Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹

Influência do padrão espacial sobre a estimativa de densidade arbórea do método de quadrantes: um estudo por meio de simulação de Monte Carlo

O método de quadrantes tem sido bastante utilizado em levantamentos fitossociológicos de florestas tropicais. O método pressupõe que as árvores tenham padrão espacial completamente aleatório para que a estimativa da densidade (árvores ha-1) não apresente viés. Neste trabalho, analisou-se através de simulação de Monte Carlo de florestas hipotéticas, o efeito de desvios da Completa Aleatoriedade Espacial (C AE) em direção a padrões agrupados e regulares, sobre a estimativa da densidade obtida pelo método de quadrantes para populações com diferentes densidades, bem como a influência do tamanho da amostra sobre as estimativas. O aumento do tamanho da amostra não mostrou efeito significativo na redução de viés. Entre os padrões de distribuição dos indivíduos testados através de simulação, o viés na estimativa da densidade obtida pelo método de quadrantes oscilou entre +70,3% (distribuição perfeitamente regular, correspondente ao padrão em lattice) e -75,7% (distribuição fortemente agrupada, correspondente ao padrão agrupado com raio médio de agrupamento de 25 m). Com exceção das florestas com padrão espacial completamente aleatório e com padrão regular em lattice aleatorizado, em todos os outros padrões espaciais testados não houve relação clara entre a densidade da floresta e a precisão da estimativa de densidade efetuada pelo método de quadrantes. O método de quadrantes superestima a densidade em florestas com padrão regular, e subestima a densidade em florestas com padrão agrupado. Seria importante saber, a priori, o padrão espacial dos indivíduos na floresta para que fosse possível aplicar o método de quadrantes e interpretar corretamente os seus resultados, sem viés

Efeito do fogo sobre o banco de sementes em faixa de borda de Floresta Estacional Semidecidual, SP, Brasil Fire impact on the seed bank of a seasonal semideciduous forest edge, São Paulo State, Brazil

Os incêndios estão entre as principais causas da perda de diversidade em florestas tropicais. O presente estudo teve como objetivo avaliar o efeito do fogo sobre o banco de sementes em fragmento de floresta estacional semidecidual e verificar se a intensidade desses efeitos se altera em função da distância da borda. O estudo foi realizado na Estação Ecológica dos Caetetus, Estado de São Paulo. Cinco dias após a passagem do fogo, foram coletadas amostras da camada superficial do solo (5 cm de profundidade), em duas faixas: 0 a 20 m e 20 a 50 m de distância da borda, na área atingida pelo fogo e em floresta não queimada adjacente utilizada como controle. Na floresta não atingida pelo fogo a densidade foi de 257 sementes.m-2 e na área queimada de 97 sementes.m-2. Quarenta espécies ocorreram na área não queimada e 26 espécies na área queimada. Ervas e gramíneas tiveram densidade relativa superior na área queimada. Para as espécies arbóreas as perdas decorrentes do fogo foram maiores na faixa mais externa do fragmento (menor riqueza e densidade), provavelmente devido à amplificação dos efeitos do fogo causada pelos efeitos de borda.Fire has been one of the main causes of diversity loss in tropical forests. The aim of this study was to evaluate the effects of fire on the seed bank in a seasonal semideciduous forest fragment, and to verify whether these impacts are influenced by distance from the edge. The study was carried out at Caetetus Ecological Station (São Paulo state, Brazil). Surface soil samples (5 cm depth) were collected at two different distances from the edge (0-20 and 20-50 m), five days after fire. The same sampling procedure was applied to an unburned neighboring forest for comparison. In the unburned forest, density was 257 seeds.m² and in the burned area it was 97 seeds.m². Forty species occurred in the unburned forest and 26 species in the burned area. Relative density of herbs and grasses was higher in the burned area. The closer to the border, the higher were the losses observed for tree species, likely amplified by the interaction between fire and edge effects

Giardiasis as a neglected disease in Brazil: systematic review of 20 years of publications

Giardiasis is an intestinal infection that affects more than two hundred million people annually worldwide; it is caused by the flagellated protozoan Giardia duodenalis. In tropical countries and in low or middle-income settings, like Brazil, its prevalence can be high. There is currently no systematic review on the presence of G. duodenalis in patients, animals or water sources in Brazil. This systematic review was performed according to recommendations established by Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). As databases for our searches, we have used PubMed, Embase, Scopus and the Brazilian database SciELO using the keywords «Giardia*» and «Brazil». This systematic review identified research studies related to G. duodenalis in water, giardiasis in animals, prevalence of giardiasis across Brazilian regions, genotyping of strains isolated in humans, and giardiasis in indigenous populations. We also propose a network of G. duodenalis transmission in Brazil based on genotypes analyses. This is the first time within the last twenty years that a review is being published on the occurrence of G. duodenalis in Brazil, addressing relevant issues such as prevalence, molecular epidemiology and analytical methods for parasite detection. || Giardiasis is an intestinal disease that affect millions of people worldwide, including children. Its main route of transmission is by ingestion of food or water contaminated with the protozoan G. duodenalis. Transmission does not require an animal host, although transmission from animals to human (zoonotic transmission) has been confirmed as an important vector of human giardiasis. This study is a comprehensive description of the impact of giardiasis in Brazil based on studies published in the country from the past 20 years. We describe Giardia prevalence in humans (including indigenous populations), animals and water supplies. In addition, we create a transmission network model for the disease, based on genotype data previously identified in animal and human hosts as well as in environmental samples. The data compiled here will be useful for design of policies to prevent giardiasis transmission in Brazil.1110CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQSem informaçã

