Growth and functional leaf traits of coppice regrowth of Bertholletia excelsa during an El Niño event in the central Amazon / Crescimento e características funcionais foliares de rebrotas de Bertholletia excelsa durante um evento de El Niño na Amazônia Central

The most severe drought of this century in the Amazon rainforest, which was caused by El Niño, occurred from 2015 to 2016. With a focus on the ecophysiology of the regrowth of the Brazil nut tree, Bertholletia excelsa, it was investigated how the progression of the drought of 2015-2016 affected the physiological traits of the coppice regrowth of B. excelsa. The experiment was carried out in a ten-year-old plantation of Brazil nut trees, which had been subjected to thinning and coppice regrowth two years earlier. In the sprouts grown on the stumps of cut trees, the following treatments were applied: (T1) thinning to one sprout per stump; (T2) thinning to two sprouts per stump, and (T3) maintenance of three sprouts per stump. Thinning treatments did not alter the growth and ecophysiological traits of the Brazil nut tree sprouts, though the phosphorus content of the leaves was higher in T1. However, the progression of the drought in 2015-2016 negatively affected the growth (height) and gas exchange of sprouts of all treatments. In addition, an increase of around 37% was observed in the intrinsic wateruse efficiency. Concerning photochemical performance, no alterations were observed. Therefore, drought stress promoted a negative effect on sprout growth and affected traits related to the photosynthesis of the B. excelsa sprouts independently of the number of sprouts per stump.(AU)

A seca mais severa deste século na floresta amazônica, causada por El Niño, ocorreu de 2015 a 2016. Com foco na ecofisiologia da rebrota da castanheira da Amazônia, foi investigado como a progressão da seca de 2015-2016 afetou as características fisiológicas das rebrotas de uma talhadia de B. excelsa. O experimento foi realizado em uma plantação de castanheiras com dez anos, a qual havia sido submetida a um desbaste e rebrota de talhadia dois anos antes. Nas rebrotas crescidas sobre os tocos das árvores cortadas foram aplicados os seguintes tratamentos: (T1) desbrota para manter um broto por cepa; (T2) desbrota para manter dois brotos por cepa; e (T3) manutenção de três brotos por cepa. Os tratamentos de desbrota não alteraram o crescimento e as características ecofisiológicas dos brotos da castanheira, exceto para o teor foliar de fósforo, que foi maior em T1. Porém, a progressão da seca em 2015-2016 afetou negativamente o crescimento em altura e as trocas gasosas dos brotos de todos os tratamentos. Além disso, foi observado um aumento de cerca de 37% na eficiência intrínseca do uso da água. Quanto ao desempenho fotoquímico, não foram observadas alterações. Portanto, o estresse hídrico promoveu efeito negativo no crescimento da brotação e afetou características relacionadas à fotossíntese das brotações de B. excelsa, independentemente do número de brotações por cepa.(AU)

The Role of Phosphate Fertilization on Physiological Responses of the Young Bertholletia excelsa Plants Grown in a P-Deficient Amazon Ferralsol.

Phosphorus (P) reacts with soil minerals, which makes it less available to plants. Considering that Amazonian soils have a low pH and nutrient availability, both of these properties contribute to an increase in P limitation. Here, we investigate how the addition of P to the substrate affects morpho-physiological traits of Brazil nut trees (Bertholletia excelsa Bonpl.). The experiment was carried out in a greenhouse with 24-month-old saplings, and the P treatments consisted of a control (Ferrasol without P addition) and 100, 200, 400, and 500 mg P kg-1 of added to the soil. When B. excelsa saplings were fertilized with phosphate, the N:P leaf ratio reduced from 50 to 26. Addition of P favored the photochemical efficiency of PSII (FV/FM), and the application of 200 mg kg-1 increased photosynthesis (PN) by 50%. Furthermore, phosphorus enhanced light and nutrient use efficiency. An increase in B. excelsa dry biomass was observed when 200 mg P kg-1 was added, with maximum yield occurring at 306.2 mg P kg-1. Physiological parameters suggest robust responses by B. excelsa to P fertilization. In addition, our findings reveal the critical role of P on B. excelsa growth in Ferralsol, as well as the potential of P fertilization to improve functional traits of this important Amazonian tree.

