The LULUCF sector covers emission estimates from Land Use, Land Use Change and Forestry. The LULUCF sector differs from the other sectors in that it contains both sources and sinks of carbon dioxide. Removals are given as negative figures and emissions are reported as positive figures according to the guidelines. For 2015 emissions from LULUCF were estimated to be a net source of approximately 4153 Gg CO2 equivalents or 8.0 % of the total reported Danish emission.
The land area including lakes has been estimated to 43056 km2. No permanent ice is occurring and only very small insignificant areas with rocks. The climate is according to IPCC 2006 Guidelines cold and wet. The average temperature in the standard 30 year, 1961-1990 was 7.7 °C with a minimum temperature in February of 0.3 °C and a maximum in July of 17.0 °C. Year 2015 had an average mean temperature of 9.1 °C which is 1.4 °C above the average (www.dmi.dk).
Denmark is an intensive agricultural country where most of the area is affected by agriculture. Approximately 2/3 of the total Danish land area is cultivated or 2.6 mill hectare and 14.8 per cent forested. Together with high number of cattle and pigs there is a high (environmental) pressure on the landscape. To reduce the impact an active policy has been adopted to protect the environment. The adopted policy aims at doubling the forested area within the next 80-100 years, restoration of former wetlands and establishment of protected national parks. In Denmark almost all natural habitats and all forests are protected. Therefore only limited conversions from forest or wetlands into cropland or grassland are occurring.
The land area is classified into the six IPCC major land use classes: Forestry (FL), Cropland (CL), Grassland (GL), Wetlands (WE), Settlement (SE) and Other Land (OL). OL is restricted to beaches and sand dunes. Rivers and lakes inside the 7000 km coast line are included in WE. Denmark has a high production of Christmas trees. In 2015 Statistics Denmark recorded 22101 hectare with Christmas trees and a production of 10 mill. trees. Of this is 9 mill. exported. By definition are areas with Christmas trees included in the forest area.
Fertilisation of Forests and Other Land is negligible and all fertiliser consumption is therefore reported in the agricultural sector. Field burning of biomass is prohibited in Denmark. Wildfires in forest are reported. This is normally around 0-10 hectares per year. Controlled burning of heathland is taking place of approximately 300-700 hectares to maintain the heath.
The distribution of the land use and the conversion between these from 1990 to 2015 is given in Table 1.
Table 2 gives an overview of the emission from the LULUCF sector in Denmark.
Forests have been sinks in Denmark for the last decade but due to the age distribution of the forests - containing a majority of mature forests - a slight decrease of the carbon stock was previous observed, as the old forests are regenerated with young trees. Currently the NFI indicates that forests are a sink, although in 2015 it was only a small sink. Land converted to Forest land (Afforestation) has been estimated to be net source. The reason for this not a declining carbon stock in the afforested area but the fact that biomass are removed from Cropland and Grassland when afforestation is made.
Cropland is ranging from being a net source of 4412 Gg CO2 in 1990 and reduced to be a net source of 2655 Gg CO2 in 2015. The major reason is an increased input of organic matter to the mineral soils and a less cultivated area on organic soils. Grassland has been estimated to be net source of approximately 1200 Gg CO2-eqv. per year. The emission from Wetlands has decreased over the years due a decreased peat extraction in Denmark combined with restoration of former wetlands primarily on Cropland and Grassland.
Settlements are a small source. This is due to conversion from primarily Cropland and Grassland to Settlement and a loss of biomass and carbon stock in the soil.
Harvested Wood Products is assumed to be a net sink of -171.5 kt CO2-eq.
The total area with forest in 2015 has been estimated to 637 574 hectares covering 14.8 % of the land area. Of this were 544 541 hectares forest planted before 1990. From 1990 to 2015 the afforested area has been estimated to 103 017 hectares and the deforested area to 9 986 ha. In the later years a large part of the deforestation is conversion of Christmas trees into cropland as part of their crop rotation and removal of forest on sandy heathland converting them into grassland.
The area estimates are based on both vector maps and remote sensing. From 1881 to 2000, a National Forest Census has been carried out roughly every 10 years based on questionnaires sent to forest owners. Since the data was based on questionnaires and not field observations, the actual forest definition may have varied. All values for growing stock, biomass or carbon pools based on data from the National Forest Census were estimated from the reported data on forest area and its distribution to main species, age class and site productivity classes. The two last censuses were carried out in 1990 and 2000.
In 2002, a new sample-based National Forest Inventory (NFI) was initiated (Nord-Larsen et al., 2008). This type of forest inventory is very similar to inventories used in other countries, e.g. Sweden or Norway. The NFI has replaced the National Forest Census.
The NFI is a continuous sample-based inventory with partial replacement of sample plots based on a 2 x 2 km grid covering the Danish land surface. The sample plots has been systematically divided into five non-overlapping, interpenetrating panels that are each measured in one year and constitute a systematic sample of the entire country. Hence all the plots are measured in a 5-year cycle. The first year with a full sampling was therefore 2007.
Estimation of carbon stock changes in the Danish forests is based on a combination of surveys and the National Forest Inventory (NFI). The data quality and the methodology in activity data for forests therefor differ between 1990 to 2000, between 2000 and 2007 and after 2007 giving different trends in the emission estimates. The forest has been estimated to be a general sink from 1990 to 2000, a source from 2000 to 2007 and then again a general sink from 2007 an onwards Table 2.
From 1990 to 2015 the afforested area has been estimated to 103017 hectares.
