Assessing the impact of peat erosion on growing season CO2 fluxes by comparing erosional peat pans and surrounding vegetated haggs

Abstract

Peatlands are recognised as an important but vulnerable ecological resource. Understanding the effects of existing damage, in this case erosion, enables more informed land management decisions to be made. Over the growing seasons of 2013 and 2014 photosynthesis and ecosystem respiration were measured using closed chamber techniques within vegetated haggs and erosional peat pans in Dartmoor National Park, southwest England. Below-ground total and heterotrophic respiration were measured and autotrophic respiration estimated from the vegetated haggs. The mean water table was significantly higher in the peat pans than in the vegetated haggs; because of this, and the switching from submerged to dry peat, there were differences in vegetation composition, photosynthesis and ecosystem respiration. In the peat pans photosynthetic CO 2 uptake and ecosystem respiration were greater than in the vegetated haggs and strongly dependent on the depth to water table (r 2 [ 0.78, p \ 0.001). Whilst in the vegetated haggs, photosynthesis and ecosystem respiration had the strongest relationships with normalised difference vegetation index (NDVI) (r 2 = 0.82, p \ 0.001) and soil temperature at 15 cm depth (r 2 = 0.77, p = 0.001). Autotrophic and total below-ground respiration in the vegetated haggs varied with soil temperature; heterotrophic respiration increased as water tables fell. An empirically derived net ecosystem model estimated that over the two growing seasons both the vegetated haggs (29 and 20 gC m -2 ; 95% confidence intervals of -570 to 762 and -873 to 1105 gC m -2 ) and the peat pans Wetlands Ecol Manage (2019) 27:187-205 https://doi.org/10.1007/s11273-019-09652-9( 0123456789().,-volV) ( 01234567 89().,-volV) (7 and 8 gC m -2 ; 95% confidence intervals of -147 to 465 and -136 to 436 gC m -2 ) were most likely net CO 2 sources. This study suggests that not only the visibly degraded bare peat pans but also the surrounding vegetated haggs are losing carbon to the atmosphere, particularly during warmer and drier conditions, highlighting a need for ecohydrological restoration.

Developing an Automated Gas Sampling Chamber for Measuring Variations in CO2 Exchange in a Maize Ecosystem at Night

“…In his study, the temperature variations were always below 1.3 • C in the measurement period. The recorded temperature change value is similar to that of the larger volume chamber [7,22,23] and is much lower than the 2 • C recorded in many other closed chambers [1,24].…”

“…Through a series of linear regression calculations, NEE is obtained, and the CO 2 concentration value that changes with time in the chamber can be seen [4]. In previous research, it was noted that the CO 2 flux can be calculated after continuously monitoring the concentration change in the chamber for 3-6 min [5][6][7]. To measure the daytime net CO 2 exchange variation, eight to twelve [5] measurement cycles are implemented manually each day.…”

An operational land cover and land cover change toolbox: processing open‐source data with open‐source software

“…Using the overlying vegetation to define the class would have missed these areas overlying blanket bog, whilst classing these all as bog would have missed the variation in overlying vegetation which requires differing management strategies. In this study, we used peat depth and extent mapped via other remote sensing methods (Gatis, Luscombe, et al., 2019); if these data were not available, it would not be possible to map degraded blanket bog as accurately. In this case, we would suggest mapping the overlying vegetation classes rather than a Degraded blanket bog class.…”

“…Dartmoor National Park, located in southwest England, covers 954 km 2 and ranges in elevation from 30 to 621 mASL. The western side of the park is dominated by upland moorland of which 315 km 2 has been mapped as underlain by peat (Gatis, Luscombe, et al., 2019) with some ecohydrological degradation (Carless et al., 2019). The eastern side is generally lower in altitude and dominated by grasslands.…”

“…As degraded peat cannot be reliably identified by the overlying vegetation (Gatis, Luscombe, et al., 2019), it was decided to use previously mapped peat extent to define the area of blanket bog. The tool will run without this layer but this will impact the land cover accuracy for peat discrimination in particular—see Sections 4.1 and 4.3 for greater discussion.…”