ABSTRACT Until the mid-XX century, little awareness on the ecological services or socio-environmental problems and benefits related to aquatic plants culminated in bottlenecks on their natural history, especially for the Neotropics. In this context, Acta Botanica Brasilica (ABB) organized this special issue to promote the advancement of knowledge on this ecological group in the Neotropics, supported by Sociedade Botânica do Brasil’s group of aquatic plants specialists. We selected and evaluated manuscripts gathering unprecedented findings, resulting from studies on aquatic plants, with little investigated or documented approaches, such as the improper use of methodological paradigms and aspects of biogeography, ecophysiology, morphoanatomy, structuration of communities, functional ecology, and human use. Here we present a synthesis of these reports’ findings that shall contribute to deepening the knowledge on the natural history, sustainable use, and conservation of aquatic plants and guide future research, mainly in Neotropical aquatic ecosystems. The publication of special issues on themes with insufficient knowledge to Science can reduce such gaps and expand the journal’s perspectives. Therefore, we believe that this special issue of ABB will boost the understanding of aquatic plants’ natural history as much as incentivizing journals with specific scopes of the area of Plant Biology to similar initiatives.

ABSTRACT Species distribution modeling (SDM) studies of aquatic macrophytes are still attached to methodological paradigms focused on terrestrial plants, such as the use of bioclimatic layers. Our goal was to evaluate the applicability of this paradigm based on a SDM study of Egeria densa, Pontederia crassipes, and Salvinia auriculata in the São Francisco river, Brazil. We compared performances of optimizations of computed models using AUC and TSS with distribution records of these species and bioclimatic layers, or limnological layers generated from the interpolation of data obtained in the field. We calculated models using six algorithms. The models calculated using layers of limnological variables had higher performances than did those calculated using layers of bioclimatic variables, except when the Maximum Entropy Default algorithm was used. We attribute these results to the specificities of the data obtained to develop the limnological layers, such as observations obtained in different habitats of the river and during different hydrologic periods. We conclude that the use of bioclimatic layers, a methodological paradigm traditionally used for SDM of aquatic macrophytes, can be questionable for some situations, such as in investigations at local and regional scales.

ABSTRACT Initiatives directed at managing information on aquatic plants can support different areas of scientific research, educational practices and political decisions for sustainable management and protection of wetlands and natural resources, as well as reveal knowledge gaps regarding aquatic plants and wetlands. Furthermore, such initiatives can contribute directly to consolidating wetland classification systems in Brazil. The objectives of this work are to present and explore the use of a data repository and online platform created specifically for the management of data on aquatic plants in Brazil. The data repository for aquatic plants was developed to store information on species occurrence records in a standardized form considering: systematics, taxonomy, habit, life form, geographic distribution, hydrographic basin, wetland, bibliographic references and herbarium material. A total of 3,903 records referring to the Southeast Region of Brazil were generated for the data repository. This total encompassed 1,036 species distributed among 132 families and 466 genera. Our results illustrate the diversity of information available regarding aquatic plants, circumscribe this group of species and serve as a source of data about them. Similar databases and electronic infrastructures can be developed for other flora in the future.

Resumo Descrita no ano de 2015, o conhecimento da biogeografia de Pleurophora pulchra é limitado, fato que impossibilitou sua inclusão na primeira avaliação sobre Áreas Prioritárias para Conservação da Flora do Domínio Caatinga (APCFCs) e Unidades de Conservação (UCs). Nesse contexto, propusemos descrever o potencial biogeográfico de P. pulchra na Caatinga através de modelagem de distribuição de espécies (MDE), visando ampliar as discussões sobre APCFCs e UCs. Utilizamos o algoritmo Maxent para computar o modelo final (MDEf), e o teste Binomial para avaliar o desempenho dos mesmos. Constatamos que P. pulchra está ajustada a ambientes de elevada aridez, com baixa precipitação anual, grande sazonalidade na precipitação, temperaturas estáveis nos meses mais frios e solos pouco espessos, variando de imperfeitamente à bem drenados. O MDEf revelou áreas com adequabilidade ambiental predominantemente na depressão sertaneja meridional da Bahia, Pernambuco e Paraíba, além de áreas do planalto da Borborema da Paraíba. As UCs APAs Cariri e Lago de Sobradinho, APCFCs Jatobá e Cariri Paraibano se destacaram pela representatividade da área com adequabilidade ambiental superior a 0.5. O resultado do teste binomial indicou bom desempenho de MDEf (p < 0.001 t =1) e, portanto, reforçou a possibilidade de novos registros de P. pulchra nas áreas supracitadas.

