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• The 2019 wildfires raised global concern about wildfires, their causes and effects. • Fire has distinct roles in fire-prone and fire-sensitive ecosystems. • In fire-prone ecosystems, we need to overcome taboos regarding the use of fire. • In fire-sensitive systems, strategies to reduce fires are urgent. • Climate-change and increasing human impact change fire regimes. In the recent past, wildfires have received much attention both by science and by the media, especially in relation to deforestation, degradation and climate change and when affecting fire-sensitive ecosystems. On the other hand, fire is a natural process in many ecosystems, in particular those to be considered fire-dependent; here, maintaining natural fire regimes is important to maintain biodiversity and ecosystem services. In many regions of the world we are still in the need for a better understanding of fire effects on plant populations, communities and ecosystems. For instance, responses of individuals and populations to heat and fire can differ among distinct fire-prone ecosystems, and community level responses often vary depending on historical disturbance regimes or the fire regime as such. Effects on ecosystem processes, e.g. on carbon cycles, can vary greatly in scale and are even more difficult to predict. This adds up to uncertainties regarding appropriate fire management strategies, both in fire-prone and fire-sensitive ecosystems. Here, we introduce a set of opinion papers on fires in Brazil and a forthcoming Virtual Special Issue of Flora – Morphology, Distribution, Functional Ecology of Plants on "Fire and vegetation", with contributions expected from a broad range of topics related to fire, plants, and vegetation. This special issue will contribute to the development not only of more knowledge on fire effects on plants and vegetation, but also to advances in fire management policies in different ecosystems around the world. The main issue, after all, is to go beyond simple classification of fires as 'good' or 'bad', but rather to develop strategies to deal with changing fire regimes and their effects in a dynamic world increasingly modified by human actions. [ABSTRACT FROM AUTHOR]

Countries have pledged to different national and international environmental agreements, most prominently the climate change mitigation targets of the Paris Agreement. Accounting for carbon stocks and flows (fluxes) is essential for countries that have recently adopted the United Nations System of Environmental-Economic Accounting - ecosystem accounting framework (UNSEEA) as a global statistical standard. In this paper, we analyze how spatial carbon fluxes can be used in support of the UNSEEA carbon accounts in five case countries with available in-situ data. Using global multi-date biomass map products and other remotely sensed data, we mapped the 2010–2018 carbon fluxes in Brazil, the Netherlands, the Philippines, Sweden and the USA using National Forest Inventory (NFI) and local biomass maps from airborne LiDAR as reference data. We identified areas that are unsupported by the reference data within environmental feature space (6–47% of vegetated country area); cross-validated an ensemble machine learning (RMSE=9–39 Mg C ha - 1 and R 2 =0.16–0.71) used to map carbon fluxes with prediction intervals; and assessed spatially correlated residuals (<5 km) before aggregating carbon fluxes from 1-ha pixels to UNSEEA forest classes. The resulting carbon accounting tables revealed the net carbon sequestration in natural broadleaved forests. Both in plantations and in other woody vegetation ecosystems, emissions exceeded sequestration. Overall, our estimates align with FAO-Forest Resource Assessment and national studies with the largest deviations in Brazil and USA. These two countries used highly clustered reference data, where clustering caused uncertainty given the need to extrapolate to under-sampled areas. We finally provide recommendations to mitigate the effect of under-sampling and to better account for the uncertainties once carbon stocks and flows need to be aggregated in relatively smaller countries. These actions are timely given the global initiatives that aim to upscale UNSEEA carbon accounting. [ABSTRACT FROM AUTHOR]

Numerical models have been developed to investigate and understand responses of biogeochemical cycle to global changes. Steady state, when a system is in dynamic equilibrium, is generally required to initialize these model simulations. However, the spin‐up process that is used to achieve steady state pose a great burden to computational resources, limiting the efficiency of global modeling analysis on biogeochemical cycles. This study introduces a new Semi‐Analytical Spin‐Up (SASU) to tackle this grand challenge. We applied SASU to Community Land Model version 5 and examined its computational efficiency and accuracy. At the Brazil site, SASU is computationally 7 times more efficient than (or saved up to 86% computational cost in comparison with) the traditional native dynamics (ND) spin‐up to reach the same steady state. Globally, SASU is computationally 8 times more efficient than the accelerated decomposition spin‐up and 50 times more efficient than ND. In summary, SASU achieves the highest computational efficiency for spin‐up on site and globally in comparison with other spin‐up methods. It is generalizable to wide biogeochemical models and thus makes computationally costly studies (e.g., parameter perturbation ensemble analysis and data assimilation) possible for a better understanding of biogeochemical cycle under climate change. Plain Language Summary: Land carbon cycle models, a critical component of earth system models, have been developed to investigate and understand ecological responses to global changes. However, the model spin‐up process to achieve steady state are usually time‐consuming and pose great computational burden. The spin‐up problem hinders our ability to study some key issues in land carbon cycle modeling, such as sensitivity analysis. This paper applies a new SASU framework to accelerate spin‐up of Community Land Model matrix version 5. Compared with traditional native dynamic approach, SASU speeds up the spin‐up by approximately 50 times, achieving the fastest spin‐up speed than all the previously recorded methods. Our SASU method is applicable to biogeochemical models and, therefore, liberates the models for computationally costly studies, such as parameter perturbation ensemble analysis and data assimilation. Key Points: A new semi‐analytical spin‐up (SASU) framework combines the default accelerated spin‐up method and matrix analytical algorithmSASU accelerates CLIM5 spin‐up by tens of times, becoming the fastest method to our knowledgeSASU is applicable to most biogeochemical models and enables computationally costly study, for example, sensitivity analysis [ABSTRACT FROM AUTHOR]

