The multi-annual carbon budget of a peat-covered catchment

Abstract

This study estimates the complete carbon budget of an 11.4 km 2 peat-covered catchment in Northern England. The budget considers both fluvial and gaseous carbon fluxes and includes estimates of particulate organic carbon (POC); dissolved organic carbon (DOC); excess dissolved CO 2 ; release of methane (CH 4 ); net ecosystem respiration of CO 2 ; and uptake of CO 2 by primary productivity. All components except CH 4 were measured directly in the catchment and annual carbon budgets were calculated for the catchment between 1993 and 2005 using both extrapolation and interpolation methods. The study shows that: Over the 13 year study period the total carbon balance varied between a net sink of − 20 to − 91 Mg C/km 2 /yr. The biggest component of this budget is the uptake of carbon by primary productivity (− 178 Mg C/km 2 /yr) and in most years the second largest component is the loss of DOC from the peat profile (+39 Mg C/km 2 /yr). Direct exchanges of C with the atmosphere average − 89 Mg C/km 2 /yr in the catchment. Extrapolating the general findings of the carbon budget across all UK peatlands results in an approximate carbon balance of − 1.2 Tg C/ yr (±0.4 Pg C/yr) which is larger than previously reported values. Carbon budgets should always be reported with a clear statement of the techniques used and errors involved as this is significant when comparing results across studies.

Impact of gully erosion on carbon sequestration in blanket peatlands

“…The baseline is a pre-erosion carbon balance of -20.3 gC m -2 yr -1 which derives directly from the Tallis (1994) sequestration data. This value is reasonable in the context of reported carbon sequestration values for northern peatlands (Gorham 1991), but is at the lower range of values reported by Worrall et al (2003Worrall et al ( , 2009 for blanket peatlands in the northern Pennines, and is at the lower end of measured UK values reported in Billett et al (2010, this Special). This is consistent with the southerly position and relative dryness of the southern Pennines; however, it should be noted that the values are also lower than measured data at an intact Bleaklow site (Billett et al this Special).…”

Carbon balance of UK peatlands: current state of knowledge and future research challenges

“…The overall C balance of the largest catchment at Moor House (Trout Beck; 11.4 km 2 ) has been the focus of a recent paper by Worrall et al (2009). Using both direct measurements (e.g.…”

“…The method used for estimating excess dissolved CO 2 in runoff from fresh soil water samples drawn from piezometers in described in Worrall et al (2009). POC fluxes losses (surface lowering) are measured from annual measurements of nests of erosion pins (12 pins per plot).…”

“…(3) Surface exchange of CO 2 and CH 4 was measured using a closed chamber method (see Worrall et al 2009). …”

Changing temperature and rainfall gradients in the British Uplands

“…Such additional rainfall may also drive increased fluxes of fluvial carbon from the peatlands in the uplands. It has been suggested that discharge is the major control of dissolved organic carbon fluxes from peatlands, which could explain a large proportion of recent increased flux estimates (Worrall et al 2003(Worrall et al , 2009. Similarly, it is likely that discharge acts as a crucial control on particulate carbon fluxes from upland peatlands, particularly in winter when peat may be more susceptible to loosening by freeze-thaw (Holden et al 2007a) and given that there are large areas of bare peat and open ditches with available sediment for mobilisation (Holden 2005, Holden et al 2006.…”