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

Abstract

Abstract. This study compares the CO 2 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 mugo ssp. 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 CO 2 (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 (−130 ± 31 and −300 ± 66 g C m −2 a −1 in the first and second year, respectively) than the natural bog forest at Schechenfilz (−53 ± 28 and −73 ± 38 g C m −2 a −1 ). The strong net CO 2 uptake can be explained by the high gross primary productivity of the 44-year old spruces that overcompensates 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 CO 2 uptake of the drained spruce forest, the site is a strong net CO 2 source when the whole lifecycle 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 ha −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.

Near‐neutral carbon dioxide balance at a seminatural, temperate bog ecosystem

“…Similar magnitudes of −49 and −61 g C m −2 yr −1 were reported for an Irish blanket bog by Sottocornola and Kiely []. Hommeltenberg et al [] determined −53 ± 28 g C m −2 yr −1 and −73 ± 38 g C m −2 yr −1 for a near‐natural forested bog in Southern Germany. NEE ranging from 10 to −76 g C m −2 yr −1 dependent on water availability and snow cover was detected at a cool‐temperate bog in Canada [ Lafleur et al , ].…”

Soil carbon stock changes in transitional mire drained for forestry in Latvia: a case study

“…On one hand, the benefits of drainage on forest productivity are evident; it results in a better tree growth Zalitis & Indriksons, 2009). On the other hand, there may be negative consequences to soil carbon storage (Simola, Pitkänen, & Turunen, 2012;Pitkänen, 2013;Hommeltenberg et al, 2014). On the contrary, some authors have found that carbon stock in forest organic soils can remain stable or even continue to increase after drainage (Minkkinen & Laine, 1998b).…”

“…One of the main drivers determining, whether forest organic soil will be carbon source or sink after drainage, is climatic variables. In the boreal vegetation zone drained organic soils in forest often continue to act as a sink (Minkkinen & Laine, 1998b Hommeltenberg et al, 2014). In some cases, emissions from soil can be large enough to turn the whole drained forest ecosystem into CO 2 emitter, especially in the long term (Hommeltenberg et al, 2014).…”

“…In the boreal vegetation zone drained organic soils in forest often continue to act as a sink (Minkkinen & Laine, 1998b Hommeltenberg et al, 2014). In some cases, emissions from soil can be large enough to turn the whole drained forest ecosystem into CO 2 emitter, especially in the long term (Hommeltenberg et al, 2014). On a broad scale, carbon loss from organic soil in temperate climate conditions is larger than in the boreal region (Armentano & Menges, 1986).…”

Comparing chamber and eddy covariance based net ecosystem CO2 exchange of fen soils

“…There are numerous studies of NEE measurements in peatlands by the EC technique but they are mostly restricted to boreal ( Cai et al, ), subarctic ( Aurela et al, ) or forest ecosystems ( Dunn et al, ; Hommeltenberg et al, ) and often focus on (near‐) natural site conditions ( Lafleur et al, ). Only few EC measurements of NEE on temperate agricultural utilized or rewetted peatlands are currently available from the Netherlands ( Hendriks et al, ; Jacobs et al, ; Veenendaal et al, ; Parmentier et al., ).…”