Notas sobre a ocorrência das serpentes Thamnodynastes pallidus e T. hypoconia (Dipsadidae) no estado do Maranhão, Nordeste do Brasil

We present here observations on records of the snakes Thamnodynastes pallidus and T. hypoconia in eastern Amazon, made during field sampling. Specimens of  both species were collected at Arari municipality, Maranhão state lowland (“Baixada Maranhense”) region, northeast Brazil, on a fluvial plain characterized by a mosaic of extensive natural floodplains, open vegetation and small forest remnants, as well as anthropic areas. The record of T. hypoconia is the second one of the species in Maranhão state and the first one in the eastern Amazon domain; it also fills a gap on the species distribution in the state. Pholidosis, color and morphometry of specimens are described.São apresentados novos registros das serpentes Thamnodynastes pallidus e T. hypoconia na Amazônia oriental, obtidos em amostragens realizadas em campo. Exemplares de ambas as espécies foram coletados em Arari, na região da Baixada Maranhense, Nordeste do Brasil. O registro de T. pallidus é o primeiro da espécie no Maranhão e o reporte de T. hypoconia corresponde à primeira ocorrência do táxon nos domínios da Amazônia oriental, além de preencher uma lacuna de sua distribuição no estado. Thamnodynastes pallidus e T. hypoconia são espécies amplamente distribuídas pela América do Sul

Prevalência e fatores relacionados a metahemoglobinemia em indivíduos da atenção básica de Anápolis-Go / Prevalence and factors related to metahemoglobinemia in individuals in primary care of Anápolis-Go

Introdução: A metemoglobinemia é uma enfermidade de grande importância devido a sua sintomatologia inespecífica e a consequências potencialmente fatais. Todavia, no Brasil, sua prevalência ainda não foi descrita na atenção primária, inviabilizando estratégias da saúde pública para identificação e a realização de diagnóstico precoce. Objetivo: Avaliar a prevalência e fatores relacionados a metemoglobinemia, utilizando um CO-oxímetro de pulso, em pacientes de Unidades Básicas de Saúde do município de Anápolis - GO. Metodologia: Foram incluídos 482 pacientes, acima de 18 anos, que estavam realizando consultas ambulatoriais na atenção básica da cidade de Anápolis-GO entre agosto a outubro de 2016. Os indivíduos responderam um questionário sobre dados socio-demográficos e tiveram medidas suas taxas de carboxiemoglobina, metahemoglobina e oxi-hemoglobina. Resultados: Utilizando-se a definição de metemoglobinemia quando a metemoglobina (MetHbA)> 1%, a prevalência de metahemoglobinemia nos pacientes na atenção básica foi de 16%. Observou-se correlação negativa entre a saturação de oxigênio e a concentração de metahemoglobina (coeficiente: -0,30; p< 0,0001) e correlação positiva entre a concentração de monóxido de carbono e a concentração de metahemoglobina (coeficiente: 0,14; p=0,002). A regressão logística multivariada demonstrou que a saturação de oxigênio, OR:0,49; IC 95% 0,40-,60; p<0,0001 e a concentração de monóxido de carbono OR:1,27; IC 95% 1,13-1,43; p=0,001 predizem a presença de metahemoglobinemia. Conclusão: Foi identificada prevalência considerável (16%) de metemoglobinemia nos pacientes da atenção básica. São fatores relacionados a presença de metemoglobinemia a redução da saturação de oxigênio e o aumento da concentração de monóxido de carbono.

The number of tree species on Earth

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global groundsourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are 73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species$^{1,2}$. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies$^{3,4}$. Here, leveraging global tree databases$^{5,6,7}$, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions

Native diversity buffers against severity of non-native tree invasions.

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species1,2. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies3,4. Here, leveraging global tree databases5-7, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions

The global biogeography of tree leaf form and habit

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17-34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling