The following section provides an overview about the field sites.
The project takes part at three experimental peatland sites in the English uplands, which are typical of grouse managed blanket bog, showing mostly over 50% cover of ling heather (i.e. Calluna vulgaris) over deep peat but with some other blanket mire species, including Sphagnum spp., present at low frequency/cover. The sites are predominantly under current rotational burning and the peatlands are mainly 'intact' (i.e. not eroded). At each site two similar sub-catchments are paired, serving as control (continuation of the current burn regime) versus treatment areas (replacing burning with alternative mowing). The following initial Phase 1 (Defra) criteria were met:
1) > 30 % tall heather (and other bog species should be present);
2) fairly flat intact peat areas (assures access with mowing equipment) with additional slope areas;
3) two ~ 400 x 300 m (~12 ha) sub-catchment areas (i.e. with a central water stream);
4) > 100 cm peat depth across the main flat peat areas, lower at slopes;
5) relatively easy access but remote to ensure site safety.
The project considers one large-scale mowing treatment (across the treatment sub-catchment) with additionally three small-scale treatments at small experimental plots within the overall treatment and a control sub-catchments. The main mowing treatment reflects the current mosaic nature of burn strips and maintain a succession of heather ages. Mowing and burning are applied every other year (ca. 20% of tall heather) and will be done at all sites to reflect a usual burn management (size of patches of about 0.2 ha and a rotation cycle of about 10-15 years). There was no burning inside the proposed two sub-catchments in the 2012/13 season (i.e. to allow a pre-treatment monitoring period). The small-scale plot-level treatments in the sub-catchment consist of: a) mowing: no management (uncut), leaving brash, removing brash and either with or without Sphagnum pellet addition, and b) burning: either with or without Sphagnum pellet addition.
At each site there are two sub-catchments, each containing four monitoring areas (ca. 50 x 50 m), with a total of 24 small (5 x 5 m) permanent monitoring plots, consisting of 20 plots within the treatment (mown) sub-catchment, i.e. 5 in each monitoring area, and 4 plots within the control (burnt) sub-catchment, i.e. one per monitoring area. In the treatment areas, 4 plots (one in each treatment monitoring area) are left as permanently un-managed (i.e. uncut; specifically allowing continued heather growth), the other plots were mown in 2013. Additionally, a pair of 3 monitoring locations across slope transects contain water table depth (50 cm deep) and soil temperature sensors (surface), which are located near three of the monitoring areas in each sub-catchment to capture a range of slope and aspect conditions. A weather station (2 m tall on a simple mast with guy-ropes) is located between the two paired sub-catchments. One water flow meter station (simple V-notch weir) is located at each central stream sub-catchment outlet.