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

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Mites (Arachnida, Acari) on Citrus sinensis L. Osbeck orange trees in the state of Amazonas, Northern Brazil Ácarofauna de Citrus sinensis L. Osbeck no estado do Amazonas, Brasil

Despite the importance of citriculture in Brazil, very little is known about mite populations in citrus crops in the Northern Region. In the municipality of Manaus, 12 sprayed sweet orange orchards were surveyed every two weeks during seven months to record mite species amount, and to describe the abundance and distribution of the most important species. The size and age of the orchards varied from 3,360 to 88,080 m² and seven to 25 years, respectively. In the fourteen sampling period, leaves, twigs and fruits were collected from 12 trees, one per orchard. In total, 3,360 leaves, 672 twigs and 1,344 fruits were sampled from 168 trees. Mites were manually extracted from the fruits, and by the washing method on leaves and twigs. We identified pests with the potential to cause economic loss. Fourteen species of phytophagous and mycophagous mites from Eriophyidae, Tarsonemidae, Tenuipalpidae, and Tetranychidae were recorded. Brevipalpus phoenicis (Geijskes 1939) and Phyllocoptruta oleivora (Ashm., 1879), the two commonest phytophagous mites in other Brazilian regions were dominant, showing that local orchards are susceptible to their infestation. Eleven predatory mites were recorded, comprising 10% of the mite population, belonging to Phytoseiidae and Ascidae. Phytoseiidae was the richest family, with ten species. The results are discussed in relation to the temporal variation aspects and habitat use of the most important species. Long-term research encompassing chemical applications followed by evaluations of the mite community are necessary for a better management of the orchards, taking into consideration the seasonal phenology of key pests.<br>Apesar da importância da citricultura no Brasil, pouco se conhece sobre as populações de ácaros em plantações de citros no norte do país. No município de Manaus, 12 pomares de laranja doce pulverizados foram avaliados a cada duas semanas, durante sete meses, para o registro de ácaros plantícolas e para descrever a abundância e a distribuição das espécies mais importantes. O tamanho e a idade dos pomares variaram de 3.360 a 88.0080 m² e de sete a 25 anos, respectivamente. Nos 14 períodos de coleta, folhas, galhos e frutos foram coletados de uma árvore em cada pomar. No total, 3.360 folhas, 672 galhos e 1.344 frutos foram coletados de 168 árvores. Os ácaros foram extraídos dos frutos manualmente e pelo método de lavagem nas folhas e galhos. Identificamos espécies pragas com potencial de causar danos econômicos. Registramos 14 espécies de fitófagos em quatro famílias (Eriophyidae, Tarsonemidae, Tenuipalpidae, and Tetranychidae). Brevipalpus phoenicis (Geijskes 1939) (Tenuipalpidae) e Phyllocoptruta oleivora (Ashm., 1879) (Eriophyidae), as duas espécies fitófagas mais abundantes em outras regiões, foram dominantes, mostrando que a cultura de citros local é suscetível à infestação. Registramos 11 espécies de predadores das famílias Phytoseiidae e Ascidae, compreendendo 10% da população total. Phytoseiidae foi a família mais diversa, com 10 espécies. Foram discutidos aspectos da variação temporal e utilização de hábitat das espécies mais abundantes. Estudos de longo prazo, envolvendo a aplicação de acaricidas e avaliações da comunidade de ácaros, são necessários para um melhor manejo dos pomares, levando-se em consideração a fenologia das pragas-chave

Plantas de ocorrência espontânea como substratos alternativos para fitoseídeos (Acari, Phytoseiidae) em cultivos de seringueira Hevea brasiliensis Muell. Arg. (Euphorbiaceae) Weeds as alternative substrates to phytoseiids (Acari, Phytoseiidae) in rubber tree Hevea brasilienis, Muell. Arg. (Euphorbiaceae) cultivation

O objetivo deste estudo foi determinar as espécies de plantas espontâneas em áreas de cultivo de seringueira que poderiam servir com reservatório de ácaros predadores. O trabalho foi conduzido em Olímpia, Estado de São Paulo, Brasil, em dois cultivos de seringueira. A cada três meses, cerca de 1.000 cm³ de folhas de cada uma das cinco espécies de plantas espontâneas dominantes em cada cultivo foi tomada para determinar os fitoseídeos. Como as plantas espontâneas dominantes variaram durante o estudo, um total de 20 espécies foi verificado. Somente Cecropia sp. foi dominante em todo estudo, em ambos os cultivos. Um total de 336 fitoseídeos pertencentes às seguintes espécies foi encontrado: Euseius citrifolius Denmark & Muma, 1970, E. concordis (Chant, 1959), Galendromus annectens (DeLeon, 1958), Iphiseiodes zuluagai Denmark & Muma, 1972, Neoseiulus anonymus (Chant & Baker, 1965) e N. tunus (DeLeon, 1967). E. citrifolius (189 espécimes) e N. tunus (138 espécimes) foram os mais abundantes. A maior abundância (231espécimes) e diversidade (5 espécies) foram observadas sobre Cecropia sp. Sobre esta planta foi encontrado o maior número de ácaros por amostra (29 espécimes), seguida por Piper duncum Linnaeus (22), Guarea sp. (18) e Ageratum conyzoides Linnaeus (12). E. citrifolius tem sido determinado como um dos ácaros predadores mais abundantes sobre seringueiras cultivadas na região onde este trabalho foi conduzido. Cecropia sp. parece ser uma das plantas espontâneas mais importantes consideradas como reservatório de E. citrifolius porque está continuamente presente nos cultivos. Estudos complementares poderiam indicar a viabilidade de se manejar esta planta nas áreas de cultivo de seringueira para permitir o controle biológico dos ácaros-praga desta cultura.<br>The objective of this study was to determine weed species of rubber tree cultivation areas that could serve as reservoirs of predatory mites. The work was conducted in Olímpia, State of São Paulo, Brazil, in two rubber tree plantations. Every three months, about 1.000 cm³ of leaves of each one of the five dominant weeds in each plantation was taken to determine the phytoseiids. As the dominant weeds varied during the study, a total of 20 species were evaluated. Only Cecropia sp. was a dominant weed throughout the study, in both plantations. A total of 336 phytoseiids of the following species were found: Euseius citrifolius Denmark & Muma, 1970, E. concordis (Chant, 1959), Galendromus annectens (DeLeon, 1958), Iphiseiodes zuluagai Denmark & Muma, 1972, Neoseiulus anonymus (Chant & Baker, 1965) and N. tunus (DeLeon, 1967). E. citrifolius (189 specimens) and N. tunus (138 specimens) were the most abundant species. The highest abundance (231 specimens) and diversity (5 species) were observed on Cecropia sp. On this plant was found the largest number of mites per sample (29 specimens), followed by Piper duncum Linnaeus (22), Guarea sp. (18) and Ageratum conyzoides Linnaeus (12). E. citrifolius has been determined as the most abundant predatory mite on rubber trees in the region where this work was conducted. Cecropia sp. seems to be the most important of the weeds considered as reservoir of E. citrifolius because it is continuously present in the plantations. Complementary studies could indicate the viability of managing this weed in or around rubber tree plantations to promote the biological control of mite pests on that crop