甘南白龙江2种次生林不同器官C、N、P、K计量特征

Stoichiometric Characteristics of C,N,P,and K in Different Organs of Two Secondary Forests in Bailongjiang,Gannan

为明确甘南白龙江2种次生林各器官C、N、P、K生态化学计量特征,掌握养分元素在不同次生林分配格局及各器官养分受限状况等情况,对该地区红桦和辽东栎2种主要次生林各器官(根、主干、各级枝、叶片)进行取样,分析其含水率、C、N、P和K含量以及各元素之间化学计量特征,结果表明:1)2种次生林叶片含水率最大,红桦各器官含水率在34.09%~59.01%,从大到小依次为叶片>一级枝>根>二级枝>三级枝,辽东栎各器官含水率在33.98%~52.66%,叶片>根>一级枝>二级枝>三级枝>四级枝,叶片含水率均最高,其次为根,枝级越高含水率越小。2)2种次生林叶片的C、N、P、K含量最高。辽东栎C含量在387.19~529.64 g·kg^(-1),叶片C含量最高,其他各器官含量相差不大,C属于弱变异。N含量在5.03~19.54 g·kg^(-1),从大到小依次是叶片>三级枝>四级枝>根>二级枝>一级枝>主干。叶片P和K含量也是最高,除根的K含量以外,其他器官都表现出2种元素含量从形态学的下端到上端依次增加。N与K含量呈显著性相关,P变异系数较大,属于强变异。红桦C、P和K变化一致,除根以外,从主干到叶片3种元素含量依次增加,P含量从根到叶片依次增加,C变异系数最小属于弱变异,K含量属于强变异。3)2种次生林叶片的C∶N、C∶P、C∶K和P∶K最小,N∶P最大。红桦叶片的N∶K也是最小,C∶N与N∶K呈显著性负相关,C∶P与N∶P以及C∶K与N∶K呈显著性正相关。辽东栎的N∶K除叶片,从根到四级枝依次减小,C∶P与N∶P呈显著性正相关,C∶K与N∶K和P∶K也呈显著性正相关。由此可见,甘南白龙江2种次生林各器官营养元素含量与相应器官的功能结构密切相关。

The objectives of this study were to clarify the ecochemical characteristics of carbon(C),nitrogen(N),phosphorus(P)and potassium(K)in the organs of the two secondary forests(Betula albosinensis and Quercus wutaishanica)occurring in the reaches of the Bailongjiang River in Gannan,and to master the distribution pattern of nutrient elements in different secondary forests and the nutrient limitation status of each organ.Samples were collected from different organs(root,trunk,branch and leaf)of the two species.The contents of water,organic C,total N,total P,and total K were measured.The stoichiometric characteristics of each element was analyzed.The results showed that 1)among different organs of the two species,the highest moisture content was found in the leaf.The moisture contents in different organs of B.albosinensis ranged from 34.09%to 59.01%and with the order of leaf>primary branch>secondary branch>tertiary branch;for Q.wutaishanica,the order was leaf>root>primary branch>secondary branch>tertiary branch>fourth branch,ranged from 33.98%to 52.66%.2)The contents of C,N,P,and K in the leaves of two species were the highest.The content of organic C in Q.wutaishanica was between 387.19-529.64 g·kg^(-1).The content of organic C in the leaf was the highest,there was no significant difference in carbon content among other organs,carbon belonged to weak variation.The content of total N was between 5.03-19.54 g·kg^(-1) with the order of leaf>tertiary branch>tertiary branch>root>secondary branch>primary branch>trunk.The contents of total P and K in the leaf were also the highest.Except for total K in root,the contents of K and P increased from the lower end to the upper end of the morphology.There existed a significant correlation between total N and total K contents,and the coefficient of variation of total P was large,P belonged to strong variation.The variations of C,P,and K in B.albosinensis were in the same trends,except for the root,the contents of the three elements increased from the trunk to the leaf,while the content of P increased from the root to the leaf.Carbon belonged to weak variation,and the total potassium belonged to strong variation.3)In the leaves of the two species,the ratios of C∶N,C∶P,C∶K and P∶K were the smallest,and the and N∶P was the largest.The ratio of N∶K of B.albosinensis leaf was also the smallest,the ratios of C∶N and N∶K were significantly and negatively correlated,significant correlations were found between the ratios of C∶P and N∶P,as well as C∶K and N∶K.Except for the leaf,the ratio of N∶K of Q.wutaishanica decreased from root to quaternary branch,the ratios of C∶P and N∶P were significantly and positively correlated,C∶K was also significantly and positively related to N∶K and P∶K.It can be seen that the contents of nutrient elements in the organs of the two secondary forests in the reaches of the Bailong River in Gannan are closely related to the functional structure of the corresponding organs.