Table 4 Intervention/exposure groups generated iteratively during the review process with brief descriptions of definitions

Cropped-vs-bare

Actively cropped fields compared to those with no vegetation (extracted or de-vegetated)

Drained and restored-vs-undrained

Drained and then restored peatlands compared to pristine fen

Drained-vs-undrained

Drained peatlands compared to pristine/undrained peats, or heavily drained peatlands compared to lightly drained peats

Dry-vs-wet

Dry peat soils compared to wetter soils

Extracted and restored-vs-natural

Both extracted and then restored peats compared to unextracted/pristine peats

High intensity farmed-vs-low intensity farmed

Intensively compared with extensively farmed peats (in terms of a wide variety of unspecified farming activities)

Fertilised and grazed-vs-unfertilised and mown

Both fertilised and grazed compared to unfertilised and ungrazed but mown peats

Fertilised-vs-less fertilised

High fertilisation rates compared to low fertilisation rates

Grass-vs-forest

Grass fields compared to forested fields

Grazed-vs-mown

Grazed peatlands compared to ungrazed but mown fields

Irrigated-vs-non-irrigated

Rain fed irrigated peatlands compared to non-irrigated peats

Mineral soil dressed-vs-undressed

Peats with added mineral soil compared to soils lacking mineral addition

Old abandoned-vs-recently abandoned

Peats abandoned for a longer period compared to more recently abandoned peats

Old afforested-vs-recently afforested

Peats planted with trees for a longer period compared to more recently planted forest peatlands

Poor-vs-rich

Peats described by authors as ‘poor’ compared to those described as ‘rich’ (corresponding to natural gradients in nutrient status and acidity)

Restored-vs-unrestored

Previously extracted peats with deliberately raised water tables compared to extracted and unaltered peatlands