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Scattered trees in wood-pastures represent outstanding conservation value by providing microhabitats for a variety of organisms. They also diversify ecosystem services by creating shade for livestock, and capturing and storing carbon. However, trees in wood-pastures are declining Europe-wide and an appropriate legal environment to maintain them is mostly lacking. Here we looked beyond the well-documented beneficial effects of trees and assessed potential ecosystem disservices, which may drive the controversial appreciation of trees. In a grazing exclusion experiment, we assessed the effect of trees on herbage production in wood-pastures from semi-arid continental to humid montane areas in the temperate deciduous forest ecoregion, and found that trees have a suppressive effect throughout the year, although herbage nutritive value, as indicated by herbage nitrogen content, seems to be improved in spring. When we up-scaled the local ecosystem disservice on herbage yield to entire wood-pastures, the loss remained below 3%, which is lower than reported gains in livestock production due to free access to shade. Thus, the motivation for the under-appreciation of trees by land managers and decision makers may lie in that trees suppress herbage production, but the importance of this effects is offset by the magnitude of the beneficial services of trees. We recommend current wood-pasture stakeholders to revisit their attitude towards scattered trees and encourage tree planting campaigns and tree-based climate mitigation strategies to consider the protection of trees in wood-pastures and the establishment of young ones in currently open pastures up to traditionally low tree cover proportions, as livestock production is unlikely to be compromised by this action. • Wood-pastures are widespread, high nature and cultural value landscapes. • Scattered trees in wood-pastures boost biodiversity and diversify ecosystem services. • In temperate deciduous forest ecoregions, they reduce sub-canopy biomass production. • When scaled up to the whole wood-pasture, the loss of biomass remains negligible. • Climate strategies are encouraged to involve scattered trees on pastureland. [ABSTRACT FROM AUTHOR]

• MAOM-C content was modeled for arable fields with different management. • Organic fertilization, crop rotation, and soil texture define MAOM-C content. • A POM-C/MAOM-C ratio indicator was developed and tested. • This indicator contains information on MAOM-C saturation deficits. • POM-C/MAOM-C ratio indicators might support climate mitigation strategies. Soil organic matter (SOM) is indispensable for soil health and, in the context of climate change, is considered a significant CO 2 sink. Improving agricultural management to increase long-term soil organic carbon (SOC) stocks for mitigating climate change requires tools that estimate short and long-cycling SOM pools. In this study, we analyzed changes in fast-cycling particulate organic matter (POM) and slow-cycling mineral-associated organic matter (MAOM) induced by common management practices, i.e., fertilization and crop rotation in topsoils from 25 Central European long-term field experiments. When relating MAOM-C contents to recent MAOM-C saturation levels, estimated sequestration potentials were only met in coarse-textured soils under appropriate agricultural management or fine-textured soils under extreme organic fertilization. Soil texture, organic fertilization, and below-ground OC inputs through root exudates and root biomass were decisive for estimating MAOM-C, allowing for calibration of a mixed-effects model (Nakagawa's: marginal R2 m = 0.6, conditional R2 c = 0.89). While the models containing soil texture and organic fertilization parameters can be validated and generalized (R2 = 0.43), the below-ground OC input predictor substantially decreases the generalizability of the validated models (R2 = 0.14). According to quantile regression models, we estimate the average difference in MAOM-C concentration between well-managed and control site (without organic fertilization) topsoils to 4.1 mg g−1 soil. In dependence on the soil bulk density, this amounts to 1.38 – 1.84 t ha−1 MAOM-C stocks or 5.06 – 10.1 t ha−1 CO 2 -equivalents. POM-C was difficult to predict (R2 = 0.28), presumably due to strong POM dynamics. The POM-C / MAOM-C ratio can inform on the effects of agricultural practices in before/after management change comparisons. Under increasing SOC concentration, an increasing POM-C / MAOM-C ratio indicates that the effects of organic fertilization do not transfer to real effects on long-term SOC sequestration. Because MAOM-C depends on soil texture, this ratio is also a covariate of soil texture, limiting it for comparisons between sites with different textures. However, our data indicate that agricultural long-term field experiment soils constantly approximate MAOM-C saturation when the POM-C/MAOM-C ratio is >0.35. This ratio might be used as a management goal to prevent organic over-fertilization and N loss, especially on coarse-textured soils. Thereby, the POM-C / MAOM-C ratio can help to optimize SOC management and sequestration on agricultural soils and support climate change mitigation strategies in Central Europe. [ABSTRACT FROM AUTHOR]