Abstract Having been recently described (2015), knowledge of the biogeography of Pleurophora pulchra is limited, which made its inclusion in the first evaluation of Priority Areas for Conservation of the Flora of the Caatinga Domain (PACFCs) and Conservation Units (CUs) impossible. We describe the biogeographical potential of P. pulchra in the Caatinga using species distribution modeling (SDM), with the aim of broadening discussions about PACFCs and CUs. We used the Maxent algorithm to compute the final model (SDMf), and the Binomial test to evaluate their performance. We found that P. pulchra tends to occur in environments with high aridity, low annual precipitation, intense precipitation seasonality, stable temperatures in the colder months, and thin soils that range from poorly to well drained. The SDMf revealed areas with environmental suitability predominantly in the Southern Sertaneja Depression of the states of Bahia, Pernambuco and Paraíba, as well as areas of the Borborema Plateau in Paraíba. The CUs APAs Cariri and Lago de Sobradinho, and the PACFCs Jatobá and Cariri Paraibano stood out as having environmental suitability values above 0.5. The binomial test exhibited good performance for SDMf (p < 0.001 t =1), reinforcing the possibility of new records of P. pulchra in the aforementioned areas.

Os eforços de campo e os dados de herbários não nos permitiam quantificar a diversidade plantas aquáticas no Norte do Brasil e, com isso, nos impediam de traçar padrõres biogeográficos sobre essa comunidade. Assim, o presente estudo teve por objetivos identificar e quantificar as macrófitas aquáticas dos estados do Norte do Brasil, analisando duas plataformas de dados de herbarios (SpeciesLink e Flora do Brasil). O checklist baseou-se em levantamento bibliográfico (revistas e artigos publicados entre 1980 e 2000) e em coletas de campo, na qual foi utilizada amostragem de "caminhamento". Após a elaboração do checklist, verificaram-se os registros das espécies para os estados da região, consultando-se as coleções das plataformas SpeciesLink e Flora do Brasil. Foi analisada a similaridade de especies de macrófitas aquáticas do Neotrópico, Norte do Brasil e ecossistemas aquáticos de distintas regiões do país. Foram registradas 539 espécies, sendo 48 endêmicas do Brasil. As famílias mais representativas foram Poaceae (89 espécies), Podostemaceae (55), Cyperaceae (50) e Fabaceae (47). Ressaltamos a inédita riqueza de Podostemaceae, devida a nossos esforços de coleta em ambientes propícios, 25 espécies sendo endêmicas. Os estados que apresentaram maior número de registros de espécies foram Amazônia e Pará, independentemente da plataforma de dados analisada. As espécies anfíbias e/ou emergentes (505 espécies) foram dominantes na riqueza total dos sete estados analisados. Foram constatadas diferenças significativas quanto aos resultados de riqueza e composição florística dos estados, obtidos pelas plataformas Flora do Brasil e SpeciesLink. A análise de similaridade florística evidenciou a formação de grados entre estados do Norte ou ecossistemas aquáticos brasileiros cujos sistemas climatológicos apresentam semelhanças. Em síntese, observamos uma flora rica de plantas aquáticas no Norte do Brasil, apesar da carência de registros para o Acre, Rondonia e Tocantins. Destacamos o número recorde de espécies endêmicas de Podostemaceae (25 spp.) e as divergências quanto aos resultados de riqueza registradas pelo SpeciesLink e Flora do Brasil.

Field collection and herbaria data did not allow to quantify the diversity of aquatic plants from Northern Brazil, so we could not detect biogeographic patterns. Therefore, our objectives were to identify and quantify the aquatic macrophytes of North Brazilian states, analyzing herbaria data plataforms (SpeciesLink and Flora do Brasil). The checklist was produced by bibliographic search (articles published between 1980 and 2000), herbaria collections of the platforms SpeciesLink and Flora do Brasil and field expeditions, where we utilized asystematic sampling. We also analyzed the floristic similarity of aquatic macrophytes among Northern Brazil, wetlands of distinct Brazilian regions and the Neotropics. We recorded 539 species, of which 48 are endemic to Brazil. The states with highest number of species were Amazonas and Pará, independently on platform. The most represented families were Poaceae (89 species), Podostemaceae (55), Cyperaceae (50) and Fabaceae (47). We highlight the unprecedent richness of Podostemaceae, due to our own field collection efforts on favorable habitats, 25 species being endemic. Emergent and/or amphibious plants (515) were dominant in total species richness and were best represented in lotic habitats. We found significant differences in richness and floristics among states, obtained from the platforms. There is floristic similarity among Northern states and other Brazilian wetlands. In conclusion, we observed a rich aquatic flora in Northern Brazil, in spite of scarcity of records for Acre, Rondonia and Tocantins; we highlight the unprecedent number of endemic species of Podostemaceae (25) and contrasting richness between SpeciesLink and Flora do Brasil.

