翅果油树叶性特征的动态变化

以山西翼城翅果油树(Elaeagnus mollis)自然保护区的翅果油树为研究对象,利用LI-3000A叶面积测定仪测量其单叶面积,用Li-6400便携式光合作用测定系统测定单位叶面积饱和光合速率(Aaraa),用H2SO4-H2O2消煮法测定叶氮含量,计算叶性参数比叶面积(SLA)、单位叶重量饱和光合速率(Amass)、光合氮利用率(PNUE)和单位重量叶氮含量(Nmass)的值,并研究它们与径级之间的关系.结果表明:随着翅果油树径级的增加,SLA、Nmass、Aarea、Amass和PNUE值先下降后上升,当翅果油树径级为7.5 cm左右时,SLA、Nmass、Aarea、Amass和PNUE值均降到最小值,表明径级为7.5 cm左右的翅果油树其光合能力最弱、光合氮利用率较低且生存压力较大.翅果油树叶性参数是研究翅果油树种群动态变化的有效指标,可为研究翅果油树种群动态提供更为便捷的方法.

Dynamic Changes of Traits of Leaves from Elaeagnus mollis

We investigated leaf traits of Elaeagnus mollis in the Elaeagnus mollis Nature Reserve of Yicheng County, Shanxi Province. Leaf areas were estimated with use of a Li-3000A Leaf Area Meter, and the maximum photosynthetic rate per unit area （Aarea） was measured by Li-6400 portable photosynthesis system. N content was measured by the H2SO4-H202 method. We also calculated the SLA, the maximum photosynthetic rate per unit mass （Amass）, photosynthetic N use efficiency （PNUE） and leaf N content per unit mass （Nrnass）. AS well, we analyzed the interaction between them and size classes. With increasing size of E. mollis, SLA, Aa~a, Nr, ass and PNUE decreased and then increased. With size of about 7.5 cm, SLA, Aarea, Nrnass and PNUE reached the minimum value, so the photosynthetic capacity and PNUE were comparatively low under this condition, and the survival pressure became greater. Leaf trait variables of E. mollis are effective targets to study population dynamics changes and are convenient for study.