Amazonia Research Articles

Kinetic study of isoprene hydroxy hydroperoxide radicals reacting with sulphur dioxide and their global-scale impact on sulphate formation.

Isoprene is the most relevant volatile organic compound emitted during the biosynthesis of metabolism processes. The oxidation of isoprene by a hydroxy radical (OH) is one of the main consumption schemes that generate six isomers of isoprene hydroxy hydroperoxide radicals (ISOPOOs). In this study, the rate constants of ISOPOOs + sulphur dioxide (SO2) reactions that eventually generate sulphur trioxide (SO3), the precursor of sulphate aerosol (SO42-(p)), are determined using microcanonical kinetic theories coupled with molecular structures and energies estimated by quantum chemical calculations. The results show that the reaction rates range from 10-27 to 10-20 cm3 molecule-1 s-1, depending on the atmospheric temperature and structure of the six ISOPOO isomers. The effect of SO3 formation from SO2 oxidation by ISOPOOs on the atmosphere is evaluated by a global chemical transport model, along with the rate constants obtained from microcanonical kinetic theories. The results show that SO3 formation is enhanced in regions with high SO2 or low nitrogen oxide (NO), such as China, the Middle East, and Amazon rainforests. However, the production rates of SO3 formation by ISOPOOs + SO2 reactions are eight orders of magnitude lower than that from the OH + SO2 reaction. This is indicative of SO42-(p) formation from the direct oxidation of SO2 by ISOPOOs, which is almost negligible in the atmosphere. The results of this study entail a detailed analysis of SO3 formation from gas-phase reactions of isoprene-derived products.

The Floating Primary Health Center Model in the Amazon Rainforest.

The Floating Primary Health Center Model in the Amazon Rainforest.

Leaf litter nutrient content reveals benefits to traditional cropping systems in the Amazon

Soil fertility in the Amazon rainforest is very dependent to litter decomposition as a source of organic carbon and nutrients. Thus, land use that promote high litter decomposition might play a positive influence on soil chemical properties. The present study aimed to quantify the nutritional content of litter in anthropized and natural environments in Southern Amazonas. The study was conducted on two properties in the municipality of Canutama, in four areas: native forest, annatto, cupuassu, and guarana. In each area, 10 conical collectors (0.21 m²) were installed at a height of 0.3 m from the ground. The samples collected in each area for each month were dried in a forced circulation oven at 60ºC until reaching constant mass and weighed. Macro- and micronutrient content analyses were performed by sulfuric solubilization (N), nitric perchloric solubilization (Ca, Mg, P, K, Na, S, Cu, Fe, Mn, and Zn) and incineration (B). Variance analysis and comparison of means by Tukey test at the 5% probability level were applied to the data obtained, along with a multivariate analysis. This comparison was carried out by evaluating the overall average of a whole year of litter formation, as well as for formation within each month evaluated. Sulfur (S) was the only macronutrient that did not differ between environments (0.1 and 0.2 g kg-1). Macronutrients and micronutrient contents of litter (N: 16.92; Mg: 1.08; Cu: 16.00; Zn: 31.70; B: 104.40; g kg-1) were significantly highest in the annatto area. Annato also presents higher K (9.92 g kg-1) and P (0.70 g kg-1) contents. The litter of natural forest and guarana are richer in P (0.88 g kg-1) and Ca (g kg-1), respectively. Cupuassu litter showed lower nutritional contents, especially in macronutrients contents (N: 9.04; P: 0.51; K: 0.28; Ca: 0.76; Mg: 0.44; g kg-1). This indicates that traditional Amazonian agroecosystems may positively to improve quality of litter and impact nutrient cycling in soils highly weathered in the region.

