Cobertura de líquens em um gradiente borda-interior na Amazônia Central

Nas florestas tropicais, o efeito de borda é considerado um dos fatores que afetam o equilíbrio do ecossistema. Como consequência desse distúrbio, inúmeros grupos de organismos têm suas populações afetadas. Os líquens são particularmente sensíveis às mudanças microclimáticas, pois retiram nutrientes diretamente da atmosfera e apresentam pequena capacidade de regulação de perda e ganho de água. Eles são classificados quanto às formas e o crescimento. O objetivo deste trabalho foi testar se líquens com diferentes características morfo-anatômicas apresentam tolerância distinta às condições de borda florestal. A hipótese testada é de que líquens com características morfo-anatômicas que minimizem a perda de água são menos susceptíveis ao efeito de borda. Nas árvores amostradas foram amostrados 389 pontos com líquens do tipo “A” (líquens crostosos com córtex liso e sem protalos) e 123 com líquens do tipo B (líquens hidrófilos, sem córtex definido, que retêm água nos protalos). Embora não tenha havido relação entre a distância de borda e a cobertura dos liquens do tipo “A”, a cobertura relativa dos líquens do tipo B diminuiu com o aumento da distância da borda. Houve relação negativa entre a distância da borda e a temperatura ao meio dia e foi encontrada uma relação entre a distância da borda e a umidade relativa do ar. Nos 10 primeiros metros de distância da borda os líquens do tipo B apresentaram uma maior cobertura relativa, já nas distâncias subsequentes houve uma inversão, onde os líquens do tipo A passaram a ter maior cobertura relativa

Density-dependent regulation in a weed Bidens sulphurea (Cav.) Sch. Bip. (Asteraceae)

The density effects on performance of a weed Bidens sulphurea (Asteraceae) were evaluated experimentally. There are very few studies available to improve the process of density-dependent to invasive species. It was used an experimental set-up in which the population of this weed species is partitioned into different density groups (1, 2, 4 and eight plants per pot) based on local conspecific density to investigate density-based population strategies. The difference between the greatest and the lowest density (8 and 1 plant per pot) was considerably high, around 41%, regarding the variables measured (stem height and diameter, leaf number and size). Plants at higher densities have become taller and thinner as a consequence of intraspecific competition. Therefore, the results suggest that the responses of B. sulphurea in dense populations can affect the persistence of population over time. These results may be useful in the future for the biological control of this species.

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 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,18,19 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

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 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,18,19 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

Fragmentação de habitats e dominação das assembléias por plantas pioneiras: evidências de uma velha paisagem da floresta atlântica nordestina

A fragmentação florestal tem afetado a capacidade de regeneração de espécies arbóreas nos fragmentos florestais, o que sugere que, futuramente, esses abrigarão apenas uma parcela ínfima da flora original. O presente estudo teve como objetivo comparar: (i) a riqueza da assembléia de plântulas, jovens, e adultos, (ii) avaliar se o banco de plântulas apresenta uma maior proporção de indivíduos de espécies pioneiras e com sementes pequenas, e (iii) se há uma diferenciação taxonômica entre os estágios de plântula, juvenis e adultos. Foram amostradas plântulas (indivíduos com até 50 cm de altura, sem indícios de propagação vegetativa) e juvenis (indivíduos com DAP g 2 e h 5 cm) em parcelas de 0,1 ha em 20 fragmentos com tamanhos entre 3,4 e 91,1 ha, em uma paisagem severamente fragmenta. A comparação com a flora de adultos foi possível por conta de um levantamento pretérito. Foram encontradas diferenças entre a riqueza de espécies nos três estágios ontogenéticos, com a riqueza do estágio de plântulas apresentando 27% menos espécies que a riqueza no estágio de adultos. Não foi observada diferença entre os estágios de plântulas e juvenis, nem entre juvenis e adultos. Além disso, o estágio de plântulas apresentou em média 10% mais indivíduos e 11% mais espécies arbóreas com sementes pequenas do que o estágio de juvenis. Através da técnica do NMDS, foi identificada uma diferenciação na composição taxonômica entre os estágios ontogenéticos. Nossos resultados sugerem que o longo período de fragmentação florestal mantém a flora arbórea dos fragmentos florestais sempre em estágios iniciais de regeneração, e com a composição funcional e taxonômica simplificadas, não alcançando a complexidade estrutural e ecológica de uma floresta madur

Tolerance Mitigates Gall Effects When Susceptible Plants Fail to Elicit Induced Defense

Variations in plant genotypes and phenotypes are expressed in ways that lead to the development of defensive abilities against herbivory. Induced defenses are mechanisms that affect herbivore insect preferences and performance. We evaluated the performance of resistant and susceptible phenotypes of Bauhinia brevipes (Fabaceae) against attacks by the gall-inducing insect Schizomyia macrocapillata (Diptera). We hypothesized that there is a positive relationship between resistance to S. macrocapillata and host plant performance because resistance can have a high adaptive value. We evaluated plant architecture, nutritional leaf quality, leaf fluctuating asymmetry, and reproductive capacity between phenotypes. Plant performance was evaluated at three ontogenetic stages: seed, seedling, and juvenile. Overall, there were no differences in vegetative and reproductive performance or asymmetry between the resistant and susceptible mature plants. We found no relationship between leaf nutritional quality and resistance to S. macrocapillata. Plant performance was consistent across ontogeny for both phenotypes, except for five variables. Contrary to our expectations, the susceptible plants performed equally well or better than the resistant plants, suggesting that tolerance and overcompensation to herbivory in B. brevipes may be mediated by induced defense. Our study highlights the importance of multiple layers of plant defense against herbivory, where plant tolerance acts as a secondary barrier in plants susceptible to gall-inducing insects