The Atlantic Forest fragments have suffered from the impacts of climate change, resulting in the increased production of coarse woody debris (CWD), which needs to be evaluated in space and time to generate accurate estimates of carbon accumulation. Thus, the goals of this study were (i) to quantify the CWD volume, necromass, carbon stock, and annual increment of carbon (AIcarb) over a period of 4 years; and (ii) to select the optimal combination of climatic, topographic, edaphic, and intrinsic forest variables to accurately predict AIcarb using machine learning and multivariate analysis. The CWD volume, necromass, and carbon stock increased between 2017 and 2020. The AIcarb was 1.09 MgC ha−1 year−1 (2017–2018), 1.24 MgC ha−1 year−1 (2018–2019), and 2.31 MgC ha−1 year−1 (2019–2020). Statistical analysis indicated that climate variables had greater weight in the CWD carbon increment in the 2018–2019 and 2019–2020 periods, while edaphic, topographical, and intrinsic forest variables were more important for the 2017–2018 period. Our findings showed that the carbon increase in CWD was linked to temporal and spatial variables within forests. These results demonstrate the importance of this parameter in the carbon cycle of forest ecosystems and highlight that there should be greater international research efforts to quantify this carbon pool. [ABSTRACT FROM AUTHOR]

This paper performs Fourier cointegration and causality tests to analyze the effect of renewable energy generation, globalization, and agricultural activities on ecological footprint and carbon dioxide (CO 2) emissions in BRIC countries for the period 1971–2016. The Fourier ADL cointegration test supports a long-run relationship between the considered variables in Brazil and China. The long-term elasticities indicate that globalization increases the pollution indicators, while renewable energy generation significantly reduces environmental pressure in China. Moreover, globalization increases CO 2 emissions, while renewable energy generation improves environmental quality in Brazil. The causality results show the existence of bidirectional causality between agriculture and environmental degradation; unidirectional relationships from globalization to the ecological footprint and CO 2 emissions; and renewable energy generation to the ecological indicators. Overall, these findings reveal the importance of renewable energy in combating environmental degradation. Based on the above results, renewable energy generation can significantly reduce environmental pollution in Brazil and China. However, renewable energy does not affect environmental pressure in Russia and India. Therefore, these countries should differentiate the current renewable energy generation policies to achieve their sustainable development goals. [ABSTRACT FROM AUTHOR]

Background: The application of different approaches calculating the anthropogenic carbon net flux from land, leads to estimates that vary considerably. One reason for these variations is the extent to which approaches consider forest land to be "managed" by humans, and thus contributing to the net anthropogenic flux. Global Earth Observation (EO) datasets characterising spatio-temporal changes in land cover and carbon stocks provide an independent and consistent approach to estimate forest carbon fluxes. These can be compared against results reported in National Greenhouse Gas Inventories (NGHGIs) to support accurate and timely measuring, reporting and verification (MRV). Using Brazil as a primary case study, with additional analysis in Indonesia and Malaysia, we compare a Global EO-based dataset of forest carbon fluxes to results reported in NGHGIs. Results: Between 2001 and 2020, the EO-derived estimates of all forest-related emissions and removals indicate that Brazil was a net sink of carbon (− 0.2 GtCO2yr−1), while Brazil's NGHGI reported a net carbon source (+ 0.8 GtCO2yr−1). After adjusting the EO estimate to use the Brazilian NGHGI definition of managed forest and other assumptions used in the inventory's methodology, the EO net flux became a source of + 0.6 GtCO2yr−1, comparable to the NGHGI. Remaining discrepancies are due largely to differing carbon removal factors and forest types applied in the two datasets. In Indonesia, the EO and NGHGI net flux estimates were similar (+ 0.6 GtCO2 yr−1), but in Malaysia, they differed in both magnitude and sign (NGHGI: -0.2 GtCO2 yr−1; Global EO: + 0.2 GtCO2 yr−1). Spatially explicit datasets on forest types were not publicly available for analysis from either NGHGI, limiting the possibility of detailed adjustments. Conclusions: By adjusting the EO dataset to improve comparability with carbon fluxes estimated for managed forests in the Brazilian NGHGI, initially diverging estimates were largely reconciled and remaining differences can be explained. Despite limited spatial data available for Indonesia and Malaysia, our comparison indicated specific aspects where differing approaches may explain divergence, including uncertainties and inaccuracies. Our study highlights the importance of enhanced transparency, as set out by the Paris Agreement, to enable alignment between different approaches for independent measuring and verification. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this paper is to describe the benefits of sugar cane ethanol in Brazil, appointing the productivity of this type of fuel based on hectares of plantation, its carbon dioxide cycle and the contribution to reduce the greenhouse effect. In the following step the uses of ethanol for hydrogen production by steam reforming is analyzed and some comparison with natural gas steam reforming is performed. The sugar cane industry in Brazil, in a near future, in the hydrogen era, could be modified according to our purpose, since besides the production of sugar, and ethylic and anhydric alcohol, Brazilian sugar cane industry will also be able to produce biohydrogen. Fuel cells appear like a promising technology for energy generation. Among several technologies in the present, the PEMFC (proton exchange membrane fuel cell) is the most appropriate for vehicles application, because it combines durability, high power density, high efficiency, good response and it works at relatively low temperatures. Besides that it is easy to turn it on and off and it is able to support present vibration in vehicles. A PEMFC''s problem is the need of noble catalysts like platinum. Another problem is that CO needs to be in low concentration, requiring a more clean hydrogen to avoid fuel cell deterioration. One part of this paper was developed in Stockholm, where there are some buses within the CUTE (clean urban transport for Europe) project that has been in operation with FC since January 2004. Another part was developed in Guaratinguetá, Brazil. Brazil intends to start up a program of FC buses. As conclusion, this paper shows the economical analysis comparing buses moved by fuel cells using hydrogen by different kinds of production. Electrolyze with wind turbine, natural gas steam reforming and ethanol steam reforming. [Copyright &y& Elsevier]

