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Forest fragmentation is the main cause of biodiversity loss in the Anthropocene and it is triggering a top-down cascade effect that may influence leaf litter decomposition. However, the link between biodiversity loss and changes in ecosystem processes is not fully understood. We conducted an experiment to evaluate whether the exclusion of vertebrates affects the decomposition rates of different litter types (grass, a pioneer species and a mix of litters from a well preserved secondary forest). To answer this question, we placed litter bags inside artificial exclusion plots that were built in two types of vegetation coverage (abandoned pastureland and preserved forest) in the Atlantic forest of southeast Brazil. Our hypothesis is that vertebrate exclusion will change decomposition rates of different litter types due to the top-down cascade effect on soil invertebrates. We found out that vertebrate exclusion did not affect decomposition rates, possibly due to the overlap of ecological functions in the soil fauna responsible for the decomposition process. Furthermore, grass litter was decomposed faster (k value), possibly due to its initial nutrient content and hence litter quality which plays a significant role on decomposition rates.

Urbanization has threatened rural communities’ livelihoods worldwide, changing their agro-food systems from locally produced traditional items to industrialized foodstuffs. The main objective was to investigate the relationship between livelihood conditions and the agro-food transition process in rural communities of the Center-West, Northeast, and Amazon regions of Brazil. We hypothesized that traditional agroecosystems and local food habits changed with greater access to market economies. The study was conducted with semi-structured questionnaire interviews to verify agro-food patterns, subsistence farming, natural resource use, and socioeconomic conditions. Moreover, we used stable isotope ratios from the inhabitants’ fingernails to determine the food source and trophic chain diversity. Data from questionnaires were analyzed using a Bayesian clustering model to characterize the socioeconomic conditions and agro-food patterns among rural and urban communities. The isotopic data were appraised through a nonparametric model to assess food differences among Brazilian regions and different community types. The Bayesian model allowed us to determine the optimal number of groups according to descriptive socioeconomic and agro-food variables sorted by each specific location. We also verified a food change from C3 (more natural) to C4 (more processed) with an increase in δ13C and a decrease in δ15N in the city and town localities. This indicates a livelihood shift from locally produced foods to processed items toward urban areas. Although remote villages showed more maintenance of their agro-food systems, increased access to market economies and the supermarket diet is changing the livelihood conditions of rural communities, which can compromise their traditional farming and food sovereignty.

A planta de soja tem a associação simbiôntica com micro-organismos que têm a capacidade de fixar nitrogênio (N) e liberá-lo para as plantas. Nas cultivares de soja de alto potencial produtivo, a demanda por N estaria sendo atendida através da fixação biológica de nutrientes (FBN) ou haveria a necessidade de complementação deste nutriente para a cultura. Este trabalho teve como objetivo verificar a resposta da cultivar de soja Desafio inoculada com bactérias Bradyrhizobium japonicum e Bradyrhizobium elkanii, e com adubação nitrogenada suplementar na fase reprodutiva, via solo e via foliar. Os tratamentos constituíram da testemunha (sem aplicação de N), 30 e 60 kg de N ha-1 via solo e solução a 2% de N aplicados nas fases R1 e R5.3. O delineamento foi de blocos casualizados com quatro repetições e as sementes foram inoculadas com bactérias das espécies Bradyrhizobium japonicum e Bradyrhizobium elkanii (estirpes Semia 587 e Semia 5019). A aplicação tardia de N em R1 e em R5.3 proporcionou aumento na produtividade de grãos de 478,6 kg ha-1 e 472,8 kg ha-1, respectivamente. A aplicação via solo de N em R1 apresenta melhor índice de colheita, quando comparada com a R5.3. A aplicação tardia de solução de 2% de N, via foliar, não proporciona aumento na produtividade da cultura da soja. Palavras-chave: Glycine max. Produtividade. Fixação Biológica. Adubação Nitrogenada. Abstract The soybean plant has the symbiotic association with microorganisms that has the ability to fix nitrogen (N) and release it to the plants. Soybean cultivars with high productive potential, N demand would be met through biological nutrient fixation (BNF) or there would be a need to complement this nutrient for the crop. The objective of this work was to verify the response of soybean inoculated with bacteria of the genus Rhizobium and Bradyrhizobium, the supplementary nitrogen fertilization in the reproductive phase, soil and leaf pathway. The treatments consisted of control (without application of N), 30 and 60 kg of N ha-1 via soil and 2 % N solution applied in phases R1 and R5.3. The design was randomized blocks with 4 replications and the seeds were inoculated with bacteria of the species Bradyrhizobium japonicum and Bradyrhizobium elkanii (strains Semia 587 and Semia 5019). The late application of N in R1 and R5.3 increased grain yield of 478.6 kg ha-1 and 472.8 kg ha-1, respectively. The application, via soil, of N in R1 presents a better harvest index, when compared to R5.3. The late application of 2% N solution, via leaf, did not increase the soybean crop yield Keywords: Glycine max. Productivity. Biological Fixation. Nitrogen Fertilization

