Can a bog drained for forestry be a stronger carbon sink than a natural bog forest?

Year: 2014

Authors: Hommeltenberg J., Schmid H.P., Drösler M., Werle P.

Autors Affiliation: Karlsruhe Institute of Technology KIT, Institute of Meteorology and Climate Research IMK-IFU, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany; Technical University of Munich, Department of Atmospheric Environmental Research, Hans-Carl-von-Carlowitz-Platz 2/i, 85354 Freising, Germany; University of Applied Sciences Weihenstephan-Triesdorf, Department of Vegetation-Ecology, Weihenstephaner Berg 4, 85354 Freising, Germany

Abstract: This study compares the CO2 exchange of a natural bog forest, and of a bog drained for forestry in the pre-Alpine region of southern Germany. The sites are separated by only 10 km, they share the same soil formation history and are exposed to the same climate and weather conditions. In contrast, they differ in land use history: at the Schechenfilz site a natural bog-pine forest (Pinus mugossp. rotundata) grows on an undisturbed, about 5 m thick peat layer; at Mooseurach a planted spruce forest (Picea abies) grows on drained and degraded peat (3.4 m). The net ecosystem exchange of CO2 (NEE) at both sites has been investigated for 2 years (July 2010-June 2012), using the eddy covariance technique. Our results indicate that the drained, forested bog at Mooseurach is a much stronger carbon dioxide sink (g^\’130 ± 31 and g^\’300 ± 66 g C mg^\’2 ag^\’1 in the first and second year, respectively) than the natural bog forest at Schechenfilz (g^\’53 ± 28 and g^\’73 ± 38 g C mg^\’2 ag^\’1). The strong net CO2 uptake can be explained by the high gross primary productivity of the 44-year old spruces that over-compensates the two-times stronger ecosystem respiration at the drained site. The larger productivity of the spruces can be clearly attributed to the larger plant area index (PAI) of the spruce site. However, even though current flux measurements indicate strong CO2 uptake of the drained spruce forest, the site is a strong net CO2 source when the whole life-cycle since forest planting is considered. It is important to access this result in terms of the long-term biome balance. To do so, we used historical data to estimate the difference between carbon fixation by the spruces and the carbon loss from the peat due to drainage since forest planting. This rough estimate indicates a strong carbon release of +134 t C hag^\’1 within the last 44 years. Thus, the spruces would need to grow for another 100 years at about the current rate, to compensate the potential peat loss of the former years. In contrast, the natural bog-pine ecosystem has likely been a small but stable carbon sink for decades, which our results suggest is very robust regarding short-term changes of environmental factors.

Journal/Review: BIOGEOSCIENCES

Volume: 11 (13)      Pages from: 3477  to: 3493

More Information: We gratefully acknowledge the Thunen Institute (TI) for funding the project Organic Soils, and the Bavarian Environment Agency for funding the project Effect of peatland restoration on climate change – Assessment of mitigation potential of peatland restoration in Bavaria within framework of Klip2020. The Schechenfilz site is additionally part of the TERENO and ICOS-ecosystems projects, funded by the BMBF and the Helmholtz Association. We acknowledge support by the Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology. We thank Steffi Rohling (Technical University of Munich Center of Life and Food Sciences Weihenstephan, Chair for Forest Growth and Yield) and Niko Rosskopf (Humboldt University Berlin, Faculty of Agriculture and Horticulture, Department of Crop and Animal Sciences) who provided their data of forest growth and soil parameters, respectively. We thank Enrico Frahm, Barbel Tiemeyer and Michel Bechtold (Thunen Institute Braunschweig, Institute of Climate-Smart Agriculture) for running several mini-diver gauges to measure water table fluctuations at both sites and providing their data. We acknowledge Stephan Thiel, Katja Heidbach and Elisabeth Eckart for perfect field work collaboration and Matthias Mauder for his valuable comments on the manuscript. Access to the sites was made possible by Christof Bosch, Mooseurach; the NORIS-estate and the District Government of Upper Bavaria.
KeyWords: Alpine environment; bog; carbon flux; carbon sink; climate conditions; coniferous forest; data set; eddy covariance; environmental factor; forestry; primary production, Germany
DOI: 10.5194/bg-11-3477-2014

Citations: 50
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