Experts from the Land Use, Land Use Change and Forestry (LULUCF) sector are one of HoliSoils’ main target stakeholders. The LULUCF group at the Joint Research Centre (JRC) Bioeconomy Unit provides science-based support to the European Commission’s services in understanding how forests mitigate and interact with climate change in the context of EU and international climate policies. Many of the results developed in HoliSoils are directly targeted to these experts and HoliSoils has established a good and regular dialogue with the group, not least through Anu Korosuo who represents JRC on the HoliSoils Stakeholder and End-User Advisory Board (SEAB).
Partners from the HoliSoils project were invited to present the project and its results so far at the 2023 JRC LULUCF workshop, held in May. The main purpose of these meetings is to provide understanding on how LULUCF regulation is interpreted and of the methods used by different member states for their GHG inventories. The May workshop focused on the needs and opportunities to enhance LULUCF reporting to support climate change mitigation targets for 2030 and beyond.
Aleksi Lehtonen (Luke) presented the HoliSoils project while Mart-Jan Schelhaas (WUR) presented on EFISCEN-Space, the high-resolution forest resource model being updated as part of the project. Hans Verkerk (EFI), also a partner in HoliSoils, presented the ForestPaths project, of which he is coordinator. HoliSoils is working with ForestPaths and other relevant EU-funded projects to ensure synergies between activities and avoid duplicating efforts.
The LULUCF workshop combined overview sessions on the state-of-art of the GHG inventories and the revised LULUCF regulation. Specific sessions focused on moving to higher Tiers in reporting, and on the use of geographically-explicit data and new advances in remote sensing in GHG inventories.
Interesting for HoliSoils is that countries will need to improve their GHG inventory methods in the near future. While many countries do well with forest biomass reporting, there is room for improvement: most countries use Tier 1 but will need to move to Tier 2 by 2028. HoliSoils is providing tools to support such a transition, with a model ensemble tool currently in a beta phase and soon to be launched. Also of interest is the HoliSoils peat map (and other maps) under development, which will support spatially explicit reporting and improve land-use change estimates by providing soil data, contributing to the reporting needed for biodiversity and emission hot-spots.
I am Qian Li, now working in the Natural Resources Institute Finland (Luke) in the HoliSoils project. I graduated with a PhD in 2021, then joined Luke as a post-doctoral researcher. My background is on peatland green-house gases (GHG) emissions and carbon (C) cycle under the effect of climate warming. Now in the HoliSoils project, my research focuses on how forest management and natural disturbances affect the GHG emissions and soil processes of peatland forests.
My research in HoliSoils
I mainly work in Ränskälänkorpi, a drained peatland forest located in the Southern Finland. This site has three different forest management practices: clearcutting, selection harvesting, and non-harvested control.
We measure total respiration (CO2 emissions) and other greenhouse gases (CH4 and N2O) exchange by putting a manual chamber on top of soil and linking it with a gas concentration analyzer. Then the concentration change of gas emit/uptake by soil is analyzed by the analyzer linked with the chamber. We do it to discover which forest management practices can help mitigate climate change through reducing greenhouse gas emissions. This information can also help policy makers when they consider how to manage forests to achieve the climate targets.
To understand the production, consumption and transportation of gases inside soil layers, we also measure the gas concentration in the soil profile by taking gas samples through the silicon tubes buried underground.
We are also interested in knowing about the drivers of soil processes. So, we also take soil samples from surface to 1 meter deep to analyze microbial community structure and soil chemistry.
In this site, we also study how natural disturbances i.e. storms or windthrows impact soil C and N cycle. In addition to causing breakdown of tree stands, such disturbances can also destroy the upper soil layer by uprooting, or adding woody debris to soil surface, which all impact the soil processes. Especially extreme events are expected to be more frequent due to climate change, so it’s now urgent to know the consequences of such disturbances on ecosystems.
My feeling to be a member of HoliSoils family
HoliSoils is an EU project in which there are partners from several different European countries as well as from Uruguay and Japan. After joining this project and communicating with them, I have extended my knowledge scale of what kind of research topics they are focusing on and what novel techniques or analysis they are using in their research.
