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Carbon emissions/removals estimates under Land use, land-use change and forestry (LULUCF) sector: field measurements, remote sensing and modelling

Land use, land-use change and forestry (LULUCF) sector is the only sector in National green-house gas (GHG) Inventory that accounts for carbon (C) removals, therefore it has been recognized as important for reaching the long-term climate mitigation objectives. Recently, an issue of uncertainty of the LULUCF sector estimates is strongly being emphasized and scientific community is facing a growing need to facilitate national reporting regarding C emissions/removals under LULUCF sector.
National level estimates often require long-term and comprehensive datasets at national scale, like national forest inventories (NFI), but these data are not always available. To overcome this gap, multi-source data integration, remote-sensing and modelling approaches are commonly used, but all these methods carry many issues.
This session invites contributions on national and subnational carbon budget estimates (past, present and future) in different land uses (forests, crops, grasslands, urban areas) using multiple data sources and different calculation methods. NFI-based, remote sensing and modelling studies on C stocks and/or fluxes in different ecosystem pools (live biomass, dead wood, litter or soil) are encouraged.
Aim is to provide extensive overview of different methodological approaches that can be used for national scale estimates and highlight main issues regarding data integration and model calibration and validation process.

Co-organized by BG3/SSS10
Convener: Maša Zorana Ostrogović SeverECSECS | Co-conveners: Dóra Hidy, Bostjan Mali, Hrvoje Marjanovic
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Fri, 30 Apr, 13:30–15:00

Chairpersons: Maša Zorana Ostrogović Sever, Hrvoje Marjanovic

5-minute convener introduction

Weilin Huang et al.

Mycorrhizae, a plant-fungal symbiosis, is an important contributor to below ground-microbial interactions, and hypothesized to play a paramount role in soil carbon (C) sequestration. Ectomycorrhizae (EM) and arbuscular mycorrhizae (AM) are the two dominant forms of mycorrhizae featured by nearly all Earth plant species. However, the difference in the nature of their contributions to the processes of plant litter decomposition is still understood poorly. Current soil carbon models treat mycorrhizal impacts on the processes of soil carbon transformation as a black box. This retards scientific progress in mechanistic understanding of soil C dynamics.

We examined four alternative conceptualizations of the mycorrhizal impact on plant litter C transformations, by integrating AM and EM fungal impacts on litter C pools of different recalcitrance into the soil carbon model Yasso15. The best performing concept featured differential impacts of EM and AM on a combined pool of labile C, being quantitatively distinct from impacts of AM and EM on a pool of recalcitrant C.

Analysis of time dynamics of mycorrhizal impacts on soil C transformations demonstrated that these impacts are larger at the long-term (>2.5yrs) litter decomposition processes, compared to the short-term processes. We detected that arbuscular mycorrhizae controls shorter term decomposition of labile carbon compounds, while ectomycorrhizae dominate the long term decomposition processes of highly recalcitrant carbon elements. Overall, adding our mycorrhizal module into the Yasso model greatly improved the accuracy of the temporal dynamics of carbon sequestration.

A sensitivity analysis of litter decomposition to climate and mycorrhizal factors indicated that ignoring the mycorrhizal impact on the decomposition leads to an overestimation of climate impacts. This suggests that being co-linear with climate impacts, mycorrhizal impacts could be partly hidden within climate factors in soil carbon models, reducing the capability of such models to mechanistically predict impacts of climate vs vegetation change on soil carbon dynamics.

Our results provide a benchmark to mechanistic modelling of microbial impacts on soil C dynamics. This work opens new pathways to examining the impacts of land-use change and climate change on plant-microbial interactions and their role in soil C dynamics, allowing the integration of microbial processes into global vegetation models used for policy decisions on terrestrial carbon monitoring.

How to cite: Huang, W., van Bodegom, P., Viskari, T., Liski, J., and Soudzilovskaia, N.:  Implementation of mycorrhizal mechanism into a soil carbon model improves the prediction of long-term processes of plant litter decomposition, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-277, https://doi.org/10.5194/egusphere-egu21-277, 2020.

