LULUCF Sector Research Articles

Carbon concentration of living tree biomass of Pinus sylvestris, Picea abies, Betula pendula and Betula pubescens in Sweden

ABSTRACT This study examined the carbon (C) concentration of the major tree species (Scots pine, Norway spruce, and Birch) in Sweden based on destructively sampled biomass data. The examination was made using single trees and comprised three components: branches with needles, stemwood with bark, and stump with roots. We developed a weighted C concentration estimator accounting for fresh weights of tree components to infer the C concentration at the population level. Significant differences in C concentration (%) were found among species, with the highest in pine (50.671 ± 0.211), followed by spruce (49.518 ± 0.164) and the lowest in birch (49.347 ± 0.241). Additionally, the C concentration varied among tree components, regardless of tree size, growth rate, and site conditions. At the national level, we applied the estimated species- and component-specific C concentration constants to the measured total biomass of the major tree species from the National Forest Inventory. This extrapolation revealed that the average C concentration of major trees across all forestlands in Sweden was approximately 50.012%. These findings have significant implications for accurate C sequestration reporting in the LULUCF sector.

The land sector in the low carbon emission strategies in the European Union: role and future expectations

ABSTRACT The Land-Use, Land-Use Change and Forestry sector (LULUCF) role is of critical importance in contributing to the ambitious targets set by the European Union (EU) to reduce by 55% net greenhouse gas (GHG) emissions by 2030, compared to 1990 levels, and to become carbon neutral by 2050. The EU LULUCF regulation, approved in 2023, sets out binding targets for each individual Member State to be achieved by 2030, totaling 310 MtCO2e of net removals for the whole EU. However, it remains poorly understood to what extent the EU LULUCF climate target matches with the Member States’ strategies. The alignment between the EU governance and its Member States’ visions for the long-term will determine the achievement of the climate targets. The objective of this study is to understand the LULUCF expected contribution to the EU’s 2030 and 2050 climate goals. In doing so, we explored the European and country-level visions of LULUCF with respect to climate change mitigation and adaptation, as expressed in their Long-Term Strategies (LTSs) and national projections; we evaluated whether national level projections for LULUCF are aligned with the EU short and long term targets. We found that most countries’ LTSs envisage policies and measures in the LULUCF sector, however they are, often general and not comprehensive. Furthermore, the majority of countries’ quantitative future projections of GHG emissions and removals from LULUCF differ from the pathway set in EU targets; thus, countries may need to either update existing policies or conceive and plan new policies and actions.

Role of land cover in Finland’s greenhouse gas emissions

We present regionally aggregated emissions of greenhouse gases (GHG) from five land cover categories in Finland: artificial surfaces, arable land, forest, waterbodies, and wetlands. Carbon (C) sequestration to managed forests and unmanaged wetlands was also assessed. Models FRES and ALas were applied for emissions (CO2, CH4, N2O) from artificial surfaces and agriculture, and PREBAS for forest growth and C balance. Empirical emission coefficients were used to estimate emissions from drained forested peatland (CH4, N2O), cropland (CO2), waterbodies (CH4, CO2), peat production sites and undrained mires (CH4, CO2, N2O). We calculated gross emissions of 147.2 ± 6.8 TgCO2eq yr−1 for 18 administrative units covering mainland Finland, using data representative of the period 2017–2025. Emissions from energy production, industrial processes, road traffic and other sources in artificial surfaces amounted to 45.7 ± 2.0 TgCO2eq yr−1. The loss of C in forest harvesting was the largest emission source in the LULUCF sector, in total 59.8 ± 3.3 TgCO2eq yr−1. Emissions from domestic livestock production, field cultivation and organic soils added up to 12.2 ± 3.5 TgCO2eq yr−1 from arable land. Rivers and lakes (13.4 ± 1.9 TgCO2eq yr−1) as well as undrained mires and peat production sites (14.7 ± 1.8 TgCO2eq yr−1) increased the total GHG fluxes. The C sequestration from the atmosphere was 93.2 ± 13.7 TgCO2eq yr−1. with the main sink in forest on mineral soil (79.9 ± 12.2 TgCO2eq yr−1). All sinks compensated 63% of total emissions and thus the net emissions were 53.9 ± 15.3 TgCO2eq yr−1, or a net GHG flux per capita of 9.8 MgCO2eq yr−1.