1. The size of lakes and the size distribution of lakes are important parameters controlling lake function, and how lakes interact with landscapes, the atmosphere and ecosystems. A baseline digital database of lakes could be used to improve understanding of lake function, to extrapolate lake information to regional and global scales, and as a basis for detecting future changes to lakes. 2. This paper examines the capabilities of synthetic aperture radar (SAR) imagery produced by the Japanese Earth Resources Satellite (JERS-1) to map the number and size distribution of lakes in western Arctic Canada, Central Canada and the Pantanal (Brazil). 3. For the Arctic and Pantanal, the total area found within one lake size category increases towards smaller lakes. The opposite was true for the area in Central Canada. The number of lakes in the smallest size category, 0.01 to 0.1 km2, was underestimated for all regions owing to the resolution of the mosaics - 100 × 100m. The number of large lakes in the Pantanal was over-estimated through confusion with intermittent floodways that are scrubby grasslands and bare sand in the dry season and which exhibit low backscattering and therefore appear dark like lakes. 4. The lake distributions were combined with existing data to produce preliminary regional estimates of carbon accumulation. Lakes may accumulate as much as 1.7 and 1.3 t C km-2 yr-1 for the Arctic Canadian and Central Canadian areas, respectively. No estimates were produced for the Pantanal because there are no applicable data on carbon accumulation rates available for that region. [ABSTRACT FROM AUTHOR]

An accurate estimate of carbon fluxes associated with tropical deforestation from the last two decades is needed to balance the global carbon budget. Several studies have already estimated carbon emissions from tropical deforestation, but the estimates vary greatly and are difficult to compare due to differences in data sources, assumptions, and methodologies. In this paper, we review the different estimates and datasets, and the various challenges associated with comparing them and with accurately estimating carbon emissions from deforestation. We performed a simulation study over legal Amazonia to illustrate some of these major issues. Our analysis demonstrates the importance of considering land-cover dynamics following deforestation, including the fluxes from reclearing of secondary vegetation, the decay of product and slash pools, and the fluxes from regrowing forest. It also suggests that accurate carbon-flux estimates will need to consider historical land-cover changes for at least the previous 20 years. However, this result is highly sensitive to estimates of the partitioning of cleared carbon into instantaneous burning vs. Long-timescale slash pools. We also show that carbon flux estimates based on ‘committed flux’ calculations, as used by a few studies, are not comparable with the ‘annual balance’ calculation method used by other studies. [ABSTRACT FROM AUTHOR]

The western Tropical Atlantic Ocean is a biogeochemically complex region due to the structure of the surface current system and the large freshwater input from the Amazon River coupled with the dynamics of precipitation. Such features make it difficult to understand the dynamics of the carbon cycle, leading to contrasting estimates in sea‐air CO2 exchanges in this region. Here, we demonstrate that these contrasting estimates occur because the western Tropical Atlantic Ocean can be split into three distinct sub‐regions in terms of the sea‐air CO2 exchanges. The sub‐region under the North Brazil Current domain acts as a weak annual CO2 source to the atmosphere, with low interannual variability. The sub‐region under the North Equatorial Current influence acts as an annual CO2 sink, with great temporal variability. The third sub‐region under the Amazon River plume influence shows greater interannual variability of CO2 exchanges, but it always acts as a net oceanic sink for CO2. Despite this large spatial variability, the entire region acts as a net annual CO2 sink of −1.6 ± 1.0 mmol m−2 day−1. Importantly, the Amazon River plume waters drive 87% of the CO2 uptake in the western Tropical Atlantic Ocean. In addition, we found a significant increasing trend in sea surface CO2 partial pressure in the North Brazil Current and North Equatorial Current waters. Such trends are more pronounced than the increase in atmospheric CO2 partial pressure, revealing the sensitivity of carbon dynamics in these sub‐regions to global climate change. Key Points: Sea‐air CO2 release (uptake) shown in the North Brazil Current (North Equatorial Current) domainStrong CO2 uptake under the Amazon River plume influence, which accounts for 87% of the CO2 uptake by the western Tropical Atlantic OceanIncreasing trend of sea surface CO2 partial pressure in the North Brazil Current and the North Equatorial Current waters [ABSTRACT FROM AUTHOR]

