HoliSoils Season’s Greetings 2023!

The dedication and collaboration of all HoliSoils partners contributed to making 2023 a very productive and rewarding year for the project. To celebrate the continued efforts of our partners, the latest HoliSoils festive video takes a brief look back at the highlights of the year, with a “multilingual” twist and wishes the consortium, stakeholders and supporters a happy holiday season!

Enjoy the video!

Slovak media and forestry professionals discover more about HoliSoils’ progress

Photo: HoliSoils – Technical University of Zvolen

Stakeholders from the forestry sector in Slovakia were recently able to learn more about the preliminary results of the HoliSoils project as well as the national PROBIOFOR project (Trade-offs between biomass production and biodiversity in beech and spruce forests under changing environmental conditions) at a workshop and field visit organised by the Technical University of Zvolen. This event, which brought together more than 40 participants from the state and private forestry sector, was held on 12 October and was attended by, among others, the Administration of the Protected Landscape of the Poľana Mountains, the State Nature Protection of Slovakia, Pro Silva Slovakia, the National Forestry Centre and the Technical University of Zvolen and Slovak public media journalists.

The workshop started with four introductory lectures explaining to the participants climate change and its effects on forest ecosystems, the adaptation potential of tree species and the carbon balance of forest ecosystems. The programme continued with an excursion to the old-growth forest of Dobroc (a national nature reserve since 1913), including a visit to the test area established for the HoliSoils project.

The preliminary results that were shared with the participants can be summarised as follows:

  • Norway spruce trees are more affected by extreme weather conditions than European beech and silver fir. Fir and beech trees even created a larger increment in 2022 than in 2021, which was vice versa for the spruce trees.
  • Norway spruce trees strongly suffered from the drought of 2022, which together with a mild winter condition lowered its ability to protect against bark beetle invasion, leading to a large-scale disturbance in 2023.

  • Soil water storage and its availability to trees was also heavily affected by the drought in 2022. As early as April, the soil water content had already dropped below 10%, touching 5%, on the test site in spruce monoculture, whereas it remained at a level of around 20–30% on the test site in the nearby mixed forest by the end of June.

  • Soil CO2 fluxes were larger in the mixed forest compared to the spruce monoculture, likely due to higher microbial diversity and activity in the soil. It was also shown that the largest differences between the spruce monoculture and the mixed forest were at higher temperatures during the summer. However, during the drought, the differences were almost negligible. Carbon increment in the above- and below-ground biomass was approximately between 3.5 and 4.5 t C ha-1 yr-1, whereas the C emission from the soil was found to be around 5 – 6 t C ha-1 yr-1 in the spruce and 7 – 8 in the mixed forest. During the field trip, it was stressed that soil carbon and fluxes have to be considered when discussing the potential of forest ecosystems to sequester carbon from the atmosphere.

Journalists from the main public Slovak radio and television stations took part in the workshop. The reportage was broadcast on the RTVS Regina show on 17 October 2023.

Photo: HoliSoils – Technical University of Zvolen

Learn more about HoliSoils in this MAIA’s webinar!

MAIA's second webinar on Climate Change and Agriculture

On 8 September, tune in to this webinar organised by the MAIA Project to learn more about some European projects working on agroforestry and climate change.

This is the second of a series of three webinars on the same topic, climate change and agriculture. This webinar will feature presentations from three speakers representing different European Union-funded projects focusing on agroforestry: Reforest, AGFORWARD, and HoliSoils.

Raisa Mäkipää, the coordinator of this latter project, will join the discussion to present HoliSoils and its work for forest soils.

Register now!

Storms and windthrows have significant effects on soil GHG emissions and processes

The IBFRA conference is organised for the 20th time this year with a focus on Climate Resilient and Sustainable Forest Management. This bi-annual conference brings together researchers, companies, policymakers, and members of civil society to discuss the future of boreal forests.

