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.

Cuticular wax composition contributes to different strategies of foliar water uptake in six plant species from foggy rupestrian grassland in tropical mountains.

The cuticle is the outermost region of the epidermal cell wall of plant aerial organs. The cuticle acts as a two-way lipid barrier for water diffusion; therefore, it plays a vital role in foliar water uptake (FWU). We hypothesised that the chemical composition of the cuticular waxes influences the FWU strategy that plants adopt in a foggy tropical ecosystem. We analysed the leaf cuticular waxes of six plant species known by their different FWU strategies, in both qualitative and quantitative approaches, to test this hypothesis. We also investigated the fine structure of the plant cuticle by scanning electron microscopy. Neither the total wax loads nor the amounts of single wax compound classes correlated to the FWU. In contrast, the qualitative chemical composition of the cuticular waxes was related to the water absorption speed but not to the maximum water absorbed. The presence of wax crystals might interfere with the FWU. Our findings suggest that a complex three-dimensional network of the cuticular compounds contributes to different strategies of FWU in six plant species from foggy tropical mountaintops.

Oxidant-antioxidant balance and tolerance against oxidative stress in pioneer and non-pioneer tree species from the remaining Atlantic Forest.

The extensive land occupation in Southeast Brazil has resulted in climatic disturbances and environmental contamination by air pollutants, threatening the Atlantic forest remnants that still exist in that region. Based on previous results, we assumed that pioneer tree species are potentially more tolerant against environmental oxidative stress than non-pioneer tree species from that Brazilian biome. We also assumed that reactive oxygen species (ROS) are accumulated in higher proportions in leaves of non-pioneer trees, resulting in changes in the oxidant-antioxidant balance and in more severe oxidative damage at the cellular level than in the leaves of pioneer trees. We tested these hypotheses by establishing the relationship between oxidants (ROS), changes in key antioxidants (among enzymatic and non-enzymatic compounds) and in a lipid peroxidation derivative in their leaves, as well as between ROS accumulation and oscillations in environmental stressors, thus permitting to discuss comparatively for the first time the oxidant-antioxidant balance and the tolerance capacity of tree species of the Atlantic Forest in SE Brazil. We confirmed that the non-pioneer tree species accumulated higher amounts of superoxide and hydrogen peroxide in palisade parenchyma and epidermis, showing a less effective antioxidant metabolism than the pioneer species. However, the non-pioneer species showed differing capacities to compensate the oxidative stress in both years of study, which appeared to be associated with the level of ROS accumulation, which was evidently higher in 2015 than in 2016. We also applied exploratory multivariate statistics, which revealed that the oscillations in these biochemical leaf responses in both functional groups coincided with the oscillations in both climatic conditions and air pollutants, seemingly showing that they had acclimated to the stressful oxidative environment observed and may perpetuate in the disturbed forest remnants located in SE Brazil.

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.

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.

Germination of native grasses with potential application in the recovery of degraded areas in Quadrilátero Ferrífero, Brazil / Germinação de gramíneas nativas do Quadrilátero Ferrífero com potencial aplicação na recuperação de áreas degradadas

Native grasses are potential species to be used in land rehabilitation. However, due to the lack of better knowledge of their performance, preference is given to exotic plants, which may be invasive and negatively affect the local biodiversity. In order to better understand the propagation of native species of the Quadrilátero Ferrífero (Minas Gerais, Brazil) using their seeds, and in so doing, indicate possible candidates for land rehabilitation, this study investigated the germination patterns of the following grasses: Andropogon bicornis L.; Andropogon leucostachyus Kunth; Setaria parviflora (Poir.) Kerguélen; Cenchrus brownii Roem. & Schult; Echinolaena inflexa (Poir.) Chase, and Apochloa euprepes (Renvoize) Zuloaga & Morrone. The spikelets (depending on the species, removing or not the structures that surround the caryopsis) were treated as follows: T1-Control, T2-moistening with 0.2% potassium nitrate, T3-heating at 80 ºC for 2 minutes, T4-scarification with sulfuric acid (except genus Andropogon) and, for genera Andropogon and Setaria T5-storage at room temperature and T6- refrigerated storage. The treatment was repeated four times for 25 caryopses incubated at 25 ºC and constant light. Significant variation was observed when comparing germination rates from week to week, treatment to treatment and species to species. The most efficient treatment for genus Andropogon was T6, followed by T2 for A. bicornis and T3 for A. leucostachyus. T6 was also the most effective treatment for S. parviflora, followed by T5 and T2. C. brownii showed similar results when applying T1, T2 and T3 (mean 39%). E. inflexa and A. euprepes showed high levels of dormancy that were not overcome by the proposed treatments. A. bicornis, A. leucostachyus, S. parviflora and C. brownii showed higher germination potential, thus being possible candidates for the recovery of degraded areas. Future studies are indicated to find the most effective treatments for germination in field conditions.

