太岳山典型阔叶乔木冠层叶片性状的分布格局

以太岳山4种阔叶乔木不同冠层高度的叶片为研究对象,用LI-3000A叶面积仪和Li-6400便携式光合作用测定系统分别测定了这4种乔木不同冠层高度叶片的叶面积大小和单位面积的叶光饱和速率(Aarea);同时测定了其叶氮含量;计算了其比叶面积(SLA)、单位面积叶氮含量(Narea)、单位重量叶氮含量(Nmass)、单位重量的叶光饱和速率(Amass)和光合氮素利用效率(PNUE),对植株不同冠层高度叶片的SLA、叶氮和光合特性的空间分布格局进行了比较研究,结果表明:Aarea、Amass、Nmass、PNUE、SLA和Narea在树冠上层、中层和下层的差异均达到了极显著水平(P<0.001),表明树冠不同高度的叶片性状参数差异较大;在相同SLA下,Nmass和Narea在冠层中的分布均表现为中层>上层>下层,并出现平行位移现象;Aarea和Nmass都以中层值最大,表明冠层光合能力分布格局以中层相对较高。

Distribution pattern of leaf traits in canopy of typical broad-leaved trees in Taiyue Mountain

Leaves of 4 different specie of broad-leaved trees were investigated at Qiliyu Farm in Taiyue Mountain of southern Shanxi Province.The leaf area was estimated with Li-3000A Leaf Area Meter,the saturated photosynthetic rate(Aarea)with Li-6400 portablephotosynthesis system.The nitrogen content was measured by spectrophotometric method;quantified correlations among SLA,leaf nitrogen content per unit area(Narea),leaf nitrogen content per unit mass(Nmass),net photosynthesis based on leaf mass(Amass)and photosynthetic nitrogen use efficiency(PNUE)were performed and the comparison of the distribution pattern of SLA,leaf nitrogen content and photosynthetic traits among different plant canopies showed that there were significant differences(P<0·001)among Aarea、Amass、Nmass、PNUE、SLA and Narea in top,middle and bottom layers.It also showed that there were significant differences of leaf traits parameters among the three canopies.Under the same SLA,Nmaaa and Narea of leaves in the canopy all declined in the sequence of middle layers>top layers>bottom layers.It was found that there was a strategy shift in the Nmass and Narea.The middle layers had the higher Aarea and Nmass than top slices and bottom slices,which showed that the middle layers had the highest leaf photosynthetic capacity.