Measurements and statistical analysis of CO2 efflux and related parameters from crop and forested lands

The LULUCF sector (land use, land use change and forestry) can act as a carbon dioxide (CO2) sink, either by increasing the removal of greenhouse gasses from the atmosphere or by reducing their current emissions. This paper intends to analyze the results of the CO2 monitoring methodology by the chamber method in order to estimate the effect of different land use cover and management techniques. For this purpose, seasonal CO2 efflux field measurements were conducted in two types of ecosystems (forested land and wheat crop) located in the adjacent area of Bucharest. CO2 efflux was analysed for each land cover in relation to the physical characteristics of the soil, respectively soil temperatures and humidity, but also together with the main weather parameters. The measurements were performed simultaneously in both land covers at relevant time intervals. The difference in measured values between the two ecosystems was recorded but the results of the statistical analysis showed a lack of differences in the correlation between the CO2 efflux. This indicates that the CO2 efflux can be affected by particular elements of the environment which facilitates differences in soil temperature and humidity in the same weather conditions.

The combined impacts of land use change and climate change on soil organic carbon stocks in the Ethiopian highlands

Land Use Change (LUC), especially deforestation in tropical regions, significantly contributes to global anthropogenic greenhouse gas (GHG) emissions. Here, we address potential combined impacts of LUC and Climate Change (CC) on Soil Organic Carbon (SOC) stocks in the Ethiopian highlands. The soil model Q was employed to predict SOC stocks for various combinations of LUC and CC scenarios until the year 2100. Four reference scenarios (cropland, bushland, natural forest, and Eucalyptus plantations under contemporary climatic conditions) were evaluated against reported measurements of SOC stocks. We studied impacts of six common LUC scenarios, including deforestation and planting Eucalyptus, on SOC stocks under contemporary and future climates. To assess the impact of CC, effects of elevated temperature (mean annual temperature + 2.6 °C) together with three litterfall scenarios (no change in litterfall, a 5% reduction and 22% increase, designated CC0, CCd, and CCi, respectively) were considered to test potential vegetation responses to increases in temperature and atmospheric CO2 concentrations. Most of the tested combinations of LUC and CC led to losses of SOC stocks. Losses were most severe, both relatively and absolutely, in the deforestation scenarios: up to 30% was lost if natural forest was converted to cropland and temperature increased (under the CC0 scenario). Gains in SOC stocks of 4–19% were modelled when sparse vegetation was converted to more dense vegetation like Eucalyptus plantation with substantially increased litterfall (the CCi scenario). Elevated temperature accelerated decomposition rates, leading to circa 8% losses of SOC stocks.We conclude that effects of LUC and CC on SOC stocks are additive and changes in litterfall caused by LUC determine which has the largest impact. Hence, deforestation is the biggest threat to SOC stocks in the Ethiopian highlands, and stocks in sparse vegetation systems like cropland and bushland are more sensitive to CC0 than LUC. We recommend conservation of natural forests and longer rotation periods for Eucalyptus plantations to preserve SOC stocks.Finally, we suggest that use of the Q model is a viable option for national reporting changes in SOC stocks at Tier 3 within the LULUCF sector to the United Nations Framework Convention on Climate Change (UNFCCC) as it is widely applicable and robust, although it only requires input data on a few generally available variables.

