不同利用方式下草地土壤碳积累及汇/源功能转换特征研究

土地利用变化是影响土壤碳储量的主要人为因素,准确掌握不同利用方式下土壤碳积累及汇/源功能转换特征,对预测土壤碳释放量趋势有着很重要的意义。为明确不同利用方式下草地土壤碳储量及碳汇/源功能的动态变化特征,以位于科尔沁沙地东南围封草地与放牧地为研究对象,采用有机碳密度法分析了0~30 cm土层有机碳储量及其在5-11月的变化规律。结果表明:围封草地土壤有机碳含量随着土层的加深呈递减的变化,放牧地土壤有机碳含量随着土层的加深不同土层间无显著差异。5-11月围封草地0~30 cm土层土壤有机碳密度变化为2.8~4.0 kg/m2,变幅为1.2 kg/m2。5-9月放牧地0~30 cm土层土壤有机碳密度变化为3.4~4.7 kg/m2,变幅为1.3 kg/m2。围封草地在5-8月为土壤碳源过程,8-9月为土壤碳汇过程,9-11月为土壤碳源过程。放牧地土壤碳库较稳定,无明显的碳汇/源的变化过程。合理的放牧利用有助于土壤碳的积累,减少碳释放。

Study on the characteristics of soil carbon accumulation and conversion of carbon sink and source of grassland under different land use types

Land-use change is the main affecting factor of soil carbon storage. It is very important to predict the trend of soil carbon release under different land-use patterns so that the soil carbon accumulation and conversion of soil carbon sink and source could be better understand. The organic carbon density and variation patterns of organic carbon storage within 0 to 30 cm soil layer of fenced grassland and grazing land in the southeast of Horqin sandy land were studied from May to November. The results showed that the soil organic carbon content of enclosed grassland decreased significantly with the soil depth, but not for the grazing land. Soil organic carbon density of the fenced grassland within 0 to 30 cm soil layer varied from 2.8 kg/m~2 to 4.0 kg/m~2. And it was from 3.4 kg/m~2 to 4.7 kg/m~2 for the grazing land. In general, it was the carbon source process from May to August and from September to November, and it was the carbon sink process from August to September for the fenced land. However, soil carbon storage of the grazing land was more stable, the conversion process of soil carbon sink and source was no significant. It suggested that the reasonable grazing utilization contributed to accumulation of soil carbon and could reduce carbon emission.