Chih-Hsin Cheng et al.

The cropland afforestation policy was initiated in 2002 in Taiwan and had been approaching the 20-year term. From the scientific perspective, it is a critical issue to understand the public welfare role and ecosystem services provided by the cropland afforestation. In this study, we investigated the changes of soil organic carbon (SOC) on plantations after 14 years conversion from the sugarcane fields. Soil samples were collected at 0-10 and 10-20 cm depth. Soil organic C concentration, bulk density, soil aggregation, and the stable isotopic 13C of the SOC and aggregates were determined. The results indicated the SOC stocks on the afforested plots were between 1000 and 1500 g m-2 significantly higher than those under the sugarcane plots (p < 0.05). The analyses of stable 13C indicated that the net increases in SOC stocks on the afforested plots were mainly attributed to the inputs of the forest-derived SOC that outweighed the loss of sugarcane-derived SOC. The afforestation also enhanced the aggregation with higher stability and SOC concentration. The comparatively depleted 13C values in the stable macroaggregates further suggested the ecological function from this new SOC source. Combining with the stand development and aboveground biomass accumulation, we expected the cropland afforestation would provide ecosystem services and functions.

How to cite: Cheng, C.-H., Lee, P.-C., and Fang, X.-Y.: Enhancement of soil organic carbon storage and aggregation following cropland afforestation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1833, https://doi.org/10.5194/egusphere-egu21-1833, 2021.

Bart Kruijt et al.

There are many initiatives to re-wet drained nature or former agricultural land. These young wetlands provide a natural habitat for a range of endangered species, while serving as a natural climate buffer by retaining water, regulating air temperature, and sequestering CO2 from the atmosphere. However, wetlands may also emit CH4, which has a global warming potential (GWP) of about 30. Thus, all carbon fluxes need to be quantified in order to assess if, from a climate perspective, CO2 uptake outweighs CH4 emission.

To assess the net effect of young wetlands on Greenhouse Gas exchange, we study the CO2 and CH4 fluxes of two recently rewetted areas near Groningen, the Netherlands. The fluxes are measured directly using the Eddy Covariance (EC) technique on a moveable station, alternating between the two sites. Meteorological observations are performed at these stations as well, along with other supportive measurements such as soil/water temperature. The alternating time gaps are filled by interpolation based on observed ecosystem responses. Footprint analysis provides insight into the role of various vegetation types inside these swamps. The resulting carbon budgets provide insight into GHG exchange over typically small temporal and spatial scales.

The study also examines the feasibility of these moveable stations, as they may reduce the relatively high research costs of EC measurements. The data from moveable stations is reliable if the data is regular, as the time gaps are filled by interpolation. At this stage, the timeseries is too short to draw any conclusions upon the reliability of the data. However, the moveable stations appear to be feasible from a practical point of view, as the station can be relocated relatively easy within the time span of a day.

The first results suggest both substantial CO2 uptake and CH4 emissions but a full year of data was not collected yet. Observed exchange compares well to similar studies previously performed.  

Ultimately, annual budgets of the carbon exchange response will be correlated to weather conditions but also to hydrological measures such as water levels. This should allow extrapolation of the data, which may serve as a basis for policy makers to manage the carbon balance when re-wetting nature to achieve net mitigation of greenhouse warming potential.

How to cite: Kruijt, B., Berghuis, H., Biermann, J., Jans, W., Franssen, W., Nijhof, E., Peltenburg, A., Lettink, R., Jacobs, C., Hutjes, R., and Veraart, J.: Greenhouse gas exchange of young rewetted swamp in northern Netherlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8483, https://doi.org/10.5194/egusphere-egu21-8483, 2021.

Giulia De Luca et al.

Although characteristics of the carbon balance and the organic carbon stock changes of arable lands have been the primary research focus of numerous studies, uncertainity is still a major factor in this area of research. Our aim is to determine the dynamics of carbon cycling in croplands in regards to a crop rotation consisting of different crop types and to clarify the factors driving the carbon fluxes between its main components.