우리나라 산림지부문 입목바이오매스 탄소저장량의 불확도 평가

The Paris Agreement recommends its member parties to enhance transparency in Greenhouse Gas (GHG) inventory by sector. IPCC guidelines provide recommendations for reducing uncertainties of GHG emissions and removals for the accurate assessment. Thus, this study aimed to assess the uncertainties of estimated carbon stocks for living biomass in the forestry sector. Living biomass is an essential indicator for monitoring GHG removals in the LULUCF sector. This study made a comparative assessment of the uncertainty by applying error propagation methods (simple multiplication, addition and subtraction) and the Monte Carlo Simulation (MCS) suggested in the IPCC guidelines. The findings showed that the overall uncertainty for the simple multiplication in the error propagation was found to be as high as ±28.0% due to higher uncertainties of country-specific emission factors. In contrast, the overall uncertainty was as low as ±3.6% for the addition and subtraction considering the sensitiveness of activity data and emission factors as explanatory variables, while that for the MCS was at around ±6.0%. Despite the slightly higher uncertainty for MCS compared with addition and subtraction, it is reasonable to apply uncertainty assessment using MCS considering the international reliability and comparability. Additionally, since living biomass causes various error sources including measurement error and volume equations by tree species, there is a need for research to assessing different error sources for uncertainty.

Energy system transformation for attainability of net zero emissions in Thailand

This study analyzed energy and technological implications in the energy sector to attain net zero emissions in Thailand by 2050. The study used AIM/Enduse, a bottom-up type energy system model, as an analytical tool. A business-as-usual and a net zero emission scenario are analyzed. Net zero emission scenarios are assessed in terms of net zero greenhouse gas emissions (NZE-GHG). Results show that the GHG emissions from the energy sector in the BAU would reach 635 MtCO2e in 2050. Decarbonization of the energy sector and transition towards net zero emission by 2050 in Thailand would require rapid deployment of renewable energy sources like solar, wind and biomass. In net zero scenario, installed capacity of solar PV and wind for power generation in 2050 would reach 64 GW and 40 GW, respectively. In addition, this study assesses the role of green hydrogen in achieving net zero target. The 200 GW solar capacity would be required to produce green hydrogen for decarbonizing the transport, industrial as well as power sector. The high carbon sequestration from LULUCF sector in Thailand will make it possible to reach net zero emission with carbon dioxide capture and storage (CCS) technology in the energy sector. Additional bioenergy or CCS technologies will need to be deployed in the power sector if the renewables cannot be deployed to the desirable extent.

THE CONTRIBUTION OF ROMANIA TO CLIMATE CHANGE – THE EFFECTS OF ACCOUNTING THE GHG EMISSIONS FROM LAND USE, LAND-USE CHANGE AND FORESTRY (LULUCF)

This study aimed to analyze Romanian (RO) involvement in the LULUCF sector by considering the Intergovernmental Panel on Climate Change (IPCC) good practice guidance (GPG). Trends were assessed using the Mann-Kendall (MK) test for trend estimation to determine the total greenhouse gas (GHG) (GHGCO₂-eq.) emissions/ removals. The results emphasized the increasing average annual levels of emissions/removals in both the EU-28 and RO when the subperiods from 1990-2005 and 2005-2017 were analyzed. Kendall’s analysis of GHG removal showed a positive trend in Romanian GHG removals, and no trend was observed for the EU-28. In comparison, the emissions indicated an increasing trend for RO and a decreasing trend for the EU-28. The GHGCO₂-eq. generated by the LULUCF sector decreased to an average annual rate of 0.5% per year in the EU-28. In Romania, these emissions increased by approximately 0.2% per year on average. Between 1990 and 2017, the CO2 total absorption increased to 0.9% per year. The methane absorption also increased by 11.7% per year, and no significant increasing trend was observed for methane. The dynamics of GHGCO₂-eq. emissions/removals in RO and LULUCF sectors showed that settlement had decreased in wetlands, and settlement of other land areas had increased. Assessing GHG gas emissions is essential for allowing each sector to promote specific strategies, policies and action plans. This will improve the national-level monitoring of the LULUCF sector and make this information more accessible to decision makers by raising awareness of the Romanian position within the EU-28

Multisektorski pristup u tranziciji prema niskougljičnom razvoju i ciljevima Zelenog akcionog plana EU – iskustva Republike Hrvatske