By analyzing 6,480 tree leaf samples from 57 sites within Brazilian biomes, we considered whether vegetation types in terrestrial ecosystems reflect biogeochemical diversity and whether they fit into a leaf economics spectrum (LES). To achieve this, we investigated the relations among leaf carbon (C) and nitrogen (N) concentrations, their isotope natural abundance and C:N ratio. In addition, we tested their correlations with mean annual temperature (MAT) and precipitation (MAP), as climatic factors. We found consistent differences in the C and N concentrations and their isotopic composition among the vegetation types. MAP is the main climatic driver of changes in N, C:N ratio, δ15N, and δ13C, correlating negatively with N and positively with C:N ratio. These relations show that these biomes follow an LES. The Caatinga had the highest δ15N values, suggesting that N residence time in soil is longer due to low leaching and plant uptake. We observed that MAP is not the only factor influencing δ13C values in different biomes; instead canopy effect probably explains the highest values observed in the Cerrado. Our results reinforce earlier findings that life diversity in the tropics reflects biogeochemistry diversity and leaf δ15N opens the possibility for investigating plant trade-offs dictated by the LES. Finally, we expect our findings to contribute to a better understanding of the tropics in global climate models.

Throughout evolutionary history, elasmobranchs have developed diverse reproductive strategies. Little focused work, however, has addressed how neonatal nutritional state is affected by differing degrees of maternal investment associated with these markedly different reproductive strategies. To investigate the effect of maternal investment on the nutritional quality of pups during the early life history of an extremely viviparous elasmobranch, quantitative biomarker analysis including lipids, fatty acids and stable isotopes was conducted. Using the cownose rayRhinoptera bonasus(histotrophic viviparous) as a model, we found that pups were initially born in a positive nutritional state, enriched in physiologically important essential fatty acids and nitrogen and carbon stable isotope values (δ15N and δ13C), a result of maternal intrauterine transfer. A systematic decrease in some fatty acids and δ15N values, as well as a decrease in cholesterol with growth, confirmed that these substrates were derived from maternal resources and used in initial metabolic processes following birth. An observed increase in condition factor, plasma essential fatty acids and triglyceride:cholesterol ratio with increasing body size identified a progression towards successful independent foraging with pups not displaying marked nutritional deficiency or fasting phases. Our multi-tracer approach allowed the identification of 2 size classes of young rays (

Parasitism is a dynamic ecological phenomenon that is constantly influenced by the environment and intrinsic factors of the host. We aimed to evaluate the influence of vegetation, environmental temperature, reproductive conditions, sex, and body condition (BC) on the detection of Trypanosoma spp. in the blood of Thrichomys fosteri in the Pantanal region, an enzootic area for trypanosomiasis. Whole blood was collected from the tip of the tail, and nPCR was performed for Trypanosoma spp. detection from the DNA extracted from the resultant blood clot. Statistical analyses were performed using generalized linear models. Our results showed that there is a greater probability of detection of Trypanosoma spp. in the bloodstream of animals with the highest BC values in periods with mild temperatures. Since T. fosteri is an abundant and common prey for carnivores, even in periods with low temperatures and consequent decrease in the reproduction and activities of the blood-sucking arthropod vectors, the maintenance of Trypanosoma spp. in the studied area would be guaranteed via predation (trophic network) of T. fosteri individuals with good BC and patent parasitemia. Furthermore, T. fosteri, which displays Trypanosoma spp. in the bloodstream, would be reproducing adequately because we found no influence between the reproductive condition and the detection of Trypanosoma spp. in T. fosteri. The caviomorph rodent T. fostei is an important species for the maintenance of Trypanosoma spp. in the Pantanal biome.

The Earth has undergone numerous geological and biological changes over billions of years. The evolution of plants and animals had a direct relationship with the elements’ changes in the atmosphere and the development of the biogeochemical cycles on Earth. The Anthropocene is the age of the Homo sapiens leaves its geological signature on the planet. Human domination and/or interference in the biogeochemical cycles results in an environmental change that affects not only ecosystems, in general, but also the biota and global biodiversity. In this way, we are creating another mass extinction event, the “sixth extinction wave” as well as transforming the ecosystems’ functions and services. Resumo A Terra passou por inúmeras mudanças geológicas e biológicas ao longo de bilhões de anos. A evolução de plantas e animais teve uma relação direta com as mudanças dos elementos na atmosfera e o desenvolvimento dos ciclos biogeoquímicos na Terra. O Antropoceno é a idade em que a espécie Homo sapiens deixa sua assinatura geológica no planeta. A dominação e/ou interferência humana nos ciclos biogeoquímicos resulta em mudanças ambientais que afetam não apenas os ecossistemas, em geral, mas também a biota e a biodiversidade global. Dessa forma, estamos criando um novo evento de extinção em massa, a “sexta onda de extinção” (“the sixth extinction wave”), além de transformar as funções e os serviços ambientais dos ecossistemas.

