金沙江白鹤滩水库巧家淹没区维管植物资源及区系分析

Species Resources and Floristic Composition of Vascular Plants in Inundated Area of Baihetan Reservoir at Qiaojia Section of Jinsha River

白鹤滩水电站是我国在金沙江修建的世界上在建规模最大的水电站,电站竣工形成水库后,库区内金沙江原有河岸带及河岸带以上至825 m高程区域成为被水库蓄水淹没的淹没区,且在该淹没区内会形成落差达60 m的库岸水位消落区.为掌握白鹤滩水库淹没区内的本底维管植物资源,也为白鹤滩水库成库后形成消落区的生态演变、生态保护和治理修复工作中适宜植物的筛选提供基础数据,在2020年白鹤滩水库还未建成蓄水前对库区巧家段淹没区的本底维管植物资源进行了实地调查,并就其区系成分特征进行了分析.研究表明:①白鹤滩水库建成前金沙江巧家段淹没区本底维管植物有50科160属207种,其中河岸带有18科52属59种,河岸带以上至825 m高程区域有49科154属199种,二者共有17科46属51种;无论是在整个淹没区,还是在河岸带或河岸带以上至825 m高程区域均表现为禾本科(Gramineae)物种数量最多,菊科(Compositae)物种数量次之.②无论是在河岸带还是在河岸带以上至825 m高程区域中,草本植物均为本底维管植物中占绝对优势的生长型;一年生植物和地上芽植物均为本底维管植物中的优势生活型.③金沙江巧家段淹没区本底维管植物区系成分具有明显的热带分布性质,属于热带分布类型的有28科118属,分别占淹没区总科数和总属数的56.0%和73.75%.其中,河岸带本底维管植物有50%的科和67.31%的属为热带区系类型;河岸带以上至825 m高程区域本底维管植物有55.1%的科和72.73%的属为热带区系类型.该研究对掌握白鹤滩水库巧家段淹没区本底维管植物组成和特征,预测白鹤滩水库消落区未来植物物种组成、植被演变、消落区生态保护和治理修复工作中适宜植物的选择具有特别意义.

The objective of the study is to inventory the local vascular plant resources in the area to-be-inundated by the upcoming impoundment of Baihetan reservoir of Jinsha river at Qiaojia section,and to provide background data for monitoring the vegetation change of the area and assist hopefully selecting suitable plants for the future ecological protection and rehabilitation of the drawdown zone of Baihetan reservoir.In year 2020,before the initial impoundment of Baihetan reservoir,we investigated the species resources and studied the floristic composition characteristics of the local vascular plants in the to-be-inundated area of Baihetan reservoir region at Qiaojia section,including the present riparian zone of Jinsha river and its immediate upper zone(henceforth referred to as immediate upper zone)between the upper limit of the present riparian zone and the area 825 m above sea level(which will be the highest water level of Baihetan reservoir in full operation).It was found that:①207 vascular plant species belonging to 160 genera and 50 families distributed in the to-be-inundated area of Baihetan reservoir region of Jinsha river at Qiaojia section,among which 59 and 199 vascular plant species belonging to 52 and 154 genera,and 18 and 49 families,respectively,were found in the present riparian zone and the immediate upper zone.51 species belonging to 46 genera and 17 families were shared by these two zones.Whether in the area to-be-inundated,or in the present riparian zone,or in the immediate upper zone,Gramineae and Compositae had the first and the second largest number of species,respectively.②Either in the riparian zone or the immediate upper zone,herbaceous plants were the dominant growth form,annual plants and chamaephytes were the dominant life forms.③The local vascular plants in the area to-be-inundated including both the riparian zone and the immediate upper zone had marked tropical characteristics.28 families and 118 genera were tropical areal types,accounting for 56.0%and 73.75%of total families and genera found in the area to-be-inundated,respectively.Among them,50%of families and 67.31%of genera of vascular plants found in the riparian zone were tropical areal types,and 55.1%of families and 72.73%of genera of vascular plants found in the immediate upper zone were tropical areal types.Based on the results of this study,we suggest that,in the screening of suitable plants for ecological protection and rehabilitation of the drawdown zone of Baihetan reservoir,more attention should be paid to tropical areal types of flooding-tolerant terrestrial herbaceous plants.