中文摘要：

利用叶绿素荧光这一光合作用的敏感指针，对比研究了荆条灌丛下和对照裸地的栓皮栎（Quercusvariabilis）幼苗荧光参数在不同天气类型下的反映，同时也测定了栓皮栎幼苗的光曲线，得到了光饱和点和半饱和光强。结果表明，灌丛下与裸地的叶片Fu／Fm和Y（Ⅱ）、qL和qN、Y（NPQ）和Y（NO）等在晴天、多云、阴天下均有不同的反映，均表现出荆条灌丛的庇荫效应。结论：1）栓皮栎幼苗的光饱和点为1942μmol·m^-2·s^-1，半饱和光强为235μmol·m^-2·s^-1，显现出栓皮栎并不具有对强光的特殊耐受力；2）晴天中午时段裸地叶片有明显的光抑制，但这种光抑制处于可逆的范围；3）Fv／Fm等叶绿素荧光参数反映出灌丛下栓皮栎幼苗叶片的光合活性高、光保护能力强，光合状况优于对照，荆条灌丛对栓皮栎幼苗生长具有明显的保护效应。

英文摘要：

For the purpose of investigating the nurse effect of Vervain family to Quercus variabilis seed- lings, the paper analyzed the leaf chlorophyll fluorescence parameters of Q. variabilis seedlings planted in bare land and under vervain family on different weather conditions by using the photosynthetic sensitive pointer of chlorophyll fluorescence. It measured the light curve of Q. variabilis seedlings and determined light saturation point and half saturation light intensity, Ik. The results showed chlorophyll fluorescence parameters, Fv/Frn and Y （ Ⅱ ）, qL and qN , Y（NPQ） and Y（NO）, of Q. variabilis seedlings planted in bare land and under vervain family on different weather conditions all had different reactions, but all the reactions expressed the nurse effect of vervain family. Conclusion. 1） the light saturation point of Q. variabilis seedlings was 1 942 μmol·m^-2·s^-1 , the half saturation light intensity was 235 μmol·m^-2·s^-1 , indicating Q. variabilis seedlings didn＇t have special tolerance to intensive light. 2） There were clearly light inhibitions on clear days during noon hours for the Q. variabilis seedlings on bare lands, but the light inhibitions were reversible. 3） The Q. variabilis seedlings planted under vervain family had high photosynthetic activity, intensive light protection ability, and better light environments than planting on bare lands, which could be showed through chlorophyll fluorescence parameters, Fv/Fm and Y（ Ⅱ ）. There was significant nurse effect of vervain family to Q. variabilis seedlings.