典型榆树疏林碳氮储量及其分配特征

Stock and allocation of carbon and nitrogen in typical Ulmus pumila dominated savanna in Inner Mongolia,China

榆树疏林是科尔沁沙地和浑善达克沙地植被演替的顶级群落。以退耕还林后天然恢复的科尔沁沙地榆树疏林和无破坏的浑善达克沙地榆树疏林为研究对象,运用样方调查法、生物量估算法及相关的数理统计方法,比较分析2种典型榆树疏林碳氮储量及其分配特征。结果表明:1)除土壤无机碳储量外,浑善达克沙地榆树疏林各组分的碳氮储量均显著高于科尔沁沙地榆树疏林,其中总的碳氮储量分别为科尔沁沙地榆树疏林的1.97和1.82倍;2)2种榆树疏林碳氮分配特征相似,最大贡献者均为土壤,其所占比例相应地均超过了55%和80%,而最小贡献者则均为枯落物;3)与浑善达克沙地榆树疏林相比,退耕还林后的科尔沁沙地榆树疏林可能具有更大的碳汇潜力和固氮功能。

Ulmus pumila is widely distributed on the fixed sand dune in Horqin and Hunshandake sandy lands,Inner Mongolia. U. pumila-dominated savanna is the climax community of vegetation succession in these regions. Taking the typical U. pumila-dominated savanna（ ＂the savanna ＂ hereinafter） in Horqin sandy land after the＂grain for green＂project and Hunshandake sandy land without disturbance as the research objects,the present study compared the stock and allocation patterns of carbon（ C） and nitrogen（ N） of the savanna in the two sandy lands by plot-level inventories,biomass estimation and the mathematical statistic methods. The results show that： 1） Except soil inorganic C stock,the C and N stocks in the total ecosystem and its different components in the savanna of Hunshandake sandy land were all significantly higher than those of the corresponding components in the same type of savanna of Horqin sandy land. The total ecosystem C and N stocks in the savanna of Hunshandake sandy land were 1. 97 times and 1. 82 times,respectively,as much as that of Horqin sandy land. 2） The C and N allocation patterns of the two savannas were similar. The soil was the largest contributor to the total ecosystem C and N stocks,and the corresponding portions were more than 55% and 80%,respectively,in both savannas.On the contrary,the forest floor contributed little to the total ecosystem C and N stocks in both savannas.3） Compared with the savanna of Hunshandake sandy land,that of Horqin sandy land may have greater carbon and nitrogen sequestration potential.