Calibration of the SMAP Soil Moisture Retrieval Algorithm to Reduce Bias Over the Amazon Rainforest

Calibration of the SMAP Soil Moisture Retrieval Algorithm to Reduce Bias Over the Amazon Rainforest

“Tenía una mujer, pero nunca la vimos”. Una mirada femenina al auge de la goma elástica (Bolivia, XIX-XX)

The extractive rubber boom in Bolivian Amazonia (1880-1920) not only reconfigured interethnic relations between indigenous peoples and white settlers but also reshaped the geopolitics of the region, as well as the way in which the Amazon rainforest itself was perceived by the national and international imaginaries. However, the historical and anthropological literature usually presents us with a hyper-masculinised view that tends to ignore or render almost invisible the role of women during the rubber era. Our aim is precisely to describe and analyse the roles played by mestizo and indigenous women in these extractive circuits, in order to reconstruct their agency as protagonists and to render their presence visible as active participants of the rubber industry.

Isolation, genetic identification of Amazonian yeasts and analysis of thermotolerance and alcohol tolerance of <i>Saccharomyces cerevisiae</i> from <i>Theobroma grandiflorum</i> and <i>Eugenia stipitata</i>

<abstract> <p>Although yeasts of the <italic>Saccharomyces cerevisiae</italic> species are industrially significant, few studies have investigated their presence in environmental samples from the Amazon rainforest. This study aimed to isolate <italic>S. cerevisiae</italic> yeasts associated with trees of the Amazon Forest and investigate their thermotolerance, alcohol tolerance, and single nucleotide polymorphism (SNP) characteristics, along with those of regional strains from previous research and reference strains from the industry. We collected fruits, bark and decaying plant material from <italic>Theobroma grandiflorum</italic>, <italic>Spondias mombin</italic> L., <italic>Mangifera indica</italic> L., and <italic>Eugenia stipitata</italic>, and isolated yeasts using the culture media. To identify the yeasts, we conducted morphological and biochemical analyses, including sugar assimilation and fermentation, and sequencing analyses of the rDNA (ITS and LSU (D1 and D2)). We also performed fermentation tests to determine the optimum temperature, thermotolerance and ethanol tolerance. Finally, we subjected the selected strains to SNP analysis to study the reported genes that are important for alcohol tolerance in <italic>S. cerevisiae</italic>: FPS1 (farnesyl diphosphate synthase1) and ASR1/YPR093 (alcohol sensitive RING/PHD finger1) genes. As a result, we isolated 53 yeasts, and 10 of which exhibited a sugar assimilation and fermentation profile that was similar to that of <italic>S. cerevisiae</italic>. These ten isolates were identified using sequencing of the ITS and LSU regions, which revealed the species to be <italic>Wickerhamomyces anomalus</italic> (n = 4), <italic>Torulaspora pretoriensis</italic> (n = 3), <italic>Debaryomyces hansenni</italic> (n = 1), and <italic>Saccharomyces cerevisiae</italic> (n = 2). Through the analysis of the ASR1 and FPS1 regions, we found an SNP at nucleotide 1552 A > G (FPS1), which was associated with ethanol tolerance under our experimental conditions. This work is significant because it is one of the first studies to focus specifically on the isolation of <italic>S. cerevisiae</italic> from samples in the Amazon region. Furthermore, the SNP analysis allowed us to differentiate isolates that showed greater tolerance to ethanol.</p> </abstract>

Diet of crab-eating fox (Cerdocyon thous) in two conservation units of the Amazon rainforest, Brazil.

The present study aimed to evaluate the diet of the free-living crab-eating fox by identifying the stomach contents of the 17 crab-eating foxes (Cerdocyon thous) roadkilled in two conservation units, both located in the Amazon rainforest. The food items were quantified by frequency of occurrence (FO) and percentage of occurrence (PO). The stomach contents were analysed for dry matter (DM), crude protein (CP), crude fibre (CF), ether extract (EE), and mineral matter (MM). Nitrogen-free extractives (NFE), metabolisable energy (ME) values, as well as the energy need for maintenance were estimated. The composition of the diet for the crab-eating fox presented 29 food items from the different taxonomic groups, with a greater diversity of items of animal origin (n=22), although the highest frequency of occurrence was gramineae (Poaceae) (41.18%). Among the items of animal origin, 21% were mammals, 18% reptiles, 10% amphibians, 9% invertebrates and 3% birds. A high content of CF (62.76%) were determined. Nitrogen-free extractive and dry matter averages were 5.91% and 141.82 kcal/100g, respectively. The average maintenance energy was 447.01 kcal/day. These findings suggesting that the crab-eating foxes have a generalist diet with an omnivorous diet in the Amazon basin, feeding on gramineae, fruits, insects, snakes, amphibians, birds and small mammals and have the same feeding habit that present in other Brazilian biomes.

