秦岭种子植物区系中的热带地理成分研究

对秦岭种子植物区系中的热带地理成分进行了研究，本区的热带地理成分共包括泛热带成分，热带亚洲和热带美洲间断成分，旧世界热带成分，热带亚洲至热带大洋洲成分，热带亚洲至热带非洲成分及热带亚洲成份等6种类型，共283属，648种，属数和种数分别占秦岭种子植物总属数及总种数的30．27％，18．80％，它们是秦岭植物区系组成的一个重要方面，在各类地理成分中，秦岭植物区系与泛热带成分联系最为密切，从热带地理成分的类型，分布以及在秦岭植被组成中的作用来分析，本区植物区系具有明显的温带性质，热带区系成分仅处于从属地位，多分布于低海拔地段或秦岭南坡，但本区植物区系的起源则带有强烈的热带渊源，而各类热带成分内部均有一定数量的属或分布至亚热带，或分布到北温带，又从一个侧面反映了秦植物区系的过渡性特点。

The analysis on the tropical geographical elements of the seed plant flora in the Qinling Mt.

The tropical geographical elements of the flora about of the seed plant in the Qinling Mt.is studied in this paper.The tropical geographical elements in this area belong to 6 categories,such as Pantropic,Tropical America and tropical Asia disjuncted,Old World tropics,Tropical Asia to tropical Australasia,Tropical Asia to tropical Africa and Tropical Asia (Indo Malesia) ect.There are 283 genera,648 species in Qinling Mt.,They make up 30.27 per cent of the total genera and 18.80 per cent of the total species.The dominant element of the tropical geographical composition is the Pantropic and there are 125 genera in this mountain.It makes up 44.17 per cent of all tropical elements.From the quantity component,geographical distribution,characteristics and the phytocoenology function of the tropical geographical elements,the nature of the flora in Qinling Mt.is temperate.The tropical geographical elements are only on the subordinate status,and they distribute in low elevation sector or on the southern side of Qinling Mt.,Some genera of the tropical elements distribute in subtropical,some in the north temperate.This phenomenon shows the transition of the geographical elements of the flora is very obvious.But the origin of the flora in Qinling Mt.has the clear tropical nature.