As a researcher who mainly focuses on experiments and field monitoring, I now have a deeper understanding of how models can use our experimental data and help us predict. As my first job after PhD, I am so happy to join Luke and HoliSoils project. This work experience not only brings me the knowledge and skills in science but also extends my network, which could help me to build my future career.
Extreme heatwaves, wildfires, floods, droughts… The effects of climate change are no longer predictions: they are happening right now. And, according to the experts of the Intergovernmental Panel on Climate Change (IPCC), they will continue to happen and become more and more intense in the future.
So, what can we do to stop them?
Most importantly, we need to reduce the emissions of greenhouse gases (GHG), such as carbon dioxide (CO2) from fossil fuel burning and deforestation, and nitrous oxide (N2O) and methane (CH4) from agriculture. But this is still not enough. In order to achieve carbon neutrality (that is, a net zero difference between what we emit and what we put back in the soil) we will need additional efforts to sequester CO2 from the atmosphere and store it in the soil.
This can be done, for example, by avoiding deforestation and improving the management of agricultural soils.
Soils play a crucial role for C sequestration:
They store the largest amount of C compared to all other terrestrial ecosystems.
They also store twice to three times more C than the atmosphere and – because the soil and the atmosphere interchange C – this means that even small changes in the soil C stocks can have a huge impact on the concentration of CO2 in the atmosphere.
C improves the fertility and other functions of the soils, so having soils rich in C is beneficial for food production.
Basically, storing more C in the soil can help to mitigate climate change and feed the world!
How can we restore carbon in the soil?
Carbon is naturally brought to the soil through plant photosynthesis and organic matter deposition. It leaves the soil once microbes and other organisms decompose it and respire it back to the atmosphere. Hence, storing additional soil organic C (SOC) can be done in two ways:
By increasing the amount of C entering the soil (e.g., the amount of CO2 fixed by the plants, or the amount of organic material added to the soil)
By decreasing the C output from the soil (e.g., decreasing the rate of microbial decomposition)
Researchers have found that the most efficient way to store C is to increase the C input to the soil.
How much should we increase the C input?
Assuming that we aim to increase the SOC stocks by a certain fixed target, we estimated the additional C input required to reach this target, and assessed whether this amount is realistic with current land use management practices. Following the4 per 1000 initiative, we set the target to an annual 4‰ increase of the SOC stocks.
In order to address these questions, we used mathematical models that simulate the processes that influence the accumulation of C in the soil and estimated the additional C input required to reach a 4‰ objective in Europe.
The methods used
We used data from 16 long-term agricultural experiments where agricultural practices with organic matter addition were carried out for several years under controlled conditions. At these experiments, pedo-climatic conditions were monitored over time in order to see the effect of organic matter addition on the system.
Mathematical models are largely used by soil scientists and policy makers to predict the evolution of SOC stocks with time, following changes in land management practices and climate. They help to better understand the behavior of the system, and to predict its future responses to external changes. However, they are still highly uncertain. This is mainly due to the uncertainty of:
The processes described in the models, which are still largely unknown;
The data used to run them, such as climate and soil variables;
The parameters that are included in the model equations, which are usually considered constant although they actually vary in space and time, and which values are not always related to measurable physical processes.
In order to estimate some of this uncertainty, instead of running one single model we ran a multi-model ensemble, which allowed to consider different ways of representing soil processes.
We also calibrated model parameters in order to correctly reproduce the evolution of measured SOC stocks. This means that we adjusted the values of model parameters to reproduce the conditions of the sites that we studied.
Feasibility of the 4 per 100
On average across the models and across the sites, we found that the C input had to increase by 119% compared to the initial conditions. That is, an additional 1.5 ± 1.2 Mg C ha-1 would need to be annually input to the soil in order to increase the SOC stocks by 4‰ each year.
