关键词: 裸子植物, 丰富度, 特有性, 多样性中心, 种系分化

Abstract

China has the richest flora of gymnosperm in the world, which is crucial for understanding the change of global distribution and phylogeny of gymnosperm. We mapped the geographical range of 202 native gymnosperm species in China with records of altitudinal range and horizontal distribution at the county level, and explored the spatial distribution characteristics of Chinese gymnosperm at the family, genus and species levels. The uniqueness and similarity among the richness centers were analyzed with respect to their gymnosperm family and genus composition, and the endemism. Generally, Chinese gymnosperm shows a decreasing trend of richness from south to north. The richness is high in mountainous areas and low in large plains and on large plateaus. From the species, genus to family levels, the area with high gymnosperm richness increases, and the center with high richness shifts southward. About 85% of all Chinese gymnosperm species are harbored in just 5% of Chinese land area. We classified these regions into six richness centers: (1) Eastern Himalaya-Hengduan Mountains-Qinling Mountains; (2) joint area of Yunnan-Guizhou-Guangxi and the South Mountain Ranges; (3) central China mountains; (4) Huangshan-Wuyi Mountains; (5) southern mountains of Hainan Island; and (6) central part of Changbai Mountains. The floristic relationship of gymnosperm among the centers is obviously related with their geographic location, and the effect of isolation by distance. Among the six centers, Hengduan Mountains is a major variation center of gymnosperm in China.

Key words: Gymnosperm, richness, endemism, diversity center, China