Restored cut-away peatland as a sink for atmospheric CO 2

Abstract

In a field study, we examined the relationship between vegetation, abiotic factors and the CO exchange dynamics of a cut-away peatland 20 years after production had ended. The main objective was to determine the effect of rewetting on the CO exchange dynamics, measured separately in Eriophorum vaginatum tussocks and intertussocks (almost non-vegetated surfaces) using closed-chamber techniques, one growing season before and three growing seasons after the rewetting treatment. Rewetting lowered total respiration (R ) and increased gross photosynthesis (P), which resulted in a higher incorporation of CO into the system. The seasonal CO balance for the almost continuously submerged section of the rewetted site became positive 2 years after rewetting (9.1 g CO-C m), and it was still higher in the 3rd year (64.5 g CO-C m), i.e. the system accumulated carbon. In the driest section of the rewetted site the seasonal balance increased strongly, but the balance was still negative during the 3 years following rewetting with losses from the system of 44.1, 26.1, 38.3 g CO-C m in 1995, 1996 and 1997 respectively. At the control site seasonal balance during 1995-1997 varied between ecosystem C losses of 41.8 and 95.3 in an area with high Eriophorum cover and between 52.1 and 109.9 g CO-C m with lower cover. Simulation of a cut-away peatland with dense Eriophorum vegetation (Eriophorum cover 70%) showed that if the water level (WT) is low, the seasonal CO balance of the ecosystem can reach the compensation point of no net C change (P = R) only if weather conditions are favourable, but with a high WT the seasonal CO balance would be positive even under varying weather conditions. It can be concluded that with dense Eriophorum vegetation a restored cut-away peatland acts as a functional mire and becomes a sink for atmospheric CO.

Derivation of greenhouse gas emission factors for peatlands managed for extraction in the Republic of Ireland and the United Kingdom

“…The basic R eco models, based upon the Arrhenius equation (Lloyd and Taylor, 1994), are nonlinear models related to soil temperature. GPP was related to PPFD using the Michaelis-Menten-type relationship that describes the saturating response of photosynthesis to light (Tuittila et al, 1999). GPP model coefficients and associated standard errors were estimated using the LevenbergMarquardt multiple non-linear regression technique (IBM SPSS Statistics for Windows, Version 21.0.…”

CO<sub>2</sub> flux determination by closed-chamber methods can be seriously biased by inappropriate application of linear regression

“…Jensen et al, 1996;Xu and Qi, 2001;Pumpanen et al, 2003Pumpanen et al, , 2004Reth et al, 2005;Wang et al, 2006). Also, it is often applied to quantify the net CO 2 exchange between the atmosphere and low-stature canopies typical for tundra (Vourlites et al, 1993;Christensen et al, 1998;Oechel et al, , 1998Oechel et al, , 2000Zamolodchikov and Karelin, 2001), peatlands (Alm et al, , 2007Tuittila et al, 1999;Bubier et al, 2002;Nykänen et al, 2003;Burrows et al, 2004;Drösler, 2005;Laine et al, 2006), forest understorey vegetation (Goulden and Crill, 1997;Heijmans et al, 2004) and agricultural crop stands (Dugas et al, 1997;Wagner et al, 1997;Maljanen et al, 2001;Steduto et al, 2002). Advantageously, the closed-chamber method is relatively low in cost and power consumption, simple to operate and can therefore be used in remote, logistically difficult areas.…”

“…Vourlites et al, 1993;Oechel et al, 1993Oechel et al, , 1998Oechel et al, , 2000Jensen et al, 1996;Alm et al, 1997Alm et al, , 2007Goulden and Crill, 1997;Christensen et al, 1998;Tuittila et al, 1999;Maljanen et al, 2001;Xu and Qi, 2001;Bubier et al, 2002;Nykänen et al, 2003;Pumpanen et al, 2003;Burrows et al, 2004;Heijmans et al, 2004;Drösler, 2005;Reth et al, 2005;Laine et al, 2006;Wang et al, 2006). Usually, the authors justify the use of linear regression by keeping the closure time short and assuming the concentration change over time to be still in the linear range.…”

Land-use scenarios for Finnish cut-over peatlands - based on the mineral subsoil characteristics

“…This value was an average of studies by Roderfelt et al (1994) and Tuittila et al (1999). The rate used for average forested after-use sites was 90 g C m -2 yr -1…”

“…Different after-use forms are likely to affect on the future carbon fluxes. Roderfelt et al (1994) have measured carbon accumulation of 64 g C m -2 yr -1 on a mire regeneration site and Tuittila et al (1999) 64.5 g CO 2 -C m -2 yr -1 in early stages of mire regeneration. These rates are quite similar to the recent apparent rate of carbon accumulation (RERCA) in Finnish natural mires, ranging from 40 to 81 g C m -2 yr -1 (Tolonen & Turunen,1996a, Pitkänen et al 1999.…”