The extension of forest area is a globally accepted tool to offset CO 2 emissions from deforestation and the combustion of fossil fuels. The common assumption is that in addition to the perceived climate benefits increasing forest area will also support biodiversity, thus making afforestation a “win-win scenario”. Based on the existing scientific evidences, we show that joined climate and biodiversity benefits are strongly context-dependent and that the outcome of afforestation is often highly questionable. In Europe, grasslands managed at low intensity contribute substantially to biodiversity conservation and carbon storage. However, many of these grasslands have been lost due to abandonment and subsequent spontaneous succession towards woody vegetation, or due to land use intensification. Moreover, grasslands are the ecosystems most often deliberately afforested in the context of EU carbon-centered policies that may thus counteract biodiversity conservation programmes. By reviewing the main EU policies targeting forests and grasslands, we found a striking ambivalence between policies and funding schemes addressing grassland conservation on the one hand (e.g. Habitats Directive, green payments within the Common Agricultural Policy) and those supporting afforestation on the other (e.g. rural development funds). We suggest three measures towards a better harmonization of the European Union policies that target forest and grassland ecosystems: (1) promoting the alignment of the decisions taken across different policy sectors; (2) focusing on the whole range of ecosystem services and biodiversity issues rather than on carbon management only; (3) valuing systems managed at low-intensity for their multifunctionality. [ABSTRACT FROM AUTHOR]

• We introduce biogas-concrete carbon capture utilization, and storage supply chains. • These innovative supply chains have the potential to permanently remove CO 2 from the atmosphere and store it in concrete. • This climate mitigation solution is available today and can be adopted in a seamless manner. • We quantify the trade-offs between supply chains that store CO 2 in concrete and underground. Bioenergy with carbon capture and storage (BECCS) is a carbon dioxide removal (CDR) solution necessary to achieve net-zero-carbon-emissions goals. While the BECCS potential from large industrial emitters has been quantified, the BECCS potential of small emitters, such as biogas facilities, has not been investigated. Moreover, most BECCS solutions rely on the expected availability of large geological storage capacity for future CDR implementation, although the deployment of CO 2 transport and storage supply chains is still a barrier for geological carbon storage ambitions. An alternative opportunity for permanent sequestration of CO 2 is concrete, in which captured CO 2 can be permanently fixed through carbon dioxide mineralization technologies. We describe and discuss this solution by quantifying the potential of a European bioenergy with carbon capture, utilization, and storage (BECCUS) supply chain, which relies on biogenic CO 2 from biogas facilities as a CO 2 source, and on carbon dioxide mineralization in concrete as a permanent CO 2 sink. This solution is available today, can be adopted seamlessly, and does not need economies of scale for its deployment. We find that European biogas facilities produce 24 Mtons of biogenic CO 2 per year, of which 4 Mtons of CO 2 per year are emitted from facilities already upgrading biogas into bio-methane. We estimate that carbon dioxide mineralization in recycled concrete aggregates in Europe could permanently store up to 8 Mtons of CO 2 per year. Despite the limited storage potential, BECCUS supply chains would reduce CO 2 transportation distance and system complexity compared to BECCS supply chains, and would result in a marketable product, namely concrete. Overall, carbon dioxide mineralization in recycled concrete aggregates combines carbon utilization with permanent sequestration, hence contributing to carbon-neutrality goals. [ABSTRACT FROM AUTHOR]

