3种典型陆地生态系统土壤137Cs和有机碳含量研究

选择位于广东小良的自然林、光裸地和森林恢复地3种典型陆地生态系统类型,通过研究土壤137Cs和土壤有机碳(SOC)的含量与分布,分析137Cs与SOC的关系,尝试运用137Cs法研究典型陆地生态系统类型的土壤侵蚀与土壤碳动态.结果显示,自然林为研究区土壤137Cs的背景点,其0~40cm土壤中的137Cs平均活度值为(0.99±0.28)Bq/kg,137Cs背景值为(448.1±56.3)Bq/m2,0~40cm的SOC储量为5.93kg/m2.森林恢复地和光裸地土壤中没有检出137Cs,表明森林恢复地和光裸地发生了严重的土壤侵蚀.自然林土壤137Cs深度分布形态为非指数衰减形态,137Cs浓度峰值出现在次表层.自然林的各土层137Cs活度与SOC含量的相关关系不显著(P>0.1).研究区137Cs含量的背景值很低.基于137Cs法计算研究区及相似地区的SOC侵蚀量有一定局限性.

137Cs inventories and soil organic carbon content in soils of three typical terrestrial ecosystems

The soil and soil organic carbon(SOC) erosion in three typical terrestrial ecosystems(natural forest,barren land and restored forest) were investigated using 137Cs.Study sites were located in Xiaoliang of Guangdong province.Soil 137Cs inventories and SOC content were measured;the 137Cs distribution and the relationships between 137Cs and SOC were analyzed.The natural forest was the reference site of the study region.In the natural forest,the average activity of 137Cs in 0~40 cm soil horizon was(0.99±0.28) Bq/kg,137Cs reference inventory was(448.1±56.3) Bq/m2,and SOC storage of 0~40cm horizon was 5.93 kg/m2.137Cs was undetected in soils of the barren land and the restored forest.Heavy soil erosion had occurred on the barren land and the restored forest.In the natural forest,the distribution of 137Cs in profile had a non-exponential decrease shape with depth while the peak values of 137Cs concentration occurred in the sub-surface horizon.The correlation between 137Cs activity and SOC content in different soil layers of the natural forest was non-significant(P>0.1).137Cs reference inventory was very low in the study region.The calculation of the soil and SOC erosion by using 137Cs in the study area or other relevant areas would be limited.