Metabarcoding of Soil Fungal Communities in Rupestrian Grassland Areas Preserved and Degraded by Mining: Implications for Restoration.

Rupestrian grasslands are vegetation complexes of the Cerrado biome (Brazilian savanna), exhibiting simultaneously great biodiversity and important open-pit mining areas. There is a strong demand for the conservation of remaining areas and restoration of degraded. This study evaluated, using next-generation sequencing, the diversity and ecological aspects of soil fungal communities in ferruginous rupestrian grassland areas preserved and degraded by bauxite mining in Brazil. In the preserved and degraded area, respectively, 565 and 478 amplicon sequence variants (ASVs) were detected. Basidiomycota and Ascomycota comprised nearly 72% of the DNA, but Ascomycota showed greater abundance than Basidiomycota in the degraded area (64% and 10%, respectively). In the preserved area, taxa of different hierarchical levels (Agaromycetes, Agaricales, Mortierelaceae, and Mortierella) associated with symbiosis and decomposition were predominant. However, taxa that colonize environments under extreme conditions and pathogens (Dothideomycetes, Pleoporales, Pleosporaceae, and Curvularia) prevailed in the degraded area. The degradation reduced the diversity, and modified the composition of taxa and predominant ecological functions in the community. The lack of fungi that facilitate plant establishment and development in the degraded area suggests the importance of seeking the restoration of this community to ensure the success of the ecological restoration of the environment. The topsoil of preserved area can be a source of inocula of several groups of fungi important for the restoration process but which occur in low abundance or are absent in the degraded area.

Cadmium behavior in a karst environment hydrological cycle.

Karst regions are important water providers, supplying approximately 25% of the world population. These areas present higher vulnerability to contamination due to hydrodynamics, which hampers the natural depuration of these waters until reaching the underground environment. High concentrations of cadmium (Cd) are observed in the São Miguel watershed, state of Minas Gerais, Brazil. This toxic element is generally and predominantly released into the atmosphere by burning materials that have Cd in their composition, potentially contaminating surface and groundwater. Therefore, the objective of the study is to map Cd concentrations in the hydrological cycle of the São Miguel karst watershed and, through natural background level values (NBL 90%) of rainwater, surface water and groundwater, to understand the seasonal behavior of this element, and to identify the most vulnerable areas to contamination. To achieve this goal, rainwater, surface, and groundwater seasonal monitoring were conducted in 87 sampling stations. A total of 335 samples were collected, distributed over a watershed area of 520 km2. Concentrations of cadmium above 1 µg/L were found in 21.49% of samples during the rainy season. The origin and distribution of Cd were related to rainfall. For rainwater samples, 90% presented Cd concentration of 3.06 µg/L. When these waters precipitate, they contaminate surface waters (NBL 90% = 1.50 µg/L) and groundwater (NBL 90% = 2.81 µg/L). This study presented a hydrochemical cycle map and proposed NBL values of Cd for surface water and groundwater, helping to understand how the environment is contaminated by this element.

Influence of soil texture on nutrients and potentially hazardous elements in Eremanthus erythropappus.

Understanding the factors that control uptake rates and allocation of chemical elements among plant organs is a fundamental prerequisite to improve phytostabilization techniques of hazardous elements in contaminated areas. The present study shows evidence that different substrate textures (coarse and fine laterite) do not significantly change the partitioning of root and shoot dry biomass and with few exceptions, do not significantly affect the final average concentration of elements in Eremanthus erythropappus, but change the root:shoot allocation of both essential nutrients and elements potentially toxic to biota. Growth on coarse laterite resulted in significant higher K (30%), Mg (34%), P (25%), S (32%), Cu (58%), and Na (43%) concentrations in roots and lower Cd concentration (29%). In shoots, coarse laterite led to reduction in K, Fe, Al, and Cr and increase in Na and Sr concentrations. Changes in element allocation could be, in part, a result of differences in the water availability of substrates. Matric potential in coarse laterite was significantly lower in at least 47% of the days analyzed throughout the year. Changes in element phytoextraction or phytostabilization potential could influence the efficiency of rehabilitation projects in areas degraded by mining activities.

Avaliação da implantação de fossas sépticas na melhoria na qualidade de águas superficiais em comunidades rurais / Evaluation of the implementation of septic tanks improving the quality of surface waters in rural communities

Na maioria dos municípios brasileiros, as comunidades rurais são núcleos populacionais agrupados em torno de córregos que fornecem a água e recebem seus efluentes. Buscou-se nesta pesquisa avaliar as condições dos corpos d'água na bacia hidrográfica do córrego Pau Grande, Ouro Branco, Minas Gerais, antes e depois da instalação de 20 fossas sépticas na comunidade de Castiliano, construídas em 2006. O monitoramento da bacia foi realizado entre 2005 e 2009, em 6 pontos amostrais, onde foram medidos vazão, oxigênio dissolvido, demanda bioquímica de oxigênio, fósforo total, coliformes fecais totais, turbidez e pH. Os pontos a jusante das fossas apresentaram um aumento de mais de 100% nos valores de oxigênio dissolvido e redução em mais de 800% na quantidade de coliformes fecais. Investimentos relativamente baixos, como a construção das fossas, podem trazer melhorias à qualidade dos recursos hídricos em áreas rurais.

