•Latin America can significantly contribute to the mitigation of N2O emissions.•Mitigation of N2O emissions from agriculture requires an integrated approach.•Major goals include the evaluation of N2O ...sources and technological innovation.
Latin America encompasses a dizzying array of ecosystems and socioeconomic models, and the region will be highly vulnerable to the projected impacts of climate change in the next century. At the same time, Latin America can significantly contribute to the mitigation of greenhouse gases (GHG) emissions within a sustainable development framework. Land use conversion with associated biomass burning, agriculture with N fertilizers and animal waste are the main anthropogenic sources of nitrous oxide (N2O) emissions in the region, and have increased markedly in the last decades. Effective sustainable management for the mitigation of N2O emissions requires the proper evaluation of all sources, many of which are still roughly estimated or unknown, testing alternatives to reduce primary sources, and technological innovation for higher resource-use efficiency within the farm. Current barriers might be overcome through policies that support sustainable practices that reduce negative environmental impacts and simultaneously maintaining ecosystem function and services.
Tropical forests harbor a significant portion of global biodiversity and are a critical component of the climate system. Reducing deforestation and forest degradation contributes to global ...climate-change mitigation efforts, yet emissions and removals from forest dynamics are still poorly quantified. We reviewed the main challenges to estimate changes in carbon stocks and biodiversity due to degradation and recovery of tropical forests, focusing on three main areas: (1) the combination of field surveys and remote sensing; (2) evaluation of biodiversity and carbon values under a unified strategy; and (3) research efforts needed to understand and quantify forest degradation and recovery. The improvement of models and estimates of changes of forest carbon can foster process-oriented monitoring of forest dynamics, including different variables and using spatially explicit algorithms that account for regional and local differences, such as variation in climate, soil, nutrient content, topography, biodiversity, disturbance history, recovery pathways, and socioeconomic factors. Generating the data for these models requires affordable large-scale remote-sensing tools associated with a robust network of field plots that can generate spatially explicit information on a range of variables through time. By combining ecosystem models, multiscale remote sensing, and networks of field plots, we will be able to evaluate forest degradation and recovery and their interactions with biodiversity and carbon cycling. In conclusion, improving monitoring strategies will allow a better understanding of the role of forest dynamics in climate-change mitigation, adaptation, and carbon cycle feedbacks, thereby reducing uncertainties in models of the key processes in the carbon cycle, including their impacts on biodiversity, which are fundamental to support forest governance policies, such as Reducing Emissions from Deforestation and Forest Degradation.
We provide a synthesis of what regional scientific research networks in less developed regions of the world can do and why they might be relevant for societal decisions and practice. We do so through ...a focus on three regional science network initiatives that aim to enhance understanding of the multiscalar dynamics of global environmental change (GEC) regionally and globally, namely the Southern Africa Regional Science Initiative (SAFARI 2000), the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), and the Inter-American Institute for Global Change (IAI). With a view to aiding future efforts at regional research network formation, we assess whether and how these three networks enhanced regional science, and the extent to which they sought and managed to bridge the science-policy gap that challenges GEC science as a whole. Identifying key decisions and attributes bearing on their successes, the analysis attends specifically to how the three networks sought to build capacity, how differences and similarities between them affected their level of autonomy from governments, and how this and other factors influenced their functioning and achievements.
Synthesis centers offer a unique amalgam of culture, infrastructure, leadership, and support that facilitates creative discovery on issues crucial to science and society. The combination of ...logistical support, postdoctoral or senior fellowships, complex data management, informatics and computing capability or expertise, and most of all, opportunity for group discussion and reflection lowers the “activation energy” necessary to promote creativity and the cross-fertilization of ideas. Synthesis centers are explicitly created and operated as community-oriented infrastructure, with scholarly directions driven by the ever-changing interests and needs of an open and inclusive scientific community. The last decade has seen a rise in the number of synthesis centers globally but also the end of core federal funding for several, challenging the sustainability of the infrastructure for this key research strategy. Here, we present the history and rationale for supporting synthesis centers, integrate insights arising from two decades of experience, and explore the challenges and opportunities for long-term sustainability.