Multi-stage algorithm for detecting landing strips in the Amazon rainforest

Multi-stage algorithm for detecting landing strips in the Amazon rainforest

Estrutura populacional e distribuição espacial de Guadua weberbaueri Pilg. em florestas nativas e antropizadas da Amazônia Ocidental brasileira

ABSTRACT Brazilian forestry laws do not provide specifications for the management of bamboo-dominated forests. This study aimed to characterize the bamboo population structure, its spatial distribution and the effects of shoot density on the diversity and density of dominant tree species in the southwest of the Amazon Rainforest. An inventory was carried out in forest with and without anthropogenic interference, and the height and diameter at breast height of the trees were measured, as well as the diametrical, vertical and spatial distribution of the shoots. The bamboo diametrical distribution presented an irregular behavior in the two areas under study and the vertical distribution behaved irregularly in the forest without anthropization, in an asymmetric negative way when compared to the forest that suffered anthropogenic disturbance. The bamboo spatial distribution did not show changes in its aggregate pattern between the studied environments, and its density did not present a significant correlation with the density and diversity of tree species.

Caracterização química e rateio de fontes de águas pluviais na Reserva Biológica de Cuieiras, Amazônia central, Brasil

ABSTRACT The Amazon rainforest plays a crucial role in the global climate system, acting as a major carbon sink and influencing regional and global weather patterns. Understanding the chemical composition of rainwater is essential for assessing the impact of anthropogenic activities, such as deforestation and industrial emissions, on atmospheric chemistry and hydrology. This work aimed to characterize the chemical composition of rainwater in a biological reserve of primary forest in the central Brazilian Amazon at 60 km of a large urban center. Rainwater samples were collected from March 2008 to March 2010 and were analyzed by ion chromatography, ICP-MS, and TOC-V. This is the only and longest rainfall monitoring carried out in this reserve. The results showed that the rainwater is rich in organic carbon (TOC), representing 77% of total carbon. The most abundant ions were NH4 + and Cl-. Few elements were detected, with emphasis on Al and Fe. In the dry season, most species were enriched. The lower amount of precipitation, biomass burning and the lower capacity to remove pollutants from the atmosphere are the main reasons for this seasonal difference. Only 7% had characteristics of acid rain (pH < 4.5), with acidity dominated by NO3 -. A positive matrix factorization indicated contribution of sources: crustal (48%), secondary aerosol (26%), biogenic (22%), and industrial emissions (4%). Although the forest has primary characteristics, the proximity to the urban center indicates some anthropogenic influence on the chemical composition of rainwater.

Bioconversão de resíduos de aves para produção de proteases por Aspergillus sp. isolado do solo da floresta Amazônica

ABSTRACT: Feathers are by-products that are generated in significant quantities by the poultry industry. Microbial bioconversion has been investigated as a promising strategy for the processing of feathers, since, along with the degradation of these keratinous materials, bioprocessing can result in value-added products. Thus, from the perspective of industrial microbiology, chicken feathers can be considered a raw material for obtaining microbial proteases. Within this context, this research investigated and characterized the production of extracellular proteases by Aspergillus sp., isolated from soil of the Amazon Rainforest. The enzymatic production was evaluated using several growth substrates (whole feathers, feather meal, human hair, casein, gelatin, peptone and chicken beaks). With highest enzyme production was obtained the feather meal (FM) and peptone. After 48 h of fermentation, FM degradation was 15.82%. The crude protease showed optimal activity at pH 5.0 and 37 °C and enzymatic activity was enhanced with the addition of 1 and 5 mM of CaCl2, MnSO4, KCl, MgSO4 and CuSO4. The detergents Tween 20 and Triton x-100, at concentrations 0.5 and 1% (v/v), tended to stimulate activity. The presence of 0.5 and 1% (v/v) of organic solvents (methanol, acetone, butanol, acetonitrile, isopropanol and DMSO), maintained the enzymatic activity. β-mercaptoethanolstimulated proteolytic activity in the enzymatic assays. This study suggested new direction for waste management with industrial applications giving rise to green technology for sustainable development.