When converting land to forest land the standing living above- and below ground biomass are removed from that land. The consequence of this is that in the conversion year afforestation is typical a net source because of the removal of biomass and a very low gain in carbon stock in the small tree plants. For land converted from cropland a standard default loss value of 5.9 ton C per ha is assumed, equivalent to the average harvest of living biomass for all cereals grown in Denmark from 2000 to 2010, including straw, stubble and glumes.
The estimated annual carbon stock changes in the afforested areas are given in Table 2. The values given are after subtracting the C-stock on the land from where it was converted from and thus not the actual increase C-stock in the afforested area.
From 1990 to 2015 the deforested area has been estimated to 9 986 ha. A large part of this deforestation is conversion of Christmas trees into cropland as Christmas trees are normally grown on cropland, conversion to Wetland as a consequence of clearing of some areas in the State forests towards more open areas and removal of perennial vegetation to create heath land (Grassland).
The Cropland and Grassland area are based on data from the EU subsidiary systems and very detailed combined with data from Statistics Denmark. A drawback of the detailed agricultural information is, however, that one field in one year can be classified as Cropland and the next year as Grassland and then again converted back to Cropland. This creates large interannual conversion rates between cropland and grassland but mainly towards grassland as an extensification currently takes place in Denmark. The switching between Cropland and Grassland will, however, have no effect on the emission estimates except for an estimated release of N2O from mineralisation of organic matter.
Since 1990 the estimated Cropland and Grassland area decreased with 144682 hectares, mainly into settlement, afforested areas and new wetlands. The area with settlement and other infrastructures has increased with almost 34958 hectares.
The Cropland area is subdivided into four classes: agricultural cropland, permanent wooden crops, hedgerows and other agricultural land. Agricultural cropland accounts for approximately 2.5 mill. hectares, 13000 hectares with permanent wooden crops. Permanent wooden crops include fruit trees, fruit bushes and willow plantations for energy purposes. Hedgerows and small biotopes, not classified as forest, account for app. 60000 hectares. Approximately 100000 hectares has been classified as other agricultural land (field margins etc.)
The major changes in the carbon stocks in Cropland and Grassland are stock changes in the mineral soils and the organic soils. The changes in mineral cropland soils are estimated with a nationally developed dynamical carbon turn over model (C-TOOL). Documentation for the C-TOOL model is available from Department of Agroecology, Aarhus University. The emission calculation from organic soils is based on nationally developed emission factors. Mineral are general in an equilibrium state but organic soils are large emitters of CO2. Initiatives with ban of straw burning, mandatory growing of catch crops in autumn, a switch in the crops grown and increased yield levels has moved the mineral soils into a steady state. Overall has all the initiatives lead to a declining emission from the mineral soils from 1990 to 2015. Also a decreased area with utilized organic agricultural soils has reduced the emission over time. The variation between years is mainly due to that the emission estimate for mineral soils are made with a yield and temperature dynamic model. As the crop yield differs between years and the degradation in the soil depends on the actual soil temperatures this create a large fluctuations between years.
Denmark has signed the Kyoto Protocol and is committed to reduce its GHG emission with 21% from 1990 to the average of the first commitment period, 2008-2012. Besides the mandatory inclusion of Afforestation and Deforestation under Article 3.3. of the Kyoto Protocol, has Denmark elected Forest Management, Cropland Management and Grassland Management under Article 3.4 to cover its reduction commitment.
The total estimated emissions, removals and accounting parameters for the first Commitment Period showed a net accounting of 8793 Gg CO2-eq for all five years or 1759 Gg CO2-eq./yr.
Afforestation was shown to be a sink of -183.9 Gg CO2-eqv in the first commitment period for afforestation taking place in the period 1990 to 2012. The total Deforestation taking place in the first commitment period from 2008 to 2012 has been summed up to a net source of 439.8 Gg CO2-eqv.
Forests planted before 1990 has in 2008 to 2012 shown a carbon sequestration of 20611.7 Gg CO2-eqv. For Forest Management has Denmark a cap of 916.7 Gg CO2-eqv. Because it has shown that the emission from Deforestation is larger than the sink from Afforestation under Article 3.3 the difference can be added to the Danish cap. Therefore an amount of 1172.6 Gg CO2-eqv. can be added to the Danish reduction commitments from Forest Management.
The accounting quantity for Cropland Management and Grazing Land Management is based on the net-net principle. It means that only the difference between the emission in the first commitment period (2008-2012) and the emission in 1990 can be included in the accounting quantity.
For Cropland has the emissions since 1990 decreased. Cropland Management therefore add to the Danish reduction commitment. It has been estimated that the total accounting quantity for Cropland Management for the first commitment period is -8249.5 Gg CO2-eqv.
For Grassland has the emission increased since 1990. The major reason is the difficulties to split the land use into Cropland and Grassland. These two land use categories should therefore be seen as a whole. It has been estimated that the total accounting quantity for Cropland Management for the first commitment period is 552.4 Gg CO2-eqv. The total accounting quantity for Cropland and Grazing Land Management is therefore estimated to -7697.0 Gg CO2-eqv in the first commitment period equivalent to -1539.4 Gg CO2-eqv. per year.
In the second Commitment Period Denmark has continued its commitment to include Forest Management, Cropland Management and Grazing Land Management. Denmark has not elected Natural Disturbances, newly established forest (CEF-ne), Revegetation and Wetland Drainage and Rewetting.
In table 3 is shown the accounting estimates for 2013-2015. Afforestation is adding to the fulfill the Danish reduction commitment, whereas deforestation is a source. Due to an increased standing stock in the forest, Forest Management is a net sink. The activities in Cropland Management which has reduced the emissions has resulted in a net reduction in the Danish commitment. The emissions in Grazing land Management has increased primarily due to loss in biomass when land is converted to Grazing land.