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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]

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]