Simulating cropland soil carbon changes following a reduction in tillage intensity is necessary to determine the utility of this management practice in climate change mitigation. In instances where reduced or no tillage increases soil carbon stocks, this is typically due to reduced decomposition rates of plant residues. Although some soil carbon models contain a priori decomposition rate modifiers to account for tillage regime, these are typically not calibrated to specific climatic regions, and none are currently available for the Rothamsted Carbon Model (RothC). Here, we present a modelling framework to estimate a tillage rate modifier (TRM) for the decomposition rate constants in RothC-26.3 which determine decay between soil carbon pools. We demonstrate this for north-west Europe, using published data assembled through a recent systematic review with propagation of error from input parameters throughout the framework. The small magnitude of soil carbon change following a reduction in tillage intensity in this region is reflected in our TRM estimates for no-till of 0.95, with 95% Credible Intervals [0.91, 1.00], and reduced tillage of 0.93 [0.90, 0.97], relative to conventional high-intensity tillage with a default TRM of 1. These TRMs facilitate realistic simulation of soil carbon dynamics following a reduction of tillage intensity using RothC, and our simple, transparent, and repeatable modelling framework is suitable for application in other climatic regions using input data generalisable to the context of interest. • We estimate rate modifiers to capture reduced tillage in the soil carbon model RothC. • Our model is parametrised from systematic review data with propagation of error. • Our framework can be used in other regions to derive empirical rate modifiers. [ABSTRACT FROM AUTHOR]

• Synthetic natural gas (SNG) by CO 2 electroreduction (ER) is matched to natural gas. • Significant CO 2 savings with SNG are possible under moderate ER performance. • Only high ER energy efficiencies (>60%) can lead to manageable OPEX. • By-product valorization or higher carbon taxes may be needed for profitability. Capture and utilization of industrial CO 2 emissions into low-carbon fuels is a promising alternative to store renewable electricity into chemical vectors while decarbonizing the economy. This work evaluates the viability pathways of producing synthetic natural gas (SNG) by direct CO 2 electroreduction (ER) in Power-To-Synthetic Natural Gas electrolyzers (PtSNG). We perform an ex-ante techno-economic (TEA) and life cycle analysis (LCA) for a 2030 framework in Europe. ER performance is varied in defined scenarios and assessed using a built-in process model of the PtSNG system, revealing uncharted limitations and benchmarks to achieve. Results show that substitution of fossil natural gas with renewable SNG could avoid more than 1 kg CO 2e /kg SNG under moderate ER conditions when using low-carbon electricity (< 60 kg CO 2e /MWh). SNG profitability for 2030 would rely on: i) higher CH 4 current densities (800–1000 mA/cm2), ii) improvements in energy efficiency (higher than 60%), and iii) valorization of the anodic product or additional carbon incentives. Our study proves that if market and technology evolve appropriately in the coming years, the SNG by CO 2 ER may be a mid-term climate change mitigation technology, among others. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Purpose: This paper aims at indicating the potential of agricultural measures in sequestering carbon as an option for climate change mitigation. The related value for society is estimated. Principle results: Agricultural practices like agroforestry, introducing hedges, low and no tillage and cover crops have an important potential to increase carbon sequestration. The total technical potential in the EU-27 is estimated to be 1566milliontonnesCO2-equivalent per year. This corresponds to 37% of all CO2-equivalent emissions in the EU in 2007. The introduction of agroforestry is the measure with the highest potential, i.e. 90% of the total potential of the measures studied. Taking account only of the value for climate change mitigation, the introduction of agroforestry is estimated to have a value of 282euro/ha in 2012 that will gradually increase to 1007euro/ha in 2030. Major conclusions: This implies that there is a huge potential which represents an important value for society in general and for the agricultural sector in specific. At the European level, only in the last few years policy makers have recognized the important benefits of agroforestry. In their rural development programmes some European countries now support farmers to introduce agroforestry. But still the current level of support is only a small fraction of the societal value of agroforestry. If this value would be fully recognized by internalizing the positive externality, we expect that agroforestry will be introduced to a very large extent in the next decades, in Europe and the rest of the world, and this will importantly change the rural landscapes. [Copyright &y& Elsevier]