【摘要】 对青藏高原海北站区的自然土壤和扰动土壤进行高分辨率采样,测定土壤根系、有机碳及其14C含量;用14C示踪技术探讨土地利用变化对高寒草甸土壤有机质更新的影响.研究表明,土地利用变化对高寒草甸土壤碳循环影响显著.耕作活动导致扰动土壤有机碳储量比自然土壤增加29.35%;扰动土壤剖面10~50 cm深土壤有机质的14C含量相对富集;自然土壤大多数有机碳储存在土壤表层,更新时间<50 a,同一深度扰动土壤有机碳储量显著少,更新时间长(171~294 a);自然土壤10 cm以下有机碳主要为更新时间>1 000 a的稳定碳所控制,扰动土壤的相应值出现在40 cm以下;自然土壤有机质更新产生的CO2通量为114 gC.m-2.a-1,扰动土壤为48.7 gC.m-2.a-1.更多还原

【Abstract】 High-resolution sampling,measurements of root contents,organic carbon contents and 14C contents,and 14C tracing of the selected disturbed and undisturbed soils in the Haibei Prefecture were made,in order to investigate the effects of land use change on soil organic matter turnover of alpine meadow in the Tibetan Plateau.The results demonstrated that land use change has significant impact on soil C cycle.The increase in soil organic carbon storage is about 29.35% for the disturbed soil after 25-year cultivation;the 14C contents of organic matter in the upper soil horizons of the disturbed soil are lower than those of the undisturbed counterparts.However,organic matter in subsoil horizons(from10 to 50 cm) is relatively enriched in 14C in the disturbed soil.In the undisturbed soil,most of the organic carbon in the surface is resident in "active" C pool with a turnover time of less than 50 years.In the disturbed soil,turnover time significantly increases(to 171-294 a),as compared to its undisturbed counterparts.At deeper depths(below 10 cm in the undisturbed soil,and below 40 cm in the disturbed soil),the organic carbon is dominated by passive C pool with a turnover time greater than 1000 years.The CO2 flux due to organic matter turnover of the soil is 48.7 gC·m-2·a-1 for the disturbed soil and 114 gC·m-2·a-1 for the undisturbed soil.更多还原