模拟林冠损伤对藜蒴栲群落林下植被生物多样性的影响

以2008年冰雪灾害对森林生态系统的破坏为背景,通过人工去除林冠层保留树干模拟森林的机械损伤,研究粤北小坑流域藜蒴栲群落林下植被的变化.结果表明:(1)试验1.5年后,去除林冠层、林下添加枯枝落叶的处理,林下灌木、草本科、种及乔木幼苗种的数量显著增加(P＜0.05);去除林冠层且地表枯落物层保持不变的处理,林下草本科、种数量增加显著,乔木幼苗及灌木科、种差异不显著(P＞0.05);林下添加枯枝落叶,林冠层不做处理,林下植被各生活型物种数有所减少,但差异不显著.(2)去除林冠层后,一些阳生种如野桐、山乌桕、山苍子、红紫珠、蕨状苔草、广东蛇葡萄等大量入侵并占据优势地位,林下植被盖度显著提高.(3)去除林冠层在短期内可显著增加林下植被生物多样性,添加枯落物对林下植被生物多样性影响不显著.

Impact of Simulated Forest Canopy Damage on Understory Biodiversity of Natural Castanopsis fissa Community

According to the destruction of forest ecosystem caused by frozen rain and snow disaster in 2008, a simulation experiment of forest mechanical damage was carried out by trimming canopy layer of Castanopsis fissa natural forest at Xiaokeng Basin in northern Guangdong, and the change of understory vegetation was studied. The results are as follows: (1) 1.5 years after pretreatment, the family and species number of shrub, herb and the arbor seedling increased significantly (P<0.05) in the treatment plot of TD (trimming canopy + canopy detritus adding); the family and species number of herb increased obviously but the number of arbor seedling and shrub had no evidently change (P>0.05) in the treatment plot of TR (trimming canopy + removing canopy detritus); the family and species number of arbor seedlings, shrub and herb in the treatment plot of UD (untrimming + canopy detritus adding) decreased slightly. (2) The pioneer species such as Mallotus Lour., Sapium discolor, Litsea cubeba, Callicarpa rubella, Carex filicina, Setaria palmifolia and Ampelopsis cantoniensis became dominant species in the plots of TD and TR, and their coverage of understory vegetation increased significantly. (3) Forest canopy trimming can significantly increase the biodiversity of undergrowth in a short period whereas canopy detritus adding has no measurable impact on it.