Sampling completeness changes perceptions of continental scale climate–species richness relationships in odonates

Aim: Insects are one of the least studied taxa, with most species lacking basic ecological and biogeographical information. This problem is particularly acute in the tropics, where low sampling effort hampers accurate estimates of species richness at scale and potentially confounds efforts to identify the drivers of biogeographical gradients. Here, we evaluate the quality of the data on the distribution and diversity of odonate species in the Neotropics, while also examining the influence of sampling completeness on climate–richness relationships using a comprehensive database of odonates. Location: The Neotropics. Taxon: Odonata. Methods: Using 56,535 records collected from 1970 to 2021, we assess whether climate–species richness models vary under different scenarios of survey completeness. Results: Our survey compilation revealed that most Neotropical diversity of Odonata likely remains unknown. Only 1% of the one-degree cells covering the Neotropics held reliable information on odonate species richness, with particularly severe gaps in the Caribbean, Central America, northeastern Brazil and northern Chile. Temperature, precipitation and potential evapotranspiration exert consistent effects on Odonata richness across the entire Neotropics, regardless the level of survey completeness. Whereas seasonality-related variables are less important predictors of species richness at the biogeographical scale. Main Conclusions: By highlighting areas where inventories are more reliable and identifying regions that require increased data collection efforts and mobilization, our assessment offers a roadmap for improving the reliability of odonate inventories in the Neotropics. Furthermore, our findings underscore the importance of accounting for varying levels of survey completeness in macroecological models to reveal robust climate–species richness relationships. Simultaneously, they highlight strong climatic predictors of species richness, irrespective of survey effort intensity. These predictors provide a solid foundation for modelling and predicting odonate species richness in the Neotropics.Fil: Alves Martins, Fernanda. Centro de Investigación en Biodiversidades y Recursos Energético; Portugal. Universidad de Porto; PortugalFil: Stropp, Juliana. Museo Nacional de Ciencias Naturales; EspañaFil: Juen, Leandro. Universidade Federal do Pará; BrasilFil: Ladle, Richard J.. Universidad de Porto; Portugal. Centro de Investigación en Biodiversidades y Recursos Energético; PortugalFil: Lobo, Jorge M.. Museo Nacional de Ciencias Naturales; EspañaFil: Martinez Arribas, Javier. Centro de Investigación en Biodiversidades y Recursos Energético; PortugalFil: Marco Júnior, Paulo De. Universidade Federal de Goiás; BrasilFil: Schlemmer Brasil, Leandro. Universidade Federal Do Mato Grosso;Fil: Ferreira, Victor Rennan Santos. Universidade Federal do Pará; BrasilFil: Bastos, Rafael Costa. Universidade Federal do Pará; BrasilFil: Córdoba Aguilar, Alex. Universidad Nacional Autónoma de México; MéxicoFil: Medina Espinoza, Emmy Fiorella. Universidade Federal do Pará; BrasilFil: Dutra, Silvia Viviana. Universidade Federal do Norte do Tocantins; BrasilFil: Vilela, Diogo Silva. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Cordero Rivera, Adolfo. Universidad de Vigo; EspañaFil: del Palacio, Alejandro. Universidad Nacional de Avellaneda; ArgentinaFil: Ramírez, Alonso. North Carolina State University; Estados UnidosFil: Carvalho Soares, Anderson André. Universidade Federal do Pará; BrasilFil: Farias, Antonio Bruno Silva. Universidade Federal de Sergipe; BrasilFil: Resende, Bethânia Oliveira de. Universidade Federal do Pará; BrasilFil: Santos, Bruna dos. Universidade de Sao Paulo; BrasilFil: Bota Sierra, Cornelio A.. Universidad de Antioquia; Colombia. University of Alabama at Birmingahm; Estados UnidosFil: Mendoza Penagos, Cristian Camilo. Universidade Federal do Pará; BrasilFil: Veras, Daniel Silas. Universidade Federal do Pará; BrasilFil: Pessacq, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónica. Universidad Nacional de la Patagonia "San Juan Bosco". Centro de Investigación Esquel de Montaña y Estepa Patagónica; ArgentinaFil: Miguel, Thiago Barros. Instituto Federal de Educação Ciências e Tecnologia de Mato Grosso; BrasilFil: Mendes, Thiago Pereira. Universidade Estadual do Maranhão; BrasilFil: Neiss, Ulisses Gaspar. Instituto Nacional de Pesquisas da Amazônia; Brasil. Instituto de Criminalística; BrasilFil: Almeida, Wanessa Rejane de. Universidade Federal de Sergipe; BrasilFil: Hortal, Joaquín. Museo Nacional de Ciencias Naturales; España. Universidade Federal de Goiás; Brasi