Regeneration processes and ecophysiological properties of young growths in the floor of natural forests of deciduous tree species and hiba arborvitae

木柴幼龄生长的光补偿点在4 ~ 6 μ mol量子m^<-2> s^<-1>范围内，与生长在同一林地上的其他木本树种相比，木柴幼龄生长的光补偿点并没有特别低，反而更高。除新叶展开季节外，两种树种幼龄间的光补偿点差异不大。而净光合作用的光饱和速率明显较高。由于季节到达林冠下的太阳辐射能明显较高，因此附着常绿叶片的Hiba arborvitae幼体在落叶乔木新叶出现前和落叶乔木落叶后两个季节进行了活跃的光合作用。落叶树水原栎的幼苗在整个生长季节都被上层树木的叶子严重遮蔽，导致日剩余产量低。从幼苗的反复普查来看，水原橡树在发芽后很难存活超过三到五年。而hiba babavitae的幼枝生长不会枯萎死亡，而是通过所谓的匍匐枝繁殖来增加其分布密度。在以落叶乔木为主的林冠下，杉木幼生种群的生长发育将由其特有的可利用资源提供。

Light compensation points of young growths of hiba arborvitae were in the range of 4 to 6 umol quanta m^<-2> s^<-1> : they do not have particularly lower compensation points but rather higher values compared with other woody species growing on the same forest floors. Between young growths of hiba arborvitae and mizunara oak there were no large differences in the light compensation point, except for the new leaf expansion season. However, light-saturated rates of net photosynthesis were obviously high in hiba arborvitae. Hiba arborvitae young growths, attaching evergreen leaves, performed active photosynthetic production in two seasons, before new foliage emergence and after foliage fall of the overstory deciduous trees, because of the significantly high solar radiant energy reaching under the forest canopy during the seasons. Seedlings of deciduous mizunara oak were heavily shaded throughout the growing season by foliage of the overstory trees, and it resulted in low daily surplus production. From the repeated census of the young growths it was apparently hard for mizunara oak to survive for more than three or five years after germination. In contrast the young growths of hiba arborvitae did not wither and die and their distribution density was rather increased by so called creeping branch propagation. Such growth and development of the hiba arborvitae young growth population would be provided by the resource availability peculiar to under the forest canopy dominated by deciduous trees.