The paper will describe a multisectoral approach in development of long-term planning documents based on the example of developing background papers for low-carbon development strategy in the Republic of Croatia until 2030, with a view to the year 2050. As part of its obligations under the Regulation on the Governance of the Energy Union and Climate Action (EU 2018/1999), the Republic of Croatia is obliged to develop an Integrated National Energy and Climate Plan and a Long-Term Decarbonisation Strategy. New strategic goals of the Green Plan for Europe, intended to meet the goals of the Paris Agreement and raise global competitiveness of the European economy, set an ambitious goal of net zero greenhouse gas emissions by 2050. Fulfilling that vision requires a multidisciplinary approach as it does not suffice to reduce emissions from energy, industry, general consumption and transport, but it is necessary to increase removals in agricultural and LULUCF sectors. The paper will describe the development process, the engagement of numerous stakeholders, the methodological approach and the main outcomes. The analyses include detailed modelling in energetics, by economic sectors and natural carbon storage of the LULUCF sector. There are comments on synergistic energy challenges and on maintaining a secure food supply, as well as on sustainable forest management, achieving clean air, use of space and more.

Low-carbon development strategy of Russia considering the impact on the economy

The article considers the impact of national climate policy on the development of the Russian economy and energy sector. Implementation of an aggressive scenario (which is aimed at containing at any cost the rise in global temperature within 1.5 °C compared to the pre-industrial era) is unacceptable to Russia from socioeconomic perspective given it leads to lowering the average annual GDP growth rate by 1.8 percentage points by 2050. Effective long-term development strategy with low GHG emissions level should focus on structural and technological modernization of the economy; improve the absorption potential of the LULUCF sector; stimulate only those structural changes in the energy sector that involve production and technological chains within the country and do not provide for excessive price growth. Russia retains a significant potential for energy efficiency growth, and the necessary condition for activating this process is sustainable economic growth as it involves modernization of the production facilities and using available and competitive industrial capacities. The implementation of a reasonable scenario, based on these principles, would allow Russia to fulfil the nationally determined contributions within the Paris Agreement while ensuring economic growth at the rate not less than the global average one.

Стратегия низкоуглеродного развития: перспективы для экономики России

As a party to the Paris Agreement Russia pledged not to exceed the net greenhouse gas (GHG) emissions’ level of 70–75% to that existed in 1990. Energy efficiency improvement, structural shifts in production and the increase of Russian forests’ carbon sink capacity were the key contributors to curbing the GHG emissions in Russia during the last 25 years. The decreasing carbon intensity of the GDP was a natural result of economic growth and implementation of voluntary business projects to improve the efficiency of the industrial sector using investments in modernization of the production facilities. Russia disposes significant potential to reduce GHG emissions, but the feasibility and efficiency of respective measures should be evaluated considering the implications to economic growth. Implementation of the socalled aggressive scenario to halt global temperature growth at any cost within 1.5 °C as compared to the pre-industrial era is unacceptable to Russia from socioeconomic perspective given its leading to lowering the average annual GDP growth rate by 1.8 percentage points by 2050. In addition, tough measures to reduce GHG emissions involve energy costs skyrocketing to unprecedented levels – from the current 13% of the GDP to 30% of the GDP by 2040. Such a burden would hardly be compatible with economic growth or, in any case, provide for the economic growth’s providing for improvement of the communities’ standard of living. Russia needs the long-term development strategy with low GHG emissions level focused on improving the quality of living, modernizing and increasing the competitiveness of the national economy. Such a strategy rests on the following principles: 1) Russia has been the world leader in the GHG emissions reduction since 1990, so no solid reason exists for its soonest switching to excessively stringent climate commitments which result in ungrounded additional restrictions to its socio-economic development pace; 2) The core impediment to sustainable development of Russia is not a high level of the GHG emissions, but economic stagnation. Given that the reasonable scenario of the GHG emissions reduction implies the development path that allows the national economy to grow at a rate of 3% average annual GDP as the least; 3) Action priorities in the area of the GHG sinking should involve improvement of the LULUCF sector potential by promoting sound natural resources management policy and voluntary projects to increase carbon sink and reservoir capacity of the forest and wetland ecosystems; 4) Action priorities to reduce GHG emissions assume the imperative and expediency of economic stimulating of the structural change in the energy sector that involves production and technological chains within the country and do not provide for excessive price growth. Such change includes increasing use of natural gas (as the most “clean” fossil fuel) and nuclear energy (given Russia’s leading position in the nuclear technology area), as well as cogeneration of electricity and heat. Pronounced increase in using renewables, energy storage systems and electric vehicles should be acceptable only if production of these is successfully localized and costs are reduced. Sustainable economic growth is a prerequisite for intensifying energy efficiency improvement as it involves modernization of the production facilities and using available and competitive industrial capacities. Specific measures targeted at energy savings will be inefficient given economic stagnation. A reasonable (smart) scenario of the Russia long-term economic development with the low GHG emissions level should comply with the principles above and its driving force propelled by structural and technological modernization of the economy that fully involves economic potential of the energy resource and power sector. The implementation of this development scenario would allow Russia to comply with the Paris Agreement national commitments while ensuring economic growth at the pace not yielding to that of the global average.

