Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?

Most Amazonian soils are highly weathered and poor in nutrients. Therefore, photosynthesis and plant growth should positively respond to the addition of mineral nutrients. Surprisingly, no study has been carried out in situ in the central Amazon to address this issue for juvenile trees. The objective of this study was to determine how photosynthetic rates and growth of tree saplings respond to the addition of mineral nutrients, to the variation in leaf area index of the forest canopy, and to changes in soil water content associated with rainfall seasonality. We assessed the effect of adding a slow-release fertilizer. We determined plant growth from 2010 to 2012 and gas exchange in the wet and dry season of 2012. Rainfall seasonality led to variations in soil water content, but it did not affect sapling growth or leaf gas exchange parameters. Although soil amendment increased phosphorus content by 60 %, neither plant growth nor the photosynthetic parameters were influenced by the addition of mineral nutrients. However, photosynthetic rates and growth of saplings decreased as the forest canopy became denser. Even when Amazonian soils are poor in nutrients, photosynthesis and sapling growth are more responsive to slight variations in light availability in the forest understory than to the availability of nutrients. Therefore, the response of saplings to future increases in atmospheric [CO2] will not be limited by the availability of mineral nutrients in the soil

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Efeito dos genótipos para alphaS1-caseína sobre as frações proteicas e lipídicas do leite de cabra Effect of genotypes for αs1-casein on proteic and lipidic fractions in goat milk

O alto polimorfismo encontrado no lócus do gene da αS1-caseína em caprinos, classificado em quatro níveis de expressão - alto, médio, baixo e nulo -, está associado à produção de 3,6; 1,6; 0,6 e 0g/L/alelo, respectivamente. O estudo foi realizado para investigar possíveis variações na produção de leite e seus constituintes, no perfil de caseínas e na lipólise da gordura. Quarenta e quatro cabras foram distribuídas em cinco genótipos: dois homozigotos, um para alta (AA) e outro para produção intermediária (EE), e três heterozigotos chamados AE, AF e EF, para αs1-caseína. Para a lipólise, o leite foi subamostrado em quatro alíquotas que sofreram tratamento térmico no momento da ordenha e após 24h de resfriamento. Diferenças entre genótipos foram observadas para a produção de caseína e de suas frações. As demais variáveis não diferiram entre genótipos. O genótipo AA apresentou os maiores conteúdos de caseína (28,6g/L) e de αS1-cn (22,3%). Os demais genótipos apresentaram média de 20,4g/L. Os grupos AE e AF apresentaram média de 12,1, EE-10,1 e EF-9,1% de αS1-cn. O resfriamento do leite por 24 horas aumentou a taxa de lipólise no leite. A genotipagem das cabras para αS1-cn pode ser usada como ferramenta de seleção com objetivo de obter produtos lácteos com distintos perfis de proteínas.A high polymorphism is found in the locus of goat αS1-casein gene and it is classified in four levels of expression, named high, medium, and low, associated with production of 3.6, 1.6, 0.6, and 0 g/L/allele, respectively. The study was conducted to investigate possible variations on milk yield and components, profile of casein, and lipolysis of fat. Forty-four goats were assigned to five distinct genotypes as two homozygous, one for high (AA) and the other for intermediate yield (EE); and three heterozygous named AE, AF, and EF for the αs1-casein. For lipolysis, milk was sampled in four aliquots which were treated soon after milking and 24 hours after cooling. Differences were observed for both casein yield and its fractions. No difference was found for other variables. The AA genotype presented the higher content of both casein (28.6g/L) and αS1-cn (22.3%). Other genotypes averaged 20.4g/L for casein content. Values of αS1-cn were 12.1% for heterozygous and 10.1 and 9.1% for both EE and EF genotype respectively. Cooling the milk for 24 hours increased the rate of lipolysis. Genotyping goats for the αS1-cn can be used as a tool for selecting animal targeting milk products with distinct profiles of proteins