Extensive pastures are commonly converted to sugarcane areas in Brazil. In soils cultivated with sugarcane, tillage and fertilization are management practices commonly carried out. Soil management practices alter the physical and chemical properties increasing or decreasing metal availability. The purpose of this study was to quantify soil metal concentrations during pasture-to-sugarcane conversion correlating these changes with physical and chemical properties. The results showed that the concentration of metals in soil samples occurred according to the following order Fe > Mn > Cr > Zn > Cu > Pb > Cd. Significant increases in soil metal concentrations due the sugarcane cultivation were observed to Cd and Cu. The soil physical and chemical properties presented correlations with soil metal concentrations. There was a strong relationship on inorganic fertilization to change in soil metal concentrations. The principal component analysis (PCA) explained 55.4% of the total data variance, separating factors in two groups that pointed to an influence of fertilization on metal grouping. Inorganic fertilizer application may input 1.06 g·ha–1·year–1 Cd. The Cd concentration ranged from 0.15 to 1.07 mg·kg–1, representing addictions of 9.54 mg·ha–1·year–1 Cd in soil. The metal concentrations observed after five years of pasture-to-sugarcane conversion did not represent environmental risks since the concentrations remained below the Brazilian official determinations.

The synergistic effects of coastal urbanization have dramatically impacted biological communities. Yet, few studies have investigated how urbanization can influence the diet quality and trophic ecology of coastal sharks. In a preliminary study, we examined for spatial variation in the nutritional ecology of a highly active marine predator, the blacktip (Carcharhinus limbatus) exposed to regional differences in coastal urbanization in southeast Florida. We used medium-term nutritional indicators (i.e., body condition and whole blood stable isotopes [δ

texto completo Brazilian soil scientists have increased the use of the term “soil quality” in their scientific publications in the last decade. However, it remains unclear if those publications only mention “soil quality” in a broad context, or the studies are focused on soil quality assessments, integrating soil chemical, physical and biological indicators. The objective of this systematic review was to carry out a critical analysis of the conception in using the term “soil quality” in recent publications derived from studies performed in Brazil. For this purpose, the terms [(“soil health” or “soil quality” or “qualidade do solo”) and (“Brazil*” or “Brasil*”)] were searched in databases of Web of Science, Scopus, and Scielo from 2014 to 2021. Initially, 1,284 peer-reviewed papers were found, subsequently selected according to the criteria established in two filters: (i) First filter - studies carried out in Brazil, which mentioned at least one of the terms of interest (“soil health” or “soil quality” or “qualidade do solo”) and that evaluated soil biological, physical or chemical indicators, assessing at least one of them; (ii) Second filter - studies in which all three groups of soil indicators were assessed and integrated, and presented a specific discussion about soil quality. According to the results, 36 % of the papers met the first criteria (n = 464), and only 2 % (n = 30) attended the second filter. The terms “soil health” or “soil quality” or “qualidade do solo” were mentioned 7 and 37 times per paper for those papers selected in the first and second filter, respectively. We evidenced in our study that the term soil quality in agricultural science papers has been predominantly used in a broad context, mostly to refer to the suitable soil conditions for plant growth. Thus, we concluded that even if the use of soil quality term is increasing in Brazilian literature, there are still very few researchers working specifically with soil quality assessments, in its full conception (i.e., integrating chemical, physical and biological indicators). Therefore, there is a promising research field to be explored to promote scientific advances in the soil quality area (e.g., new concepts, assessment frameworks, on-farm monitoring protocols), as well as disseminate the soil quality assessment among the Brazilian farmers, environmentalists, and other stakeholders.

Introduction: There are few contemporary prospective cohorts of Trypanosoma cruzi ( T.cruzi )-infected individuals. This study aimed to determine the incidence of new-onset cardiomyopathy and death attributable to T. cruzi infection. Methods: We enrolled 1088 individuals: 499 T. cruzi -seropositive blood donors identified in routine donor screening, 488 age- and sex-matched T. cruzi - seronegative blood donors, and 101 patients with established Chagas cardiomyopathy recruited from a tertiary center. Subjects underwent cardiovascular evaluation with ECG and echocardiogram at the baseline (2008-2010) and follow-up (2018-2019) visits. Cardiomyopathy was diagnosed based on ECG and echocardiographic findings at baseline and follow-up. Vital status was determined by linkage with the national Brazilian mortality system. Results: Mortality was 80.9 deaths/1000 person-years (py) in established cardiomyopathy and 15.1 deaths/1000py in T. cruzi -seropositive donors with cardiomyopathy at baseline. The mortality rate among T. cruzi -seropositive blood donors without cardiomyopathy at baseline and T. cruzi -seronegative controls was similar, with mortality rates of 3.67 and 3.62 events/1000 py, respectively. In T. cruzi -seropositive donors, age (hazard ratio [HR] = 1.05 per year), anti-T.cruzi antibody level (HR = 1.40 per unit increase in serology assay signal/cut off) and the presence of cardiomyopathy at baseline (HR = 3.01) were independent predictors of mortality. The incidence of new-onset cardiomyopathy in T. cruzi -seropositive donors was 13.8 events/1000 py (95% CI 9.5-19.6) compared with 4.6 events/1000 py (95% CI 2.3-8.3) in controls, with an absolute incidence difference attributable to T. cruzi infection of 9.2 (95% CI 3.6 - 15.0) events/1000py. T. cruzi antibody level at baseline was the main independent predictor of subsequent new-onset cardiomyopathy with an adjusted odds ratio of 1.37 (95% CI 1.07-1.76) per unit increase in antibody level. Conclusions: We present a comprehensive description of the natural history of T. cruzi infection in a contemporary patient population. The results highlight the central importance of total anti- T. cruzi antibody titer as a marker of Chagas disease activity and risk of progression.

