Geoportal  

 

Berlin Environmental Atlas

01.06 Soil-Scientific Characteristic Values (Edition 2013)

map view Text in Deutsch verfuegbar content    back forward

01.06.6 Organic Carbon Stocks


Description

Soil organic matter consists of approximately 50 % carbon and is of elementary importance to the hydrological and nutritional balance of soils. As a result of the concentration and mineralization of organic matter, and therefore carbon, soils play a major role in the global carbon cycle.

Soils constitute the largest form of terrestrial carbon storage and besides oceans the largest form of carbon storage of the world (IPCC 2000). A major influence on the carbon dynamic in soils is land use. Soils in urban environments are subjected to very high land use pressure, and suffer significant anthropogenic impact. On the one hand, this results in higher carbon stocks than in natural systems, for instance due to horticultural activities. On the other, the destruction of natural soil functions leads to higher levels of mineralization of organic matter and therefore the release of carbon dioxide (CO2) into the atmosphere. This is an important fact, as the concentration of organic matter in soils, and therefore their function as carbon storage, takes place over a very long period of time.

A particular role in the global carbon cycle is played by carbon sinks. Carbon sinks are also present in urban environments. Hydromorphic soils such as peat are notable in this context. Peat soils can potentially store up to ten times more carbon than other ecosystems (Batjes 1996). Due to changes in the hydrological balance of agricultural soils, most peat soils emit CO2 and MH4 (methane). For this reason, the protection and conservation of peat soils is of particular importance to local, regional and global climate protection. With a total area of 7 %, but almost 50 % of the carbon storage in the soils of Berlin, it becomes clear that peat soils have an important role to play as a carbon sink. Horticultural and other sites with long-term pedogenesis such as graveyards, old forest sites and historical parks are also valuable carbon sinks due to their long-term storage of carbon.

As a result of their function as carbon sinks, soils play a very important role in climate protection, which should attract attention in terms of planning and authorization processes (Dahlmann et al. 2012). According to Dahlmann et al. (2012) it is reasonable for soils containing a high amount of carbon stocks to be protected from land use with negative impacts, such as sealing of non-sealed soils. It is also advantageous to re-cultivate existing structures, especially peat soils. For this reason, the soil buffer for the carbon budget is also considered in the assessment of the filter and buffer function of soils (e.g. map 01.12.3).

The calculation based on this map shows that a total of 5.28 million tonnes of carbon are stored in Berlins soils. This is equal to 19.3 million tonnes of CO2.

Berlins total CO2 emissions amounted to approximately 18 million tonnes in 2009 (Statistic BBB 2012). This means that Berlins soils store more CO2 than was emitted by Berlin in 2009 as a result of primary energy consumption.

Methodology

Calculation of the carbon stocks in Berlin’s soils is based on the organic matter amounts [kg/m²] provided by the Berlin Soil Database (Gerstenberg 2013). The organic matter amounts were derived from the organic matter content of the topsoil layer, taking into account the peat content [mass-%], the effective bulk density and the thickness of the organic topsoil layers (see also Map 01.06.05 Organic Matter Content). For the calculation of peat layers, a bulk density of 0.9 [g/cm³] was postulated. The organic matter content was divided by a factor of 1.72, according to the Soil-Scientific Mapping Directive (2005). To calculate the organic carbon stocks for all of Berlin, the organic carbon contents were multiplied by the area of the Berlin block structure.

The carbon stocks of Berlin’s soils determined in this manner correspond only to a first assessment and are in part methodologically uncertain. This is because the organic matter contents displayed in the Berlin block structure are based on a soil map which is only conceptual in nature. In addition, the organic matter content, the thickness of the mineralic top soil layers and peat layers, and bulk density are in part merely estimates. The "carbon stocks" thematic soil map 01.06.6 is therefore only an approximate representation of reality. Within the scope of the research project "Berliner Moorböden im Klimawandel" (free translation: Berlin peat soils and climate change) in progress at the Humboldt University in Berlin, more detailed data on the organic carbon stocks of Berlin’s soils is currently being collected, and will serve to enhance knowledge about carbon stocks in Berlin’s soils in the future.

map view Text in Deutsch verfuegbar content    back forward

umweltatlas_logo_klein