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Understanding linkages between biotic and abiotic processes operating in highly seasonal environments such as the Savannas in the Neotropics is tremendously challenging but has been aided considerably through biogeochemical markers. Stable isotope ratios have been widely used as spatial and temporal integrative markers, signaling environmental information. Our objective in this study was to examine the relationship of tissue δ18O and environmental factors and among multiple tissues in Saffron Finches, since this species is primary resident and abundant in the region. We conducted this study in a private farm in the central Brazilian savannas. We sampled 194 individuals in seven field samplings between January 2017 and March 2018. We collected whole blood, feathers and claws and analyzed them for δ18O in both the yellow (YEL) and dull (DULL) plumage categories. We built different sets of environmental variables as predictors of blood δ18O. Median blood δ18O varied widely throughout the year (13.4–18.8 ‰), differing in most pairwise comparison of months. Primary and tail feathers for both categories showed narrower isotopic median ranges compared to blood. Claw δ18O showed smaller isotopic ratio variation than the other tissues. Our results showed that δ18O values in avian blood are related to local climatic variables and reflect changes through time. The amount of precipitation, humidity and temperature were the most important environmental predictors. Therefore, the use of δ18O in different avian tissues could be used as a proxy to infer different environmental and ecological aspects related to the Saffron Finch.

The present study aimed to assess the effect of fourteen years of implementation of a successional and biodiverse agroforestry system (AFS) in a degraded agricultural field located in the Cerrado region of Central Brazil on the carbon and nitrogen dynamics. To track short term soil N dynamics we sampled instantaneous soil N rates in four seasonal periods (wet-dry, dry, dry-wet, wet) and to track long term C and N dynamics we measured C and N stable isotopes in the plant-litter-soil system. As additional data we determined the aboveground biomass; resorption rates of foliar and, soil C and N stocks. The measured aboveground biomass was 19.2 Mg C ha-1. The mean resorption rate of foliar N was 49.3%. C:N ratio was 20.4 ± 1.4 and 14.2 ± 0.32 in the litter layer and the topsoil, respectively. Soil N-NH4+ was predominant over N-NO3-. After 40 days, the cumulative N-N2O emission was 0.33 kg ha-1. The mean C and N stocks were 3.8 Mg N ha-1 and 43.6 Mg C ha-1, respectively. The averaged soil δ15N was 6.8‰. Soil δ13C was -20.3‰. After 14 years of implementation, approximately 40% of the total C in the topsoil (0-20 cm depth) was derived from the AFS biomass input, predominantly from the C3 photosynthetic pathway. The studied biodiverse AFS that replaced a degraded agricultural field in the Cerrado region showed to be responsive both in terms of soil and plant C and N pools and fluxes., O presente estudo teve como objetivo avaliar o efeito de quatorze anos de implementação de um sistema agroflorestal (SAF) sucessional e biodiverso em uma área agrícola degradada localizada na região de Cerrado do Brasil Central sobre a dinâmica de carbono e nitrogênio. Para verificar a dinâmica de N no curto prazo foram feitas medidas das taxas de transformação de N no solo em quatro períodos sazonais (chuva-seca, seca, seca-chuva e chuva) e para determinar a dinâmica de C e N no longo prazo foram analisadas as razões isotópicas de C e N no sistema planta-serapilheira-solo. Além disso, os seguintes parâmetros foram medidos: biomassa acima do solo, taxas de retranslocação de N foliar, e estoques de C e N no solo. A biomassa acima do solo foi de 19,2 Mg C ha-1. A taxa média de reabsorção de N foliar foi de 49,3%. A relação C:N foi de 20,4 ± 1,4 e 14,2 ± 0,32 na camada de serapilheira e na camada superficial do solo, respectivamente. O N-NH4 + do solo foi predominante sobre o N-NO3-. Após 40 dias, a emissão cumulativa de N-N2O foi de 0,33 kg ha-1. Os estoques médios de C e N foram de 3,8 Mg N ha-1 e 43,6 Mg C ha-1, respectivamente. O valor médio de δ15N do solo foi de 6,8‰, enquanto o valor médio de δ13C no solo foi de -20,3‰. Após 14 anos de implementação, aproximadamente 40% do C total na camada superficial do solo (0-20 cm de profundidade) mostrou ser derivado da entrada de biomassa oriunda do SAF, que é predominantemente do tipo fotossintético C3. O SAF estudado, que substituiu um campo agrícola degradado na região do Cerrado, mostrou-se responsivo tanto em termos de estoques e fluxos de C e N do solo e da planta.