Molecular genotyping, diversity studies and high-resolution molecular markers unveiled by microsatellites in Giardia duodenalis.

BackgroundGiardia duodenalis (synonyms G. lamblia and G. intestinalis) is an enteric protozoan parasite of a wide range of mammalian hosts, including humans and various domestic and wild animals. There is considerable genetic variability in G. duodenalis and isolates of this parasite have been divided into eight genetic assemblages. Microsatellites markers can be used to discriminate isolates with a high level of sensitivity. This study was conducted to identify and characterize genomic microsatellites (simple sequence repeats-SSRs), sequences of one- to six-nucleotide motifs repeated in tandem, present in the available genomes of G. duodenalis and to develop new markers that can serve as a tool for detection and for characterizing the genetic diversity of this parasite.Methodology/ principal findingsFor each genetic assemblage, polymorphism levels for the microsatellite markers were evaluated. After performing the analysis using the MISA and SciRoKo software, 1,853 simple sequence repeats (SSRs) were identified. In all the genomes, trinucleotide repeats were the most common class followed by tetranucleotide. Many of the SSR loci are assemblage-specific, and 36 SSR loci shared among all the genomes were identified. Together with hypothetical proteins, variant-specific surface proteins represented nearly half of the annotated SSR loci. The results regarding the most common repeat among the SSRs led us to infer that positive selection occurred to avoid frameshift mutations. Additionally, based on inter- and intra-genetic assemblages polymorphism analyses, we unveiled previously undetected genetic variation, indicating that the microsatellite markers we developed are useful molecular tools for epidemiological inferences based on population genetics patterns and processes.ConclusionsThere is increasing demand for the development of new molecular markers and for the characterization of pathogens at a higher resolution level. In this study, we present 60 G. duodenalis microsatellites markers that exhibited high polymerase chain reaction (PCR) amplification efficiency among the different genetic assemblages. Twenty of these markers presented nucleotide sequence polymorphisms and may be used as a genotyping tool. The monomorphic markers can be used for the detection of the parasite at the species and genetic assemblage level. These polymorphic markers revealed a genetic diversity that was previously undetectable, thus they can be considered valuable molecular tools for high resolution markers in future studies investigating Giardia and may also be used for epidemiological inferences based on populations genetics patterns and processes

Giardiasis as a neglected disease in Brazil: Systematic review of 20 years of publications

<div><p>Introduction</p><p>Giardiasis is an intestinal infection that affects more than two hundred million people annually worldwide; it is caused by the flagellated protozoan <i>Giardia duodenalis</i>. In tropical countries and in low or middle-income settings, like Brazil, its prevalence can be high. There is currently no systematic review on the presence of <i>G</i>. <i>duodenalis</i> in patients, animals or water sources in Brazil.</p><p>Methods</p><p>This systematic review was performed according to recommendations established by Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). As databases for our searches, we have used PubMed, Embase, Scopus and the Brazilian database SciELO using the keywords «<i>Giardia</i>^<i>*</i>» and «Brazil».</p><p>Results</p><p>This systematic review identified research studies related to <i>G</i>. <i>duodenalis</i> in water, giardiasis in animals, prevalence of giardiasis across Brazilian regions, genotyping of strains isolated in humans, and giardiasis in indigenous populations. We also propose a network of <i>G</i>. <i>duodenalis</i> transmission in Brazil based on genotypes analyses.</p><p>Conclusion</p><p>This is the first time within the last twenty years that a review is being published on the occurrence of <i>G</i>. <i>duodenalis</i> in Brazil, addressing relevant issues such as prevalence, molecular epidemiology and analytical methods for parasite detection.</p></div

Prevalence of giardiasis found in indigenous population in Brazil.

<p>The table shows the indigenous tribe, the localization of the tribe across the country, prevalence, number of individuals enrolled in each study and the year of publication.</p

Result of each database search for the terms «<i>Giardia</i>^<i>*</i>» and «Brazil».

<p>Searches for articles in Portuguese, English, Spanish and French were made using four databases, including the Brazilian SciELO.</p