Analysis of ghg emissions from forested peatlands

Background and Objective

Drained peatlands emit large amounts of CO₂. This is visible by peat loss and loss of terrain height, respectively. In natural „wet“ peatlands, dead plant material is not completely decomposed and forms peat. Previously by photosynthesis obtained carbon from the atmosphere is stored in peatlands. Thus, natural peatlands are a think for CO₂. Although natural peatlands are a source for CH₄, the ghg potential is lower compared to drained peatlands with high CO₂ emissions. Over a long term, rewetting converts drained peatlands into natural peatlands. At our intensive sites in Buchenhorst and Johanngeorgenstadt, we investigate how ghg emissions (CO₂, CH₄ and N₂O) change during this process. These measurements are planed long-lasting, since rewetting is a long-term process.

The two intensive sites are part of the German Peatland Monitoring Programme for Climate Protection – Forest (MoMoK-Wald).

Approach

Greenhouse gas emissions are analyzed with five automatic chamber systems per site. They consost of one transparant and on dark chamber each. They are placed successively on the ground to capture the released gases from the soil. The transparent chambers are used for the analysis of CO₂ fluxes. Transparency of the chamber is important since CO₂ fluxes are driven by photosynthesis, e.g. Dark chambers are used to analyse CH₄ and N₂O fluxes aswell as CO₂ fluxes without photosynthesis. With this method, all three gases can be analyzed from one measurement plot. Gas samples from the chambers are transmitted to two gas analysers. They analyse the mixing ratio of the samples every second. So, emissions can be analyzed around the clock. Additionally, several other parameters which influence ghg emissions are recorded. These are radiation parameters, soil moisture, and soil temperature as well as all common meteorological parameters. Soil physical and chemical were analysed for both sites. The water level is recored using a level logger. The change of the terrain height is measured using metal rods anchored in the mineral soil. Changes the breast height diameter are recorded for selected trees. Both sites are equiped with remote data transmission.

Site Buchenhorst

• Mecklenburg-Vorpommern - Mecklenburgische Seenplatte
• Fen
• Alder

Site Johanngeorgenstadt (Großes Eisenstraßenmoor)

• Saxony - Erzgebirge
• Erzgebirge
• Peat bog (slope bog)
• Spruce

Our Research Questions

• How do ghg emissions change during rewetting (short- and long-term)
• How fast does the ecosystem shift from a ghg source to a sink
• How do tree stands affect rewetting
• How do tree stands react on rewetting