Rainfall is generally partitioned into throughfall, stemflow, and interception in ecosystems. Stemflow variability can affect the hydrology, ecology, and soil chemistry patterns. However, the influence of canopy structure and rainfall characteristics on stemflow production in sugarcane plantations which are important for renewable energy production remain poorly understood. By using funnels attached to the sugarcane stems, the present study determined the stemflow amount during the period of sugarcane growth and its relationship with plant development. Approximately, 14% of gross rainfall reached the soil as stemflow, and the funneling ratios was 60. In general, it was observed a positive relationship between stemflow rates with both leaf area index and plant height. This was attributed to an increasing number of acute branching angles of the sugarcane leaves as well as high stem tillering and density. However, at the end of growth cycle, stemflow rate was lower than in previous periods which can be attributed to changes in sugarcane canopy such as stems inclination and lodging, reducing the effectiveness of water conveyance along the stem. Our study showed the need to include stemflow to better understand the hydrology of sugarcane plantations.

Tropical streams have been intensively impacted by agricultural activities. Among the most important agricultural activities in Brazil, sugarcane production represents a large impact for economic development and for environmental conditions. Permeating sugarcane fields, several headwater streams can be affected by sugarcane cultivation, in special, aquatic biogeochemical cycles because of the deforestation, fertilization, crop residues and higher temperatures in the tropics. In this study, we analyzed the effects of sugarcane cultivation on methane fluxes and concentrations, assuming that carbon cycles are influenced by agricultural activities in headwater streams. Our study aimed to (1) measure methane fluxes and concentrations in tropical streams located in Southeastern Brazil, (2) Analyze whether seasonal cycles influence methane fluxes and concentrations, (3) Evaluate the influence of sugarcane cultivation on methane fluxes and (4) Analyze the association between water chemistry in the methane concentrations in tropical streams. We found mean fluxes of CH

Agricultural systems are heterogeneous across temporal and spatial scales. Although much research has investigated farm size and economic output, the synergies and trade-offs across various agricultural and socioeconomic variables are unclear. This study applies a GIS-based approach to official Brazilian census data (Agricultural Censuses of 1995, 2006, and 2017) and surveys at the municipality level to (i) evaluate changes in the average soybean farm size across the country and (ii) compare agricultural and socioeconomic outcomes (i.e., soybean yield, agricultural production value, crop production diversity, and rural labor employment) relative to the average soybean farm size. Statistical tests (e.g., Kruskal&ndash, Wallis tests and Spearman&rsquo, s correlation) were used to analyze variable outcomes in different classes of farm sizes and respective Agricultural Censuses. We found that agricultural and socioeconomic outcomes are spatially correlated with soybean farm size class. Therefore, based on the concepts of trade-offs and synergies, we show that municipalities with large soybean farm sizes had larger trade-offs (e.g., larger farm size was associated with lower crop diversity), while small and medium ones manifest greater synergies. These patterns are particularly strong for analysis using the Agricultural Census of 2017. Trade-off/synergy analysis across space and time is key for supporting long-term strategies aiming at alleviating unemployment and providing sustainable food production, essential to achieve the UN Sustainable Development Goals.

Phosphorus (P) use in global food and bioenergy production needs to become more efficient and sustainable to reduce environmental impacts and conserve a finite and critical resource (Carpenter & Bennett, Environmental Research Letters, 2011, 6, 014009; Springmann et al., Nature, 2018, 562, 519). Sugarcane is one crop with a large P footprint because production is centered on P‐fixing soils with low P availability (Roy et al., Nature Plants, 2016, 2, 16043; Withers et al., Scientific Reports, 2018, 8, 2537). As global demand for processed sugar and bioethanol continues to increase, we advocate that improving P efficiency could become a key sustainability goal for the sugarcane industry. Here, we applied the 5R global P stewardship framework (Withers et al., Ambio, 2015, 44, 193) to identify more sustainable options to manage P in Brazilian sugarcane production. We show that current inputs of P fertilizer to the current crop area could be reduced by over 305 Gg, or 63%, over the next three decades by reducing unnecessary P fertilizer use, better utilization of recyclable bioresources and redesigning recommendation systems. Adoption of these 5R options would save the sugarcane industry in Brazil 528 US$ million and help safeguard global food and energy security., Improving phosphorus efficiency could become a key sustainability goal for the sugarcane industry. Here, we applied the 5R global phosphorus stewardship framework to identify more sustainable options to manage phosphorus in Brazilian sugarcane production. We show that current inputs of phosphorus fertilizer to this crop could be reduced by over 305 Gg, or 63%, over the next three decades by reducing unnecessary phosphorus fertilizer use, better utilization of recyclable bioresources and redesigning recommendation systems. Adoption of these 5R options would save the sugarcane industry in Brazil 528 US$ million and help safeguard global food and energy security.

