【作者】 陶贞；

【导师】 沈承德；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 地球化学， 2005， 博士

【摘要】 本文对海北高寒草甸生态系统定位研究站和内蒙古草原生态系统定位研究站的6个土壤剖面进行了高分辨率薄层取样,测试、分析了样品的根系和有机碳含量、有机质的放射性和稳定碳同位素组成、磁化率等,研究了土壤有机碳动力学过程,得出如下结论: 青藏高原高寒草甸土壤有机碳库显著大于内蒙古草原土壤碳库,海北站表层土壤（0-10cm）的有机质含量比内蒙古站的相应值高2倍左右。 高寒草甸土壤剖面有机质由快循环组分、慢循环组分和稳定组分组成;根生物量的垂直分布特征是0-60cm贮存的根生物量占整个剖面根生物量的90%左右。天然土壤的根系主要分布在表层,向下根系量显著减少;扰动土壤表层根系量较少,随深度增加缓慢减少。 高寒草甸土壤CO₂通量变化于73.3-181 gCm^-2a^-1之间,内蒙古典型草原土壤CO₂通量变化于390-866 gCm^-2a^-1（王庚辰等2004）,后者是前者的5倍左右。高寒草甸表层土壤产生的CO₂是土壤剖面CO₂通量的主要贡献者。土壤CO₂通量与海拔高度负相关。 土壤有机质的δ¹3C值随深度增加而增加。其剖面变化可分为快速增加、缓慢增加和增加很小或者有轻微波动变化3个阶段。内蒙古站土壤有机质的¹3C富集程度大于海北站的相应值。 植被类型制约土壤剖面的有机碳动力学过程。 土壤磁化率、根生物量在一定程度上可以反映土壤有机碳动力学过程。 在脆弱的草原地区,严禁过度放牧,加强土壤表层的保护,引种深根系植物,增加植被的地下生物量,实现有机物质向深部的转移,减少水土流失等是提高草原土壤碳汇能力的有效措施。更多还原

【Abstract】 High-resolution sampling, measurement and analysis of root content, organic matter content, ¹⁴C specific activity, δ¹³C and magnetic susceptibility of selected all 6 soil profiles in Haibei Research Station of Alpine Meadow Ecosystem in the Tibetan Plateau and Inner Mongolia Grassland Ecosystem Research Station, CAS, were made in an attempt to detect the soil organic carbon dynamics of grassland. The results as follows:The soil organic carbon storage in the alpine meadow in the Tibetan Plateau is pronounced larger than that in Inner Mongolia grassland ecosystem. Organic matter content of topsoil （0-10cm） in Haibei Station is two times higher than that of Inner Mongolia Station.Soil organic matter consists of fast component, slow component and passive component. The vertical distribution of soil root content is that root content（0⁶0cm） comprises some 90% of root content of total the profiles.The roots of the natural soils are mainly in the upper soil horizons and rapidly decrease with depth; there are less roots in the disturbed soils and gradually decrease with depth.The soil CO₂ flux ranges from 73.3 gC m^-2a^-1 to 181 gC m^-2a^-1 and 390 g m^-2a^-1 to 866 gC m^-2a^-1 （Wang gengchen et al 2004） for the alpine meadow and for Inner Mongolia typical grassland, respectively. The latter is about 5 times as high as the former. The CO₂ emitted from the surface soil comprises an important part for the soil CO₂ flux of the alpine meadow soil profiles.The soil CO₂ flux has negative correlation with elevation.δ¹³C values of soil organic matter increase with depth. Their vertical changes are divided into three segments: rapidly increase segment, gradually increase segment andless increase or slightly fluctuation variable segment. The extent of 13C enrichment of soil organic matter in Inner Mongolia Station is larger than that in Haibei Station.Vegetation types control the soil organic carbon dynamics.Soil organic carbon dynamics can be reflected to some extent by the soil quality magnetic susceptibility and root content.The powerful measures for increasing the capacity of soil reservoir in the flimsy grassland consist of forbiding overgrazing, not disturbing of the surface soil horizons, introducing of deep-rooted plants, and controlling the loss of water and soil.更多还原