中国亚热带地区植物区系地理成分及其空间格局的数量分析

A quantitative analysis on the floristic elements of the Chinese subtropical region and their spatial patterns

选择我国亚热带区域 76个地区 (不包括行政单元 )的植物区系调查和研究资料 ,采用主成分分析(PCA)、TWINSPAN聚类和样带梯度分析方法 ,研究了我国亚热带区域植物区系地理成分的构成特征和各成分之间的关系 ;各研究区域间植物区系地理成分构成的相关性和空间分异特征 ;并分析了贯穿我国亚热带区域的东经 1 0 8.5°～ 1 1 1 .5°和北纬 2 9°～ 31°两条样带的几种区系地理成分的分布梯度。结果表明 :① 1 5种区系地理成分可以归为热带成分、温带成分、干旱区成分和东亚中心成分 4组 ;我国亚热带各地区区系地理成分中泛热带和北温带分布的比例最高 ;干旱区分布诸类比例极小 ;东亚中心成分的比例突出 ,特有性强 ;②样点的PCA排序明显反映了北、中、南亚热带在区系地理成分构成上的差异 ,但亚热带东西部的差异不明显 ;③样带分析清晰地反映了热带、温带成分之比的梯度格局 ;川东鄂西地区特有分布中心的地位和世界分布与特有成分相反的分布格局。

WT5BZ]Using the methods of PCA and TWINSPAN, floristic data of seventy six mountain floras in the Chinese subtropical region were quantitatively analyzed to reveal the compositional characteristics of its floristic elements, the relationships of its different floristics elements, and the correlation as well as the spatial differentiation of its floristic element composition. Moreover, a north south transect between 108.5°～111.5° E and an east west transect between 29°～31° N were set up to analyze the spatial gradients of several floristic elements. The results are summarized as follows: ① In the subtropical region, the 15 areal types of genera of seed plants of China fall into 4 groups: tropical, temperate, arid and eastern Asian, with the pantropic elements and the northern temperate elements being of the highest percentage, the eastern Asian elements being of a very high percentage, and the endemism being of a very high degree, while the arid elements being of a very low percentage. ② As shown by the result of PCA, the northern, middle and southern parts of the Chinese subtropical region are well differentiated in terms of their floristic composition, but the eastern and the western parts are not clearly differentiated. ③ The transect analysis has clearly shown the gradient pattern of the ratio of tropical vs. temperate elements, the status of the region from eastern Sichuan to Western Hubei as a distribution center of the Chinese endemic genera, and the contrary distribution pattern of the cosmopolitan elements and the Chinese endemic elements in the Chinese subtropical region.