北京松山国家级自然保护区典型植被类型表层土壤碳密度及周转速率特征

为阐明不同植被类型下表层土壤有机碳的分布特征，本文选取北京松山国家级自然保护区内胡桃楸阔叶林、蒙古栎阔叶林、油松针叶林、针阔叶混交林、灌丛和草甸6种典型植物群落作为研究对象，基于野外调查、采样与实验室分析对不同植被类型下表层土壤有机碳含量、密度及周转速率进行了研究。结果表明：草甸表层土壤有机碳含量和密度最高，分别为188.5 g/kg和10.9 kg/m²，周转速率最低，为0.019 6/a；针阔叶混交林表层土壤有机碳含量和密度最低，分别为68.6 g/kg和5.7 kg/m²，周转速率为0.074 9/a；灌丛表层土壤有机碳周转速率为0.077 4/a。土壤有机碳含量整体上随土壤深度增加而逐渐减少。土壤水分的增加和土壤温度的下降使表层土壤有机碳含量及密度呈上升趋势，而使有机碳周转速率呈下降趋势。土壤有机碳密度随海拔升高呈逐渐上升趋势。海拔通过影响不同植被群落土壤水热条件来影响微生物活动及凋落物的分解，进而影响表层土壤有机碳含量、密度和周转速率。本文为松山国家级自然保护区典型植被类型土壤碳储量和周转研究提供了有效参考。

Surface Soil Carbon Density and Turnover Rate of Typical Vegetation Types in Beijing Songshan National Nature Reserve

In order to illuminate the distribution of surface soil organic carbon (SOC) in different vegetation types, this paper chose six typical plant communities in Beijing Songshan National Nature Reserve as research subjects, including Juglans mandshurica forest, Quercus mongolica forest, Pinus tabuliformis forest, mixed coniferous broad leaved forest, brushwood and meadow. Based on the field investigation, sampling and laboratory analysis, surface SOC content, density and turnover rate of different vegetation types were studied. The results showed that surface SOC content and density in meadow are the highest with value of 188.5 g/kg and 10.9 kg/m², respectively. Surface SOC turnover rate is the lowest in meadow, only 0.0196/a. Surface SOC content and density in mixed coniferous broad leaved forest are the lowest, which are 68.6 g/kg and 5.7 kg/m², respectively, and surface SOC turnover rate is 0.0749/a. Surface SOC turnover rate in brushwood soil is 0.0774/a. In general, surface SOC content decreases gradually with increasing soil depth in each sample-plot. Increased soil moisture and decreased soil temperature enhance the surface SOC content and density, but has negative impact on surface SOC turnover rate. SOC density increases with higher altitude. Altitude affects surface soil organic carbon content, density and turnover rate by influencing soil hydrothermal conditions of different vegetation communities, that in turn alters the microbial activities and litter decomposition. This study provides an effective reference for the research on soil carbon storage and turnover of different vegetation types in Beijing Songshan National Nature Reserve.