Resumo Os estudos florísticos e taxonômicos de macrófitas aquáticas contribuem para a quantificação da flora, vislumbrando a riqueza e diversidade presente nos ecossistemas aquáticos. O presente estudo objetiva caracterizar a composição florística, fornecer chaves de identificação e detectar as formas biológicas das macrófitas aquáticas presentes em três reservatórios de abastecimento público, localizados em diferentes regiões fitogeográficas do estado de Pernambuco (Zona da Mata/Litoral, Agreste e Sertão). As coletas foram realizadas no período de abril de 2007 a fevereiro de 2010. Foram coletados indivíduos férteis ou não, encontrados na margem e interior dos reservatórios. Foram amostradas 59 espécies e 23 famílias, entre as quais foram mais representativas: Fabaceae (10 espécies), Asteraceae (9), Poaceae (8) e Cyperaceae (6). Dentre formas biológicas, as mais comuns foram as anfíbias com 36 espécies (61,01%) e as emergentes, com 14 espécies (23,73%). Comparativamente a outros estudos florísticos foi observado que as famílias mais representativas encontradas nesse estudo também são comuns a outros ecossistemas aquáticos. A elevada representatividade das anfíbias e emergentes deve-se, principalmente, a resistência dessas espécies a variação do volume de água nos reservatórios. Por se localizarem em diferentes zonas fitogeográficas, a flora dos reservatórios mostra-se bem distinta, com apenas uma espécie em comum.

Abstracts Floristic and taxonomic studies of aquatic macrophytes contribute to quantification of the flora showing its richness and diversity in these ecosystems. This study aims to characterize floristic composition, provide identification keys and detect life forms of aquatic macrophytes in three public water-supply reservoirs, located in different phytogeographic regions of Pernambuco (Zona da Mata/Litoral, Agreste and Sertão). The plants were collected from April 2007 to February 2010. Fertile or sterile specimens were collected on the shore and inside the reservoirs. 59 species were sampled belonging to 23 families. The most representative families were: Fabaceae (10 species), Asteraceae (9), Poaceae (8) and Cyperaceae (6). The most common life forms were amphibious with 36 species (61.01%) and emergent with 14 species (23.73%). Compared to other floristic studies, the most representative families in this study were also common in other aquatic ecosystems and the high number of amphibious and emergent plants was due mainly to the resistance of these species to variation in water level in the reservoirs. Since they are located in different phytogeographic zones, the flora of the reservoirs proved to be quite distinct, with only one species in common.

Resumo O presente estudo teve por objetivo avaliar a riqueza, formas biológicas e composição florística de macrófitas aquáticas ao longo do eixo rio-barragem de um reservatório no Nordeste do Brasil. Foram estabelecidas seis estações de amostragem ao longo de suas regiões lótica, de transição e lêntica. As coletas ocorreram nos meses de junho e julho de 2008 (período de estiagem), e em janeiro e fevereiro de 2009 (período chuvoso). Foram coletados indivíduos em estagio fértil ou vegetativo, tendo as espécies sido categorizadas quanto às formas biológicas e os percentuais de frequência de ocorrência. A similaridade florística entre os pontos de amostragem foi calculada utilizando-se o índice de Jaccard. Foram identificadas 43 espécies, das quais 18 estiveram presentes na região lótica, 16 na de transição e 25 na lêntica. Salvinia auriculata Aubl. e Paspalum repens P.J. Bergius ocorreram em 100% das unidades amostrais. As regiões lótica e de transição contemplaram, predominantemente, espécies anfíbias e emergentes, diferindo da região lêntica, onde espécies flutuantes, emergentes e submersas foram mais evidentes. A similaridade entre os ecossistemas lótico e de transição foi maior que 50%, enquanto que entre esses ambientes e a região lêntica foi menor que 25%.

Abstract This study aimed to evaluate aquatic-macrophyte richness, life forms and floristic composition along the longitudinal axis of Sobradinho Reservoir - Bahia. Six sampling stations were selected along the lotic, transition and lentic stretches. Sampling was conducted in June and July 2008 (drought season), and in January and February 2009 (rainy season). Individuals in both fertile and vegetative stages were sampled and the species were classified according to life form and occurrence frequency. Floristic similarity among sampling stations was expressed by the Jaccard index. Forty-three species were recorded, 21 of these being present in the lotic stretch, 21 in the transition stretch and 30 in the lentic stretch. Salvinia auriculata Aubl. and Paspalum repens P.J. Bergius occurred in 100% of the sampling units. The lotic and transition regions were predominantly colonized by emergent and amphibious macrophytes, whereas the lentic region was colonized by plants with floating and submersed habits. The analysis showed a high similarity (> 50%) between lotic and transition stretches, and low similarity (< 25%) between these and the lentic stretch.