中文摘要：

南方红豆杉为国家Ⅰ级重点保护植物,山西省东南部为其自然分布最北界.本文调查了南方红豆杉在山西省的野生分布,对其进行了群落划分、物种多样性、结构特征和竞争特性的研究.结果表明：山西省南方红豆杉主要形成南方红豆杉＋鹅耳枥群落、南方红豆杉-荆条群落、南方红豆杉-海州常山群落和南方红豆杉＋栓皮栎群落,集中分布于陵川县磨河和阳城县蟒河自然保护区,其他地区均为散生;群落垂直结构明显,南方红豆杉已进入主林层,混交林林冠层高8-10 m,纯林高5-6 m;群落间的总体物种多样性指数和均匀度指数存在显著差异.南方红豆杉植株矮小,平均高5.16 m,乔木层、演替层分别占43.4%和56.6%,更新层缺乏;胸径〈16 cm的个体占67.6%,胸径32-40 cm的个体占4.0%,幼苗稀少,仅发现4株幼苗;大量的小径级个体虽可保证南方红豆杉在一定时间内维持稳定的种群结构,但幼苗缺失必将引起未来种群的衰退.山西省野生南方红豆杉分布相对集中,多数是小径级个体,导致其种内竞争激烈,种内竞争强度占61.8%;鹅耳枥和栓皮栎是研究地区的主要组成树种,对南方红豆杉造成的种间竞争压力最大.

英文摘要：

Taxus chinensis var. mairei is a national Category Ⅰ protective species in China,with its northernmost natural distribution to the southeast of Shanxi Province,China. This study was conducted to investigate the natural distribution of T. chinensis var. mairei in Shanxi Province. The community classification,species diversity,population structure and competition intensity of T. chinensis var. mairei were studied. The results showed that T. chinensis var. mairei mainly formed four community types,including the community of T. chinensis var. mairei ＋ Carpinus turczaninowii,the community of T. chinensis var. mairei- Vitex negundo var. heterophylla,the community T. chinensis var. mairei- Clerodendrum trichotomum and the community of T. chinensis var. mairei ＋ Quercus variabilis. T. chinensis var. mairei was concentratedly distributed in Mohe of Linchuan County and Manghe Nature Reserve of Yangcheng County,and scattered in some other areas. The communities had an obviously vertical structure,with T. chinensis var. mairei trees growing into main canopy which were about 8-10 m high in mixed forests and 5-6 m high in pure forests. The species diversity index and evenness index had significant difference among the four community types. The average height of T. chinensis var. mairei was 5.16 m. The individuals in tree layer and succession layer were43.4% and 56. 6%,respectively,while they were scarce in the regeneration layer. 67. 6% of the trees were small-diameter（ DBH16 cm） and only 4. 0% were large-diameter（ 32 cm≤DBH 40cm）. T. chinensis var. mairei was considered to be lack of seedlings because only 4 seedlings were found,which might result in the declination of this species in future. T. chinensis var. mairei inShanxi Province showed relatively concentrated distribution,with most individuals being smalldiameter,resulting in tense intraspecific competition which accounted for 61.8% of the total intensity. The interspecific competition to T. chinensis var. mairei was mainly from C. turczaninowii and Q. v