A field-scale eddy covariance (EC) station was established in 2017 at a cropland site in Central Hungary in order to obtain the cropland’s annual net ecosystem exchange of CO2 (NEE). Net ecosystem carbon budget (NECB) was calculated considering vertical and lateral C fluxes as well. Soil management is a conventional management with yearly deep ploughing and mineral fertilizer application.

During the three years of our experiment the crop rotation included winter wheat, winter rapeseed, sorghum and winter wheat. The largest net CO2 uptake was observed during the sorghum season (from sowing to harvest, -309 g C m-2 yr-1). However, extreme autumnal drought resulted in the incomplete germination of rapeseed in 2018, which led to carbon loss (108 g C m-2 yr-1) during this vegetation period. Results show a significant difference between the two winter wheat seasons – sown in 2017 and 2019 – which can be explained by the differing precipitation of the two periods. Despite the strong CO2 uptake of winter wheat and sorghum, NECB ranged between negligible C gain (-18.26 g C m-2 year-1, sorghum) to C losses of up to 108 g C m-2 year-1 (rapeseed). During three years the C loss was 420 g C m-2 as C export through harvest and fallow periods counterbalanced the crops’ CO2 uptake.

As a conclusion we can state this cropland could not sequester enough carbon to maintain the soil organic carbon pool and in order to reduce the risk of the depletion of soil carbon stock further efforts are needed in the field of soil management practices.

How to cite: De Luca, G., Balogh, J., Pintér, K., Fóti, S., Bouteldja, M., Malek, I., and Nagy, Z.: Soil carbon balance in Hungarian crop rotation systems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10977, https://doi.org/10.5194/egusphere-egu21-10977, 2021.

Darija Bilandžija et al.

In order to mitigate climate change and reduce the anthropogenic greenhouse gas (GHG) emissions, the Kyoto protocol has been adopted in 1997 and the Paris Agreement entered into force in 2016. The Paris Agreement have ratified 190 out of 197 Parties of the United Nations Framework Convention on Climate Change (UNFCCC) and Croatia is one of them as well. Each Party has obliged regularly to submit the national inventory report (NIR) providing the information on the national anthropogenic GHG emissions by sources and removals by sinks to the UNFCCC. Reporting under the NIR is divided into six categories / sectors, and one of them is land use, land use change and forestry (LULUCF) sector, where an issue of uncertainty estimates on carbon emissions and removals occurs. As soil respiration represents the second-largest terrestrial carbon flux, the national studies on soil respiration can reduce the uncertainty and improve the estimation of country-level carbon fluxes. Due to the omission of national data, the members of the University of Zagreb Faculty of Agriculture, Department of General Agronomy have started to study soil respiration rates in 2012, and since then many different studies on soil respiration under different agricultural land uses (i.e. annual crops, energy crop and vineyard), management practices (i.e. tillage and fertilization) and climate conditions (i.e. continental and mediterranean) in Croatia have been conducted. The obtained site specific results on field measurements of soil carbon dioxide concentrations by in situ closed static chamber method will be presented in this paper.

How to cite: Bilandžija, D., Galić, M., and Zgorelec, Ž.: Soil respiration under different agricultural land use types in Croatia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15734, https://doi.org/10.5194/egusphere-egu21-15734, 2021.

Yan Huang et al.