In most Brazilian cities, rural communities are clustered in the surroundings of streams that supply water and receive their effluents. The aim of this study was to evaluate the conditions of the quality water in Pau Grande catchment, located in Ouro Branco, Minas Gerais, Brazil, before and after the construction of 20 septic tanks in the community of Castiliano, build in 2006. The monitoring of the basin was conducted between February 2005 and November 2009, using 6 control points. Several water parameters were evaluated: river flow, dissolved oxygen, biochemical oxygen demand, total phosphorus, total coliform, turbidity and pH. Monitoried points downstream of the construction sites showed an increase of more than 100% in dissolved oxygen and a decrease of fecal coliform bacteria (over 800%). Relatively small investments can bring major improvements to the quality of water resources in rural communities areas.

Growing Eremanthus erythropappus in crushed laterite: A promising alternative to topsoil for bauxite-mine revegetation.

Topsoil is the preferred substrate for areas requiring rehabilitation after bauxite mining. However, topsoil is sometimes lacking and so there is a need to test the suitability of other, locally available substrates. In an abandoned bauxite mine in Southeastern Brazil, small patches of native vegetation spontaneously established in shallow depressions over weathered laterite, suggesting that granulometric reduction may have facilitated the establishment of plants. To test this hypothesis, blocks of laterite collected in the area were crushed to simulate texture observed in the vegetation patches. Topsoil collected in a preserved ferruginous field near to the extraction area was also used as a substrate in which Eremanthus erythropappus seedlings, a native woody species, were grown. Seedlings were cultivated without fertilizers in these two substrates and also directly over the exposed and uncrushed laterite. The species proved to be very promising for the revegetation, showing a high survival rate in all substrates. Higher annual growth rates and higher final biomass values were observed in topsoil, but the granulometric reduction of laterite doubled plant growth rate in comparison to the exposed laterite. This result was likely due to the increased availability of essential nutrients to plants and to the improvement in physical conditions for root growth and functioning. Moreover, seedling allometry was not altered by the type of substrate, suggesting that the species was highly tolerant to the new substrate conditions, a fundamental characteristic for success of revegetation of bauxite extraction degraded areas.

Life-form spectra of quartzite and itabirite rocky outcrop sites, Minas Gerais, Brazil / Formas de vida em campos rupestres sobre quartzito e itabirito, em Minas Gerais, Brasil

Vascular species and their respective life-forms and coverage were recorded in a Brazilian quartzite and itabirite rocky outcrop site at Serra de Ouro Preto, producing the floristic, frequency and vegetational spectra. Three habitats in both lithologies were defined by geomorphology as: 1) Sloped areas near the mountain summit, with grasslands; 2) Plateaus in the middle of the slope, with grasslands; and 3) Lower and/or concave parts of the slopes, with woody savannas. The life-forms followed Raunkiaer's System. We aimed to answer the following questions: Do quartzite and itabirite rocky outcrops have different biological spectra? Are the biological spectra different in the geomorphologic habitats? Do the floristic, vegetational and frequency spectra differ from one another? What spectrum stacks up to a rocky outcrop physiognomy description? The results portrayed that: a) the most represented life-forms were the phanerophytes and hemicryptophytes; b) the floristic and frequency spectra did not differ from each other, but both differed from the vegetational one; c) all the floristic spectra were similar, but there were significant differences in the frequency and vegetational spectra among the lithology and geomorphology habitats; d) higher phanerophyte and lesser hemicryptophyte coverages were found in the itabirite areas and also in the lower or concave parts of the slopes of both lithologies; and e) the vegetational spectrum was more efficient for the studied rocky outcrop comparison. Relationships between the environmental aspects and life-form spectra are discussed. This study will help advance the development of restoration projects for these areas by adding knowledge of their flora composition, structure and function.

Realizou-se um levantamento das espécies vasculares e suas respectivas formas de vida e coberturas, em campos rupestres na Serra de Ouro Preto, sobre quartzito e itabirito, para construção dos espectros florísticos, de freqüência e vegetacional. Em cada litologia foram delimitados, pela geomofologia, três tipos de habitats: 1) Áreas inclinadas, nos topos das montanhas, com campos limpos; 2) Platôs, na parte mediana das encostas, com campos limpos e 3) Partes mais baixas ou côncavas das encostas, com campos sujos. As formas de vida seguiram o sistema de Raunkiaer. Averiguaram-se as seguintes questões: Campos rupestres sobre itabirito e quartzito possuem diferentes espectros biológicos? Os habitats estratificados pela geomorfologia diferem quanto aos espectros biológicos? Os espectros florísticos, de frequência e vegetacional diferem entre si? Qual espectro se destaca como descritor da fisionomia de campos rupestres? Os resultados evidenciaram que: a) fanerófitas e hemicriptófitas são as formas de vida predominantes; b) os espectros florísticos e de frequência não diferiram entre si e ambos foram estatisticamente diferentes do espectro vegetacional; c) os habitats estratificados pela litologia e geomorfologia apresentaram espectros florísticos similares, mas os espectros de frequência e vegetação mostraram diferenças significativas; d) maior cobertura de fanerófitas e menor cobertura de hemicriptófitas foram encontradas nas áreas sobre itabirito, assim como nas partes mais baixas ou côncavas das encostas, em ambas litologias; e e) o espectro vegetacional mostrou-se mais eficiente para comparação dos habitats. Aspectos do ambiente relacionados com a distribuição de formas de vida são discutidos. Este estudo subsidia programas de restauração ambiental, ampliando o conhecimento da vegetação de campos rupestres.