Background: The recent studies of the variations in the atmospheric column-averaged CO2 concentration ( X CO 2 ) above croplands and forests show a negative correlation between X CO 2 and Sun Induced Chlorophyll Fluorescence (SIF) and confirmed that photosynthesis is the main regulator of the terrestrial uptake for atmospheric CO2. The remote sensing techniques in this context are very important to observe this relation, however, there is still a time gap in orbital data, since the observation is not daily. Here we analyzed the effects of several variables related to the photosynthetic capacity of vegetation on X CO 2 above São Paulo state during the period from 2015 to 2019 and propose a daily model to estimate the natural changes in atmospheric CO2. Results: The data retrieved from the Orbiting Carbon Observatory-2 (OCO-2), NASA-POWER and Application for Extracting and Exploring Analysis Ready Samples (AppEEARS) show that Global Radiation (Qg), Sun Induced Chlorophyll Fluorescence (SIF) and, Relative Humidity (RH) are the most significant factors for predicting the annual X CO 2 cycle. The daily model of X CO 2 estimated from Qg and RH predicts daily X CO 2 with root mean squared error of 0.47 ppm (the coefficient of determination is equal to 0.44, p < 0.01). Conclusion: The obtained results imply that a significant part of daily X CO 2 variations could be explained by meteorological factors and that further research should be done to quantify the effects of the atmospheric transport and anthropogenic emissions. [ABSTRACT FROM AUTHOR]

With the advancement of remote sensing, it is now possible to identify and characterize greenhouse gas emissions under deferment land uses. Given the above, this study aimed to characterize the spatial–temporal variability and the main factors controlling the average atmospheric CO2 column (Xco2) in the macroregion of Ribeirão Preto (MRP), São Paulo, a significant sugarcane producer in Brazil. We obtained remote sensing data from January 2015 to December 2018. The variables used were Xco2 and sun-induced fluorescence of chlorophyll (SIF) by NASA's Orbiting Carbon Observatory-2 satellite (OCO-2), relative humidity (RH), global radiation (Qg), and the average temperature at 2 m (T2m) by the NASA-POWER platform, and leaf area index (LAI) and evapotranspiration by Penman–Monteith (ET) by MODIS sensor. We evaluated the data in trimester's averages, where descriptive statistics, Pearson correlation and linear regression have been applied. The spatial distribution was made by the inverse distance weighted (IDW). The minimum (390.40 ± 0.41 ppm) and maximum (394.75 ± 0.34 ppm) mean of Xco2 was observed in the first quarter of 2015 and third quarter of 2017. The Xco2 obtained negative correlations with the SIF (−0.81), LAI (−0.81), RH (−0.74), ET (−0.84), and Qg (−0.51). Hotspots and coldspots of Xco2 tend to vary over the years. We conclude that the temporal variation of Xco2 above sugarcane areas in southern Brazil is well represented by a periodic function. Our results indicate photosynthesis and soil exposure after harvest are factors that could act as source and sink of CO2. [ABSTRACT FROM AUTHOR]

Identification of terrestrial carbon (C) sources and sinks is critical for understanding the Earth system as well as mitigating and adapting to climate change resulting from greenhouse gas emissions. Predicting whether a given location will act as a C source or sink using terrestrial ecosystem models (TEMs) is challenging due to net flux being the difference between far larger, spatially and temporally variable fluxes with large uncertainties. Uncertainty in projections of future dynamics, critical for policy evaluation, has been determined using multi-TEM intercomparisons, for various emissions scenarios. This approach quantifies structural and forcing errors. However, the role of parameter error within models has not been determined. TEMs typically have defined parameters for specific plant functional types generated from the literature. To ascertain the importance of parameter error in forecasts, we present a Bayesian analysis that uses data on historical and current C cycling for Brazil to parameterise five TEMs of varied complexity with a retrieval of model error covariance at 1 ∘ spatial resolution. After evaluation against data from 2001–2017, the parameterised models are simulated to 2100 under four climate change scenarios spanning the likely range of climate projections. Using multiple models, each with per pixel parameter ensembles, we partition forecast uncertainties. Parameter uncertainty dominates across most of Brazil when simulating future stock changes in biomass C and dead organic matter (DOM). Uncertainty of simulated biomass change is most strongly correlated with net primary productivity allocation to wood (NPPwood) and mean residence time of wood (MRTwood). Uncertainty of simulated DOM change is most strongly correlated with MRTsoil and NPPwood. Due to the coupling between these variables and C stock dynamics being bi-directional, we argue that using repeat estimates of woody biomass will provide a valuable constraint needed to refine predictions of the future carbon cycle. Finally, evaluation of our multi-model analysis shows that wood litter contributes substantially to fire emissions, necessitating a greater understanding of wood litter C cycling than is typically considered in large-scale TEMs. [ABSTRACT FROM AUTHOR]