Since an increasing number of global gross primary productivity (GPP) products have become available and been applied in climate change research, there is an urgent need to compare their performance in capturing spatial and temporal variability, especially in the regions where the number of training data is limited or model parameters are of relatively larger uncertainty. Here, we investigated the spatial patterns of interannual trends and variations, and seasonal-cycle amplitudes of GPP in the arctic and boreal zones, and explored the differences across various GPP products during the overlapping period (2000−2010). We compared three main types of state-of-the-art GPP products, including simulations derived from terrestrial biosphere models of the Multi-scale Synthesis and Terrestrial Model Intercomparison Project using drivers under different scenarios, 3 datasets up-scaled from FLUXNET eddy covariance measurements based on machine-learning algorithms, and 2 semi-empirical or empirical remotely sensed products based on different satellite data. We also examined the differences of GPP variability across the main ecosystem types, mainly including tundra and taiga, and assessed the contributions of different ecosystems to the temporal variations of total GPP in this zone. The results showed all the products could capture the interannual and seasonal variability of GPP, but the spatial patterns varied largely, which was in-deep discussed. This study will benefit the usage of the GPP products in the carbon cycle research for the arctic and boreal ecosystems.

How to cite: Huang, Y., Yu, Z., Hu, L., and Yao, W.: Assessment of spatiotemporal patterns of gross primary productivity in the arctic and boreal ecosystems using multi-source products, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10824, https://doi.org/10.5194/egusphere-egu21-10824, 2021.

Elizabeth Keller et al.

Grasslands cover half of New Zealand’s land area, with much of it consisting of pastoral agriculture systems of varying intensity. Carbon fluxes from grazed pasture are thus a crucial part of the national carbon budget. We have used Biome-BGCMuSo v6 to model national CO2 fluxes from grasslands, calibrated with eddy covariance measurements at grazed farms at various sites around the country. We discuss the challenges of scaling up site measurements to the national level and modelling the diversity of New Zealand's pastoral sector. Model outputs will subsequently be used as a prior estimate of CO2 fluxes in an atmospheric inversion to obtain a total carbon budget for New Zealand as part of the CarbonWatch-NZ project.

How to cite: Keller, E., Graham, S., Hunt, J., Wall, A., Schipper, L., McMillan, A., Hidy, D., Barcza, Z., Bukosa, B., and Mikaloff-Fletcher, S.: Modelling carbon fluxes from New Zealand’s pastoral agriculture, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3641, https://doi.org/10.5194/egusphere-egu21-3641, 2021.

Katarina Merganicova et al.

Process-based ecosystem models are versatile tools providing profound insights into ecosystem processes and interactions between vegetation and environment. The ongoing development of the Biome-BGCMuSo model has delivered multiple improvements in model structure and parameters, and subsequently in simulated ecosystem dynamics. Since the number of parameters has increased during the model development, model parametrisation for biomes or tree species of interest is required to enable reliable model usage in the future.

Here we explore the issue of site-specific versus multi-site calibration of model parameters for the European beech (Fagus sylvatica L.) along an extended environmental gradient across Central Europe, covering Croatia, Hungary, Slovakia, Poland and the Czech Republic. First, thorough literature search for the plausible ranges of individual model parameters was conducted. This was followed by the sensitivity analysis to identify the most influential model parameters. Finally, model calibration was performed based on the generalised likelihood uncertainty estimation method and the data from long-term research plots located in the five countries. The calibration was conducted at levels of individual sites and the region as a whole to evaluate different aspects of site-specific and multi-site calibration approaches and to develop a generalised parameter set for the European beech in Central Europe.

How to cite: Merganicova, K., Dobor, L., Hollos, R., Merganič, J., Barcza, Z., Kurjak, D., Novák, J., Sitková, Z., Fleischer, P., Marjanovic, H., Hidy, D., Střelcová, K., and Hlásny, T.: Can we reach a sensible balance between generality of model parameters and accuracy of simulations?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10889, https://doi.org/10.5194/egusphere-egu21-10889, 2021.