Carbon (C) emissions from forest fires in the Amazon during extreme droughts may correspond to more than half of the global emissions resulting from land cover changes. Despite their relevant ...contribution, forest fire-related C emissions are not directly accounted for within national-level inventories or carbon budgets. A fundamental condition for quantifying these emissions is to have a reliable estimation of the extent and location of land cover types affected by fires. Here, we evaluated the relative performance of four burned area products (TREES, MCD64A1 c6, GABAM, and Fire_cci v5.0), contrasting their estimates of total burned area, and their influence on the fire-related C emissions in the Amazon biome for the year 2015. In addition, we distinguished the burned areas occurring in forests from non-forest areas. The four products presented great divergence in the total burned area and, consequently, total related C emissions. Globally, the TREES product detected the largest amount of burned area (35,559 km2), and consequently it presented the largest estimate of committed carbon emission (45 Tg), followed by MCD64A1, with only 3% less burned area detected, GABAM (28,193 km2) and Fire_cci (14,924 km2). The use of Fire_cci may result in an underestimation of 29.54 ± 3.36 Tg of C emissions in relation to the TREES product. The same pattern was found for non-forest areas. Considering only forest burned areas, GABAM was the product that detected the largest area (8994 km2), followed by TREES (7985 km2), MCD64A1 (7181 km2) and Fire_cci (1745 km2). Regionally, Fire_cci detected 98% less burned area in Acre state in southwest Amazonia than TREES, and approximately 160 times less burned area in forests than GABAM. Thus, we show that global products used interchangeably on a regional scale could significantly underestimate the impacts caused by fire and, consequently, their related carbon emissions.
The main task of this work was to verify the existing differences in the elemental composition of samples seized in the main Brazilian regions of marijuana production, previously separated by their ...carbon and nitrogen stable isotope results, and to use these differences to classify the samples according to their geographical origins. The sector field inductively coupled plasma mass spectrometry technique (HR-ICP-MS) was the analytical technique applied and the data analysis was performed using hierarchical cluster and linear discriminant analysis. Results indicate that samples from different regions present different chemical profiles that appear in accordance to the geological characteristics of each region. The most relevant parameters were carbon and nitrogen stable isotopes, copper, cobalt, barium, lanthanum, zinc, iron, yttrium and manganese. An interesting product of this work was to demonstrate the possibility of using seized samples to create a national databank for monitoring the geographical origin of marijuana consumed in the country.
The stable isotope content of samples of precipitation and of the river water throughout the Piracicaba basin in Brazil was measured over a two-year period. The isotope values of precipitation follow ...a consistent pattern of relatively depleted values of both deuterium and oxygen 18 during the rainy summers and enriched ones during the dry winters, with all values aligned slightly above the Global Meteoric Water Line. The isotopic composition of the river water throughout the basin shows a remarkable spatial coherence and much smaller scatter of data than those of the precipitation. The isotope composition of river water is close to that of the precipitation in the rainy season, however, with a consistent lower d-excess value by 1‰-2‰. This is attributed to evaporative water loss in the basin, in part an expression of the recycling of water due to the anthropogenic activity in the region. The more divergent values are recorded during high-water stages in the rivers. In many cases, the floods during the beginning of the rainy season are characterized by an enrichment of the heavy isotopes and lower d-excess values when compared to the precipitation, with the opposite situation later in the rainy season. This is interpreted as resulting from the watershed/riverflow interaction pattern, and it thus suggests that the isotope composition can monitor the hydrologic situation in the basin and its changes.
Assuming the paradigm that catchment vegetation is the main source of particulate organic matter (POM) to rivers, the main objective of this study was to determine what the proportion of original C3 ...carbon from the forest had already been replaced by C4 carbon from sugar cane and pasture in the rivers of the Piracicaba Basin. In order to achieve this objective, we first produced a detailed landcover map using Landsat5-TM images, and then we measured the carbon stable isotopic composition of the particulate riverine organic matter (δ13C-POM) in seven sites along the major rivers and in two sites along a small creek. Sugar cane and pasture (C4 plants) covered almost 60% of the basin area, while silviculture, mostly of other crops, citrus, and forest that are C3 plants, covered 35%. Isotopic studies conducted in large pristine tropical rivers of South America and of Africa have shown that catchment vegetation is the main source of carbon in suspended POM. Our study demonstrates that relatively recent changes (70-80 yr ago) in landcover in the Piracicaba River Basin have already affected the composition of the riverine POM. Therefore, as in natural ecosystems, the vegetation (allochthonous source) plays an important role in the composition of the riverine POM in agricultural systems such as the Piracicaba River Basin. This control can be supported by the good correlation between cumulative area of the basin covered with C4 plants and the δ13C of the riverine POM. However, our study, differently from others, also shows that, during the low water period, in situ processes, such as primary production, may be an important source of carbon to the riverine POM.
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