Aquatic vascular plants of South Brazil: checklist and a comparative floristic approach

ABSTRACT Aquatic ecosystems support species diversity, and knowledge of plant communities is essential for wetland conservation programs. This study provides a checklist of aquatic vascular plants of South Brazil and establishes their floristic affinities with bordering South America phytogeographical domains. The checklist was based on 52 sources, including 35 floristic lists, 17 regional taxonomic studies, and information from an electronic database on wetlands of South Brazil. Floristic similarities with published checklists for neighbouring regions were assessed. A total of 780 species distributed in 277 genera and 85 families of vascular plants were reported for South Brazil. Families with higher species richness were Cyperaceae (128), Poaceae (102), Asteraceae (69), Plantaginaceae (21), Lentibulariaceae (20), and Onagraceae (20). The most represented genera were Eleocharis (41) and Cyperus (24). A cluster analysis revealed high similarity with Iberá (Argentinian Chaco), Pampa and Atlantic Forest, and low similarity with Pantanal, Caatinga and the Amazon Rainforest. The high number of aquatic plant families recorded relative to temperate and tropical climates suggests a zone of biogeographical overlap in Southern Brazil. The compiled data set reveals high biodiversity of wetlands of South Brazil, provides a baseline for future research, and highlights the need for regional conservation planning.

摘要
水生生态系统支撑物种多样性，而植物群落相关知识对于湿地保护项目而言至关重要。本研究编制了巴西南部水生维管植物（vascular plants）名录，并明确了其与南美毗邻植物地理区的区系亲缘关系。本名录基于52份参考资料编制，其中包含35份区系名录、17份区域分类学研究文献，以及巴西南部湿地电子数据库的相关信息。研究评估了该名录与邻近区域已发表植物名录的区系相似性。巴西南部共记录到维管植物85科、277属、780种。物种丰富度较高的科依次为莎草科（Cyperaceae，128种）、禾本科（Poaceae，102种）、菊科（Asteraceae，69种）、车前科（Plantaginaceae，21种）、狸藻科（Lentibulariaceae，20种）以及柳叶菜科（Onagraceae，20种）。物种数量最多的属为荸荠属（Eleocharis，41种）与莎草属（Cyperus，24种）。聚类分析结果显示，巴西南部水生维管植物区系与伊贝拉（阿根廷查科地区）、潘帕斯草原及大西洋森林的相似性较高，而与潘塔纳尔、卡廷加及亚马逊雨林的相似性较低。相较于温带与热带气候区，本次研究记录的水生植物科数量较多，这表明巴西南部存在一个生物地理重叠带。本研究汇编的数据集揭示了巴西南部湿地的高生物多样性，可为未来相关研究提供基准，并凸显了开展区域保护规划的必要性。