The drainage microbasin of the Bule stream drains an important part of the Quadrilátero Ferrífero, known as one of the main metallogenetic provinces on the planet and of great importance for Brazilian mineral production. The surface water chemistry was analyzed to quantify the chemical weathering rates and the CO2 consumption associated with the weathering processes. Bicarbonate, calcium, magnesium, and silica are the main ions dissolved in the basin, reflecting the local lithotype composed of dolomites, phyllites, and quartzites. The main source of dissolved elements for the basin is carbonate rocks, followed by rainfall. The sulfide oxidation process appeared as the main source of sulfate for the river (approximately 90%). The total weathering rate was 1.5 × 105 mol km−2 year−1 and the total CO2 consumption was 7.3 × 104 mol km−2 year−1, where carbonate rocks are mainly responsible for these flows (> 90%). The highest values were found at high flow, where for the carbonate phases, the weathering rate was 5.38 × 102 mol km−2 day−1, and for CO2 consumption, it was 2.92 × 102 mol km−2 day−1. Despite being a microbasin, the results are relevant when compared to large basins, showing the importance of small-scale studies of rivers that drain basins with a predominance of the lithological type. [ABSTRACT FROM AUTHOR]

Land-use change has been the dominant source of anthropogenic carbon emissions for most of the historical period and is currently one of the largest and most uncertain components of the global carbon cycle. Advancing the scientific understanding on this topic requires that the best data be used as input to state-of-the-art models in well-organized scientific assessments. The Land-Use Harmonization 2 dataset (LUH2), previously developed and used as input for simulations of the 6th Coupled Model Intercomparison Project (CMIP6), has been updated annually to provide required input to land models in the annual Global Carbon Budget (GCB) assessments. Here we discuss the methodology for producing these annual LUH2-GCB updates and extensions which incorporate annual wood harvest data updates from the Food and Agriculture Organization (FAO) of the United Nations for dataset years after 2015 and the History Database of the Global Environment (HYDE) gridded cropland and grazing area data updates (based on annual FAO cropland and grazing area data updates) for dataset years after 2012, along with extrapolations to the current year due to a lag of 1 or more years in the FAO data releases. The resulting updated LUH2-GCB datasets have provided global, annual gridded land-use and land-use-change data relating to agricultural expansion, deforestation, wood harvesting, shifting cultivation, regrowth and afforestation, crop rotations, and pasture management and are used by both bookkeeping models and dynamic global vegetation models (DGVMs) for the GCB. For GCB 2019, a more significant update to LUH2 was produced, LUH2-GCB2019 (10.3334/ORNLDAAC/1851, Chini et al., 2020b), to take advantage of new data inputs that corrected cropland and grazing areas in the globally important region of Brazil as far back as 1950. From 1951 to 2012 the LUH2-GCB2019 dataset begins to diverge from the version of LUH2 used for the World Climate Research Programme's CMIP6, with peak differences in Brazil in the year 2000 for grazing land (difference of 100 000 km 2) and in the year 2009 for cropland (difference of 77 000 km 2), along with significant sub-national reorganization of agricultural land-use patterns within Brazil. The LUH2-GCB2019 dataset provides the base for future LUH2-GCB updates, including the recent LUH2-GCB2020 dataset, and presents a starting point for operationalizing the creation of these datasets to reduce time lags due to the multiple input dataset and model latencies. [ABSTRACT FROM AUTHOR]

Silicate rock weathering maintains a stable and long‐term absorption of CO2. However, the magnitude, spatial pattern, and evolution characteristics of global silicate rock weathering carbon sink (SCS) remain unclear. To solve this problem, based on high‐precision hydrometeorological data (1996–2017) and CMIP5 data (2041–2060), using the Celine model, we calculated the global silicate rock weathering carbon sink flux (SCSF) magnitude and spatio‐temporal distribution for 1996–2017. We also predicted the SCSF under two future greenhouse gas emission scenarios (RCP 4.5 and RCP 8.5). Then, we produced a spatial data set (0.5 × 0.5) of global SCSF from 1996 to 2017 and found that the global average annual SCSF was 1.67 t/km2/yr, and the SCS was 127.11 Tg/yr. In particular, Brazil's silicate rock contribution accounts for nearly a quarter of the global SCS (24.41%). Although the GEM‐CO2 model is now widely used, the SCSF, without considering the temperature, may be overestimated by 5.4%, and the maximum contribution of temperature to it can reach 240 kg/km2/yr. Moreover, the global SCS is now showing a downward trend, but the global emission of greenhouse gases in the future (2041–2060) will continue to increase the carbon sink capacity (23.8%) due to temperature changes. In summary, we have produced a set of high‐resolution spatiotemporal data of the past and the future. The above results fill up the large‐scale data gap of SCSF and provide a scientific basis for quantitatively assessing the impact of climate change on SCS. Key Points: Silicate rock carbon sink is expanded to global scale with high spatial resolutionThere is huge spatial heterogeneity in global silicate rock carbon sink fluxFrom 2041 to 2060, silicate rock carbon sink will rise in response to global warming [ABSTRACT FROM AUTHOR]

