【摘要】 利用Li-cor6400-09测定了黄土高原地区人工刺槐林(Robinia pseudoacacia L)的土壤呼吸速率;同时,对土壤呼吸测定点的土壤温度(土层深度0、5、10和15cm)、土壤含水量、土壤空隙度和土壤C和N等土壤因子进行了测定。结果表明,黄土高原人工刺槐林地土壤呼吸速率有显著的空间变异性;土壤温度、土壤水分、土壤空隙度和土壤有机C显著的影响着土壤呼吸速率变化,分别可以单独解释土壤呼吸速率变化的86、82、89和85%。偏相关分析和通径分析表明,土壤水分和土壤温度之间有较为密切的相关关系(偏相关系数为0.321),土壤水分与土壤呼吸间的正相关关系是由于温度变化所引起;土壤空隙度和有机C具有密切的相关关系(偏相关系数为0.99),空隙度和有机C对土壤呼吸速率变化具有最大的决定力(通径系数最大>30)。多元回归分析表明,包含土壤水热因子和土壤空隙度及有机C的回归模型能较好的解释土壤呼吸速率变化(R2=0.938,P<0.001)。更多还原

【Abstract】 Soil CO2 efflux (soil respiration) is an important component of global carbon cycle, and the efflux rate may be strongly affected by soil temperature, soil water, soil porosity, soil organic C and N, and other soil physical and chemical properties. The im-pact of soil temperature and moisture on soil respiration has been widely investigated. However, the relations of soil respiration with soil porosity and soil organic C has not been comprehensively studied on a spatial scale. The soil respiration rates of Robinia pseu-doacacia L. forests were measured with Li-cor 6400-09 at different locations in the Loess Plateau of China. While taking soil respi-ration measurements, soil temperature, soil moisture along with soil porosity, organic C and N in 10 cm topsoil below the measure-ment chamber were also monitored, Multivariate analysis was conducted to analyze the relations of soil respiration with soil physical and chemical factors (temperature, moisture, porosity and soil organic C and soil N). The results suggested that the spatial variation of soil respiration was significantly difference and closely correlated to soil porosity and temperature, soil water and soil organic C, and each factor alone could explain 89%, 86%, 82% and 85% of the spatial variation in soil respiration, respectively. However, stan-dardized estimation analysis indicated that the positive relation of soil respiration with soil water content was caused by the variation of soil temperature, which was closely related with soil water content (partial r = 0.321). In fact, soil water content negatively af-fected spatial variation of soil respiration with a standardized estimation value of -0.246. Among the soil factors, soil porosity was highly correlated with soil organic C with partial r = 0.99, they had the strongest influence on soil respiration with the biggest stan-dardized estimation (> 30.0). By means of a multivariate regression model driven by soil physical and chemical factors, more than 93.8% of the spatial variation of soil respiration can be explained in terms of soil porosity, soil temperature and soil water content and soil organic C.更多还原