肃北地区裸果木荒漠群落构成特征及物种多样性研究

A study on species diversity of a Gymnocarpos przewalskii community in the Subei desert

于２００６－２００８年对稀有植物裸果木在甘肃肃北的分布情况及其群落特征进行了调查研究，结果表明，在肃北北山地区裸果木主要分布在海拔１５００～１６００ｍ，在南山地区主要分布在海拔１９００～２７８０ｍ，均分布于山前冲积扇、沙砾质戈壁和干河床地带。裸果木荒漠群落物种组成共计４４种，隶属１３科，３１属，植物区系以古地中海、西亚至中亚分布型为主，约占５４．８％。植物区系与古地中海植物区系有密切的联系。其次是北温带分布型，约占１９．４％，裸果木分布区与北温带分布型植物区系联系紧密。第３是世界分布种，约占９．７％。群落的多样性指数均较高。但其高度和盖度较低，裸果木中老龄植株较多，而幼龄植株很少。种群有衰退趋势。

During 2006-- 2008, a type of rare plant in the north stribution and community characteristics of Gymnocarpos przewalskii which is of Subei were investigated. G. przewalskii is mainly distributed on Piedmont alluvial fan, gravel and dry river bed areas at altitudes of 1 500--1 600 m in the northern mountainous area of Subei and 1 900--2 780 m in the southern mountainous area of Subei. Species composition of G. przewalskii plant communities consist of 44 species that belong to 31 genera 13 families. Among them, the gravelly desert distribution elements are in the ancient Mediterranean and West Asia to Central Asia （54.8o//oo）. There is close relationship between the floras of G. przewalskii desert communities and those of the ancient Mediterranean. The North temperate distribution pattern takes second place （19.4%）. Distribution of G. przewalskii has a strong relationship with floras in North temperate distribution patterns. World distribution of the species is 9.7 ~//00. The diversity indexes of the floras are all high, but physical height and cover of floras are low. The number of old plants is more than that of young plants, which implies that the whole floras show a trend of recession.