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Tropical secondary forests sequester carbon up to 20 times faster than old-growth forests. This rate does not capture spatial regrowth patterns due to environmental and disturbance drivers. Here we quantify the influence of such drivers on the rate and spatial patterns of regrowth in the Brazilian Amazon using satellite data. Carbon sequestration rates of young secondary forests (<20 years) in the west are ~60% higher (3.0 ± 1.0 Mg C ha−1 yr−1) compared to those in the east (1.3 ± 0.3 Mg C ha−1 yr−1). Disturbances reduce regrowth rates by 8–55%. The 2017 secondary forest carbon stock, of 294 Tg C, could be 8% higher by avoiding fires and repeated deforestation. Maintaining the 2017 secondary forest area has the potential to accumulate ~19.0 Tg C yr−1 until 2030, contributing ~5.5% to Brazil's 2030 net emissions reduction target. Implementing legal mechanisms to protect and expand secondary forests whilst supporting old-growth conservation is, therefore, key to realising their potential as a nature-based climate solution. This study uses regional and global remote sensing data to assess the regrowth of secondary forests in the Brazilian Amazon biome. The authors find differences of regrowth rates due to climate, forest fires and deforestation actions and further quantify their carbon capture potential. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Summary: Understanding the pronounced seasonal and spatial variation in leaf carboxylation capacity (Vc,max) is critical for determining terrestrial carbon cycling in tropical forests. However, an efficient and scalable approach for predicting Vc,max is still lacking.Here the ability of leaf spectroscopy for rapid estimation of Vc,max was tested. Vc,max was estimated using traditional gas exchange methods, and measured reflectance spectra and leaf age in leaves sampled from tropical forests in Panama and Brazil. These data were used to build a model to predict Vc,max from leaf spectra.The results demonstrated that leaf spectroscopy accurately predicts Vc,max of mature leaves in Panamanian tropical forests (R2 = 0.90). However, this single‐age model required recalibration when applied to broader leaf demographic classes (i.e. immature leaves). Combined use of spectroscopy models for Vc,max and leaf age enabled construction of the Vc,max–age relationship solely from leaf spectra, which agreed with field observations. This suggests that the spectroscopy technique can capture the seasonal variability in Vc,max, assuming sufficient sampling across diverse species, leaf ages and canopy environments.This finding will aid development of remote sensing approaches that can be used to characterize Vc,max in moist tropical forests and enable an efficient means to parameterize and evaluate terrestrial biosphere models. [ABSTRACT FROM AUTHOR]

Tropical South America plays a central role in global climate. Bowen ratio teleconnects to circulation and precipitation processes far afield, and the global CO2 growth rate is strongly influenced by carbon cycle processes in South America. However, quantification of basin‐wide seasonality of flux partitioning between latent and sensible heat, the response to anomalies around climatic norms, and understanding of the processes and mechanisms that control the carbon cycle remains elusive. Here, we investigate simulated surface‐atmosphere interaction at a single site in Brazil, using models with different representations of precipitation and cloud processes, as well as differences in scale of coupling between the surface and atmosphere. We find that the model with parameterized clouds/precipitation has a tendency toward unrealistic perpetual light precipitation, while models with explicit treatment of clouds produce more intense and less frequent rain. Models that couple the surface to the atmosphere on the scale of kilometers, as opposed to tens or hundreds of kilometers, produce even more realistic distributions of rainfall. Rainfall intensity has direct consequences for the "fate of water," or the pathway that a hydrometeor follows once it interacts with the surface. We find that the model with explicit treatment of cloud processes, coupled to the surface at small scales, is the most realistic when compared to observations. These results have implications for simulations of global climate, as the use of models with explicit (as opposed to parameterized) cloud representations becomes more widespread. Key Points: Ecophysiological function during seasonal drought is dependent upon storage and availability of rainfall that falls during the wet seasonThe scale of coupling between land and atmosphere strongly influences this "fate of water" in simulationsSimulations tend toward "water limitation" or "light limitation" depending on this scale of coupling [ABSTRACT FROM AUTHOR]

The unprecedented loss of biological diversity has negative impacts on ecosystems and the associated benefits which they provide to humans. Bromeliads have high diversity throughout the Neotropics, but they have been negatively affected by habitat loss and fragmentation, climate change, invasive species, and commercialization for ornamental purpose. These plants provide direct benefits to the human society, and they also form microecosystems in which accumulated water and nutrients support the communities of aquatic and terrestrial species, thus maintaining local diversity. We performed a systematic review of the contribution of bromeliads to ecosystem services across their native geographical distribution. We showed that bromeliads provide a range of ecosystem services such as maintenance of biodiversity, community structure, nutrient cycling, and the provisioning of food and water. Moreover, bromeliads can regulate the spread of diseases, and water and carbon cycling, and they have the potential to become important sources of chemical and pharmaceutical products. The majority of this research was performed in Brazil, but future research from other Neotropical countries with a high diversity of bromeliads would fill the current knowledge gaps and increase the generality of these findings. This systematic review identified that future research should focus on provisioning, regulating, and cultural services that have been currently overlooked. This would enhance our understanding of how bromeliad diversity contributes to human welfare, and the negative consequences that loss of bromeliad plants can have on communities of other species and the healthy functioning of the entire ecosystems. [ABSTRACT FROM AUTHOR]