Geochemistry of selenium, barium, and iodine in representative soils of the Brazilian Amazon rainforest.

The Amazon rainforest is a heterogeneous ecosystem and its soils exhibit geographically variable concentrations of trace elements. In this region, anthropic activities - e.g., agriculture and mining - are numerous and varied, and even natural areas are at risk of contamination by trace elements, either of geogenic or anthropogenic origin. A reliable dataset of benchmark values for selenium (Se), barium (Ba), and iodine (I) concentrations in soils is needed for use as a reference in research and public policies in the region. In this study, 9 selected sites in the Brazilian Amazon rainforest within areas represented by Oxisols and Ultisols were assessed for relevant soil physicochemical characteristics, along with the concentrations of total Se (SeTot), total Ba (BaTot), and sequentially-extracted soluble Se (SeSol) and adsorbed Se (SeAd) in 3 different soil layers (0-20, 20-40, and 40-60 cm). In addition, organically bound-Se (SeOrg) and total I (ITot) concentrations in the surface layer (0-20 cm) were measured. Soil Se concentrations (SeTot) were considered safe and are likely a result of contributions of sedimentary deposits from the Andes. Available Se (SeSol + SeAd) accounted for 4.5% of SeTot, on average, while SeOrg in the topsoil accounted for more than 50% of SeTot. Barium in the western Amazon (state of Acre) and central Amazon (Anori, state of Amazonas) exceeded national prevention levels (PVs). Furthermore, the average ITot in the studied topsoils (5.4 mg kg-1) surpassed the worldwide mean. Notwithstanding, the close relationship found between the total content of the elements (Se, Ba, and I) and soil texture (clay, silt, and sand) suggests their geogenic source. Finally, our data regarding SeTot, BaTot, and ITot can be used to derive regional quality reference values for Amazon soils and also for updating prevention (PV) and investigation (IV) values established for selected elements by the Brazilian legislation.

Efeitos de longo prazo do espaçamento de plantio no crescimento e morfometria de Bertholletia excelsa / Long-term effects of plant spacing on the growth and morphometry of Bertholletia excelsa

O espaçamento de plantio determina a forma e produtividade das árvores em plantações florestais. Entretanto, seus efeitos sobre a produtividade de plantações de espécies arbóreas da Amazônia ainda são pouco compreendidos. Objetivou-se examinar os efeitos de seis regimes de espaçamento (3 x 4, 4 x 4, 4 x 5, 5 x 5, 5 x 6, e 6 x 6 m) sobre o crescimento e morfometria de plantações de Bertholletia excelsa aos 20 anos de idade. Observamos alta sobrevivência independentemente do espaçamento (> 70%). Para fins de produção de madeira, os regimes de espaçamento intermediário e dois maiores apresentaram valores mais altos de características de produção, principalmente diâmetro, biomassa e volume, embora alguns não diferiram significativamente do menor espaçamento. Um dos espaçamentos intermediários (5 x 5 m) tendeu a maior altura comercial. As copas das árvores tenderam a ser mais largas e longas nos espaçamentos maiores, indicando potencial desses regimes para a produção de frutos. As copas das árvores excederam o espaço vital de crescimento em todos os espaçamentos, sugerindo a necessidade de desbaste antes dos 20 anos em todos os espaçamentos, para reduzir a competição intraespecífica e aumentar a produtividade. Estimamos que uma densidade de 84 árvores remanescentes por hectare seria necessária para atingir um diâmetro médio de 40 cm aos 20 anos. Portanto, B. excelsa apresentou alta sobrevivência em todos os regimes de espaçamento testados, enquanto os regimes de espaçamento intermediário e maiores proporcionaram melhor crescimento e morfometria das árvores. (AU)

Natural variation of arsenic fractions in soils of the Brazilian Amazon.

