Background and Objective

Despite covering only around 5 % of the German land surface, drained peatlands and other organic soils contribute nearly 7% to Germany's greenhouse gas (GHG) emissions. Carbon dioxide (CO₂) currently constitutes approximately 90 % of the total emissions.

Organic soils account for 6.7% of the the agricultural area, but contribute 44% to the GHG balance of the sector Agriculture and agriculturally used soils reported in the sector Land Use, Land Use Change and Forestry (LULUCF). In combination with the still remaining large stocks of soil organic carbon, organic soils are important for climate protection. However, the implementation of peatland protection measures as announced in the Climate Action Programme 2020 and Climate Action Plan 2050 will require an improved data basis. This includes not only the determination of the status quo, but also the evaluation of mitigation measures such as classical re-wetting, wet peatland use (“paludiculture”) or adjusted water management. Additionally, to meet the increasing demands on emission reporting, a development of dynamical models is needed. Thus, the peatland monitoring pursues the following goals:

• long-term, consistent and spatially representative assessment of CO₂ emissions for the German emission inventory
• improved understanding of drivers and of the relationship between surface motion and changes in carbon stocks
• development of improved regionalisation approaches for drivers and CO₂ emissions
• scenario development and evaluation of mitigation measures

Approach

Over millennia, living peatlands have slowly increased in height. The reverse and much faster process, i.e. the loss of peat from drained organic soils, is visible and measurable as subsidence of the soil surface. Subsidence is caused by different physical and biogeochemical processes (loss of buoyancy, shrinkage, and mineralisation), but only mineralisation causes CO₂ emissions. Monitoring needs to distinguish these processes by not only measuring surface elevation on a regular basis, but also by identifying important drivers. These comprise, among others, information on the soil properties and the groundwater level which will be used to develop process-based models.

A measurement network of approximately 150 sites will be the core of the monitoring. Sites will be selected representatively with respect to peatland type (e.g. bog, fen) or land use (e.g. grassland, cropland, re-wetting). Furthermore, the integration of project sites testing mitigation measures as well as study sites of other monitoring programs will create synergies.

Besides gathering soil and hydrological data, the heart of the monitoring program are recurrent measurements of the surface elevation at different temporal and spatial scales. To distinguish physical and biogeochemical processes, a shrinkage model for organic soils will be parametrized and, after laboratory test, applied to field sites.

Regionalisation will comprise an update and a soil physical and chemical parametrization of the map of organic soils in Germany which is currently used in the emission inventory. Remote sensing approaches will be tested for the determination of surface movements and groundwater levels. Groundwater levels and, finally, changes in carbon stocks will be scaled up by statistical models.

Mitigation measures will be identified by a combination of remote sensing approaches and a compilation of dispersed databases. Using data measured at the site level, models applicable for scenario analysis will be developed for important peatland types and mitigation measures. Model results will be combined with spatial data to create CO₂ emission maps and to estimate mitigation effects.