Potencial uso terapêutico da ayahuasca: Uma revisão da literatura

ABSTRACT Ayahuasca is a psychoactive decoction originally used in indigenous Amazonian culture. It consists of a dense brown liquid that most frequently results from the decoction of two plants native to the Amazon rainforest, Psychotria viridis (Rubiaceae) and Banisteriopsis caapi (Malpighiaceae). The composition of the decoction is variable, as several plant species can be used in its preparation. Its psychoactive effect occurs due to the presence of N,N-dimethyltryptamine (DMT), an agonist at serotonergic receptors (5-HT1A/2A/2C) that is metabolized by the enzyme monoamine oxidase type A (MAO-A), and also the presence of β-carbolines, which are reversible MAO-A inhibitors. This joint interaction promotes a sequence of psychedelic neurochemical effects. Due to the current expansion of research on psychedelic substances and the growing public interest in the benefits of ayahuasca beyond its traditional use in the Amazon, academic research on its therapeutic capacity has been increasing. This study aimed to carry out a literature review on the scientific evidence for the therapeutic potential of ingesting ayahuasca. The review covered the period 2012-2022, and resulted in evidence on the therapeutic effects of ayahuasca on depression/anxiety, chemical dependency/alcoholism and Parkinson’s disease, as well as neuropsychological effects, and possible toxic effects on reproduction/embryonic development, among other adverse effects. The highest number of publications in the searched period dealt with the effects of ayahuasca on depression and anxiety. Further studies need to address the detailed mechanism of action of ayahuasca, as well as its potential toxicity, in order to demonstrate its safety.

Characterization of the Amazon Rainforest Backscatter at X-Band Using TanDEM-X Data

Characterization of the Amazon Rainforest Backscatter at X-Band Using TanDEM-X Data

Tick-borne Apicomplexa in wildlife and ticks of French Guiana.

Tick-borne Apicomplexa encompass a group of parasites responsible for significant medical and veterinary diseases, including babesiosis, theileriosis, and hepatozoonosis. In this study, we investigated the presence and diversity of tick-borne Apicomplexa in wildlife and ticks inhabiting the Amazon rainforests of French Guiana. To this end, we conducted molecular screening and typing using 18S rRNA sequences on a collection of 1161 specimens belonging to 71 species, including 44 species of wild mammals, five species of passerines, and 22 species of ticks. We characterized eight genovariants of Babesia, Theileria, Hemolivia, and Hepatozoon parasites, some matching known species, while others suggested potential novel species. These parasites were detected in wild mammals, including opossums, sloths, armadillos, porcupines, margays, greater grisons, and ticks, but not in passerines. Finally, similarities with surveys conducted in Brazil highlight the specific sylvatic transmission cycles of South American tick-borne Apicomplexa.