Automatic Classification by Land Use Category of National Level LULUCF Sector using Deep Learning Model

Automatic Classification by Land Use Category of National Level LULUCF Sector using Deep Learning Model

LULUCF 부문 산림 온실가스 인벤토리 구축을 위한 Sampling과 Wall-to-Wall 방법론 비교

LULUCF 부문 산림 온실가스 인벤토리 구축을 위한 Sampling과 Wall-to-Wall 방법론 비교

El financiamiento de los proyectos de carbono forestal: Experiencias existentes y oportunidades en México

Este trabajo presenta una síntesis de los mecanismos de financiamiento empleados para la mitigación de emisiones en el sector forestal a escala internacional y las experiencias desarrolladas en México. A su vez, se analizan las oportunidades de mitigación del sector Uso del Suelo, Cambio de Uso del Suelo y Silvicultura [Uscusys] mexicano para cumplir con los objetivos nacionales. A escala internacional, los proyectos forestales de carbono han participado en mercados voluntarios y de cumplimiento, aunque los proyectos de países en vías de desarrollo han tenido un papel limitado en el marco del Protocolo de Kioto. El desarrollo de nuevos mecanismos de mitigación en la Comisión Marco de las Naciones Unidas sobre el Cambio Climático ha supuesto la necesidad de ampliar los enfoques para su financiamiento, que se ha materializado en acuerdos bilaterales y multilaterales en el caso del mecanismo de Reducción de Emisiones por Deforestación y Degradación forestal más la conservación, el manejo forestal sustentable y el incremento de los almacenes forestales [REDD+], en distintos países. En México, la participación del sector forestal en los mercados voluntarios y mecanismo para un desarrollo limpio ha sido, hasta el momento, limitada. Sin embargo, el país se ha preparado para la implementación de un mecanismo REDD+ a escala nacional y ha puesto en marcha su Iniciativa de Reducción de Emisiones [IRE]. Para alcanzar los objetivos de reducción de emisiones del sector Uscusys, México debe lograr una efectiva coordinación entre políticas forestales y de cambio climático y un óptimo aprovechamiento de los mecanismos financieros que se están gestando, destacándose la experiencia de la IRE y el desarrollo de un esquema regulado de comercio de emisiones a escala nacional. En este sentido, la aceptación de créditos de compensación de distintos tipos de proyectos forestales, en una visión más amplia a la contemplada en el pago opcional del impuesto al carbono a través de bonos de carbono, podría traducirse en importantes beneficios medioambientales, económicos y sociales.