Habitat fragmentation could alter ecological traits including species trophic habits. Here, we used carbon and nitrogen stable isotope ratios to establish differences in isotopic niche width and food resource use between forest fragments and the continuous forest for the phyllostomid frugivorous bat Artibeus lituratus. Using mist nests, we captured bats from two forest fragments and two sites in continuous forest, and sampled from each individual captured three body tissues with contrasting turnover rates (skin, muscle, and liver). Samples were collected between February and March (austral summer) and between August and September (austral winter). In addition, in each sampling site and season we collected potential food resources (fruits and insects) consumed by our A. lituratus. Our findings indicate that A. lituratus had a predominantly omnivorous diet, with high consumption of insects during summer in forest fragments. The increasing consumption of insects in these fragments seems to have led to a wider isotopic niche, in relation to the continuous forest. Because A. lituratus is typically a seed disperser, changes in trophic habits in the forest fragments from frugivory to insectivory may diminish their role in forest regeneration. Abstract in Portuguese is available with online material.

Nitrogen is a critical component of the economy, food security, and planetary health. Many of the world's sustainability targets hinge on global nitrogen solutions, which, in turn, contribute lasting benefits for (i) world hunger; (ii) soil, air, and water quality; (iii) climate change mitigation; and (iv) biodiversity conservation. Balancing the projected rise in agricultural nitrogen demands while achieving these 21st century ideals will require policies to coordinate solutions among technologies, consumer choice, and socioeconomic transformation. Fil: Houlton, Benjamin Z.. University of California; Estados Unidos Fil: Almaraz, Maya. University of California; Estados Unidos Fil: Aneja, Viney. North Carolina State University; Estados Unidos Fil: Austin, Amy Theresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Bai, Edith. Chinese Academy of Sciences; República de China. Northeast Normal University; China Fil: Cassman, Kenneth G.. University of Nebraska; Estados Unidos Fil: Compton, Jana E.. Environmental Protection Agency; Estados Unidos Fil: Davidson, Eric A.. University of Maryland; Estados Unidos Fil: Willem Erisman, Jan. Department of Earth Sciences; Países Bajos. Louis Bolk Institute; Países Bajos Fil: Galloway, James N.. University of Virginia; Estados Unidos Fil: Gu, Baojing. Zhejiang University; China Fil: Yao, Guolin. University of Maryland; Estados Unidos Fil: Martinelli, Luiz A.. Universidade de Sao Paulo; Brasil Fil: Scow, Kate. University of California; Estados Unidos Fil: Schlesinger, William H.. Cary Institute of Ecosystem Studies; Estados Unidos Fil: Tomich, Thomas P.. University of California; Estados Unidos Fil: Wang, Chao. Chinese Academy of Sciences; República de China Fil: Zhang, Xin. University of Maryland; Estados Unidos

Although interspecific trophic interactions plays a principal role within elasmobranch communal nurseries, little is known over variation in foraging strategies adopted by young-of-year of sympatric species. To test the hypothesis of dietary resource partitioning between batoids within a communal nursery, we investigated two cownose ray species, Rhinoptera bonasus and R. brasiliensis, which occur in heterospecific groups, a strategy predicted to increase survival and foraging success. Using two biochemical tracers, fatty acids (FA) and stable isotopes (δ15 N and δ13 C), the combined effects of maternal investment and the formation of heterospecific groups implying competition for, or partitioning of available food resources were investigated. Through univariate and multivariate analyses of biochemical tracers in several tissues (fin clip, muscle, liver, red blood cells; RBC) and plasma, our results revealed significant interspecific differences in tracers between the two species. Total FAs (∑saturated FA, ∑monounsaturated FA and ∑polyunsaturated FA) and trophic biomarkers (i.e., docosahexaenoic acid, arachidonic acid, oleic acid and δ15 N) were the principle tracers responsible for the differences detected. These data revealed that R. brasiliensis was less enriched in physiologically important essential FAs than R. bonasus. Our findings suggest that these congeneric species differ in maternal investment strategy and moderately partition food resources over relatively fine spatial scales within a single nursery habitat to limit competition. These results provide further knowledge on the foraging strategies adopted by batoids in communal nursery areas, information that is required for improving spatial conservation and management planning.

Based on the assumptions that human food is available for dogs and isotope diet-tissue differences are similar in dogs and humans, the 'canine surrogacy approach' (CSA) has been used to infer patterns of ancient populations. The goal of this study was to test the CSA in urban (Brasilia and Piracicaba) and in rural (Ubatuba and Maraa) areas. The hair C and N isotope ratios of modern dogs were compared with those of human fingernails from different regions of Brazil. Our CSA results showed a correlation between dog and human isotopes values: in rural areas δ15N of humans and dogs was not statistically different; contrarily, in urban centres, δ15N of humans was approximately 1 ‰ higher (p