To give an order of magnitude, we estimated from Zhang et al. (2017) that the annual C input applied to European croplands, derived only from livestock manure, is around 0.3 to 0.9 Mg C ha-1. But this is already applied! Meaning that, if we wanted to provide additional 1.5 ± 1.2 Mg C ha-1, that would need to come from different sources of organic material. Doubling the C input where mineral and organic fertilizers are already applied is unlikely without the implementation of other agricultural practices, such as agroforestry systems, cover cropping, improved crop rotations, and crops with a high belowground biomass. This is the case for Europe, for example, where croplands are usually minerally fertilized and where organic fertilizers are already widely applied.
Concerning the model simulations, we found large uncertainties across models, even when they were calibrated to reproduce the observed SOC stocks of the experiments. In particular, we found that the uncertainty across models was mainly due to the way the models represented (or not) water related variables, such as precipitations and potential evapotranspiration. This indicates that the choice of the hydrological processes included in the models and their representation affect model predictions, and it suggests that major efforts should be made to better represent these processes and reduce their associated uncertainties.
Conclusions and perspectives
Despite uncertainties in model simulations, there is compelling evidence that a radical change in agricultural management will be required to cope with climate change and food security in the near future. In a recent report from the Mission Board for Soil Health and Food, the European Commission was suggested to set ambitious targets to increase SOC stocks and improve the health of European soils. Yet, we are far from being optimistic. The last fifty years of international agreements on the response of world nations to climate change have proven that, no matter how compelling evidence the scientific community provides, indicators of adverse change are still on a rise (Glavovic et al., 2021). Governments need to take action before it is too late.
Diversity in science
In the last decades, thousands of works have been published on the effects of land management, land-use change and climate change on SOC. However, studies are narrowed to a selected number of specific drivers and geographical regions. In fact, studies on agricultural management practices have mostly focused on mineral fertilization, organic amendments, and tillage, while drivers of SOC changes have only occasionally been studied in North and Central Africa, and in the Middle East and Central Asia (Beillouin et al., 2022).
Future research should focus on more local and diversified knowledge on how to preserve and restore SOC stocks, while covering understudied geographical regions.
Besides, increased knowledge on the effects of diversified practices on SOC stock changes, under different pedo-climatic conditions, will help to improve model simulations and provide reliable SOC stock projections under future climate change.
Beillouin, Damien, Rémi Cardinael, David Berre, Annie Boyer, Marc Corbeels, Abigail Fallot, Frédéric Feder, and Julien Demenois. “A Global Overview of Studies about Land Management, Land‐use Change, and Climate Change Effects on Soil Organic Carbon.” Global Change Biology 28, no. 4 (February 2022): 1690–1702. https://doi.org/10.1111/gcb.15998.
Bruni, Elisa, Bertrand Guenet, Yuanyuan Huang, Hugues Clivot, Iñigo Virto, Roberta Farina, Thomas Kätterer, Philippe Ciais, Manuel Martin, and Claire Chenu. “Additional Carbon Inputs to Reach a 4 per 1000 Objective in Europe: Feasibility and Projected Impacts of Climate Change Based on Century Simulations of Long-Term Arable Experiments.” Biogeosciences 18, no. 13 (July 2, 2021): 3981–4004. https://doi.org/10.5194/bg-18-3981-2021.
Bruni, Elisa, Bertrand Guenet, Hugues Clivot, Thomas Kätterer, Manuel Martin, Iñigo Virto, and Claire Chenu. “Defining Quantitative Targets for Topsoil Organic Carbon Stock Increase in European Croplands: Case Studies With Exogenous Organic Matter Inputs.” Frontiers in Environmental Science 10 (February 14, 2022): 824724. https://doi.org/10.3389/fenvs.2022.824724.
Chenu, Claire, Denis A. Angers, Pierre Barré, Delphine Derrien, Dominique Arrouays, and Jérôme Balesdent. “Increasing Organic Stocks in Agricultural Soils: Knowledge Gaps and Potential Innovations.” Soil and Tillage Research 188 (May 2019): 41–52. https://doi.org/10.1016/j.still.2018.04.011.
