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Question: Does flooding of rice fields after cultivation contribute to wetland plant conservation in southern Brazil? Location: Rice fields in the coastal plain of southern Brazil. Methods: Six rice fields with different management practices were randomly selected (three dry rice fields and three flooded rice fields). Six collections were carried out over the rice cultivation cycle. Richness and biomass were measured using the quadrat method. Results: A total of 88 macrophyte species was recorded. There was no statistical interaction between management practices and rice cultivation phases for macrophyte richness and biomass. Macrophyte species richness and biomass changed over time, but were similar between flooded and dry rice fields. The first three axes generated by detrended correspondence analysis explained 29% of the variation in species composition and the multivariate analysis of variance showed that there was a statistical interaction between management practices and agricultural periods. Conclusions: Rice fields may help to conserve an important fraction of the aquatic macrophyte diversity of wetlands of southern Brazil by providing the setting up of a greater number of species within the agricultural landscape. However, rice fields must not be viewed as surrogate systems for natural wetlands. The difference in species composition between flooded and dry rice fields is interesting in terms of biodiversity conservation. If rice producers could keep part of their agricultural land flooded during the fallow phase, this management practice could be an important strategy for the conservation of biodiversity in areas where natural wetlands have been converted to rice fields.