One of the EU-funded project HoliSoils’ highlights in IBFRA is a poster presentation by Qian Li, a post-doctoral researcher from the Natural Resources Institute Finland (Luke). You can meet her on Wednesday 30th of August to hear about the new research results with the topic “Greenhouse gas (GHG) emissions, organic carbon pool and microbial biomass in peatland forests soils under disturbance”.

Two experiments to examine the impact of disturbances

One of HoliSoils’ project objectives is to understand the response of soil to natural disturbances, focusing on examining soil resilience and recovery. Storms and windthrows are important disturbances in boreal forests that cause damage to stand structure and can also impact on soil.

Forest soil contains more carbon than trees, while its response to disturbances has been less studied. To examine how soil carbon stock, greenhouse gas emissions and microbial community are affected by disturbances, experiments were conducted in a spruce-dominated nutrient-rich drained peatland forest site in southern Finland.

Two soil disturbance treatments were established in September 2021 and compared with a control site:

1) Surface soil was removed to simulate the effects of uplifting surface soil by uprooted trees

2) Soil surface was covered by residuals to simulate the excess nutrient input to soil by the canopy of felling trees

The greenhouse gas (CO2, CH4, and N2O) fluxes were measured throughout the snow-free period. After one year, soil samples from two treatment sites and the control site were taken to analyse inorganic nitrogen, stable and labile soil organic carbon (SOC) pool, tannins, and microbial biomass.  

The results after one year

In the first year after treatment, CO2 emissions from topsoil-removed plots decreased. The CH4 sink also declined, even switched to CH4 source when the water level was high, indicating the role of surface soil and its microbes in regulating GHG emissions. The CO2 and N2O emissions increased with residual cover, suggesting the nitrogen input and microclimate change affecting soil microbial processes. Fungal biomass and necromass markers decreased under both treatments compared with the control. However, the organic carbon pool remained stable in the first year of treatment.

“We found a fast response of GHG emissions and microbial community to disturbances, which could lead to a change in the soil C stock.”, says Qian Li

Such soil disturbances can also be found after harvesting or mechanical site preparation, thus causing high spatial variation of GHG emissions. Research results indicated that disturbances on soil have significant effects on soil GHG emissions and processes, and this should be taken into account in the models used for GHG inventory and scenarios.

Qian Li’s background is in peatland greenhouse gases (GHG) emissions and carbon (C) cycle under the effect of climate warming. In the HoliSoils project, her research focuses on how forest management and natural disturbances affect the GHG emissions and soil processes of peatland forests.

More information

Follow the IBFRA conference online

HoliSoils dashboard on shared soil data

Profile location map from the dashboard which provides an overview of soil data shared by partners in the framework of the EU Horizon 2020 HoliSoils project.

Explore the HoliSoils dashboard which provides an overview of soil data shared by partners in the framework of the EU Horizon 2020 HoliSoils project.

Soil data for ~ 7.2k sites were processed following updated Extract Transform Load (ETL) procedures. This was implemented for the World Soil Information Service (WoSIS) which is a service provided by HoliSoils partner ISRIC – World Soil Information.

Around 3,500 out of 7,200 sites are under forest, as identified using the EU Corine Land Cover dataset (for 2018).

Key soil properties such as pH, organic carbon content, bulk density and soil texture of the shared soil profile data can be viewed and queried using the dashboard. The data can be filtered according to various criteria.

Visualisation of the ETL procedure.
Visualisation of the ETL procedure.
Data points under forest, EU Corine Land Cover dataset (2018).
Data points under forest, EU Corine Land Cover dataset (2018).
The dashboard shows the licenses, i.e., open (33%) or restricted (67%).
The dashboard shows the licenses, i.e., open (33%) or restricted (67%).
Descriptive statistics.
Descriptive statistics are presented for key soil properties.

Explore the dashboard!

