不同粒级土壤团聚体呼吸特征及其对碳排放的贡献

通过土盆培养试验研究了不同粒级黄棕壤团聚体呼吸特征及其对碳排放的贡献,结果表明:各粒级土壤团聚体及原状土在培养初期土壤呼吸速率较高,之后逐渐降低。在整个培养期间原状土保持了最大的土壤呼吸速率;土壤团聚体类型对土壤呼吸速率影响较大,3种粒级团聚体土壤呼吸速率大小表现为(5 mm)(1 mm)≈(1~5 mm),其中以5 mm团聚体对土壤碳排放的贡献最大。相关性分析表明,指数模型能较好地描述不同粒级团聚体的土壤呼吸对温度变化的响应;Q10值介于2.53~5.11之间且与土壤有机碳、全氮含量的变化规律基本一致,表现为1 mm团聚体有机碳、全氮含量和Q10值较大,5 mm、1~5 mm团聚体有机碳、全氮含量和Q10值相对较低,说明土壤团聚体粒级越小,其呼吸速率对温度越敏感。土壤有机碳、氮含量与土壤结构是影响土壤呼吸温度敏感性的重要因素。

Respiration Characteristics of Different Sized Soil Aggregates and Their Contribution to Carbon Emissions

The respiration characteristics of different sized yellow brown soil aggregates and their contribution to carbon emissions were assessed by soil pot experiment. Results showed that the respiration rates of aggregates and homogenized soil were highest at the beginning of the incubation, and then showed a descending tendency during the period of incubation. During the incubation time, the homogenized soil had the highest respiration rate. The respiration rates varied with aggregate size: (>5 mm)>(<1 mm)≈(1~5 mm). This indicated that the largest macroaggregates (>5 mm) had the highest contribution to carbon emissions. Correlation analysis showed that the respiration rates of different sized soil aggregates were significantly and exponentially correlated with soil temperature. The Q₁₀ values ranged from 2.53 to 5.11 and had the same variation tendency in different aggregates with soil organic carbon (SOC) and total nitrogen (TN). The <1 mm aggregates had the highest Q₁₀ value and SOC and TN contents, while>5mm and 1~5 mm aggregates had lower Q₁₀ values and SOC and TN contents. Our results suggested that both the contents of SOC and TN and the soil structure affected temperature sensitivity of soil respiration.