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.

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.

Made available in DSpace on 2022-04-29T08:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Apoio à Pesquisa do Distrito Federal Rufford Foundation Fundação Grupo Boticário de Proteção à Natureza The colonization and spread of non-native species are recognized as a critical driver of environmental change in mangrove ecosystems. However, environmental factors that favor non-native plant colonization in mangroves are still poorly understood. To fill this gap, we investigated the effect of selected abiotic factors controlling non-native plant species colonization in mangroves in Southeastern Brazil. We selected 18 plots in mangrove forests under different levels of anthropogenic N inputs, both colonized and non-colonized by non-native plants in the Estuarine-Lagoon Complex of Cananeia-Iguape, southeastern Brazil. We measured interstitial salinity, sediment nitrate and ammonium concentrations, and sediment physicochemical properties. We found that interstitial salinity at 10 cm depth followed by nitrate concentrations in sediment were the main factors associated with the occurrence of non-native species in the studied mangroves. Low salinity and increased N availability in sediment allowed for the success of non-native plants into mangrove forests, also resulting in high amount of dead mangrove trunks. Aiming to conserve and restore such areas, the restoration of abiotic conditions is the first step in the management of non-native species in this region. Núcleo de Estudos e Pesquisas Ambientais e Limnológicas – Programa de Pós-Graduação em Ciências Ambientais Universidade de Brasília, Área Universitária 1, Vila Nossa Senhora de Fátima, Campus de Planaltina Programa de Pós-Graduação em Ecologia Instituto de Ciências Biológicas Universidade de Brasília, Campus Darcy Ribeiro Campus Experimental de Registro Universidade Estadual Paulista Campus Experimental de Registro Universidade Estadual Paulista CAPES: 001 Fundação de Apoio à Pesquisa do Distrito Federal: 0193.0003440193.000344/2017 Rufford Foundation: 20243-1 Fundação Grupo Boticário de Proteção à Natureza: [BL0006_2012_1

The Neotropics harbor some of the most diversified woody species in the world, and to understand the nutrient dynamics in these ecosystems, it is crucial to understand the role of plant taxonomy. In addition, biological nitrogen (N) fixation (BNF) in the tropics is one of the key processes affecting the global N cycle. Our objective was to (i) investigate the role of taxonomy and sampling site as predictors of foliar carbon (C) and N concentration and its stable isotopes (i.e., δ13C and δ15N); (ii) assess differences in foliar N, C:N ratio, and δ15N among three functional groups: species of N2-fixers and non-fixers of the Fabaceae family, as well as non-Fabaceae species; and (iii) examine the effect of wood density on tree foliar properties. We hypothesized that Fabaceae specimens in symbiosis with N2-fixers would possess a higher foliar N than non-fixing plants, including those of the Fabaceae family, as well as high-density trees would have higher foliar C and C:N ratio relative to low-density trees, where the latter invest in nutrients instead of structural C. We used a data set composed of 3,668 specimens sampled in three main biomes of Brazil: Amazon, Atlantic Forest, and Cerrado. The partitioning of variance had a higher influence of taxonomy on leaf C, N, and C:N ratio. Conversely, foliar δ13C and δ15N were environmentally constrained. While family was the most important taxonomy level for C, N, and C:N ratio, species played a major role for δ13C and δ15N. Foliar N followed the pattern fixers > non-fixers > non-Fabaceae, while C:N ratio had an opposite trend. In addition, foliar C was correlated with wood density, where high-density > medium-density and low-density woods. The large variability of δ15N was observed among Fabaceae species, demonstrates the complexity of using δ15N as an indicator of BNF. The higher foliar N of Fabaceae non-fixers than non-Fabaceae specimens support the hypothesis that an N-demanding lifestyle is an inherent pattern in this family. Lastly, although observed in some studies, the prediction of foliar properties using wood density is challenging, and future research on this topic is needed.