Il nuovo regolamento comunitario LULUCF: sfide e opportunità per il settore forestale italiano

Abstract: The entry into force of the new Italian national forest law was followed by the recent approval of the new European regulation 2018/841 on the inclusion of greenhouse gas emissions (GHG) from land use, land use change and forest (the so called LULUCF sector) into the 2030 climate and energy reduction targets. While the national forest law has been extensively debated, the EU regulation has not received, at least in Italy, a due attention by the forest sector. Since the Kyoto Protocol in 1997, the accounting and reporting of GHG for the forestry sector has been strongly debated and constrained by a series of technical issues, such as the quantification of the actual contribution of anthropogenic activities to GHG removals. The new LULUCF regulation seeks to overcome these limits by proposing a novel approach for accounting GHG emissions and removals in the forestry sector for the period 2020-2030. Moreover, emissions in the forest sector become more comparable to those in other sectors. The most innovative aspects refer to the so-called Forest Reference Level (FRL), and to the inclusion of accounting procedures also for Harvested Wood Products. The FRL is an estimate of the expected GHG emissions and removals in managed forest lands, against which the future GHG emissions and removals will be calculated. Despite originally based on policy assumptions (e.g., expected harvest), the new FRL is based on estimating the theoretical development of forests resulting from the continuation of the management practices as observed in the reference period 2000-2009. Thus, the FRL incorporates the age-structure dynamics of forest stands, and allows for increasing removals in aging forests. In this way, any impact of changes in forest management on GHG emissions will be considered, as in other sectors. Considering that Member States have the responsibility to account for GHG emissions and removals for the LULUCF sector, the implementation of the new LULUCF regulation, and the inherent calculation of the FRL represent both a challenge (for defining past and future management practices and harvest) and an opportunity (for enhancing the forestry-wood and energy chain) for the forestry sector in Italy.

Understanding the implications of the EU-LULUCF regulation for the wood supply from EU forests to the EU

BackgroundIn June 2018, the European Parliament and Council of the European Union adopted a legislative regulation for incorporating greenhouse gas emissions and removals from Land Use, Land Use Change and Forestry (EU-LULUCF) under its 2030 Climate and Energy Framework. The LULUCF regulation aim to incentivise EU Member States to decrease greenhouse gas emissions and increase removals in the LULUCF sector. The regulation, however, does not set a target for increasing the LULUCF carbon sink, but rather includes a ‘no net debit’ target for LULUCF (Forests and Agricultural soils). For Managed Forest Land (MFL) an accounting framework with capped credits for additional mitigation against a set forest reference level (FRL) was agreed for 2021–2030. The FRL gives the projected future carbon sink in the two compliance periods 2021–2025 and 2026–2030 under “continuation of forest management practices as they were in the reference period 2000–2009”. This FRL was disputed by some Member States as it was perceived to put a limit on their future wood harvesting from MFL. Here we simulated with the EFISCEN European forest model the “continuation of forest management practices” and determined the corresponding wood harvest for 26 EU countries under progressing age classes.ResultsThe simulations showed that under “continuation of forest management practices” the harvest (wood removals) in the 26 EU countries as a whole can increase from 420 million m3/year in 2000–2009 to 560 million m3/year in 2050 due to progressing age classes. This implies there is a possibility to increase absolute wood harvests without creating debits compared to the forest reference level. However, the manner in which ‘continuation of forest management’ developed with a progressing age class development over time, meant that in some countries the future harvesting exceeded 90% of the increment. Since this generally is considered to be unsustainable we additionally set a harvesting cut-off as max 90% of increment to be harvested for each individual country as a possible interpretation of sustainability criteria that are included in the regulation. Using this additional limit the projected harvest will only increase to 493 million m3/year.ConclusionsThe worry from Member States (MS) that the FRL will prevent any additional harvesting seems unwarranted. Due to differences between Member States concerning the state of their forest resources, the FRL as a baseline for harvesting works out very differently for the different Member States. The FRL may have other unforeseen consequences which we discuss. Under all scenarios the living forest biomass sink shows a decline. This can be counteracted through incentivising measures under Climate Smart Forestry.

A carbon accounting tool for complex and uncertain greenhouse gas emission life cycles

Software applications for life cycle assessment of greenhouse gas (GHG) emissions have become popular over the last decade. Their objective is to provide insight into how GHG emissions could be reduced in the sectors defined by the UNFCCC. However, boundaries between these sectors are not closed and current tools are not designed to represent this complexity or to assess the numerous sources of uncertainties.In this paper, we present CAT v1.0, software developed for managed forests in the LULUCF sector, but whose emission life cycle is linked to that of other sectors. While the structure of the software follows IPCC Guidelines, it also contains additional features such as an embedded Monte-Carlo error propagation technique and a user-friendly flux manager that allows for complex cradle-to-grave representations of the wood transformation industry. The flexibility of the software is illustrated through two case studies in northeastern France.

