ABSTRACT Exotic grasses have been introduced into wetlands and can compete with native plants due to their high tolerance of flood and dry periods. Flooding can facilitate seed dispersal of exotic species and reduce the diversity of native species. We compared two grasslands to assess whether seed banks can maintain the diversity of native plants in wetlands with introduced exotic plants. We recorded a total of 136 species and a predominance of annual plants in the seed bank and vegetation together. The seed bank had high species diversity independently of the dominance of the exotic Urochloa humidicola in the vegetation. The seed banks of the native and cultivated grasslands differed significantly with a positive correlation for aquatic plants in the native grassland and negative correlation in the cultivated grassland. The seed bank revealed potential to maintain the diversity of native species in the cultivated grassland since the flood and dry seasons promoted the presence of distinct species in the seed bank, but lower richness in the vegetation reflects a dependence on the germination stage. The seasonality of flood and dry periods influences distinct growth forms, increasing the diversity of the seed bank and the vegetation.

ABSTRACT The use of computer image analysis can assist the extraction of morphological information from seeds, potentially serving as a resource for solving taxonomic problems that require extensive training by specialists whose primary method of examination is visual identification. We propose to test the ability of deep learning, SVM and random forest algorithms to classify seeds from twelve species of aquatic plants as an alternative to traditional classification methods. A total of 150 seeds of the species were collected. The attributes of colour, shape, and texture were analysed through the machine learning algorithms of deep learning, random forest, and support vector machine (SVM). Computer vision proved to be efficient at classifying species using all three algorithms, with an accuracy rate for SVM of 97.91 %, random forest 97.08 % and deep learning 92.5 %. We believe that the method performed well in our experiment and improved seed classification accuracy. As a result, the algorithms SVM and random forest were found to be enough at aquatic plant seed recognition.

Resumo Espécies vegetais sujeitas a Inundação e fogo podem manifestar estratégias de sobrevivência como o banco de sementes do solo. Pretendemos determinar a influência de fogo e inundação na riqueza, abundância e diversidade do banco de sementes. Realizamos amostragens em um ano mais seco (outubro/2013) e em um de maior inundação (outubro/2014), em dez áreas ao longo do rio Paraguai. Selecionamos 5 áreas com históricos de fogo antigo (2010, 4 anos antes da amostragem) e 5 recente (2013, 1 ano antes da amostragem). Nas áreas, marcamos transectos de 20 m, nos quais coletamos 10 amostras de solo (20 × 20 × 5 cm), cinco com e cinco sem serrapilheira. Composição e abundância do banco de sementes foram estimadas por meio de emergência de plântulas. Áreas de fogo antigo apresentaram maior abundância que áreas de fogo recente. O ano de seca apresentou maiores abundância e riqueza do que o de inundação. A remoção da serrapilheira reduziu a riqueza no ano de inundação. Não houve diferença em riqueza no ano seco. A abundância nas amostras com e sem serrapilheira foram similares. A interação entre fogo e inundação não afetou a abundancia, riqueza e diversidade do banco de sementes.

Abstract Flood and fire can harm plants but they can have survival strategies, such as the seed bank. We aimed to determine the influence of fire and flood on the richness, abundance and diversity of the seed bank. Sampling was carried out in October/2013, year of prolonged drought, and October/2014, year of a heavy flood, in ten areas along the Paraguay River. The areas were selected in satellite images, five with old burn (2010, three years before sampling) and five with recent burn (2013, three months before sampling). In each area, we marked a 20 m long transect with ten 20 × 20 cm quadrats where we collected 5 cm deep topsoil samples, five with and five without litter. Seed bank richness and abundance were determined by seedling emergence. Old burn areas presented greater abundance than recent burn. The drier year presented greater abundance, richness and diversity than flood year. Removal of litter reduced the richness only in the wetter year. There was no difference in richness in the drier year. The removal of the litter did not affect the abundance and diversity. Interaction between fire and flood did not affect richness, abundance and diversity of the seed bank.

ABSTRACT The Brazilian Pantanal is an extensive wetland with heterogeneous habitats, primarily due to the river-floodplain system and plants with differential adaptations and reproductive strategies. Factors such as altitude, distance among plant formations, and flood pulse must be considered to better understand its diversity. Aiming to assess the influence of biogeographic patterns in this system, we analyzed the floristic composition of six areas along the Paraguay River, including residual relieves, verifying the pattern of similarity, and effects of distance and altitude. We recorded 356 species in 87 families, mostly perennial (75%), and some annuals (15%) and pluriannuals (5%). Herbaceous plants were the most represented (48%), followed by arboreal (23%), shrubby (15%) and epiphytic (14%) habits, only 12% being endemic to Brazil. The studied areas showed low floristic similarity, but higher resemblance of species between neighboring areas, and no relation with altitude. The upper Paraguay River is diverse, with high spatial variability of species, predominantly perennial. The river-floodplain connectivity may be a determinant factor in species richness and occurrence of endemic species.

Matayba guianensis Aubl. é uma Sapindaceae de porte arbustivo ou arbóreo de grande ocorrência no Cerrado brasileiro, com papel fundamental no fornecimento de recursos para formigas e abelhas. Apresenta rápido crescimento e é importante para recuperação de áreas degradadas, mas pouco se conhece sobre a sua produção de mudas. Diante disso, o objetivo deste estudo foi descrever a morfologia do ramo e da germinação de sementes e plântulas de Matayba guianensis Aubl. em seu desenvolvimento pós-seminal, bem como definir o tipo de substrato e recipiente adequados para emergência de plântulas e produção de mudas desta espécie. Foram avaliados três tipos de recipientes: saco de polietileno preto; tubete e bandeja de isopor, com cinco tipos de substratos: areia; terra; terra-areia-esterco (1:1:1); substrato comercial e fibra de coco, com quatro repetições de 25 sementes em cada tratamento. O ramo, fruto, semente, plântulas e seus eventos morfológicos foram descritos. O ramo é cilíndrico, com folhas paripinadas e alternas; fruto seco, deiscente e sementes com grande quantidade de arilo; a germinação é criptocotiledonar e hipógea. Sua maior porcentagem de emergência ocorreu no recipiente isopor com 91% das sementes germinadas em substrato comercial, seguida de fibra de coco (88%). O desenvolvimento da raiz e do caule foi maior em tubete e em saco plástico, utilizando-se substrato comercial ou fibra de coco.

Matayba guianensis Aubl . is a shrubby or arborial Sapindaceae quite common in the Brazilian Cerrado with a key role in providing resources for ants and bees. It presents a rapid growth, and is important for the recovery of degraded areas, but little is known about its seedlings production. Therefore, the aim of this study was to describe the morphology of the branch and the seed germination and of seedling Matayba guianensis Aubl . in its post-seminal development and define the type of substrate and container suitable for seedling emergence and seedling production of this species. We evaluated three types of containers: black polyethylene bags, cartridge and polystyrene tray, with 5 kinds of substrates: sand, earth, earth - sand - manure (1:1:1); commercial substrate, and coconut fiber, with 4 replicates of 25 seeds per treatment . The branch, fruit, seed, seedling and their morphological events were described. The branch is cylindrical with paripinnate and alternate leaves, the fruit is dry and dehiscent. The seeds have a large amount of aryl, and the germination is cryptocotylar and hypogeal. The highest percentage of emergence occurred in styrofoam container with 91 % of the seeds germinated in commercial substrate , followed by coconut fiber (88 %). The development of root and stem were higher in tubes and plastic bags , using coconut fiber or commercial substrate.