那曲县主要草地类型土壤有机碳特征分析

摘要

[Objective] The present paper aimed to analyze the features of spatial and temporal change in the content of soil organic carbon in main grassland types in northern Tibetan grassland.[Method] Sampling on three different.grassland types in Naqu county for two consecutive years three times a year,their soil organic carbon content,vertical distribution characteristics,annual and inter annual variation law were analyzed with random distributed points method.[Result] The soil organic carbon content of each soil layer was in the order of:Kobresia pygmaea meadow ＞ Stipa purpurea grassland ＞ Carex moocrofiii grassland.There were no significant differences in Stipa purpurea grassland soil organic carbon contents among different soil layers;Carex moocroftii grassland soil organic carbon content in 0-5 cm soil layer was the lowest,which had significant difference with other layers(P ＜ 0.05),and there were no significant differences among (5-10,10-15,15-20,20-25 cm) soil layers.Kobresia pygmaea meadow soil organic carbon,soil organic carbon content in 0-5 cm soil layer had extremely significant difference with other layers(P ＜0.01),and the soil layers(5-10,10-15,15-20,20-25 cm) had no significant difference with their adjacent layers,the organic carbon content of the annual range of 15-20 and 20-25 cm soil layers in Carex moocrofiii grassland had significant differences.Different soil layers of different grassland types had no significant difference in the annual variation of organic carbon content.[Conclusion] Under some special circumstances,as a result of originally low content of soil organic carbon,there is significant difference in change of content of soil organic carbon in plants between different growth stages in the same growth cycle whereas there is comparative stability in that among different growth cycle.%[目的]本文研究了藏北草原主要草地类型土壤有机碳含量的时空变化特征.[方法]按照随机布点方式对那曲县3种不同草地类型连续2年、每年3次进行采样,分析其土壤有机碳含量、垂直分布特征、年度及年际变化规律.[结果]土壤有机碳在各土层的含量均为高山嵩草草甸＞紫花针茅草地＞青藏苔草草地.青藏苔草草地土壤有机碳含量在各土层间无显著差异;紫花针茅草地土壤有机碳含量在0～5 cm土层最低,与其余各层土壤有机碳含量有显著差异(P＜0.05),在(5～10,10 ～15,15～ 20,20～25 cm)土层间不存在显著差异;高山嵩草草甸土壤有机碳,0～5 cm土层有机碳含量与其余土层具有极显著差异(P＜0.01),(5～10,10～15,15～ 20,20～ 25 cm)各土层与相邻土层间无显著差异,与其余土层有极显著差异(P＜0.01).青藏苔草草地在(15～20,20～25 cm)土层中有机碳含量年度范围内有显著差异(P＜0.05).各草地类型不同土层中有机碳含量的年际变化均无显著差异.[结论]在某些特殊气候条件下,由于土壤有机碳含量本来就很低,在植物的同一生长周期内的不同生长阶段间土壤有机碳含量变化会出现显著差异,但是在不同生长周期间土壤有机碳含量又能保持相对稳定.