Martin, Manuel Pascal, Bassem Dimassi, Mercedes Ŕomàn Dobarco, Bertrand Guenet, Dominique Arrouays, Denis A. Angers, Fabrice Blache, Frédéric Huard, Jean‐François Soussana, and Sylvain Pellerin. “Feasibility of the 4 per 1000 Aspirational Target for Soil Carbon. A Case Study for France.” Global Change Biology, February 4, 2021, gcb.15547. https://doi.org/10.1111/gcb.15547.
Riggers, Catharina, Christopher Poeplau, Axel Don, Cathleen Frühauf, and René Dechow. “How Much Carbon Input Is Required to Preserve or Increase Projected Soil Organic Carbon Stocks in German Croplands under Climate Change?” Plant and Soil 460, no. 1–2 (March 2021): 417–33. https://doi.org/10.1007/s11104-020-04806-8.
Soussana, Jean-François, Suzanne Lutfalla, Fiona Ehrhardt, Todd Rosenstock, Christine Lamanna, Petr Havlík, Meryl Richards, et al. “Matching Policy and Science: Rationale for the ‘4 per 1000 – Soils for Food Security and Climate’ Initiative.” Soil and Tillage Research 188 (May 2019): 3–15.https://doi.org/10.1016/j.still.2017.12.002.
Zhang, Bowen, Hanqin Tian, Chaoqun Lu, Shree R. S. Dangal, Jia Yang, and Shufen Pan. “Global Manure Nitrogen Production and Application in Cropland during 1860–2014: A 5 Arcmin Gridded Global Dataset for Earth System Modeling.” Earth System Science Data 9, no. 2 (September 6, 2017): 667–78. https://doi.org/10.5194/essd-9-667-2017.
The publication synthesises information on forest management practices that can mitigate climate change by increasing soil carbon stocks and reducing greenhouse gas emissions. The study also identifies soil processes that affect soil greenhouse gas balance and discusses how models represent forest management effects on soil in greenhouse gas inventories and scenario analyses to address forest climate change mitigation potential.
“As a part of a LUKE’s working group I participated in measuring GHG emissions from forest soils. We measured CO2 and methane fluxes with LI-COR devices across southern Finland on different sites such as Tammela and Nastola. And also as a member of LUKE’s team I was helping with taking deep core samples and soil samples seeving from drained peatland at Ränskalalankorpi.
This traineeship has given me better and deeper understanding of respiration of forest soils. I have learned how to work with LI-COR and the traineeship has helped me cope with problems in the field conditions fast.
I hope I will have the opportunity to be a part of their team again.”
A new study led by the University of Helsinki provides evidence that the observed decline of carbon use efficiency and net ecosystem exchange from south to north in the boreal forest may be caused by the abundance of ectomycorrhizal fungi.
The proposed approach could easily be included in carbon balance models for quantifying ectomycorrhizal fungi carbon use without having to engage in more complex analysis of carbon and nutrient interactions underlying ectomycorrhizal fungi processes.
“The results of the study underline the need for a better understanding of the role of micro-organisms as users of carbon but also as a machinery generating carbon residues that may have longer lifespans,” says the first author of the study Annikki Mäkelä from the Faculty of Agriculture and Forestry, University of Helsinki.
The study suggests that this approach can improve prediction of biomass growth across different soils with different microbial composition.
More accurate prediction of biosphere carbon sinks
According to researchers these features of ectomycorrhizal fungi as carbon consumers and litter producers should also be incorporated into global vegetation models in order to have more precise and accurate prediction of biosphere carbon sinks and their feedbacks to climate change.
Carbon use efficiency, i.e., the ratio between net and gross primary production, describes the efficiency of vegetation to accumulate photosynthetic carbon to biomass. Other uses of carbon include maintenance and construction respiration. In this study, ectomycorrhizal fungi were included as additional consumers of plant-originating carbon.
