长苞铁杉天然更新研究Ⅱ.不同群落的幼苗建立及其环境影响

Natural regeneration of Tsuga longibracteata Ⅱ.Seedling establishment of different type communities and environmental impacts

采用野外定位观测、群落调查方法,从不同群落类型长苞铁杉幼苗样地的建立及其环境影响对福建天宝岩国家级自然保护区内分布的长苞铁杉天然更新进行研究。结果表明,群落类型对长苞铁杉幼苗建立有显著影响。2004、2005年,长苞铁杉种子在不同群落中的萌发率均存在显著差别,在同一群落中,不同年度的萌发率也存在显著差别。在长苞铁杉幼苗发生方面,光照状况不对幼苗发生起主要作用,在不同的气候背景下,光照强度对幼苗发生的影响也有所不同;较厚的凋落物层有一定的保水保温作用,可以促进长苞铁杉幼苗的发生。2004、2005年长苞铁杉幼苗存活率在毛竹林样地内最高(分别为70.5%和82.5%),在长苞铁杉毛竹混交林样地内次之(分别为22.6%和32.0%),而在相对光照强度较低的长苞铁杉阔叶树混交林、长苞铁杉猴头杜鹃混交林和长苞铁杉纯林样地内的均全部死亡。光照是长苞铁杉幼苗存活的限制因子,长苞铁杉幼苗的生长与存活需要较强的相对光照强度;较厚的凋落物层不利于长苞铁杉幼苗的存活与生长。

The seedling establishment in different type communities and environmental impacts of Tsuga longibracteata were studied by field observation and community investigation in this paper.Results showed that,seeds of T.longibracteata were sown in 5 types of communities to investigate the growth and survival of their seedlings.In 2004 and 2005,the seedling emergence rate showed evident difference in five types of community plots.The seedling emergence rate of the same community plot also showed evident difference in different years.Light intensity was not the primary limitative factor of seedling emergence.The effects of light intensity on seedling emergence rate were different under different climatic background.The thicker litter layer increased seedling emergence rate through preserving soil water and higher temperature.The seedling survival rates in Phyllostachys heterocycla forest were the highest（70.5% in 2004 and 82.5% in 2005）,those of Tsuga longibracteata and P.heterocycla mixed forest were secondly high（22.6% in 2004 and 32.0% in 2005） after one growing season.The seedlings in low light intensity communities such as T.longibracteata and broadleaf mixed forest,T.longibracteata and Rhododendron simiarum mixed forest,and T.longibracteata pure forest died out.Light intensity was the primary limitative factor of seedling survival and growth.The thick litter layer did harm to seedling survival and growth.