As ciências forenses baseiam-se na análise técnico-científica dos vestígios de crimes. A utilização de isótopos estáveis para determinação da origem geográfica de vestígios (atribuição isotópica) já é realizada em diversas partes do mundo e em variados contextos forenses. No presente artigo são apresentados os princípios biogeoquímicos e as metodologias utilizadas para atribuir amostras desconhecidas à sua origem geográfica utilizando isótopos estáveis. A aplicabilidade da ferramenta no contexto forense no Brasil é discutida para os seguintes vestígios: animais traficados, remanescentes humanos, madeira ilegal, drogas apreendidas e alimentos fraudados. Os modelos globais existentes podem ser aplicados no Brasil, sendo úteis para esclarecer algumas questões mais abrangentes. Para questões mais específicas recomenda-se utilizar as variáveis ambientais associadas aos dados isotópicos já existentes construindo isoscapes regionais específicas. Com a disponibilização dessas isoscapes, a metodologia de atribuição isotópica explicada neste artigo poderá ser amplamente explorada e resultar em modelos espaciais possíveis de serem aplicados especificamente no contexto forense brasileiro.

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

Nitrogen (N) enrichment can have large effects on mangroves’ capacity to provide critical ecosystem services by affecting fundamental functions such as N cycling and primary productivity. However, our understanding of excess N input effects on N cycling in mangroves remains quite limited. To advance our understanding of how N enrichment via water or air pollution affects mangroves, we evaluated whether increasing N inputs would decrease biological N fixation (BNF), but intensify N dynamics and N losses to the atmosphere in these systems. We measured N concentrations in sediment and vegetation, rates of BNF in sediment and litter, and net sediment ammonification and nitrification rates. We also evaluated long-term integrated N dynamics and N losses to the atmosphere using the natural abundance of N stable isotopes (δ15N) in the sediment–plant system and in estuarine water. We performed these analyses at non-N-enriched and N-enriched (that is, polluted) fringe and basin mangroves in southeastern Brazil. The δ15N in the sediment–plant system was higher at N-enriched than non-N-enriched fringe sites, indicating increased N losses to the atmosphere from N-enriched sites. However, N concentrations in sediment and vegetation were similar or lower at N-enriched relative to non-N-enriched sites. BNF and net ammonification and nitrification rates were also similar between N-enriched and non-N-enriched sites. Excess N inputs intensified N losses to the atmosphere from mangroves, but N pools, BNF, and net ammonification and nitrification rates were not affected by N enrichment, likely because excess N was quickly lost from the system by direct denitrification and volatilization.

The colonization and spread of non-native species are recognized as a critical driver of environmental change in mangrove ecosystems. However, environmental factors that favor non-native plant colonization in mangroves are still poorly understood. To contribute to filling this gap, we investigated the effect of selected abiotic factors associated controlling aquatic macrophytes colonization in mangroves in Southeastern Brazil. Furthermore, we also assessed foliar attributes of native and non-native species to evaluate whether biotic attributes favored the colonization. We selected 18 plots in mangrove forests under different levels of anthropogenic N inputs, both colonized and non-colonized by aquatic macrophytes in the Estuarine-Lagoon Complex of Cananeia-Iguape, southeastern Brazil. We measured interstitial salinity, sediment nitrate and ammonium concentrations, and sediment physicochemical properties. We also measured foliar nitrogen (N) concentrations, foliar C:N, and foliar δ13C of both native and non-native species. We found that interstitial salinity at 10 cm depth followed by nitrate concentrations in sediment were the main factors associated with the occurrence of aquatic macrophytes in the studied mangrove areas. Moreover, non-native species had about 2-fold higher foliar N concentrations as well as about a 1.5-fold lower C:N ratios compared to native species. Low salinity and increased N availability in sediment allowed for the success of aquatic macrophytes into mangrove forests, also resulting in high amount of dead mangrove trunks (up 53% of basal area).