Spider Fungi: New species of Marasmius and Pusillomyces in the aerial rhizomorph webmaker guild in Amazonia

Rhizomorphs are hair- or wire-like melanized structures with structural differentiation analogous to plant roots that help fungi spread over an area and find food resources. Some species of multiple groups of the Ascomycota and the Basidiomycota produce different types of rhizomorphs. In the Agaricales, the structures are largely found in Marasmiineae, particularly in the Omphalotaceae, Marasmiaceae, and Physalacriaceae. Many rhizomorph-forming species spread over the forest floor (ground level), while others form aerial litter-trapping rhizomorph systems that hang on living branches of the forest understorey. Here, we describe three new species that form aerial systems, two in Marasmius and one in Pusillomyces, all of which inhabit areas of the Amazon rainforest in Amazonas State, Brazil. Support for these new species is based on evidence derived from morphological and molecular phylogenetic analyses using nuclear ribosomal internal transcribed spacer region (nrITS) and nuclear ribosomal large subunit (nrLSU) markers. Marasmius foliauceps sp. nov., with a pileipellis made up of Rotalis-type broom cells, is different from all other species described to date and branched along with species of the monophyletic Marasmius sect. Marasmius subsect. Marasmius, being conspecific with specimens from Guyana. Also different from all other described Marasmius species, Marasmius arachnotropus sp. nov. has a pileipellis mostly composed of Siccus-type but in transition to Rotalis-type broom cells and branched along with species of the Marasmius crinis-equi species complex. Pusillomyces cuieirasensis is morphologicallyvery similar to Pusillomyces manuripioides to which it is sister, but it has a non-umbonate pileus and smaller basidiospores. They all form aerial litter-trapping rhizomorph systems that mimic spider webs, particularly those hanging on the understorey. Whether made of mycelia or silk, such webs serve to capture food. The aerial rhizomorph-forming ‘spider fungi’ make up a guild with hidden species diversity in tropical systems.

Notes on the diet of <em>Anolis</em> lizards (Iguanidae: Dactyloinae) from Yasuní National Park in Amazonian Ecuador

We briefly describe the diet of six species of lizards of the genus Anolis in the Yasuní National Park, located in the western part of the Amazon Rainforest. A total of 241 prey items found in the stomachs of the lizards were identified. We noted that Aranea and Hymenoptera were the most frequent diet categories used by the lizard community. In terms of prey volume, Hemiptera and insect larvae were the most representative prey. The description of the diet of Anolis provided by this study can be further combined with information related to their natural history, thus shedding light on ecological mechanisms that influence adaptation.

The Ruins of a Steel Mill: Planetary Urbanization in the Brazilian Amazon

This article studies the socio-environmental history of a steel mill in Manaus, Brazil, the largest city in Amazonia. The Companhia Siderúrgica da Amazônia Sociedade Anônima, SIDERAMA, an integrated steel mill created in 1961 and liquidated in 1997 after a convoluted history of mismanagement, was part of private and public efforts to colonize the Brazilian Amazon through industrial urbanization. Exploring its impacts at a diversity of scales, the article presents it as a historical case study of planetary urbanization. The steel mill polluted the city of Manaus, and resource extraction to feed it with materials and energy disrupted environments and societies deep into the Amazon rainforest. This process underscores the global reach of urbanization during the second half of the twentieth century and the need to rethink the role of Amazonia during the Anthropocene.

Assessing the impact of gold mining on forest cover in the Surinamese Amazon from 1997 to 2019: A semi-automated satellite-based approach

The Amazon rainforest has faced extensive deforestation for decades due to urban growth, agricultural expansion, logging and mining. Mining however has been relatively understudied in the Amazon. The objectives of this study were: (1) to develop an effective cloud-based classification approach coupled with an innovative semi-automated reclassification method; (2) to quantify the mining extent and its impacts on forest cover in Suriname from 1997 to 2019; and (3) to evaluate the impact of mining on the structure and health of the forest. Landsat 5 and 8 images were used for the initial land-use/land-cover classification using the classification and regression trees algorithm in Google Earth Engine. The resulting classified maps were reclassified in a semi-automated model to correct misclassifications between mining and urban pixels. The final maps were used to analyse the expansion of mining and its impacts on forest cover, structure (using the fragmentation metric effective mesh size), and forest health (using the phenology metric peak greenness). The combined approach resulted in an improvement in mining detection accuracy from 72% (65% producer, 79% user) to 89.5% (84% producer accuracy, 95% user). The results showed that mining increased from 69.4 km2 in 1997 to 431.6 km2 in 2019, an increase by 522% over 22 years, which led to 421.3 km2 of forest loss, of which 85% was due to artisanal and small-scale mining (ASGM). The loss of forest for ASGM resulted in greater fragmentation, with a decrease in effective mesh size by 122.8 km2 compared to a decrease by 83 km2 caused by industrial mining. Mining also caused a decrease in the health of the surrounding forest, with a larger decrease in peak greenness due to ASGM compared to industrial mining. The results demonstrate the potential of this approach that leverages cloud-based machine learning with a semi-automated reclassification to allow for rapid, accurate, and potentially global mining detection.

