长江上中游丘陵地区维管植物构成及外来种对区系特征的影响:以宜宾市南溪区和武汉市黄陂区为例

Composition of vascular plants and the influence of exotic species on floristic characteristics in hilly areas of upper and middle reaches of Yangtze River:a case study of Nanxi of Yibin and Huangpi of Wuhan City

长江流域丘陵地区是生态系统服务功能极重要和生态极敏感区,人类活动干扰导致自然生境受损和外来种入侵严重。以地形相似、与长江距离位置相同的四川省宜宾市南溪区和湖北省武汉市黄陂区为研究区域,通过对两地区的植物资源进行调查和分析,以探究长江中上游丘陵地区植物区系的构成及外来物种的影响。研究结果显示,南溪区共有维管植物1 205种,其中外来种247种;武汉黄陂区共有维管植物1 076种,外来种150种。两地单种科和寡种科较多,菊科(Asteraceae)、蔷薇科(Rosaceae)、豆科(Fabaceae)、禾本科(Poaceae)和唇形科(Lamiaceae)均为两地物种最多的大型科。两地植物区系成分都以世界广布和泛热带植物为主,温带植物次之。泛热带区系成分大于北温带成分的构成,说明两地存在一个从热带到温带的区域过渡。除去外来种后,两地共有364种相同的维管植物,地区物种相似性系数为24.09%。从区系分化强度看,两地科、属分化程度都较低(1.5~3.5),这与两地的地形地貌是一致的。外来种以菊科、豆科和茄科(Solanaceae)植物居多,南溪外来物种占物种总数的20.5%,黄陂区为13.94%。外来种虽然使两地区物种多样性增加,但对于其区系成分构成影响并不大。

The hilly area of the Yangtze River Basin is a very important and sensitive area for ecosystem service func⁃tions.The disturbance of human activities leads to the damage of natural habitat and the invasion of alien species.Taking the Nanxi District in Yibin,Sichuan Province and Huangpi District in Wuhan,Hubei Province,which have similar topog⁃raphy and the same distance from the Yangtze River,as the research areas,the plant resources in the two areas were in⁃vestigated to explore the composition of the plant flora and the influence of alien species in the hilly areas of the middle and upper reaches of the Yangtze River.The results show that there are 1205 vascular plants in Nanxi,including 247 exotic species, and 1 076 vascular plants and 150 exotic species in Huangpi. There are more monotypic families and oligotypicfamilies in both places, Asteraceae, Rosaceae, Fabaceae, Poaceae and Lamiaceae are all the five largest families with thehighest number of species in two places. The floristic components of both places are mainly cosmopolitan and pantropicalplants, followed by temperate plants. The composition of the pantropical flora is larger than that of the northern temper⁃ate zone, indicating that there is a regional transition from tropical to temperate zone. After the removal of exotic species,there are 364 identical vascular plants in both places, the species similarity coefficient is 24. 09%. From the perspective offloristic differentiation intensity, the differentiation degrees of families and genera in the two places are all relatively low,ranging from 1. 5 to 3. 5, which is consistent with the topography and landfroms of the two places. The exotic species aremainly composed of Compositae, Fabaceae and Solanaceae, with 20. 5% of the total species in Nanxi and 13. 94% inHuangpi. Although the alien species increase the species diversity in two places, their influence on their floristic composi⁃tion is not significant.