塞罕坝森林－草原交错带植物区系地理的研究

STUDY ON THE CHARACTERS OF FLORISTIC GEOGRA-PHY OF SAIHANBA FOREST-STEPPE ECOTONE

塞罕坝植物区系中，以北温带科或广布全球但以（北）温带为分布中心的科为主；属划归５类１４种地理成分，温带成分占８８．４３％，热带成分占７．４４％，泛地中海成分占３．３１％，中国特有成分仅占０．８３％；与同纬度或近纬度地区相比，本区系热带科、属贫乏；本区系具有典型的北温带性质：温带或北温带科属为主；世界广布成分相对较多；特有现象不明显，间断分布错综复杂。

There exist 295 genera and 81 families of vascular plants in Saihanba forest- steppe ecotone。 Most of the families belong to temperate nature in geographical distribution。According to the geographical range of plants at mordern times, the 295 genera of vascular plants can be classified into 14 forms in 5 categories of geographical elements,among which 88.43% belongs to the temperate genus,7.44% is of tropical or subtropical element,3.31 % belongs to the ectensive Mediterranean element and 0.83% belongs to Chinese peculiar genus。Compared with the floras of other regions locating at the same latitude in China, the tropical elementboth in family and genus is short in the present area。 All of these characters indicate the temprate nature of Saihanba ecotone flora。