In forest nurseries, irrigation management becomes more complex as different seedlings of tropical species, with different architectures, are grown close to each other. In this context, there are gaps in knowledge about the physiological responses of species with different mean leaf angles when subjected to different irrigation depths. Thus, this work aimed to analyze whether mean leaf angles affect irrigation efficiency and, consequently, physiological responses of tree seedlings. Six species with different mean leaf angles were submitted to three irrigation depths (6, 9, and 12 mm) applied daily by micro-sprinklers in a completely randomized design in a split plot scheme. The following variables were evaluated: leaf water potential, stomatal conductance, relative water content in the leaf, daily transpiration, leaching fraction, and total dry mass. In tree species seedlings with positive mean leaf angles, smaller irrigation depths are already able to increase leaf water potential, stomatal conductance, leaf relative water content, and transpiration efficiency. In contrast, when the mean leaf angles are negative, it is necessary to apply larger irrigation depths so that seedling physiological responses do not reduce the production of total dry mass.

Symbiotic nitrogen fixation (SNF) makes atmospheric nitrogen biologically available and regulates carbon storage in many terrestrial ecosystems. Despite its global importance, estimates of SNF rates are highly uncertain, particularly in tropical forests where rates are assumed to be high. Here we provide a framework for evaluating the uncertainty of sample-based SNF estimates and discuss its implications for quantifying SNF and thus understanding of forest function. We apply this framework to field data sets from six lowland tropical rainforests (mature and secondary) in Brazil and Costa Rica. We use this data set to estimate parameters influencing SNF estimation error, notably the root nodule abundance and variation in SNF rates among soil cores containing root nodules. We then use simulations to gauge the relationship between sampling effort and SNF estimation accuracy for a combination of parameters. Field data illuminate a highly right-skewed lognormal distribution of SNF rates among soil cores containing root nodules that were rare and spanned five orders of magnitude. Consequently, simulations demonstrated that sample sizes of hundreds to even thousands of soil cores are needed to obtain estimates of SNF that are within, for example, a factor of 2 of the actual rate with 75% probability. This represents sample sizes that are larger than most studies to date. As a result of this previously undescribed uncertainty, we suggest that current estimates of SNF in tropical forests are not sufficiently constrained to elucidate forest stand-level controls of SNF, which hinders our understanding of the impact of SNF on tropical forest ecosystem processes.

As duas hipóteses básicas deste estudo foram: 1) De acordo com a sequência normal de intemperismo, a carga de sedimentos originada principalmente nos Andes, a medida que vai sendo transportada rio abaixo, vai perdendo sílica e cátions básicos e concentrando alumínio. 2) A baixa proporção de matéria orgânica produzida pelas gramíneas observada nas amostras de sedimento de várzea é devido a incorporação desta matéria orgânica preferencialmente nas maiores frações granulométricas do sedimento. A fim de testar estas hipóteses foram delineadas duas ações básicas: 1) Determinar a composição química total das amostras de sedimento coletadas nas várzeas localizadas ao longo do rio Solimões/Amazonas. No sentido de auxiliar a caracterização desse material pretende-se determinar sua composição mineralógica através de análises de difração de raios-X. 2) Fracionar granulometricamente a matéria orgânica das amostras de sedimento de várzea em três diferentes tamanhos e determinar a origem da matéria orgânica de cada fração através da composição isotópica do carbono. Para tanto, foram coletadas durante o início do período de drenagem da várzea 18 amostras superficiais de sedimento depositado na várzea ao longo de 2400 km no canal principal e próximo à foz dos seguintes tributários: Içá, Jutaí, Juruá, Negro e Madeira1. Quanto a primeira hipótese, foi mostrado que paralelamente ao decréscimo à jusante na concentração de Ca, Mg e Na na forma trocável, houve um decréscimo na concentração total de Ca, Mg, Na, Fe e Al. Todavia, apesar deste decréscimo não houve uma alteração significativamente na estrutura dos minerais de argila presentes nas amostras de sedimento. Relativamente à segunda hipótese, de fato, a matéria orgânica produzida pelas gramíneas acumulou-se principalmente na fração granulométrica mais grossa do sedimento (areia grossa). Todavia, devido à menor proporção desta fração (0,4%) frente as frações mais finas - areia fina (25%) e silte + argila (75%), a incorporação da matéria orgânica originada pelas gramíneas foi geralmente pequena, sendo mais acentuada nas amostras de sedimento coletadas na região do Médio e do Baixo Amazonas. The principal hypothesis of this study were: 1) The exchangeable basic cations concentration decrease observed in the varzea sediment samples is due to the progressively leaching of the Andes born sediment load via sucessive erosion-deposition cycles. 2) The low contribution of the grass organic matter observed in varzea sediment samples is due to its preferential incorporation in the coarser sediment fractions. In order to test these hypothesis two actions were deleloped: 1) Determination of the mineralogical composition of the silt and clay fractions and the chemical composition of the varzea sediment samples collected along the Amazonas river. 2) To procedd a granulometric fractionation of organic matter contained within the varzea sediment samples into three different sizes and to determine carbon isotopic composition. In order to achieve these goals 18 samples of varzea sediment samples have been collected during the drainage period along 2400 km through the main channel and in the mouth of the following tributaries: Iça, Jutaí, Juruá, Negro and Madeira. In regard to the first hypothesis, it was showed that parallel to the decrease in the basic cations concentration, there was an decrease in the concentration of Fe and Al. In respect to the second hypothesis, the grass organic matter was concentrated within the coarsest fractions of the varzea sediment samples. Although, due to the low proportion of this fraction (0.4%) in incorporation of the grass organic matter was low, increasing in the samples collected in the Low Amazon region.