We investigate whether the recently observed trends in daily maximum and minimum near-surface air temperature (Tmax and Tmin, respectively) over South America (SA) are consistent with the simulated response of Tmin and Tmax to anthropogenic forcing. Results indicate that the recently observed warming in the dry seasons is well beyond the range of natural (internal) variability. In the wet season the natural modes of variability explain a substantial portion of Tmin and Tmax variability. We demonstrate that the large-scale component of greenhouse gas (GHG) forcing is detectable in dry-seasonal warming. However, none of the global and regional climate change projections reproduce the observed warming of up to 0.6 K/Decade in Tmax in 1983-2012 over northern SA during the austral spring (SON). Thus, besides the global manifestation of GHG forcing, other external drivers have an imprint. Using aerosols-only forcing simulations, our results provide evidence that anthropogenic aerosols also have a detectable influence in SON and that the indirect effect of aerosols on cloud’s lifetime is more compatible with the observed record. In addition, there is an increasing trend in the observed incoming solar radiation over northern SA in SON, which is larger than expected from natural (internal) variability alone. We further show that in the dry seasons the spread of projected trends based on the RCP4.5 scenario derived from 30 CMIP5 models encompasses the observed area-averaged trends in Tmin and Tmax. This may imply that the observed excessive warming in the dry seasons serve as an illustration of plausible future expected change in the region. [ABSTRACT FROM AUTHOR]

Abstract: Brazil is one of the major contributors to land‐use change emissions, mostly driven by agricultural expansion for food, feed, and bioenergy feedstock. Policies to avoid deforestation related to private commitments, economic incentives, and other support schemes are expected to improve the effectiveness of current command and control mechanisms increasingly. However, until recently, land tenure was unknown for much of the Brazilian territory, which has undermined the governance of native vegetation and challenged support and incentive mechanisms for avoiding deforestation. We assess the total extent of public governance mechanisms protecting aboveground carbon (AGC) stocks. We constructed a land tenure dataset for the entire nation and modeled the effects and uncertainties of major land‐use acts on protecting AGC stocks. Roughly 70% of the AGC stock in Brazil is estimated to be under legal protection, and an additional 20% is expected to be protected after areas in the Amazon with currently undesignated land undergo a tenure regularization. About 30% of the AGC stock is on private land, of which roughly two‐thirds are protected. The Cerrado, Amazon, and Caatinga biomes hold about 40%, 30%, and 20% of the unprotected AGC, respectively. Effective conservation of protected and unprotected carbon will depend on successful implementation of the Forest Act, and regularization of land tenure in the Amazon. Policy development that prioritizes unprotected AGC stocks is warranted to promote conservation of native vegetation beyond the legal requirements. However, different biomes and land tenure structures may require different policy settings considering local and regional specifics. Finally, the fate of current AGC stocks relies upon effective implementation of command and control mechanisms, considering that unprotected AGC in native vegetation on private land only accounts for 6.5% of the total AGC stock. [ABSTRACT FROM AUTHOR]

Ucides cordatus is an abundant mangrove crab in Brazil constructing burrows of up to 2 m depth. Sediment around burrows may oxidize during low tides. This increase in sediment-air contact area may enhance carbon degradation processes. We hypothesized that 1) the sediment CO2 efflux rate is greater with burrows than without and 2) the reduction potential in radial profiles in the sediment surrounding the burrows decreases gradually, until approximating non-bioturbated conditions. Sampling was conducted during the North Brazilian wet season at neap tides. CO2 efflux rates of inhabited burrows and plain sediment were measured with a CO2/H2O gas analyzer connected to a respiration chamber. Sediment redox potential, pH and temperature were measured in the sediment surrounding the burrows at horizontal distances of 2, 5, 8 and 15 cm at four sediment depths (1, 10, 30 and 50 cm) and rH values were calculated. Sediment cores (50 cm length) were taken to measure the same parameters for plain sediment. CO2 efflux rates of plain sediment and individual crab burrows with entrance diameters of 7 cm were 0.7–1.3 µmol m−2s−1 and 0.2–0.4 µmol burrows−1s−1, respectively. CO2 released from a Rhizophora mangle dominated forest with an average of 1.7 U. cordatus burrows−1m−2 yielded 1.0–1.7 µmol m−2s−1, depending on the month and burrow entrance diameter. Laboratory experiments revealed that 20–60% of the CO2 released by burrows originated from crab respiration. Temporal changes in the reduction potential in the sediment surrounding the burrows did not influence the CO2 release from burrows. More oxidized conditions of plain sediment over time may explain the increase in CO2 release until the end of the wet season. CO2 released by U. cordatus and their burrows may be a significant pathway of CO2 export from mangrove sediments and should be considered in mangrove carbon budget estimates. [ABSTRACT FROM AUTHOR]