Wolfgang Obermeier and the LASC task-force

The quantification of the net carbon flux from land use and land cover changes (fLULCC) is essential to understand the global carbon cycle, and consequently, to support climate change mitigation. However, large-scale fLULCC is not directly measurable, and can only be inferred by models, such as semi-empirical bookkeeping models, and process-based dynamic global vegetation models (DGVMs). By definition, fLULCC estimates between these two model types are not directly comparable. For example, transient DGVM-based fLULCC of the annual global carbon budget includes the so-called Loss of Additional Sink Capacity (LASC). The latter accounts for environmental impacts on the land carbon storage capacities of managed land compared to potential vegetation which is not included in bookkeeping models. Additionally, estimates of transient DGVM-based fLULCC differ from bookkeeping model estimates, since they depend on arbitrarily chosen simulation time periods and the timing of land use and land cover changes within the historic period (which includes different accumulation periods for legacy effects). However, DGVMs enable a fLULCC approximation independent of the timing of land use and land cover changes and their legacy effects by simulations run under constant pre-industrial or present-day environmental forcings.

In this study, we analyze these different DGVM-derived fLULCC definitions, under transiently changing environmental conditions and fixed pre-industrial and fixed present-day conditions, within 18 regions for twelve DGVMs and quantify their differences as well as climate- and CO2-induced components. The multi model mean under transient conditions reveals a global fLULCC of 2.0±0.6 PgC yr-1 for 2009-2018, with ~40% stemming from the LASC (0.8±0.3 PgC yr-1). Within the industrial period (1850 onward), cumulative fLULCC reached 189±56 PgC with 40±15 PgC from the LASC.

Regional hotspots of high LASC values exist in the USA, China, Brazil, Equatorial Africa and Southeast Asia, which we mainly relate to deforestation for cropland. Distinct negative LASC estimates were observed in Europe (early reforestation) and from 2000 onward in the Ukraine (recultivation of post-Soviet abandoned agricultural land). Negative LASC estimates indicate that fLULCC estimates in these regions are lower in transient DGVM simulations compared to bookkeeping-approaches. By unraveling the spatio-temporal variability of the different DGVM-derived fLULCC estimates, our study calls for a harmonized attribution of model-derived fLULCC. We propose an approach that bridges bookkeeping and DGVM approaches for fLULCC estimation by adopting a mean DGVM-ensemble LASC for a defined reference period.

How to cite: Obermeier, W. and the LASC task-force: Spatio-temporal comparison of different approaches to derive land use and land cover change emissions by models, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9837, https://doi.org/10.5194/egusphere-egu21-9837, 2021.

Thais M. Rosan et al.

Brazil is responsible for about one third of the global land use and land cover change (LULCC) carbon dioxide emissions. However, there is a disagreement among different methodologies on the magnitude and trends in emissions and their geographic distribution. One of the main uncertainties is associated with different LULCC datatasets used as input in the different approaches. In this work we perform an evaluation of LULCC datasets for Brazil, including the global dataset (HYDE 3.2) used in the annual Global Carbon Budget (GCB), and national Brazilian dataset (MapBiomas) over the period 2000-2018. We also analyze the latest global HYDE 3.3 dataset based on new FAO inventory estimates and multi-annual ESA CCI satellite-based land cover maps. Results show that the new HYDE 3.3 can represent well the observed spatial variation in cropland and pastures areas over the last decades compared to national data (MapBiomas) and shows an improvement compared to HYDE 3.2 used in GCB. However, the magnitude of LULCC assessed with HYDE 3.3 is lower than national estimates from MapBiomas. Finally, we used HYDE 3.3 as input to two different approaches included in GCB, a global bookkeeping model (BLUE) and a process-based Dynamic Global Vegetation Model (JULES-ES) to determine the impact of the new version of HYDE dataset on Brazil’s land-use emissions trends over the period 2000-2017. Both JULES-ES and BLUE now simulate a negative land-use emissions trend for the last two decades. This negative trend is in agreement with Brazilian INPE-EM, global H&N bookkeeping models, FAO and as reported in National GHG inventories (NGHGI), although magnitudes differ among approaches. Overall, the inclusion of the multi-annual ESA CCI Land Cover dataset to allocate spatially the FAO statistical data has improved spatial representation of agricultural area change in Brazil in the last two decades, contributing to improve global model capability to simulate Brazil’s LULCC emissions in agreement with national trends estimates and spatial distribution.