Light and nutrients are bottom-up factors in controlling biofilm in tropical shaded oligotrophic streams. Regardless of the predominant resource source (autochthonous or allochthonous), greater availability of light and nutrients favors the development and, later, grazing (top-down factor) of the biofilm, with reflections on the trophic structure of these ecosystems. The increase in primary productivity in lotic ecosystems may reflect the fractionation of dissolved inorganic carbon (DIC) by the algal cells contained in the biofilm. A global meta-analysis showed that an increase in primary productivity leads to enrichment of the carbon isotope ratios of biofilm. The objective of this study was to evaluate how top-down (grazing) and bottom-up (light and nutrient) factors act on the biofilm and whether algal biomass determines the isotopic fractionation of δ13C in headwaters of Central Brazil. The density of grazing macroinvertebrates was controlled with electric pulses. Electrified (excluding grazers) and non-electrified grids were implemented in open and shaded areas in each stream. The biofilm ash-free dry mass (AFDM) doubled in nutrient-enriched streams. The effect of grazing on the biomass of the biofilm was significant for the nutrient-enriched streams, with a 50% reduction in the AFDM. Additionally, shading influenced chlorophyll-a even in pristine streams, as the concentration increased approximately ten-fold under open canopy conditions. There was a significant negative relationship between chlorophyll-a concentrations and δ13C values. Our study provides evidence that biofilm biomass increases as a result of changes in bottom-up controls. Top-down control significantly reduced biofilm in the food web based on autochthonous organic matter.

Stable carbon isotope ratios (δ

Riparian forest width is a major driver of their capacity to retain sediments from agricultural fields. However, the relationship between forest width and ecosystem service provisioning may vary with local environmental conditions such as relief, soil, and vegetation types. In order to assess the effect of forest width, slope, hydraulic conductivity, and land cover (watershed scale) on the effectiveness of riparian buffers in retaining sediment from pastures cultivated with African C4 grasses, we used the natural abundance of carbon stable isotopes (δ13C) in the soil and stream organic sediments as indicators. The study was conducted in small streams of the upper Corumba River basin, state of Goias (Cerrado biome), Brazil. We found that slight increases from 2 to 5% mean slope were sufficient to change SOM to a mixture of C3 and C4 carbon sources inside the riparian forests. Therefore, hillslope's steepness and magnitude control soil transport downslope, but after reaching the riparian forest, sediment retention is strongly affected by the forest width. We also found that soil erosion leads to fine sediment deposition in agricultural streams, especially in those watersheds with a high occurrence of degraded pastures. We conclude that sites along the stream course with a combination of steep slopes, narrow forests, and intensive land use are the most vulnerable to sediment inputs and should be the focus of preservation and restoration by landscape managers.

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.

Biological nitrogen fixation (BNF) supports terrestrial primary productivity and plays key roles in mediating human-induced changes in global nitrogen (N) and carbon cycling. However, there are still critical uncertainties in our understanding of the amount of BNF occurring across terrestrial ecosystems, and of how terrestrial BNF will respond to global change. We synthesized BNF data from Latin America, a region reported to sustain some of the highest BNF rates on Earth, but that is underrepresented in previous data syntheses. We used meta-analysis and modeling approaches to estimate BNF rates across Latin America's major biomes and to evaluate the potential effects of increased N deposition and land-use change on these rates. Unmanaged tropical and subtropical moist forests sustained observed and predicted total BNF rates of 10 ± 1 and 14 ± 1 kg N ha−1 y−1, respectively, supporting the hypothesis that these forests sustain lower BNF rates than previously thought. Free-living BNF accounted for two-thirds of the total BNF in these forests. Despite an average 30% reduction of free-living BNF in response to experimental N-addition, our results suggest free-living BNF rate responses to current and projected N deposition across tropical and subtropical moist forests are small. In contrast, the conversion of unmanaged ecosystems to crop and pasture lands increased BNF rates across all terrestrial biomes, mostly in savannas, grasslands, and dry forests, increasing BNF rates 2-fold. The information obtained here provides a more comprehensive understanding of BNF patterns for Latin America.

