长苞铁杉幼苗在林窗不同位置的建立

Seedling establishment of Tsuga longibracteata in different location of forest gap

通过2003年12月到2005年1月对福建省天宝岩国家级自然保护区长苞铁杉林内椭圆形林窗(面积118m2)中心、中部、边缘和林下样地进行种子埋藏及幼苗定位观测实验,研究了长苞铁杉幼苗在林窗不同位置中的建立。结果表明:在林窗内不同位置对长苞铁杉幼苗建立有显著影响。林窗中心样地、林窗中部样地、林窗边缘和林下样地内长苞铁杉幼苗发生率分别为10%,10.7%,6%和6%。从林冠下到林窗中心,长苞铁杉种子的幼苗发生率略有增高趋势。在林窗中心样地和林窗中部样地中雨水冲刷是幼苗死亡的最主要原因,而在林窗边缘样地和林下样地中昆虫的取食是幼苗死亡的最主要原因。林窗位置对幼苗的存活率有显著影响,林窗中部样地幼苗存活率最高(11.4%),林窗中心样地幼苗存活率次之(6.7%),而林窗边缘样地和林下样地幼苗则均全部死亡。种子营养消耗完后,在林窗中心、林窗中部、林窗边缘和林下等4个位置样地中,林窗中心样地幼苗平均高度最高。经过一个生长季后,林窗中心样地中幼苗的根生物量、茎生物量和总生物量均略高于林窗中部样地的幼苗,但差异并不显著。林窗中心样地幼苗叶生物量、叶重比、叶/地上等指标显著高于林窗中部样地的幼苗,而茎重比则低于林窗中部样地的幼苗。

The seedling establishment of Tsuga longibracteata in elliptical gap（area 118 m^2）center,middle,edge and under canopy of T.longibracteata forest were studied by seed burial experiments from December 2003 to January 2005 in Tianbaoyan National Nature Reserve of Fujian,China.The results showed that the difference of location in gaps had evident effects on the seedling establishment of T.longibracteata.In this researching gap,the seedling emergence rates of T.longibracteata in plots of gap center,gap middle,gap edge and under canpy were 10%,10.7%,6% and 6%.The seedling emergence rate showed ratherish increased trend from the canopy to the center of gap.Rain eroding was the main factor that induced the death of seedling in gap center plots and gap middle plots,but insects feeding was the main factor that induced the death of seedling in gap edge plots and under canopy plots.Location in gap had an evident effect on seedling survival.The seedling survival rate in gap middle plots was the highest（11.4%）,that in gap center plots was secondly high（6.7%）,and seedling in gap edge plots and under canopy plots died out after one growing season.The average height of seedling in gap center plots was the highest among the 4 kinds of gap location plots when seed nutrition expending.The root biomass,stem biomass and total biomass of seedling in gap center plots were ratherish higher than those of seedling in gap middle plots,but the difference was not evident.The leaf biomass,leaf total biomss ratio and leaf upground ratio of seedling in gap center plots were evidently higher,while stem total biomss ratio was lower than those of seedling in gap middle plots.