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在东北半干旱地区的科尔沁沙地,秋冬与冬春季节由温度变化引起的土壤冻融对CO2排放具有显著影响,研究水分和冻融的交互作用对土壤呼吸的影响具有重要意义。以科尔沁沙地樟子松疏林草地、农田和草地为研究对象,通过冻融模拟实验分析水分和冻融循环对不同土地利用方式土壤呼吸的影响。结果表明,水分条件、土地利用方式和冻融循环均对土壤呼吸影响显著。冻融前草地土壤呼吸显著大于疏林草地和农田,冻融期疏林草地土壤呼吸显著大于农田,而冻融后草地土壤呼吸速率显著大于疏林草地。80%田间持水量时3种土地利用方式的土壤呼吸速率显著大于60%田间持水量时土壤呼吸速率;在培养期内(20d),60%田间持水量时疏林草地、农田和草地的土壤CO2释放量分别为21.535、19.908和25.037gCO2·m-2,80%田间持水量时分别为26.407、29.447和36.246gCO2·m-2。
In the Horqin sandy land in the semi-arid area of northeast China, freezing and thawing of soil caused by temperature change in autumn, winter and spring have a significant effect on CO2 emission. It is of great significance to study the effect of interaction between water and freeze-thaw on soil respiration. The study was conducted on the sparse grassland, farmland and grassland of Pinus sylvestris var. Mongolica in Horqin sandy land. The effects of moisture and freeze-thaw cycles on soil respiration of different land use types were analyzed by freeze-thaw simulation. The results showed that water conditions, land use patterns and freeze-thaw cycles all had significant effects on soil respiration. The soil respiration of grassland before freezing and thawing was significantly larger than that of sparse grassland and farmland. Soil respiration of sparse grassland in freezing and thawing period was significantly larger than that of farmland, while the respiration rate of grassland after freezing and thawing was significantly larger than that of sparse grassland. The soil respiration rate of three kinds of land use in the field with 80% field water content was significantly greater than that in the field with 60% field water holding capacity. Soil in the sparse grassland, farmland and grassland in the cultivation period (20d) and 60% CO2 emissions were 21.535, 19.908 and 25.037gCO2 · m-2, respectively, with 80% field capacity of 26.407, 29.447 and 36.246gCO2 · m-2, respectively.