Extreme climatic events may be translated into a higher frequency of both dry and wet years. Frequent droughts pose a challenge to water supply in terms of both quantity and quality. In order to cope with this, there has to be a documentation on the concentration of chemicals in water during such events. The southeast region of Brazil experienced a major drought event in 2014 leading to number of social, economic, and environmental impacts. The objective of the present paper is to understand the effect of an extreme drought on dissolved organic and inorganic carbon concentrations of the Piracicabal river, which is under high human pressure. Concentrations of both dissolved organic (DOC) and inorganic carbon (DIC) were monitored daily, for 30 days, during a dry month in 2014. DOC values found here were at least twice those observed in the river in non-extreme conditions. Rain events within this drought led to significant differences in discharge, DOC, and DIC. We built a dilution-concentration model which described an exponential relationship between discharge and both carbon forms. This indicated that drastic changes in concentrations of DOC and DIC are expected during such events. Our results may also apply to a number of regions in the world especially those of the developing countries where rivers are highly subjected to sewage impact.

In recent decades, the nutritional transition has been encroaching on remote rural areas of developing countries where feeding patterns are shifting from unprocessed foods to industrialized processed goods. Such changes in the Amazon region have been detected, for instance, by comparing the natural carbon (13C:12C) and nitrogen (15N:14N) isotopic ratios of people living in riverine communities with urban dwellers their putative diet. In this study, we considered how landscape variables impacted food consumption by comparing fingernail isotopic ratios of individuals in the rural settlement of Costa do Caldeirao located in the floodplain (varzea) of the Solimoes River, and in the rural settlement of Paquequer located in a non-flooded area (terra-firme) near the Madeira River banks. A total of 70 fingernails were sampled for carbon and nitrogen isotopic analysis during the low water period and again during the high water period from the same residents of the varzea and terra-firme. The consumption of C4-like resources (e.g., frozen chicken and canned meat) increased in both rural settlements during the high water period when C3-like resources (fish, cassava, rice, beans) are less available due to the flooding of lowland areas, but this difference was more pronounced in the terra-firme. The higher consumption of C4-like resources in the varzea compared to the terra-firme shows how seasonal flooding is a key factor influencing food security and health, due to stark variations in river water levels. While fish and farinha are still important staple foods, differences within rural settlements suggest that, besides seasonal variation and changes in water levels, other factors such as age, origin, and income may be crucial to understanding individual dietary behavior change in line with the nutritional transition model.

Soil nitrogen isotope composition (δ15N) is an essential tool for investigating ecosystem nitrogen balances, plant–microbe interactions, ecological niches, animal migration, food origins, and forensics. The advancement of these applications is limited by a lack of robust geospatial models that are capable of capturing variation in soil δ15N (i.e., isotopic landscapes or isoscapes). Due to the complexity of the nitrogen cycle and general scarcity of isotopic information, previous approaches have reconstructed regional to global soil δ15N patterns via highly uncertain linear regression models. Here, we develop a new machine learning approach to ascertain a finer‐scale understanding of geographic differences in soil δ15N, using the South American continent as a test case. We use a robust training set spanning 278 geographic locations across the continent, spanning all major biomes. We tested three different machine learning methods: cubist, random forest (RF), and stochastic gradient boosting (GBM). 10‐fold cross‐validation revealed that the RF method outperformed both the cubist and GBM approaches. Variable importance analysis of the RF framework pointed to biome type as the most crucial auxiliary variable, followed by soil organic carbon content, in determining the model performance. We thereby created a biogeographic boundary map, which predicted an expected multiscale spatial pattern of soil δ15N with a high degree of confidence, performing substantially better than all previous approaches for the continent of South America. Therefore, the RF machine learning framework showed to be a great opportunity to explore a broad array of ecological, biogeochemical, and forensic issues through the lens of soil δ15N.

