Ecologia e morfologia de herbáceas aquáticas em um lago artificial, Parque Nacional do Viruá, Caracaraí - RR

Abstract

Wetlands are ecosystems at the interface between aquatic and terrestrial environments, and can be natural or artificial, flooded periodically or permanently. In the Amazon, around 30% of the Amazon basin is made up of wetlands, where the large discharges of the rivers, influenced by the rainy seasons and variations in the water table, result in the Amazon basin being flooded. These areas, both natural and artificial, exhibit a diversity of Wetland Environments due to the physical and chemical characteristics of the waters and the geomorphology of the catchment areas. Aquatic herbaceous plants are the main group of plants that colonize these environments, with different morphological adaptations throughout the hydrological cycle and different life forms. In the northern region of Brazil, shallow lakes play a crucial role in the diversity of these plants, but studies on phenology, morphology and adaptations in artificial lakes are infrequent. The general aim of the study was to record the species composition, morphological adaptations and seasonal phenology of aquatic herbaceous plants in an artificial lake. The study was conducted in the Viruá National Park, in Roraima, between August 2022 and May 2023, covering one of the artificial lakes formed by the road embankment. The transects were 25 m apart and 1x1 m plots were used on the transects, running from the lake shore to the water. In addition, the floristic composition of the lake studied was compared with other Amazonian wetlands, using phytosociological measures and Jaccard and NMDS similarity analysis. Specimens were collected for morphological identification and inclusion in herbaria, with names standardized according to Flora do Brasil (2024). 62 species of aquatic and amphibious herbaceous plants were recorded, belonging to 24 families and 43 genera. The most representative families were Poaceae (16 spp.), Cyperaceae (15 spp). There were 7 life forms, with amphibians (32 spp.) and emergents (10 spp.) being the most frequent. The ordering of the physical and chemical parameters indicated that depth and transparency had the greatest influence on total species cover, while pH and electrical conductivity had the least impact. On the other hand, the species composition in Viruá National Park (PNV) showed greater affinity with igapós rivers, highlighting the importance of habitat type and geographical proximity in floristic similarity, as well as the relevant ecological role of small artificial water bodies in the region.