The impact of exotic species on heterogeneous native tropical forest requires the understanding on which temporal and spatial scales these processes take place. Functional tracers such as carbon (δ13C) and nitrogen (δ15N) isotopic composition in the soil-plant system might help track the alterations induced by the exotic species. Thus, we assess the effects from the removal of the exotic species eucalyptus (Corymbia cytriodora) in an Atlantic forest Reserve, and eucalyptus removal on the alteration of the nutrient dynamics (carbon and nitrogen). The hypotheses were: (1) the eucalyptus permanence time altered δ13C and δ15N in leaves, soils and litter fractions (leaves, wood, flowers + fruits, and rest); and (2) eucalyptus removal furthered decomposition process of the soil organic matter. Hence, we determined the soil granulometry, the δ13C and δ15N in leaves, in the superficial soil layer, and litter in three sites: a secondary forest in the Atlantic forest, and other two sites where eucalyptus had been removed in different times: 12 and 3 months ago (M12 and M3, respectively). Litter samples presented intermediate δ13C and δ15N values in comparison with leaves and soil. In the M3, the greater δ13C values in both litter rest fraction and soil indicate the presence, cycling and soil incorporation of C, coming from the C4 photosynthesis of grassy species (Poaceae). In the secondary forest, the soil δ15N values were twice higher, compared with the eucalyptus removal sites, revealing the negative influence from these exotic species upon the ecosystem N dynamics. In the M12, the leaves presented higher δ13C mean value and lower δ15N values, compared with those from the other sites. The difference of δ13C values in the litter fractions regarding the soil led to a greater fractioning of 13C in all sites, except the flower + fruit fractions in the secondary forest, and the rest fraction in the M3 site. We conclude that the permanence of this exotic species and the eucalyptus removal have altered the C and N isotopic and elemental compositions in the soil-plant system. Our results suggest there was organic matter decomposition in all litter fractions and in all sites. However, a greater organic matter decomposition process was observed in the M3 soil, possibly because of a more intense recent input of vegetal material, as well as the presence of grassy, easily-decomposing herbaceous species, only in this site. Therefore, the dual-isotope approach generated a more integrated picture of the impact on the ecosystem after removing eucalyptus in this secondary Atlantic forest, and could be regarded as an option for future eucalyptus removal studies.

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.

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.

Made available in DSpace on 2022-04-29T08:36:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-01 Fundação de Apoio à Pesquisa do Distrito Federal Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Plant invasion can primarily affect the structure and functioning of terrestrial and aquatic ecosystems. Although there is evidence that plant invasion can modify organic matter dynamics in mangroves, it is uncertain whether and to which extent these changes can affect carbon (C) and nitrogen (N) dynamics in the sediment-plant system. Here, we measured: (i) the structure of native vegetation and C and N in the sediment-plant system in subtropical mangroves subjected to aquatic macrophytes invasion in southeastern Brazil. We answered the following questions: i) Do invaded mangroves differ in aboveground biomass compared to non-invaded mangroves?; ii) Are there C4 macrophytes in these sites? iii) What are the C and N stocks in sediment of invaded mangroves? We quantified C and N concentrations and the isotopic signature of such elements (δ13C and δ15N) in the sediment-plant system, the C and N stocks in the sediment (0–20 cm depth), and mangrove aboveground biomass. Mangrove aboveground biomass was lower at invaded compared to non-invaded sites reflecting the species displacement in invaded sites. The sediment at invaded mangroves did not significantly contribute to C4 sources because of the large predominance of both mangrove and invasive C3 plants. While sediment C stocks were similar among study sites (∼47 Mg ha−1), N stocks were lower at invaded (2.7 Mg ha−1) comparing to non-invaded (3.2 Mg ha−1) mangroves. The lower N stocks at invaded sites can reflect the higher leaf N concentrations and lower C:N ratios of invasive plants compared to mangroves. Thus, the effects of macrophytes invasion in subtropical mangroves are more apparent for vegetation structure and N stocks. C stocks alteration is expected the be detectable in the future. Núcleo de Estudos e Pesquisas Ambientais e Limnológicas – Programa de Pós-Graduação Em Ciências Ambientais Área Universitária 1 Vila Nossa Senhora de Fátima Campus de Planaltina Universidade de Brasília, Distrito Federal Programa de Pós-Graduação Em Ecologia Instituto de Ciências Biológicas Campus Darcy Ribeiro Universidade de Brasília, 70910-900, Distrito Federal Campus Experimental de Registro Universidade Estadual Paulista Campus Experimental de Registro Universidade Estadual Paulista Fundação de Apoio à Pesquisa do Distrito Federal: 0193.000344/2017 CAPES: 1422671

