The communities of the limnological ecosystems have suffered with constant
modifications of the environment, due to the constructions of hydroelectric power
plants, causing impacts in both terrestrial and aquatic ecosystems, changing the
dynamics of the fauna and flora structure. In this context, the objective of the present
work was to carry out a floristic survey evaluating the degree of cover, biomass and
succession of the assembly of aquatic macrophytes in the reservoir Luís Eduardo
Magalhães (Lajeado). Five collection points were demarcated. At each sampling point a
square composed of 6 x 6 contiguous plots of 1 m x 1 m was installed. In the four
central plots of the block (4 m2), the biomass of the aquatic plants was removed in the
months of January (initial) and November 2018 (final), and the neighboring plots were
not manipulated. For analysis, the averages of water depth, pH, air temperature,
precipitation, biomass and phytosociological parameters (coverage value (VC) and
relative coverage (CR) were calculated. Using Microsoft Office Excel, following the
Braun- Blanquet (1979) was used to investigate change in the recomposition over time
for each plot in the five sites analyzed using the non-metric multidimensional (NMDS)
multi-dimensional scaling (PAST) program. The most representative families were
Cyperaceae and Onagraceae with four species each. The biological forms of larger
occurrences of the species found were emergent and amphibian. The results of the
experiment show that after the disturbance purposely provoked in the plots, the species
managed to regenerate. The submerged species Chara guairenis and Utricularia foliosa
showed the most favorable colonization, in which they probably benefited from the
solar radiation that was more intense because the plots did not have vegetation covering
these areas. The initial biomass represented by the species in the manipulated plots was
larger than the final biomass
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