Arsenic (As) in native soils of the Amazon rainforest is a concern due to its likely origin from the Andean rivers, which transport loads of sediments containing substantial amounts of trace elements coming from the cordilleras. Yet, unveiling soil As baseline concentrations in the Amazon basin is still a need because most studies in Brazil have been performed in areas with predominantly high concentrations and cannot express a real baseline value for the region. In this study, 414 soil samples (0-20, 20-40 and 40-60 cm layers) were collected from different sites throughout the Amazon basin - including native Amazon rainforest and minimally disturbed areas - and used to determine total and extractable (soluble + available) As concentrations along with relevant soil physicochemical properties. Descriptive statistics of the data was performed and Pearson correlation supported by a Principal Component Analysis (PCA) provided an improved understanding of where and how As concentrations are influenced by soil attributes. Total As concentration ranged from 0.98 to 41.71 mg kg-1 with values usually increasing from the topsoil (0-20 cm) to the deepest layer (40-60 cm) in all sites studied. Considering the proportional contribution given by each fraction (soluble and available) on extractable As concentration, it is noticeable that KH2PO4-extractable As represents the most important fraction, with >70% of the As extracted on average in all the sites studied. Still, the extractable fractions (soluble + available) correspond to ~0.24% of the total As, on average. Total, available, and soluble As fractions were strongly and positively correlated with soil Al3+. The PCA indicated that soil pH in combination with CEC might be the key factors controlling soil As concentrations and the occurrence of each arsenic fraction in the soil layers.

Rede Hospitalar Pública no Rio Grande do Norte: um estudo sobre a utilização dos leitos hospitalares por Região de Saúde / Resizing the State Public Hospital System in Rio Grande do Norte: a study on the use of hospital beds by Health Region

Estudo comparativo sobre o nível de utilização dos leitos hospitalares sob gestão pública nas oito regiões de saúde do Rio Grande do Norte (RN). O rocesso decisório dos gestores da saúde requer indicadores e ferramentas que ubsidiem uma prática estruturada de planejamento e programação.

Comparative study on the level of use of hospital beds under management in ight public health regions in Rio Grande do Norte (RN). The decision process of managers of health requires indicators and tools that support a structured practice of planning and scheduling.

Comportamento de espécies florestais em plantios a pleno sol e em faixas de enriquecimento de capoeira na Amazônia / Forest species behavior in plantations at full sun and secondary forest enrichment strips in the Amazon

Foram avaliadas espécies florestais nativas e exóticas em duas condições de plantio: a pleno sol e em faixas de enriquecimento de capoeira, a fim de gerar tecnologias para incorporação ao processo produtivo de áreas alteradas na região amazônica para minimizar a pressão do desmatamento sobre a floresta natural. Os dados analisados (DAP, altura, volume por hectare e sobrevivência) referem-se à idade de seis anos. No plantio a pleno sol, a espécie que apresentou o melhor desempenho foi Ceiba pentandra, com médias de DAP de 19,6 cm, altura de 10,2 m e volume de 390,9 m³ ha-1. Hymenaea courbaril também apresentou crescimento satisfatório, com médias de 11,5 cm de DAP, 10,8 m de altura e 144,8 m³ ha -1 de volume. Nos plantios de enriquecimento de capoeira, a Carapa guianensis foi a espécie que apresentou o melhor desempenho, com 8,3 cm de DAP, 6,4 m de altura e volume de 54,8 m³ ha -1. Acacia mangium e Sclerolobium paniculatum apresentaram crescimento superior, mas as taxas de sobrevivência foram muito baixas nas duas condições de plantio.

This work evaluated exotic and native forest species in two plantation conditions: full sun and secondary forest enrichment strips, for generating technologies into incorporate to the productive process of degraded lands in the Amazonian region, to minimize the deforestation pressure on the natural forest. The analyzed data (DBH, height, volume per hectare and survival) refers to six years old species. In the full sun plantation, the species that presented the best performance was Ceiba pentandra, with means: DBH of 19.6 cm, height of 10.2 m and volume of 390.9 m³ ha-1. Hymenaea courbaril also presented satisfactory growth, with means: DBH of 11.5 cm, height of 10.8 m and volume of 144.8 m³ ha-1. In the secondary forest enrichment plantation, Carapa guianensis was the species that presented the best performance, with means: DBH of 8.3 cm, height of 6.4 m and volume of 54.8 m³ ha-1. Acacia mangium and Sclerolobium paniculatum presented better growth. However, the survival rates were very low in both plantations.