Secondary metabolites that could contribute to the monodominance of Erythrina fusca in the Brazilian Pantanal.

Erythrina fusca is a dominant species in the Brazilian Pantanal. We hypothesized that E. fusca possess allelopathic potential and we evaluated effects of extracts on germination and development of Lactuca sativa, a bioindicator species. We tested the effect of leaves, bark, roots, and seeds extracts of E. fusca on germination and speed index, using high, moderate and low concentration (0.2, 1 and 5 mg mL-1). To evaluate effects on development, we subjected seedlings of L. sativa to the same treatments and measured root and aerial part length. High concentration of extracts reduced L. sativa germination; leaves extract caused the maximum reduction on germination of L. sativa, similar to 2,4-Dichlorophenoxyacetic acid (2,4-D); this extract has flavonoids and saponins as main compounds, classes that also occur in the bark and roots extracts in lower concentrations; bark and roots (5 mg mL-1), leaves and roots (1 mg mL-1) decreased these traits as well, but in lower magnitude. A significant reduction in root length was induced by highest concentration of all extracts (5 mg mL-1); the results suggest that erythrinic alkaloids should interfere in the root length once the seeds accumulate almost exclusively this class of compounds. Our results showed that all parts of E. fusca had adverse effects on germination or development of L. sativa, showing that different class of compounds secondary metabolites is involved in this activity. Possibly, this phytotoxicity influences monodominance of E. fusca in Pantanal, but studies are essential to evaluate effects of it on other native species.

Growth and establishment of monodominant stands affected by ENSO and flooding in the Pantanal.

Climatic factors can influence the establishment and growth of wood species, but little is known about the effect of these factors on monodominant communities in wetlands. Therefore, we asked how climatic factors, such as ENSO (El Niño-Southern Oscillation), precipitation and flooding, influence growth and establishment of the dominant species Erythrina fusca in the Pantanal. We determined the age of sampled individuals, the age of the population and evaluated the effects of climate on tree growth. We obtained samples for dendrochronological analyses using destructive (seven individuals) and non-destructive methods. We cross-dated and built a chronology, correlating results with climatic factors. We sampled 0.6 ha of the population and separated individuals into diameter classes to determine age based on diameter/age ratio obtained through dendrochronological analyses. We obtained a chronology with individuals up to 34 years old, while in the population sample, the oldest individual was 54 years old. The factors that influenced growth during the study period were precipitation (positive correlation) and El Niño (negative correlation). E. fusca individuals seem to grow more during the period of highest precipitation, and El Niño events reduce precipitation in the Pantanal, resulting in a decrease in the growth of E. fusca individuals. We detected a decrease of young individuals in the last nine years, which seems to be related to the decrease in minimum flood levels. This indicates a future decline in the number of individuals. These results allow us to propose measures to protect these monodominant formations, which mainly involve avoiding further anthropic activities, that could reduce flooding levels.

Guia ilustrado de Leguminosae Juss. arboreas do Corredor de Biodiversidade Santa Maria - PR / Illustrated Guide of Arboreal Leguminosae Juss. in the Corredor de Biodiversidade Santa Maria - PR

Leguminosae representa uma das principais famílias em estudos florísticos e fitossociológicos. Tal riqueza pode ocasionar dificuldades na identificação, principalmente em coletas de amostras estéreis. O objetivo do presente estudo foi elaborar um guia ilustrado com dicas de campo, bem como uma chave de identificação, abordando as principais características vegetativas diagnósticas das Leguminosae arbóreas do Corredor de Biodiversidade de Santa Maria, o qual une a Faixa de Proteção do Lago de Itaipu ao Parque Nacional do Iguaçu. O corredor reúne vários remanescentes de Floresta Estacional Semidecidual do sudoeste do Paraná e áreas reflorestadas. Foram coletadas amostras em diferentes áreas do corredor, sendo três remanescentes florestais (Parque Nacional do Iguaçu, Reserva Legal da Fazenda São José, Reserva Particular do Patrimônio Natural da Fazenda Santa Maria), e duas áreas reflorestadas (Faixa Seca e Faixa de Proteção do Lago de Itaipu). As Leguminosae coletadas foram fotografadas ainda em campo, com câmera semiprofissional, registrando aspectos morfológicos vegetativos como tronco, ritidoma, coloração da casca interna e/ou alburno, presença de exsudato, formato dos folíolos, presença de acúleos, glândulas, nectários extraflorais, indumento e, quando presentes, estruturas reprodutivas. As amostras foram identificadas e adicionadas ao Herbário da Universidade Estadual do Oeste do Paraná (UNOP). Foram encontradas 29 espécies de Leguminosae, para as quais foi elaborado um guia com pranchas, ilustrando as principais características vegetativas diagnósticas, bem como uma chave dicotômica, a fim de auxiliar na identificação das espécies de Leguminosae presentes no sudoeste do Paraná. Características do tronco como ritidoma, casca interna e/ou alburno, formato e coloração dos folíolos, presença de exsudado, acúleos, indumento, nectários extraflorais ou glândulas foram de grande valia em campo, pois permitiram a identificação das espécies de Leguminosae do Corredor de Biodiversidade de Santa Maria.

Leguminosae represents one of the leading families in floristic and phytosociological studies. Such variety can lead to difficulties in identification, particularly in sterile sample collection. The aim of this study was to prepare an illustrated guide with tips from the field, as well as an identification key addressing the major vegetative diagnostic features of Leguminosae trees from the Corredor de Biodiversidade de Santa Maria, which binds the protection strip of Itaipu Lake to the Iguaçu National Park. This corridor brings together several remnants of the Floresta Estacional Semidecidual in south-western Paraná and reforested areas. Samples have been collected in different areas of the corridor, three forest remnants (Iguaçu National Park, the Legal Reserve of Fazenda São José, Private Reserve of Natural Heritage Fazenda Santa Maria), and two reforested areas (Range Dry and Range of Itaipu Lake Protection). Legumes collected were photographed in the field, with prosumer camera, recording morphological and vegetative stem rhytidome, staining the inner bark and/or sapwood, exudate, analysis of the format of the leaflets, the presence of spines, glands, extrafloral nectaries, hairiness, and when present, reproductive structures. The samples were identified and housed at Herbário da Universidade Estadual do Oeste do Paraná (UNOP). Were found 29 species of Leguminosae, for which were designed with guide plates, illustrating the main diagnostic vegetative characteristics, as well as a dichotomous key to assist in the identification of Leguminosae species present in southwestern Paraná. The specimen features trunk as rhytidome, inner bark and/or sapwood, shape and color of the leaflets, presence of exudate, prickles, hairiness, extrafloral nectaries or glands were of great value in the field, which allowed the identification of species of Leguminosae of the Corredor de Biodiversidade Santa Maria.