Soil phosphorus cycling across a 100-year deforestation chronosequence in the Amazon rainforest.

Deforestation of tropical rainforests is a major land use change that alters terrestrial biogeochemical cycling at local to global scales. Deforestation and subsequent reforestation are likely to impact soil phosphorus (P) cycling, which in P-limited ecosystems such as the Amazon basin has implications for long-term productivity. We used a 100-year replicated observational chronosequence of primary forest conversion to pasture, as well as a 13-year-old secondary forest, to test land use change and duration effects on soil P dynamics in the Amazon basin. By combining sequential extraction and P K-edge X-ray absorption near edge structure (XANES) spectroscopy with soil phosphatase activity assays, we assessed pools and process rates of P cycling in surface soils (0-10 cm depth). Deforestation caused increases in total P (135-398 mg kg-1 ), total organic P (Po ) (19-168 mg kg-1 ), and total inorganic P (Pi ) (30-113 mg kg-1 ) fractions in surface soils with pasture age, with concomitant increases in Pi fractions corroborated by sequential fractionation and XANES spectroscopy. Soil non-labile Po (10-148 mg kg-1 ) increased disproportionately compared to labile Po (from 4-5 to 7-13 mg kg-1 ). Soil phosphomonoesterase and phosphodiesterase binding affinity (Km ) decreased while the specificity constant (Ka ) increased by 83%-159% in 39-100y pastures. Soil P pools and process rates reverted to magnitudes similar to primary forests within 13 years of pasture abandonment. However, the relatively short but representative pre-abandonment pasture duration of our secondary forest may not have entailed significant deforestation effects on soil P cycling, highlighting the need to consider both pasture duration and reforestation age in evaluations of Amazon land use legacies. Although the space-for-time substitution design can entail variation in the initial soil P pools due to atmospheric P deposition, soil properties, and/or primary forest growth, the trend of P pools and process rates with pasture age still provides valuable insights.

Fine root presence and increased phosphorus availability stimulate wood decay in a central Amazonian rainforest

In the Amazon basin, approximately 60% of rainforest thrives on geologically old and highly weathered soils, thus decomposition represents an important mechanism for recycling nutrients from organic matter. Although dead logs and branches constitute up to 14% of the carbon stored in terrestrial ecosystems, woody debris decomposition and mainly the effect of direct nutrient cycling by plant root interaction is poorly studied and often overlooked in ecosystem carbon and nutrient budgets. Here we monitored the decomposition of five different local woody species covering a range of wood density by conducting a long‐term wood decomposition experiment over two years with factorial root presence and phosphorous (P) addition treatments in a central Amazonian rainforest. We hypothesized that woody debris decomposition is accelerated by colonizing fine roots mining for nutrients, possibly strongly affecting wood debris with lower density and higher nutrient concentration (P). We found that root colonization and P addition separately increased wood decay rates, and although fine root colonization increased when P was added, this did not result in a change in wood decay. Nutrient loss from wood was accelerated by P addition, whereas a root presence effect on nutrient mobilization was only detectable at the end of the experiment. Our results highlight the role of fine roots in priming wood decay, although direct nutrient acquisition by plants seems to only occur in more advanced stages of decomposition. On the other hand, the positive effect of P addition may indicate that microbial nutrient mobilization in woody material is driven mainly by wood stoichiometry rather than priming by root activity.