陕南化龙山种子植物区系地理成分研究

THE STUDY ON GEOGRAPHIC ELEMENTS OFSPERMATOPHYTE FLORA IN HUALONG MOUNTAIN

化龙山种子植物区系的地理成分复杂，联系广泛，温带成分为主（有４２８属，占６０．６２％），热带成分次之（有２３５属，占３３．２８％），具有明显的暖温带向亚热带过渡特征。本区集中了丰富的中国特有成分及大量原始的温带属和众多的古老孑遗植物，是我国第三纪植物区系的重要“避难所”。区系地理成分的比较分析表明，化龙山应位于华中植物区系的边缘地带，很可能是东亚植物区系东西两大植物亚区的交汇地。

ualong Mountain is situated between the latitudes of 31°43′ and 32°18′N and the longitudes of 109°3′ and 109°36′E in southeastern Shaanxi Province. There are 1863 species of spermatophytes in Hualong Mountain, wich be long to 769 genera, 160 families. Among the genera in the flora of Hualong Mountain, 235 (33.28% i total genera) genera are tropical, 428 (60.62% in total) genera are temperate and 34 (4.82% in total) genera are endemic to China. From these figures it can be seen that the flora of Hualong Mountain have the distinct transitional characterisitics from warm temperate zone to subtropical zone. Hualong Mountain is very rich in endemic to China, and it is a part of eastern Sichuanwestern Hubei center. There are a number of endemic to China elments, primitive temperate genera a ancient relic plants in the area, this indicates that it might be an improtant refuge of tertiary flora of China. Comparative analysis of geographic elements showes that the flora of Hualong Mountain might be the border of the flora of central China and an intersection zone between SinoJapanese and SinoHimalayan flora patterns. To determine the floristic affinities of the area with others within China, nine mountain regions were selected. a comparison of the similarities among the ten mountain regions in China, based on the distribution of genera, shows that the floristic affinities of the Hualong Mountain are firstly with the Shenongjia region, the Jinfo Mountain and the Taibai Mountain, and secondly with the Fanjing Mountain, the Yulongxue Mountain and the Nanjiabawa Mountain.