How to cite: Rosan, T. M., Goldewijk, K. K., Ganzenmüller, R., O'Sullivan, M., Pongratz, J., Mercado, L. M., Aragao, L. E. O. C., Heinrich, V., Von Randow, C., Wiltshire, A., Tubiello, F. N., Bastos, A., Friedlingstein, P., and Sitch, S.: Assessment of land use and land cover datasets for Brazil and impact on C emissions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3065, https://doi.org/10.5194/egusphere-egu21-3065, 2021.

Peter E. Levy

The aim of this work was to make improved estimates of land-use change in the UK, using multiple sources of data. We applied a method for estimating land-use change using a Bayesian data assimilation approach. This allows us to constrain estimates of gross land-use change with national-scale census data, whilst retaining the detailed information available from several other sources. We produced a time series of maps describing our best estimate of land-use change given the available data, as well as the full posterior distribution of this space-time data cube. This quantifies the joint probability distribution of the parameters, and properly propagates the uncertainty from input data to final output. The output data has been summarised in the form of land-use vectors. The results show that we can provide improved estimates of past land-use change using this method. The main advantage of the approach is that it provides a coherent, generalised framework for combining multiple disparate sources of data, and adding further sources of data in future is straightforward.

How to cite: Levy, P. E.: A Bayesian data assimilation approach to estimating land-use change, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15126, https://doi.org/10.5194/egusphere-egu21-15126, 2021.

Hans Petersson et al.

Changes in carbon pools, land use and land-use change can be monitored based on field inventoried sampling units without using maps or remote sensing products. One way is to use a sampling framework. The framework can be based on a map, but the map does not necessarily need to be used for improving the estimates. The map can consist of a Member state’s total land and freshwater area. The sampling units can be distributed using a systematic grid with randomized location in the framework. A permanent design (the same sample units are re-inventoried in a periodic cycle) has been proven efficient when estimating change. Stratification into assumed homogenous strata is another way to further improve the accuracy of estimates. The distribution of sampling units can be spatially explicit (geo-referenced) in the sense that their locations are identified using GPS. This, combined with the permanent design, makes it possible to estimate both gross and net land use transfers in order to provide a land use matrix. The area-based sampling combined with the Horvitz and Thompson-estimator, makes a sampling unit representative of a certain area and all sample units together comprise the total land and freshwater area. This design makes it possible to match changes in carbon pools to land use and land-use change and to trace them back in time. 

We present a monitoring design based on the Swedish NFI and adapted to reporting under the UNFCCC/KP frameworks or the EU-regulation. Pros and cons are discussed and we compare with alternative designs (combining ground truth with remote sensing). Finally, we assess the accuracy of estimates of selected variables (sample and model errors).

How to cite: Petersson, H., Breidenbach, J., Ellison, D., Lundblad, M., and Appiah Mensah, A.: Monitoring changes in carbon pools matched to land use and land-use change based on field sampling measurements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16400, https://doi.org/10.5194/egusphere-egu21-16400, 2021.

Dmitry Schepaschenko et al.

Since the collapse of the Soviet Union and transition to a new forest inventory system, Russia has reported (FAO, 2014) almost no changes in growing stock (+1.8%) and biomass (+0.6%). Yet remote sensing products indicate increased vegetation productivity (Guay et al., 2014), tree cover (Song et al., 2018) and above-ground biomass (Liu et al., 2015). Here, we challenge the official national statistics with a combination of recent National Forest Inventory and remote sensing data products to provide an alternative estimate of the growing stock of Russian forests and assess the relative changes in the post-Soviet era. Our estimate for the year 2014 is 118.29±1.3 109 m3, which is 48% higher than the official value reported for the same year in the State Forest Register. The difference is explained by increased biomass density in forested areas (+39%) and larger forest area estimates (+9%). Using the last Soviet Union report (1988) as a reference, Russian forests have accumulated 1163×106 m3 yr-1 of growing stock between 1988–2014, which compensates for forest growing stock losses in tropical countries (FAO FRA, 2015). Our estimate of the growing stock of managed forests is 94.2 109 m3, which corresponds to sequestration of 354 Tg C yr-1 in live biomass over 1988–2014, or 47% higher than reported in the National Greenhouse Gases Inventory (National Inventory Report, 2020).