Webinar on incentives for carbon farming concludes the “Soil on 1” series

WUR webinar

The webinar series “Soil on 1” carried out by WUR, a HoliSoils partner organisation, has almost come to an end. This series of three online events aimed to explore the connection between SOC sequestration and climate, soil, and buyers/sellers of carbon credits.

In May and June, the first two webinar were organised to learn more about how SOC sequestration impacts climate mitigation and soil quality.

This last webinar will investigate the possible incentives for carbon farming including carbon credits. On 4 July, 9.00 – 10.00 CET, the discussion will focus on what SOC sequestration means for the seller (farmer) and buyer.

Click here to join the webinar!

New webinar on SOC sequestration and soil quality

WUR webinar

WUR, an organisation part of the HoliSoils Consortium, is hosting a series of webinars titled “Soil on 1” to discuss if SOC sequestration as a win-solution for the climate, soil, and buyers and sellers of carbon credits.

After a first successful webinar on SOC sequestration and climate mitigation, the second webinar will explore what SOC sequestration means for soil quality. The third and final webinar will then focus on carbon markets.

Don’t miss this chance to join the second webinar, titled “SOC sequestration & soil quality”, that will take place on Tuesday 20 June, 9.00 – 10.00 CET.

Click here to join the webinar!

HoliSoils supports key stakeholders with science and tools for GHG reporting

Amanita mushrooms growing on ground among green herb

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.

Presentations from the workshop are available from JRC’s LULUCF pages.

New webinar series on SOC-sequestration & climate mitigation

WUR webinars

HoliSoils partner organisation, WUR, organises a series of three webinars to discuss questions on the SOC-sequestration and climate mitigation: “SOC-sequestration – a win, win, win, win for the climate, soil, and buyers/sellers of carbon credits?”.

The first webinar on the role of SOC- sequestration related to fighting climate change will be on Tuesday 30 May, 9.00 – 10.00 CET.

This first session will explore the climate perspective of SOC-sequestration, with the expert Jan Peter Lesschen.

Click here to join the first webinar!

Is it feasible to increase soil carbon stocks by 4 per 1000 per year?

Soil with seedling

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.

Figure 1 Global carbon cycle between the land and the atmosphere. The values were taken from Ciais et al. (2013). Uncertainty in the atmospheric CO2 growth rate is ± 0.02 Gt C yr-1. Figure adapted from Le Quéré et al. (2018). Icons from www.flaticon.com.

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 the 4 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.

Figure 2 Annual SOC stock increase (%) for different levels of additional C input in agricultural experiments (black spots) and additional C input required to reach the 4‰ SOC increase according to the 1) non-calibrated multi-model median (MMM) (blue cross) and the 2) calibrated MMM (orange cross). Errors are shown as confidence intervals (CI) The regression line between additional C input and SOC stock increase in the EOM treatments is indicated in the figure (y=m (±〖SD〗_m)∙ x + b ± 〖(SD〗_b)).

Model uncertainties

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.

Figure 3 Required additional C input (± standard deviation, SD) relative to the unfertilized control, to reach a mean annual 4‰ SOC stock increase for 30 years across the 16 sites. The bars represent the different models and multi-model median (MMM). The non-calibrated and calibrated configurations are in blue and orange, respectively. For the MMM, the SD bar represents the median SD across models.
Figure 4 Heatmap of the simulated additional C input to reach the 4‰, for each calibrated model and each site. Darker cells show lower C input and lighter cells represent higher C input. Dendrograms above the heatmap represent the relationship of similarity among groups of models, calculated as the minimal correlation distance.

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.

Read more about this in the open access paper published in the European Journal of Soil Science: Multi-modelling predictions show high uncertainty of required carbon input changes to reach a 4‰ target

References and related articles

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.

Glavovic, Bruce C., Timothy F. Smith, and Iain White. “The Tragedy of Climate Change Science.” Climate and Development, December 24, 2021, 1–5. https://doi.org/10.1080/17565529.2021.2008855.

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.