Stable carbon isotope ratios (δ13C) of soil record information regarding C3 and C4 plants at the landscape scale that can be used to document vegetation distribution patterns. The Central Brazilian savanna (locally called the Cerrado) has a substantial potential to develop studies of patterns of dynamics and distribution of soil δ13C, due to its environmental diversity. The purpose of this work was to develop a spatial model of soil δ13C (soil δ13C isoscape) to the Cerrado, based on multiple linear regression analysis, and compare the results with the existing model to obtain greater detail of the soil δ13C distribution. The model used 219 soil samples (0–20 cm depth) and a set of climatic, pedological, topographic, and vegetation correlations. The soil δ13C isoscape model presented amplitude between −29‰ and −13‰, with the highest estimated values in the southern and the lowest values in the northern of the Cerrado. Results indicate that soil δ13C, by reflecting the relative contribution of C3 and C4 species to plant community productivity, served as a proxy indicator of the vegetation history at the landscape scale for the Central Brazilian savanna. Despite the large sampling effort, there are still regions with some gaps that the model could not estimate. However, the soil δ13C isoscape model filled most the existing gaps and provided greater detail of some unique local aspects of the Cerrado.

Nutrition transition theory describes a progressive substitution of local staples for industrialized processed foods in local diets, a process documented diversely across world regions, and increasingly observed in rural areas of the global south. Here we examine the role of conditional cash transfer programs, in particular the emblematic Brazilian

Ponds arising from groundwater in Cerrado of Central Brazil are oligotrophic but highly biodiverse environments. In this study, we used stable isotope ratios to test if there are variations in carbon and nitrogen acquisition by different primary food sources and if they are influenced by seasonality in a well-preserved pond. We hypothesized that periphyton is the main food source for macrophyte-associated fauna. We found that δ13C, but not δ15N, can distinguish between primary food sources; however, the isotopic signatures of food sources did not differ significantly between seasons. The δ15N values of macrophyte-associated fauna were significantly higher for predators compared with other trophic groups, but δ13C values did not differ significantly between groups. Emergent macrophytes and periphyton were the main food sources for scrapers (contribution of 42.5%) and collector-gatherers (contribution of 41.6%), respectively. Compared with emergent macrophytes, submerged macrophytes were associated with a greater abundance of fauna and algal biomass but were not a significant food source for associated fauna. Our findings demonstrate that in this small shallow oligotrophic pond in the Cerrado, the stable isotope ratios of carbon and nitrogen of food sources did not vary between seasons but did differ between aquatic macrophyte life forms. We point out the different functional roles of macrophyte life forms, with emergent macrophytes serving as an important food resource, while submerged macrophytes mainly provide physical structure.