As gramíneas nativas apresentam potencial para revegetação de áreas degradadas, no entanto, devido ao pouco conhecimento sobre sua biologia, dá-se preferência ao uso de espécies exóticas, que podem ser invasoras, afetando assim a biodiversidade local. No intuito de ampliar o conhecimento acerca da propagação via sementes de espécies nativas do Quadrilátero Ferrífero (QF), e desta forma, indicar possíveis candidatas a aplicação na recuperação de áreas degradadas da região, este trabalho objetivou avaliar os padrões germinativos das seguintes gramíneas: Andropogon bicornis L.; Andropogon leucostachyus Kunth; Setaria parviflora (Poir.) Kerguélen, Cenchrus brownii Roem. & Schult; Echinolaena inflexa (Poir.). Chase e Apochloa euprepes (Renvoize) Zuloaga & Morrone. As espiguetas (com presença ou não das estruturas que envolviam a cariopse, dependendo da espécie) foram submetidas aos seguintes tratamentos: T1-controle; T2-umedecimento do substrato com 0,2% de nitrato de potássio, T3-aquecimento a 80 ºC por 2 minutos, T4-escarificação com ácido sulfúrico (exceto gênero Andropogon) e para os gêneros Andropogon e Setaria, T5-armazenamento a temperatura ambiente e T6-armazenamento sob refrigeração. Os tratamentos foram realizados em 4 repetições de 25 cariopses colocadas para germinar a temperatura de 25 ºC e iluminação constante. Variação significativa foi observada quando comparadas as quantidades de germinações ocorridas entre as semanas, entre os tratamentos e entre as espécies. Para o gênero Andropogon o tratamento mais eficiente foi T6, seguido por T2 em A. bicornis e T3 em A. leucostachyus. T6 também foi o tratamento mais eficiente para S. parviflora, seguido por T5 e T2. C. brownii apresentou resultados próximos sob T1, T2 e T3 (média 39%). E. inflexa e A. euprepes apresentaram altos índices de dormência que não foram superadas pelos tratamentos propostos. A. bicornis, A. leucostachyus, S. parviflora e C. brownii apresentaram maiores potenciais de germinação, sendo possíveis candidatas para recuperação de áreas degradas no QF. No entanto, ainda são necessários estudos complementares com os tratamentos mais eficientes e testes de germinação e estabelecimento em condições de campo.

Aumento da disponibilidade de N via deposição atmosférica e fenologia reprodutiva de Habenaria caldensis Kraenzl. (Orchidaceae) no Parque Estadual do Itacolomi (PEIT) - MG, Brasil / The increase of N availability via atmospheric deposition and the reproduction phenology in Habenaria caldensis Kraenzl. (Orchidaceae) in the Parque Estadual do Itacolomi (PEIT) - MG, Brazil

Ao lado do aumento da concentração de CO2, a deposição atmosférica de N é atualmente considerada um dos mais importantes fatores de alteração do funcionamento dos ecossistemas nativos, tendo já provocado drásticas mudanças na composição florística e na ciclagem de nutrientes no hemisfério norte. Entretanto, em sistemas tropicais e subtropicais, pouco se sabe sobre os efeitos do enriquecimento de N via deposição atmosférica, sobre o seu funcionamento. A compreensão da amplitude e da direção das respostas de orquídeas ao aumento da concentração de N disponível pode ajudar a alimentar modelos de dinâmica de populações rupícolas em resposta às mudanças globais. Avaliamos as respostas de floração e frutificação em plantas de Habenaria caldensis Kraenzl. (Orchidaceae), espécie de ampla distribuição em Minas Gerais, em consequência do aumento da disponibilidade de N por meio de fertilizações com nitrato de amônio, in situ, por aspersão. Em resposta à adição de N, a antese foi adiantada em cerca de 15 dias em relação aos indivíduos do grupo controle. Pelos resultados obtidos, o aumento da disponibilidade de N via deposição atmosférica pode afetar em curto prazo a ecologia de orquídeas e possivelmente outras plantas de campos rupestres alterando seus padrões fenológicos e alométricos. Em médio e longo prazos, tais modificações podem ter relevante impacto sobre a dinâmica de populações e comunidades desse tipo vegetacional.

Along with the increased concentration of CO2, the atmospheric deposition of nitrogen is currently considered one of the most important factors of change in the functioning of native ecosystems and has caused drastic changes in their floristic composition and nutrient cycling in the northern hemisphere. In tropical and subtropical systems, however, the largest holders of the plants diversity, little is known about the effects of the nitrogen enrichment via deposition on their performance. Understanding the magnitude and direction of the responses of the orchids to the increase of the concentration of available nitrogen might be helpful to modeling of rock outcrops population dynamics in response to global changes. We evaluated the responses of flowering and fruiting in plants of Habenaria caldensis Kraenzl. (Orchidaceae), a species widely distributed in Minas Gerais, as a result of increased nitrogen availability through fertilization with ammonium nitrate, in situ, by spraying. In response to the addition of N, anthesis occurred about 15 days earlier compared to individuals of the control group. The results of this study demonstrated that the increased availability of N via atmospheric deposition can affect in a short term the ecology of orchids and possibly other plants from rock outcrops by changing their phenological and allometric patterns. In a medium and long term, such changes can have an important impact on the dynamics of populations and communities of this vegetation type.

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.

Diversity of shrub tree layer, leaf litter decomposition and N release in a Brazilian Cerrado under N, P and N plus P additions.

This study investigated changes in diversity of shrub-tree layer, leaf decomposition rates, nutrient release and soil NO fluxes of a Brazilian savanna (cerrado sensu stricto) under N, P and N plus P additions. Simultaneous addition of N and P affected density, dominance, richness and diversity patterns more significantly than addition of N or P separately. Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. The results indicate that if the availability of P is not increased proportionally to the availability of N, the losses of N are intensified.