青藏高原东缘亚高山针叶林碳氮磷生态化学计量特征

Stoichiometry of Carbon,Nitrogen,and Phosphorus of Subalpine Coniferous Forests on the Eastern Edge of Qinghai-Tibet Plateau

为深入理解针叶林生态系统植物叶片和土壤碳(C)、氮(N)、磷(P)生态化学计量特征及其内在相互关系,该研究以青藏高原东缘亚高山岷江冷杉(Abies faxoniana)林(针叶林Ⅰ)、云杉(Picea asperata)林(针叶林Ⅱ)、油松(Pinus tabuliformis)林(针叶林Ⅲ)为研究对象,测定了3种林分针叶、灌木、草本和土壤的碳、氮、磷含量及其比值。结果表明:(1)3种针叶林植物叶片C、N含量表现为草叶>针叶>灌叶>土壤;C∶N、C∶P、N∶P表现为灌叶最高、针叶和草叶次之,土壤最低。其中C、N、P含量均表现为云杉林>冷杉林>油松林;同一针叶林不同组分C、N、P含量均表现为草叶>针叶>灌叶。(2)不同针叶林C∶N和C∶P均表现出油松林>冷杉林>云杉林,而叶片C∶N、C∶P均表现为灌叶>针叶>草叶。(3)针叶林植物叶片N与P含量呈显著正相关关系,针叶与灌叶的C含量、针叶-灌叶-草叶之间的N、P含量以及C∶N、C∶P均呈显著正相关关系;针叶的C含量与其自身的N、P含量呈极显著负相关关系,针叶与土壤TP和N∶P、灌叶与土壤TP含量、草叶与土壤N∶P均呈显著负相关关系,体现了营养元素在针叶林针叶、灌叶、草叶和土壤之间的相互循环和转移。研究认为,青藏高原东缘亚高山针叶林植物生长受N限制,该区域土壤有机质的矿化作用较慢,在针叶林的保护和经营过程中,要加大对林下植被的保护,提高土壤肥力,从而达到维护森林长期生产力的作用。

To further understand the ecological stoichiometric characteristics of coniferous forest ecosystem plants and soli carbon,nitrogen,phosphorus and their internal relationships,we selected Pinus tabuliformis,Picea asperata,Abies faxoniana coniferous forest in subalpine areas on the eastern edge of Qinghai-Tibet plateau.We analyzed the carbon,nitrogen,phosphorus stoichiometric characteristics in needle,shrub,herb leaf and soil in each coniferous forest.The results indicated that:(1)C,N contents followed herb leaf>needle leaf>shrub leaf>soil.C∶N,C∶P and N∶P were the highest in shrub leaf,followed by needle and herb leaf,and the lowest in soil.There was a significantly positive correlation between the content of N and P in coniferous forest,the content of C was negatively correlated with the contents of N and P.And C content between needle and shrub leaf,N,P content,C∶N,C∶P in leaves also showed a significantly positive correlation.There was a significantly negative correlation between needle leaf and soil P,N∶P,shrub leaf and soil P,herb leaf and soil N∶P.(2)Our results demonstrated that the contents of C,N and P in the subalpine coniferous forest ecosystem were ranked in the order of P.asperata forest>A.faxoniana forest>P.tabuliformis forest.(3)The contents of C,N and P of different components were followed the order of herb leaf>needle leaf>shrub leaf.C∶N and C∶P all showed P.tabuliformis forest>A.faxoniana forest>P.asperata forest,and C∶N and C∶P showed shrub leaf>needle leaf>herb leaf.Plant growth is limited by N,and mineralization of soil organic matter was slow.Therefore,in the process of coniferous forest protection and management,we suggested to increase the protection of undergrowth and improve soil fertility,so as to maintain the long-term productivity of forests.