International audience; AbstractThe livelihood and food of rural communities is changing, possibly due to greater access to urban areas and their market economy. However, the degree of change and the main influencing factors appear to vary considerably. To characterize this process in a continuum of slave-remnant villages (Kalunga) in the Brazilian Cerrado, we assessed (i) the main influencing factors of this shift in food patterns and (ii) the isotopic composition (δ13C and δ15 N) in the fingernails of inhabitants. The stable isotope ratios from the fingernails of 87 volunteers from different Kalunga villages were used to determine the source and trophic chain diversity of food. In addition, we conducted semi-structured questionnaire interviews in 81 domestic units to verify details about food patterns, use of resources, and socioeconomic conditions. Data from the questionnaires were analyzed using a multinomial logistic regression to determine the relative influence of multiple factors on the transition process. From this, access to town and government subsidies was significantly associated with the reduction of subsistence farming and the consumption of staple foods like rice and beans. We also verified a gradual food change from C3 (more natural) to C4 (more processed) sources of food containing a smaller diversity items with an increase of δ13C and decrease of δ15 N toward the town. These results primarily indicate a transition pattern from locally produced foods to processed items that increases with greater urban access and more government subsidies in rural settings. This is the first time that an interdisciplinary approach with stable isotopes and one multinomial discriminant model has been used to assess the impacts of public policy and socioeconomic development on the livelihood of slave-remnant communities. The main issue raised here concerns the maintenance of food sovereignty in rural areas for residents who essentially live by their own efforts and livelihoods.

Padrões de distribuição espacial de isótopos estáveis podem ser apresentados em mapas chamados de isoscapes e têm sido amplamente utilizados para rastrear processos biogeoquímicos em sistemas naturais e antrópicos. Isoscapes têm o potencial de melhorar a disseminação e interpretação dos padrões espaciais de isótopos estáveis, aumentar a apropriação de resultados científicos por não-especialistas e melhorar a gestão de recursos naturais. No entanto, a abordagem de isoscape não tem sido comumente usada em estudos realizados no Brasil. Isoscapes de isótopos estáveis de oxigênio, hidrogênio, nitrogênio e carbono contribuem em áreas como migração animal, ciência forense, estudos hidrológicos e ecológicos a nível de população, comunidade e ecossistema, entre outros. Aqui nós mostramos uma revisão sobre o uso e as aplicações de isoscapes em diferentes estudos em todo o mundo. Também apontamos uma forma de mais pesquisadores brasileiros empregarem essa abordagem em seus estudos, aproveitando os métodos existentes e preenchendo lacunas espaciais e metodológicas. A incorporação de isoscapes pode ampliar o entendimento dos mecanismos e processos dos ciclos biogeoquímicos no Brasil, auxiliar na resolução de crimes, tráfico de drogas ilícitas e de animais silvestres e aumentar o conhecimento brasileiro sobre o ciclo hidrológico e os padrões de migração animal nos neotrópicos. Spatial patterns of stable isotope ratios can be represented in spatial models called isoscapes, and have been widely used to track biogeochemical processes in natural and anthropic systems. Isoscapes have the potential to improve isotope dissemination and interpretation of spatial patterns, increase scientific results appropriation by non-specialists and improve natural resource management. However, the isoscape approach has not commonly been used in studies performed in the Brazilian context. Isoscapes with oxygen, hydrogen, nitrogen and carbon stable isotopes contribute in areas such as animal migration, forensics, hydrology, and studies on population, community and ecosystem level, among others. Here, we show the well-known global use and applications of isoscapes in different studies worldwide as a background to point out the potential for more Brazilian researchers to employ this approach in their studies, taking advantage of existing methods and filling spatial and methodological gaps. The incorporation of isoscapes may broaden the understanding of mechanisms and processes of major biogeochemical cycles in Brazil, assist in solving crimes, track illicit drug origins, help to detect wild animal trafficking, and increase Brazilian knowledge about the hydrological cycle and animal migration patterns in the Neotropics.

Mangroves provide several ecosystem goods and services to society. However, mangroves are frequently subjected to land conversion, overharvesting, and pollution including increased nitrogen (N) availability. Aiming to provide useful information to predict effects of N enrichment on mangroves, we evaluated literature data on N transformation rates in sediment, dissolved N (DN) fluxes across the sediment-water interface, and natural abundance of N stable isotopes (δ15N) in the sediment-plant system in conserved mangroves and those subjected to anthropogenic N enrichment. Mangroves and terrestrial tropical forests exhibit a great overlap in rates of biological N fixation (BNF) and denitrification and nitrous oxide flux rates. Mangroves can be highly efficient users of DN forms from tidal waters, related to rapid plant uptake and an efficient conservation of DN in sediment by microbial activity. The main factors limiting N transformation rates in mangrove sediment are inorganic DN availability and microbial immobilization. The δ15N data indicated that fringe forests exhibit higher N transformation rates in sediment and higher N losses to atmosphere, compared to other mangrove types. Except for BNF, all other N transformation and flux rates seem to be intensified by increasing N availability.