Organic residues management (ORM) alter plant traits and soil properties by changing nutrient and carbon cycling. It is unclear how ORM (mulching, compost, and their combination) applied for 18 months creates a mechanism to promote changes in a P. pyrifolia field. Our aim was to evaluate the influence of ORM on P. pyrifolia nutritional status, plant traits, yield, and carbon sequestration in a 16-year subtropical P. pyrifolia field. For this purpose, we performed an experiment in a randomized block design, using a factorial scheme 2 × 2, with the use of Compost and Mulching (e.g., presence and absence). The highest values of leaves N content, plant height, stem biomass, root biomass, total biomass, yield, and above- and belowground carbon (C) density were found on plots that received compost as the ORM. For soil organic C stock, the highest values were found on plots where mulching was applied. Finally, the highest values of total C density were found on plots that received the combination of Mulching and Compost. Our findings suggest that: (i) the use of Compost is the best alternative to promote leaves N content, plant height, stem dry biomass, root dry biomass, and total dry biomass, plant yield, and above- and belowground C density into a 16-year P. pyrifolia field into subtropical conditions; and (ii) the soil organic C stocks were improved using just the mulching treatment. The results highlight the importance of considering just one organic residue practice based on a sustainable way to improve both plant production and carbon sequestration, no differences were found between the use of compost and the combination of compost and mulching. [ABSTRACT FROM AUTHOR]

A better understanding of the mechanisms controlling the magnitude and sign of carbon components in tropical forest ecosystems is important for reliable estimation of this important regional component of the global carbon cycle. We used the JULES vegetation model to simulate all components of the carbon balance at six sites along an Andes-Amazon transect across Peru and Brazil and compared the results to published field measurements. In the upper montane zone the model predicted a lack of forest vegetation, indicating a need for better parameterization of the responses of cloud forest vegetation within the model. In the lower montane and lowland zones simulated ecosystem productivity and respiration were predicted with reasonable accuracy, although not always within the error bounds of the observations. Model-predicted carbon use efficiency in this transect surprisingly did not increase with elevation, but remained close to the 'temperate' value 0.5. Upper montane forests were predicted to allocate ~50% of carbon fixation to biomass maintenance and growth, despite available measurements showing that they only allocate ~33%. This may be explained by elevational changes in the balance between growth and maintenance respiration within the forest canopy, as controlled by both temperature- and pressure-mediated processes, which is not yet well represented in current vegetation models. [ABSTRACT FROM AUTHOR]

The article focuses on the use of cavity ring-down spectroscopy (CRDS) to obtain accurate measurements of carbon dioxide (CO2) and methane (CH4) greenhouse gases in the phase B campaign of Balanço Atmosférico Regional de Carbono na Amazônia in May 2009 in Brazil. It says that measuring the concentration of carbon dioxide is important in studying the carbon cycle and its role in global warming. Results show that CRDS offer more than 0.05 ppm accuracy.

The variation of surface partial pressure of CO2 (pCO2), pH, salinity and dissolved organic carbon (DOC) in 12 coastal Brazilian lakes was examined following periods of contrasting rainfall. It was tested the hypothesis of a positive relationship of rainfall and the associated transport of terrestrial carbon with pCO2 in tropical lakes. High rainfall was followed by a large, almost 10 fold increase in pCO2 and a one unit decrease in pH in the lakes, whereas no consistent changes in DOC were observed. CO2 emissions to the atmosphere from the Brazilian coastal lakes studied here were enhanced, on average, almost 10 fold, from 28.5±6.0 mmolm-2 d-1 in drier periods to 245.3.1±51.5 mmolm-2 d-1 following heavy rain. Hence, precipitation and subsequent ventilation of groundwater CO2 in lakes might provide an important conduit to deliver CO2 resulting from soil respiration to the atmosphere. [ABSTRACT FROM AUTHOR]

Tropical deforestation is a significant driver of global environmental change, given its impacts on the carbon cycle and biodiversity. Loss of the Amazon forest, the focus of this article, is of particular concern because of the size and the rapid rate at which the forest is being converted to agricultural use. In this article, we identify what has been the most important driver of deforestation in a specific colonization frontier in the Brazilian Amazon. To this end, we consider (1) the land-use dynamics of smallholder households, (2) the formation of pasture by large-scale ranchers, and (3) structural processes of land aggregation by ranchers. Much has been written about relations between smallholders and ranchers in the Brazilian Amazon, particularly those involving conflict over land, and this article explicates the implications of such social processes for land cover. Toward this end, we draw on panel data (1996-2002) and satellite imagery (1986-1999) to show the deforestation that is attributable to small- and largeholders, and the deforestation that is attributable to aggregations of property arising from a process that we refer to as frontier stratification. Evidently, most of the recent deforestation in the study area has resulted from the household processes of smallholders, not from conversions to pasture pursuant to the appropriations of smallholders' property by well-capitalized ranchers or speculators. [ABSTRACT FROM AUTHOR]