辽东山区紫椴、花曲柳碳素积累及主要营养元素分布特征1）

以辽东山区天然阔叶混交林重要组成树种紫椴和花曲柳为研究对象，通过生物量实测法，探究紫椴和花曲柳的碳素积累的变化特征以及不同器官氮（N）、磷（P）、钾（K）元素的分配格局。结果表明：花曲柳树干的平均固碳量和连年固碳量整体上高于紫椴，随林龄的增长差距有逐渐增大的趋势；40年生花曲柳树干平均碳素密度为322．18 kg· m－3，36年生紫椴为272．63 kg· m－3。在养分分配方面，紫椴和花曲柳单株N、P、K元素的积累量顺序一致（N＞K＞P），但在不同器官中各元素积累顺序有些差异。紫椴各器官养分积累总量顺序为：树干＞树根＞树枝＞树叶；花曲柳各器官养分积累总量顺序为：树根＞树干＞树枝＞树叶。紫椴与花曲柳树叶的养分归还量占各自总体的比例分别为4．11％和17．32％，而树叶、树枝与根的养分积累比重合计分别为57．07％和75．31％，三者在生态系统养分循环中占有重要作用。

Carbon Accumulation and Distribution of Main Nutrient Elements of Fraxinus rhynchophylla and Tilia amurensis in the Mountainous Region of Eastern Liaoning Province,China

Based on the biomass data of Fraxinus rhyncoh phylla and Tilia amurensis in broad-leaf mixed forest in the mountain-ous region of eastern Liaoning Province , we studied the features of carbon accumulation and nutrient distribution ( N, P, K) in organs of these two species .The average stem carbon sequestration and the annual stem carbon sequestration of F. rhynchophylla were both higher than those of T.amurensis,and there were a gradually increasing gap of the average stem carbon sequestration and the annual stem carbon sequestration between two species during the growing age .Average stem carbon density of 40-year F.rhny chohp ylla was 322.18 kg· m-3, and that of 36-year-old T.amurensis was 272.63 kg· m-3 .Nutrients accumulation descending order of two species was N , K, and P , but there were some variations of nutrients accumulation order in different organs of two species .The total accumulation of N , P and K between organs of T.amurensis was decreased as follows: stem, root, branch, and leaf, and those of F.rhynchophylla were listed in descending order of root, stem, branch, and leaf.The proportions of nutrients accumulation in leaves annually released to soil by F.rhyncho-phylla and T.amurenis s accounted for 4.11%and 17.32%, respectively .Total proportions of nutrients accumulation in leaves, branches and roots of two species were 57.07%and 75.31%, respectively.