秦岭火地塘林区锐齿栎群落中6种植物光合特性研究

用Li-6400便携式光合测定系统测定了火地塘林区主要成林树种锐齿栎群落中6种植物的光合特性。结果表明：（1）从林冠层到草本层,光合有效辐射强度明显减弱,并且乔木层、灌木层和草本层之间的差异均达到了显著水平（P〈0．05）;（2）乔木层锐齿栎的光合速率日变化为“双峰”曲线,表现出明显的“午休”现象,而林下植物灌木层和草本层光合速率日变化整体上呈“单峰”曲线,无“午休”现象;（3）光饱和点和光补偿点均表现为乔木〉灌木〉草本。表明植物光合“午休”现象是由中午高光强、高气温和低湿度引起的。并非某些植物的特性．植物的光合特性与其生境特点相符。

Photosynthetic Characteristics of Six Plant Species in Quercus aliena var. acuteserrata Community at Huoditang Forest Region of Qinling Mountains

With Li-6400 portable photosynthesis system,the photosynthetic characteristics of six plants species in the communities of forest-formed Quercus aliena var.acuteserrata in Huoditang Forest Region,were investigated.It was shown that(1) in the community,the photosynthetic active radiation decreased from canopy to herbaceous layer and differed among the arbor,shrub and herbaceous layers(P<0.05);(2) In the arbor layer,the photosynthetic rate of Quercus aliena var.acuteserrata varied in a "double-peak" curve with clear "midday depression" and in the shrub and herbaceous layers the photosynthetic rates of the understorey plants appeared to vary in a single-peak curve without "midday depression";(3) The light saturation points and light compensation points appeared to follow the pattern of arbors>shrubs>herbs.These indicate that "midday depression" in photosynthesis results from strong sunlight,high temperature and low humidity rather than some plant characteristics and photosynthetic characteristics of plants correspond with their environment.