The European Forest Institute published a new study with the title Forest-based climate change mitigation and adaptation in Europe in the From Science to Policy series. This analysis focuses on the role of forests and wood use in contributing to mitigate climate change. The 12 authors from 7 different countries conclude that European forests and wood products can play a crucial role in achieving climate neutrality by 2050. However, their potential is not enough to compensate for a lack of actions in other areas.
In particular, the study focuses on the role of forests in the removal of green house gas emissions. Moreover, the authors investigate how to maximise the effectiveness of forests contributions to climate change mitigation and adaptation. The study recommends the adoption of a holistic approach, where multiple forest-base mitigation actions are combined to foster synergies, interactions, co-benefits, and regional applicability.
In the framework of the HoliSoils project, the Thuenen Institute is working on the soil monitoring framework. In particular, their work focuses on reviewing European GHG reporting in forest soils, developing guidelines for harmonized soil sampling methods for future reporting and providing a server for open-access harmonized European maps of forest soil properties. Furthermore, they developed a survey for GHG experts to gain their suggestions for improvement concerning GHG reporting.
Their work mainly focuses on carbon (C) data from forest soils remaining forest soils and differentiates between mineral and organic soils. On this poster, Vera Makowski and Nicole Wellbrock give an overview of the most important findings of the review process and the resultant actions within HoliSoils.
PhD candidate Elisa Bruni from the Climate and Environmental Sciences Laboratory (LSCE) in France is pleased to invite you to her doctoral thesis defence entitled “Soil organic carbon modelling: estimating carbon input changes required to reach policy objectives aimed at increasing soil organic carbon stocks”.
The defence will take place on Monday 28 March 2022 at 2:00 p.m. in Amphi 7 of AgroParisTech (Paris-Maine), located at 19 Avenue du Maine, 75015 Paris. For those who prefer to attend remotely, you can join the videoconference through the following link (Meeting ID: 930 0252 2076 / Password: 954715). The presentation will be held in English.
The thesis jury board is composed of the following experts:
Axel DON, Senior Lecturer, Thünen Institute (Germany) – Rapporteur & Examiner
Isabelle BASILE, Research Director, INRAE Centre PACA (France) – Rapporteur & Examiner
Sébastien Barot, Director of Research, IRD (France) – Examiner
Patricia Garnier, Director of Research, INRAE (France) – Examiner
Emanuele Lugato, Project manager, Joint Research Centre (Europe) – Examiner
Stefano Manzoni, Senior Lecturer, Stockholm University (Sweden) – Examiner
Claire Chenu, Director of Research, INRAE (France) – Thesis director
Bertrand Guenet, Research Fellow, INRAE (France) – Examiner
Denis Angers, Honorary Director of Research, Université de Laval (Canada) – Invited
Gaby Deckmyn, Senior Scientist, University of Antwerp (Belgium) – Invited
To partially compensate for CO2 emissions, the 4 per 1000 initiative proposed an annual 4‰ soil organic carbon (SOC) stock increase. Yet, the feasibility of such an ambitious target is still under debate. The most efficient way to increase the SOC stocks is to increase the C input to the soil. The objective of this thesis was to estimate the C input required to yearly increase the SOC stocks by 4‰ in European croplands.
To solve this problem, we built an inverse modelling approach and tested it on a SOC model, by estimating the C input required to reach the 4‰ objective at multiple long-term agricultural experiments in Europe. Then, we applied this approach to a multimodel ensemble, to assess the uncertainties of the estimations according to different representations of the SOC dynamics. As a first attempt to provide insights for policymakers on the feasibility of a 4‰ target in Europe, we applied a multi-model ensemble over the whole European cropland area, and we generated maps of the required C input under two scenarios of climate change. To improve the simulation of SOC stocks at the European scale, we tested a new, statistically derived, parametrization technique.
Our study demonstrates that there are substantial uncertainties around the C input required to reach a 4‰ target. However, a general pattern emerges at the European cropland scale, where the 4‰ target seems feasible under future scenarios of climate change, only assuming drastic increases of C input to the soil.
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