,soil volume water content（VWC） and the relative humidity（RH） at short time scale.With the decline of Ta,VWC and RH,soil respiration took on digressive trend in one month.