Fighting climate change has never been so urgent as today. As geoscientific research advances, more realistic and appalling future climate scenarios are unraveled. Decreasing greenhouse gases (GHG) emissions is not sufficient to avoid a bad outcome; hence, mitigation actions are needed to reduce climate-related risks in the future. The depletion of the soil organic carbon (SOC) pool due to land use change and soil degradation have substantially contributed to the increase in the atmospheric CO2 concentration. Likewise, the sequestration of C by the soil is crucial to reverse this issue. These are especially important processes in the tropics where the replacement of native vegetation by agriculture still occurs at a high rate. Brazil is one of the biggest agricultural producers in the world. In 2018, agriculture and land use change represented 70% of the total Brazilian GHG emissions. Fortunately, Brazil also has opportune mitigation options. Since 1965, the Brazilian Forest Code requires landowners to conserve native vegetation by means of Riparian Preservation Areas, among other categories. Riparian forests provides several ecosystem services like water protection, biodiversity conservation and carbon sequestration. Frequently, the discussion over the carbon sequestration potential of riparian forests focus on the aboveground carbon, nevertheless, SOC stocks are more stable and protected from natural and anthropogenic hazards. We consider that the mandatory reforestation of riparian zones is a significant mitigation strategy in Brazil, owing to the potential of SOC sequestration by Brazilian biomes and the extensive area to be reforested. The objective of this study was to assess the SOC stocks of the main land uses of an agricultural watershed located in the state of São Paulo, Southeastern Brazil, and estimate the change in the SOC stocks that would occur with the reforestation of the riparian areas of this watershed. In order to achieve this goal, we compared the SOC stocks of riparian forests with the two main agricultural uses of the region, namely pasture and sugarcane. The mean SOC stock at 30 cm for riparian forests was of 44 Mg.ha-1, for pastures was of 26 Mg.ha-1 and for sugarcane was of 27 Mg.ha-1. Although the riparian forests of the region are often poorly preserved, they contained considerably more SOC at 30 cm than the agricultural uses. Based on the estimates of the SOC stocks of the main land uses and the extent of the riparian zones of the sampled sites, we could foresee an accretion of 20% of organic carbon in the 30 cm soil layer of those areas. We hope that this study highlight the importance of the riparian forests and the ecosystem services they provide, and the relevance of the Brazilian Forest Code in the mitigation of climate change.

Several previous studies on targeted food items using carbon and nitrogen stable isotope ratios in Brazil have revealed that many of the items investigated are adulterated, mislabeled or even fraud. Here, we present the first Brazilian isotopic baseline assessment that can be used not only in future forensic cases involving food authenticity, but also in human forensic anthropology studies. The &delta, 13C and &delta, 15N were determined in 1245 food items and 374 beverages, most of them made in Brazil. The average &delta, 15N of C3 plants were &minus, 26.7 &plusmn, 1.5&permil, and 3.9 &plusmn, 3.9&permil, respectively, while the average &delta, 15N of C4 plants were &minus, 11.5 &plusmn, 0.8&permil, and 4.6 &plusmn, 2.6&permil, respectively. The &delta, 15N of plant-based processed foods were &minus, 21.8 &plusmn, 4.8&permil, 2.7&permil, respectively. The average &delta, 15N of meat, including beef, poultry, pork and lamb were -16.6 &plusmn, 4.7&permil, and 5.2 &plusmn, respectively, while the &delta, 15N of animal-based processed foods were &minus, 17.9 &plusmn, 3.3&permil, and 3.3 &plusmn, 3.5&permil, 13C of beverages, including beer and wine was &minus, 22.5 &plusmn, 3.1&permil, We verified that C-C4 constitutes a large proportion of fresh meat, dairy products, as well as animal and plant-based processed foods. The reasons behind this high proportion will be addressed in this study.

Considering the increasing pet owner’s concern about the food their pets are consuming, in this study we investigated the origin of the main ingredients in wet and dry foods produced in Brazil using stable isotope ratios of carbon and nitrogen. We concluded that chicken and pork seem to be the dominant ingredients in most of the samples, with larger proportions in wet cat food. Even in pet foods showing ‘beef’ as the main ingredient on the label, we found a low proportion of bovine products in both wet and dry cat foods. Comparing the contribution of plant-derived products (C3 and C4 plants) and animal-derived products (chicken–pork, bovine and fish), approximately 21 % of cat foods had more than 30 % of ingredients with plant origin in their composition. The high amount of plant-derived products in cat foods found here raises the question whether this should be mentioned on package labels.

OBJECTIVE The main objective of this study is to investigate diet patterns among rural and urban populations of the Center-West, Northeast, and Amazon regions of Brazil through the carbon and nitrogen isotopic composition of fingernails, recognizing that the extent of market integration is a key driver of food consumption. MATERIALS AND METHODS In the Center-West, Northeast, and Amazon regions of Brazil, fingernails were sampled in clusters encompassing a major city, town, and rural village. A total of 2,133 fingernails were analyzed. Fingernails were clipped by donors using fingernail clippers. In the laboratory, samples were cleaned then weighed in small tin capsules before being isotopically analyzed for carbon and nitrogen. RESULTS The overall mean δ13 C and δ15 N were -19.7 ± 2.8‰ and 10.6 ± 1.1‰, respectively. In the more remote villages, where access to food markets is more challenging, lower δ13 C prevails, suggesting that Brazilian staple foods (rice, beans, and farinha) still dominate. In areas with easier access to food markets, δ13 C values were higher, suggesting a change to a diet based on C4 plants, typical of a Brazilian supermarket diet. The variability among inhabitants in the same location expressed by a significant inverse correlation between δ13 C and δ15 N fingernail values suggested that "market integration" does not affect everyone equally in each community. DISCUSSION AND CONCLUSION The nutrition transition has not yet reached some remote villages in these regions of Brazil or that the nutrition transition has not yet reached all residents of these remote villages. On the other hand, in several villages there is a considerable adherence to the supermarket diet or that some residents of these villages are already favoring processed food.