Magnetic susceptibility as a pedogenic proxy for grouping of geochemical transects in landscapes

Magnetic susceptibility (χ lf) is a sensitive, fast, and accurate technique to detect soil pedogenic processes and features, and can improve understanding of soil-forming factors. The aim of this study was to determine catenary groupings of geochemical segments by identifying the relationship between magnetic susceptibility and the soil-forming factors within and along the landscape. Soil physical and chemical properties, as well as soil mineralogy were evaluated in twenty-two topsoil samples from three different landscapes in southern Brazil. The bulk χ lf and frequency-dependent susceptibility (χ fd) were also measured, represented by i) air-dried fine earth (< n μm, χ lf ADFE) ii) after dithionite-citrate-bicarbonate treatment (χ lf CBD), and iii) the parent material (χ lf ROCK). Geochemical segments were grouped using multivariate analysis. Our results indicate that soil parent material and climate, are first order factors for the pedogenic enhancement of magnetic minerals. Magnetic susceptibility of air-dried fine earth (χ lf ADFE) is widely variable, from 11.00 to 2.075 × 10 −8 m 3 kg −1. χ lf was higher in soils developed on basalt, and much lower for soils developed on sandstone. χ lf ADFE also reveals a strong positive linear correlation with χ lf CBD (r = 0.96) and a moderate positive linear correlation with “free” and total Fe content (r = 0.49 and 0.69, respectively). The χ fd (< 2%) indicates samples in which either non-SP grains dominate the assemblage or where the SP fraction is <0.03 nm. After CBD dissolution there is an increase in χ lf values. The rate of iron weathering and iron release, driven by hydrolysis and oxidation, and reductive dissolution of magnetite affect the formation and/or persistence of secondary iron oxides in some of the soil transects. Both principal component analysis (PCA) and cluster analysis group soils from a) crest and upper slope locations, b) down slope and sandstone areas, and c) valley floors, indicating that magnetic susceptibility is an effective proxy for soil properties for grouping and identifying pedogenic/geochemical segments along a landscape of 360 km 2

O gênero Erythroxylum P. Browne (Erythroxylaceae) do estado do Paraná, Brasil

<abstract language="eng">An inventory of the Erythroxylum's species from the State of Paraná, Brazil, was done and the following species were found: E. ambiguum Peyr., E. amplifolium (Mart.) O.E. Schulz, E. anguifugum Mart., E. argentinum O.E. Schulz, E. buxus Peyr., E. campestre A. St.-Hil., E. cuneifolium (Mart.) O.E. Schulz, E. cuspidifolium Mart., E. deciduum A. St.-Hil., E. gonocladum (Mart.) O.E. Schulz, E. nanum A. St.-Hil., E. pelleterianum A. St.-Hil., E. microphyllum A. St.-Hil., E. myrsinites Mart. and E. suberosum A. St.-Hil.. All of then are taxonomically revised and a new synonym is presented: E. cuneifolium (Mart.) O.E. Schulz var. squarrosum O.E. Schulz as synonym of E. cuneifolium (Mart.) O.E. Schulz. Is also discussed the validity of the genus name Erythroxylon Linnaeus against Erythroxylum P. Browne

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora