云南地区种子植物区系属的多度及区系过渡性的空间分布格局

植物区系地理分布格局的研究有助于更好地理解植物区系的起源、迁移和分化。研究利用覆盖云南地区全境的植物区系分布信息,探讨了云南地区植物区系属的多度及区系过渡性的地理分布格局。结果表明,所有热带区系属的多度均随着纬度升高呈递减趋势;大多数温带区系属的多度随着纬度的升高呈递增趋势。中亚分布(T13)属的多度的高值主要出现在滇西北地区,尤其是在金沙江、澜沧江和怒江的上游地区,但在其它地区十分少见。地中海、西亚至中亚分布(T12)属的多度的高值也出现在滇西北地区,但在其它地区无明显空间分布规律;中国特有分布(T15)属在滇西北地区最为丰富,其次是滇东南地区,大致以"田中线"为界,界线以西地区的中国植物特有属的多度明显低于界线以东地区。从南到北,植物区系过渡性基本上呈单调递增格局,这一格局的形成可能与区系成分的迁移和地形格局有关。大理州以南的低海拔地区,热带区系成分占据主导地位,并占据了云南大部分的土地面积,这在一定程度上证实了云南地区总体上是一个"热带山原"的假说。本研究与其它研究的不同可能源于与源数据和取样尺度的差异。

Spatial patterns of abundance of genera of areal types of seed plants and flora transition in Yunnan

The investigation of spatial patterns of flora is essential to understand floristic origin, migration and differentiation. In this paper, we investigated the spatial patterns of abundance of genera for each areal type and its transition, based on floristic information totally covered the studied area. The results showed that the abundance of genera of tropical elements decreased with the increase of latitude, while a contrary trend was observed on the abundance of genera of most of temperate elements. The most abundant genera of Central Asia types were mainly observed in Northwest Yuunan, while it was scarcely observed in else where. The greatest abun-dance of genera of the Mediterranea, West Asia to Central Asia was found in the Northwest Yunnan. The hotspots of genera endemic to China were focused in the northwest and southeast part of Yuunan. We also found that, compared with the west part of the Tanaka Line, there were more genera endemic to China in the east. From south to north, an increasing trend was found on flora transition, which may be due to historical migration of flora and topographical patterns. To the south of Dali prefecture, the tropical elements gained the dominance, which implied that Yunnan province was a tropical area. The discrepancy between our study and the previous studies may be due to different database and sampling scale.