The effect of biomass harvesting on greenhouse gas emissions from a rewetted temperate fen

Anke Günther1, Vytas Huth2, Gerald Jurasinski1, Stephan Glatzel3
1 Landscape Ecology, University of Rostock
2 Landscape Biogeochemistry, Leibniz Institute for Agricultural Landscape Research
3 Geography and Regional Research, Faculty of Earth Sciences, Geography and Astronomy, University of Vienna

O 6.2 in Biogeochemistry of wetlands

15.07.2014, 11:20-11:40, H17

The general increase in acreage under energy crop cultivation will disproportionally affect organic soils in the future. However, peatlands have to be drained for conventional agricultural use and, by this, become large sources of carbon dioxide and nitrous oxide. The new concept of agriculture on undrained peatlands (= paludiculture) offers the possibility of combining the production of biomass for bioenergy while avoiding large greenhouse gas emissions. Here, we present the first greenhouse gas balances of a simulated paludiculture system to assess its suitability as source of biomass for bioenergy production from a climate-perspective. In a temperate, rewetted peatland, we conducted closed-chamber measurements of carbon dioxide, methane, and nitrous oxide exchange in stands of the potential paludiculture crops Phragmites australis, Typha latifolia, and Carex acutiformis over two years. To simulate harvest, the biomass of half of the measurement spots was removed once per year. During the first year, all harvested plots were small sources of carbon dioxide while the control plots were sinks, irrespective of dominant vegetation. This effect was reversed during the second year, when harvested plots sequestered more carbon dioxide than the controls. Methane emissions were much larger during the first year. The dominant stands emitted different amounts of methane, but the relative pattern shifted between the two years. Nitrous oxide was not emitted in measurable amounts. Overall, net greenhouse gas balances of the study plots were close to climate neutral in both years except for the Carex stands in the first year (in CO2-equivalents: 16‑18 t ha‑1 a‑1). We did not find a negative short-term effect of biomass harvest on net greenhouse gas balances. For that reason, we assume that paludiculture may likely be a solution for the growing demand of agricultural area for bioenergy and the need for greenhouse gas mitigation.

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Letzte Änderung 01.04.2014