국가 온실가스 인벤토리 LULUCF 부문 통계 구축방안에 관한 연구

국가 온실가스 인벤토리 LULUCF 부문 통계 구축방안에 관한 연구

Effects of changes in land-use, age-structure and management on carbon dynamics of European forests

In European forests, carbon storage has increased uninterruptedly during the last 60 years, but the contribution of multiple factors affecting the carbon dynamics is not clear. The main aim of this research was to study effects of changes in land-use, age-structure and management on carbon dynamics of European forests. The specific research tasks were: i) to reconstruct the age-structure of European forests beginning in 1950, by combining available national inventory data with state-of-the-art backcasting, and to study how the mean forest age has changed since the 1950 s (Paper I); ii) to evaluate the role of afforestation on the development of mean forest age and effects of changes in forest area and structure (both age-structure and age/volume relationship) on the development of forest carbon stocks in two European case study countries (Paper II); iii) to quantify the effects of rotation length on the carbon stocks of forests (trees, soil) and wood products, and to estimate the effects of changing rotation length on climate change mitigation (Paper III), and iv) to quantify the average CO2 emissions from wildfires in Mediterranean countries, and estimate the potential of prescribed burning to mitigate CO2 emissions (Paper IV). Results show that in European forests, the share of old forests (>100 years) has decreased from 21% in 1950 to 16% in 2010, and the mean age has decreased from 62 to 59 years (Paper I). However, there exists large variation in these results at country level. In two case study countries, Finland and Czech Republic, the development of mean age was affected by afforestation, although it did not change the observed trend of mean age. In both countries, the increase of mean growing stock volume had a larger effect on the increase of forest biomass carbon stock than afforestation (Paper II). In this work, it was also found that the average carbon stocks of tree biomass could be increased by increasing the rotation length. However, this may in some cases decrease carbon stocks of soil and wood products (Paper III). In Mediterranean countries, the use of prescribed burning could also decrease the emissions from forest fires, affecting considerably also the carbon balance of the LULUCF sector (Paper IV). Despite the uncertainties related to employed data and models, this work provided valuable insights on the effects of changes in land-use, age-structure and management on the carbon dynamics of European forests. In overall, the increase of forest carbon stocks can be largely explained by the smaller harvests compared to forest growth, but the contribution of different factors varies significantly between the countries. Findings of this work call for more systematic and accurate estimation of the carbon dynamics and balance of European forests, and factors explaining them, in order to better estimate and utilize the possibilities offered by European forests for climate change mitigation.

Improving National-Scale Carbon Stock Inventories Using Knowledge on Land Use History

National-scale inventories of soil organic carbon (SOC) and forest floor carbon (FFC) stocks have a high uncertainty. Inventories are often based on the interpolation of sampled information, often using a number of covariables to help such interpolation. The rationale for the choice of these covariables is not always documented, despite the fact that many local-scale studies have identified the factors explaining spatial variability of SOC and FFC stocks. These studies indicate, among others the importance of long-term land use history. Despite this, information on the effects of land use history has never been used to explain variability of carbon stocks in national-scale inventories. We designed an alternative method to improve national-scale inventories of SOC and FCC for the Dutch sand area that takes stock of the findings of detailed case studies. Determinants for SOC and FFC stocks derived from landscape-scale case studies were used to map national-scale spatial variability and to calculate national totals. The resulting national-scale spatial distribution was compared with the SOC stock map from the current Dutch greenhouse gas inventory. Using land use history to explain SOC variability decreased the error of the SOC stock estimate in 60% of the area. The error in FFC stocks decreased in half of the forest area after including soil fertility, tree species, and forest age as explanatory factors. Estimates with reduced uncertainty will make land use and land management a more attractive and acceptable mitigation option to reduce emissions of greenhouse gases for the LULUCF sector.