The objective of this study was to determine the main patterns and factors influencing food transition in riverine people in the Brazilian Amazon. Through interviews with a semi-structured questionnaire, we inferred their food habits and provide information about general demographic, socioeconomic, resource use and environmental context. Data from the questionnaires were categorized and analyzed using a logistic regression model to assess the relative influence of socioeconomic and environment factors on the local diet. Based on a logistic regression data analysis, it was found a greater consumption of processed food significantly associated with multiple factors such as market participation, sex (female and male), government aid to forest conservation and environment context (upland and wetland). Although the local diet is composed mainly of local resources such as fish and cassava flour, increasing incomes due to direct government subsidy programs and marketing of cassava flour have influenced these local practices and habits. Through the analysis of factors influencing food transition, it was possible to evaluate those having the greatest effect on this Amazon region and propose an alternative method to subsidy food policy grounded in local opinion surveys.

Interactions between soil characteristics and soil microbiota influence soil ecosystem processes such as nitrification however, their complexity makes interpretation difficult. Furthermore, the impact of soil management systems on abundance and activity of soil microbial community is poorly understood, especially in the Neotropics. To investigate these interactions, the effects of tillage, inorganic fertilization, and plant cover on the abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were assessed by quantification of the marker gene (amoA) during different stages of soybean cultivation in a site under restoration from gravel extraction in the Central Brazilian Savanna (Cerrado). Results of molecular analysis and classic and isotope techniques showed that levels of organic C and NH4 +–N were higher in the soybean field during fallow than in an adjacent undisturbed field (Campo sujo). Ammonia oxidizer abundance and nitrification rates were also higher in the agricultural soil than in the undisturbed site, with the lowest ammonium/nitrate ratio in tilled soil. Soil δ15N was lower in the undisturbed soil than the agricultural soil. Both AOA and AOB were more abundant during soybean crop transitional stages, and this increase positively correlated with soil pH, particularly for AOB abundance, in tilled soil and within the soybean rhizosphere. The results suggest that AOB have more copiotrophic characteristics than AOA and are better able to change available ammonium in the soil. The combination of standard soil ecological methods and modern molecular analysis show the short-term modification of ammonia oxidizer abundance and soil N dynamics in a managed system within the Cerrado biome.

Much of the Brazilian savanna (known locally as the Cerrado) has been converted to pasture of African C4 grasses (exotic pastures) for livestock production. The resulting habitat simplification and decreased resource availability may be significant factors underlying the impact on some soil arthropod groups, although it is still unclear how the different soil groups respond to this impact in the Brazilian savanna. We sampled epigeic arthropods in exotic pastures, adjacent woodland savanna fragments (cerrado sensu stricto), and savanna-pasture boundaries to investigate the impact of pasture on their diversity and activity, identifying the arthropods that contribute most to the between-habitat dissimilarities and those most vulnerable to pasture implementation. We also estimated the contribution of native and exotic plants to the diets of frequently observed arthropods in each habitat using carbon and nitrogen stable isotope analysis. We found lower richness and diversity of epigeic arthropods in pastures, where we also observed decreased activity of predator groups, whereas the activity of Symphypleona and Poduromorpha springtails increased. Springtail orders and Myrmicinae morphospecies were the main contributors to the between-habitat dissimilarities. Staphylinidae, Ptiliidae, and Zodariidae morphospecies seem to be vulnerable to exotic pastures. Our isotopic models show that woodland savanna arthropods feed preferentially on native C3-plant sources, while also showing signs of exotic C4 sources in their diet. These outcomes indicate that foraging or dispersal events may occur between habitats since arthropods captured in pastures also show signs of native sources in their diet.