中文摘要：

该文研究了南亚热带地带性植被7种主要优势种的根系形态,分析了根系生物量的空间分布和径级分配,初步验证提出的地下分层结构假设。结果表明：种间根系形态差异明显,乔木层优势树种有明显的主根和发达的侧根,林下层树种根系以须根为主。不同径级的根系生物量比例不同,细根（〈2 mm）最高比例达10.73%,粗根（〉20mm）比例在46.43%~81.26%之间,并且种类之间的差异明显。不同物种根系生物量在垂直土层中的分配比例不同。对测定的优势树种而言,该文提出的地下分层结构与地上冠层的分层结构并不完全一致,可能与其生态位宽度、种间相互作用、生境有密切关系。

英文摘要：

In the Dinghu Mountain Biosphere Reserve Station of the subtropical area of southern China,representative dominant tree root system was examined with regard to their morphological characters,underground stratification and biomass distribution.Excavation of skeleton roots was carried out for seven tree species.The results demonstrated： 1） root shape varied in different dominant tree species at different layers.Tree roots in high tree stratum were dominant by the apparent taproot with significant roots up and down from plagiotropic branches or tactic braches.Shrub species and undergrowth roots were characterized by the heart fibrous root type featured both by horizontally and transversally growing branches. 2） Proportion of contrasting diameter roots in all roots was different among species,in particular,fine roots（〈2 mm） reached 10.7%,and coarse roots（〉20 mm） reached 46.4%-81.2%.Furthermore,proportion of root biomass to total one was different in varied soil layers and among tree species.3） Underground dominant species was stratified according to the supraterraneous stratification method,which rarely kept pace with the aboveground stratification.The study demonstrates that root morphological character and distribution may closely interrelate to plant interaction and structure of aboveground vegetation,and therefore further study is needed to well understand niche breadth in the habitat.