Acknowledgement: The research plots data collection was performed within the framework of the state assignment of the Center for Forest Ecology and Productivity of the Russian Academy of Sciences (no. АААА-А18-118052590019-7), and the ground data pre-processing were financially supported by the Russian Science Foundation (project no. 19-77-30015).

How to cite: Schepaschenko, D., Moltchanova, E., Fedorov, S., Karminov, V., Ontikov, P., Santoro, M., See, L., Kositsyn, V., Shvidenko, A., Romanovskaya, A., Korotkov, V., Bartalev, S., Fritz, S., Shchepashchenko, M., and Kraxner, F.: New estimate of growing stock volume and carbon sequestration of Russian forests based on national forest inventory and remote sensing data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11217, https://doi.org/10.5194/egusphere-egu21-11217, 2021.

Johannes Breidenbach et al.

In a recent Nature article, the satellite-based Global Forest Change (GFC) map was used to estimate the yearly harvest area in each of the EU26-states over the period 2004 to 2018 (Ceccherini et al. 2020). Finland and Sweden were identified as the countries with the largest harvest increases and the biggest effect on the EU’s climate policy strategy. Here, we employ more than 45,000 field observations from the Finnish and Swedish national forest inventories as reference observations to analyze the accuracy of GFC data. We find that harvested area increases only marginally, if at all, after 2015. What did increase abruptly after 2015, however, was GFC’s sensitivity to detect harvested areas and thinnings.

The results of the Nature article are therefore a consequence of an inconsistent time series in GFC due to a change in the mapping algorithm or the sensor system and are thus both incorrect and misleading. The article is thus a good example for how wrong results based on satellite data can be, if no adequate estimators utilizing reference data are used.



Ceccherini, G. et al. Abrupt increase in harvested forest area over Europe after 2015. Nature 583, 72-77 (2020).

How to cite: Breidenbach, J., Ellison, D., Petersson, H., Korhonen, K., Henttonen, H., Wallerman, J., Fridman, J., Gobakken, T., Astrup, R., and Næsset, E.: No “Abrupt increase in harvested forest area over Europe after 2015” – How the misuse of a satellite-based map led to completely wrong conclusions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13243, https://doi.org/10.5194/egusphere-egu21-13243, 2021.

David Ellison et al.

The announced goal of reversing the European trend toward a declining land carbon sink has garnered much ink. Words can, however, be misleading. Annual additions/contributions (sinks) to the land carbon sink (stocks) from growing forest and increasing forest cover have slowed marginally in recent years. However, the existing European land forest sink (stocks) has (have) expanded continuously across most or all of the 20th century and on into the 21st. More importantly perhaps, EU Member states with significant long-term investments in the forestry sector have historically witnessed strong forest expansion and notmerely with the initiation of international attention to climate change mitigation through the UNFCCC negotiating and climate commitment framework. In this context, frequent assaults on forestry from multiple directions are cause for some bewilderment. We first highlight weaknesses in claims of increased forest use intensity and illustrate that forestry in the Nordic countries has a remarkably small and stable footprint over the 20th and 21st centuries. Addressing the second problem, however, understanding why such attacks occur in the first place, is more complex. Methodologically speaking, challenges to forestry should presumably be balanced by an understanding of the many human welfare benefits forests and the practice of forestry currently provide, as well as the costs of relinquishing those practices. Perhaps due to strong preferences among NGO’s and in parts of the academic community for natural, untouched, biodiverse forests, the benefits of forestry and forest resource use are consistently under-appreciated. Striking a balance between the desire for natural and biodiverse-rich forest environments on the one hand, and the climate change mitigation (and adaptation) benefits of forestry, forest resource use and substitution on the other is presumably a political and socio-economic necessity. The real question may be to what extent bias in favor of the “natural” may ultimately disrupt real, measurable progress toward effective climate change mitigation? Continuous, positive mitigation-related contributions to the growing European land cover sink (stocks), as well as to the global carbon budget (through annual net removals and substitution), have been and should remain the norm. These goals ultimately require an aggressive EU LULUCF strategy capable of fully mobilizing forest and forest resource use in favor of the goal of climate change mitigation (and adaptation).

How to cite: Ellison, D., Breidenbach, J., Petersson, H., Korhonen, K. T., Henttonen, H., Wallerman, J., Fridman, J., Mensah, A. A., Gobakken, T., and Naesset, E.: Reversing the European Trend Toward a Declining Land Carbon Sink?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16261, https://doi.org/10.5194/egusphere-egu21-16261, 2021.

Alex Appiah Mensah et al.

Long-standing debates over the benefits of forest conservation vs. those of substitution and forest resource use continue to occupy attention in Europe and beyond. Moreover, many argue the carbon sequestration benefits of standing forest are greater than those from forest resource use and replanting. To study this question, we generate long-term scenario analyses based on different forest management strategies in Sweden, in particular comparing increasing forest use and increasing land set-asides over 100, 200 and 500 year cycles. We find that the cost of increasing land set-asides is reflected in a significant loss of the carbon benefits created by forest use (substitution and carbon sequestration). We explain this outcome through the loss of additional growth that occurs as forest in land set-asides matures and eventually reaches a steady state. For the Swedish forest, these costs are significant and may amount to the loss (lost opportunity) of annually providing and additional -14 MtCO2e in net annual removals. The EU-based LULUCF carbon accounting framework, however, does not recognize this benefit and thus may effectively encourage land set-asides at the expense of real, measurable forest and forest resource-based climate change mitigation.

How to cite: Appiah Mensah, A., Petersson, H., Berndes, G., Egnell, G., Ellison, D., Lundblad, M., Lundmark, T., Lundström, A., Stendahl, J., and Wikberg, P.-E.: On the Role of Forestry in Climate Change Mitigation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16472, https://doi.org/10.5194/egusphere-egu21-16472, 2021.

Bostjan Mali et al.

With the advent of global warming, forests are becoming an increasingly important carbon sink that can mitigate the negative effects of climate change. An understanding of the carbon dynamics of forests is, therefore, crucial to implement appropriate forest management strategies and to meet the expectations of the Paris Agreement with respect to international reporting schemes. One of the most frequently used models for simulating the dynamics of carbon stocks in forests is the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3). We applied this model in our study to evaluate the effects of harvesting on the carbon sink dynamics in Slovenian forests. Five harvesting scenarios were defined: (1) business as usual (BAU), (2) harvesting in line with current forest management plans (PLAN), (3) more frequent natural hazards (HAZ), (4) high harvest (HH) and (5) low harvest (LH). The simulated forest carbon dynamics revealed important differences between the harvesting scenarios. Relative to the base year of 2014, by 2050 the carbon stock in above-ground biomass is projected to increase by 28.4% (LH), 19% (BAU), 10% (PLAN), 6.5% (HAZ) and 1.2% (HH). Slovenian forests can be expected to be a carbon sink until harvesting exceeds approximately 9 million m3 annually, which is close to the calculated total annual volume increase. Our results are also important in terms of Forest Reference Levels (FRL), which will take place in European Union (EU) member states in the period 2021-2025. For Slovenia, the FRL was set to –3270.2 Gg CO2 eq/year, meaning that the total timber harvested should not exceed 6 million m3 annually.

How to cite: Mali, B., Jevsenak, J., and Klopcic, M.: The effect of harvesting on national forest carbon sinks up to 2050 simulated by the CBM-CFS3 model: a case study from Slovenia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13486, https://doi.org/10.5194/egusphere-egu21-13486, 2021.

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