Restoring afforested peat bogs: results of current research

Published source details Anderson R. (2010) Restoring afforested peat bogs: results of current research. Forestry Commission report. Forestry Commission Report, 6.
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This study is summarised as evidence for the following.

	Action	Category
	Cut/remove/thin forest plantations Action Link
	Cut/remove/thin forest plantations and rewet peat Action Link
	Rewet peatland (raise water table) Action Link
	Rewet peatland (raise water table) Action Link

Cut/remove/thin forest plantations

A replicated, paired, controlled study in two afforested blanket bogs in Scotland, UK (Anderson 2010) reported that plots where trees were felled developed greater cover of sheathed cottongrass Eriophorum vaginatum, and typically less cover of forest mosses, than plots that remained forested. These results were not tested for statistical significance. After five years, felled plots had greater cottongrass cover (16–45%) than forested plots (11–19%). In contrast, felled plots typically had less cover of forest mosses: silk moss Plagiothecum undulatum in four of four comparisons (felled: <1%; forested: 3–6%) and plait moss Hypnum cupressiforme in three of four comparisons (felled: 18–35%; forested: 44–57%). Amongst felled plots, the effect on cottongrass and silk moss was generally larger when debris was left in place rather than removed. Between 1996 and 1998, six blocks of six 40 x 100 m plots were established in drained, conifer-forested bogs. Twelve plots (two plots/block) received each felling treatment: felling and removing debris, felling and leaving debris in place, or no felling. Within each treatment, half of the plots were also rewetted. Five years after intervention, vegetation cover was recorded (details not reported).

(Summarised by: Nigel Taylor)
Cut/remove/thin forest plantations and rewet peat

A replicated, paired, controlled study in two afforested blanket bogs in Scotland, UK (Anderson 2010) reported that plots restored by tree felling and rewetting had greater cover of sheathed cottongrass Eriophorum vaginatum, and less cover of forest mosses, than plots that remained forested and drained. These results were not tested for statistical significance. After five years, restored plots had sheathed cottongrass cover of 44–45% (vs 11% in plots that remained forested and drained), plait moss Hypnum cupressiforme cover of 18–32% (vs 57%) and waved silk moss Plagiothecum undulatum cover of <1% (vs 6%). The combined effect of felling and rewetting was larger than the effect of felling or rewetting alone in 10 of 12 comparisons. Between 1996 and 1998, six blocks of six 40 x 100 m plots were established in drained, conifer-forested bogs. Each treatment was replicated once/block: rewetting with tree felling (debris left in place), rewetting with tree felling (debris removed), rewetting only, tree felling only, tree removal only, no intervention. Rewetting was achieved by damming plough furrows every 20 m. In rewetted plots, the water table was 8–32 cm below the peat surface during the growing season (vs drained plots: 11–38 cm below). Vegetation cover was recorded five years after intervention (details not reported).

(Summarised by: Nigel Taylor)
Rewet peatland (raise water table)

A replicated, paired, controlled study in two degraded blanket bogs in Scotland, UK (Anderson 2010) reported that rewetted plots developed greater cover of sheathed cottongrass Eriophorum vaginatum, and typically less cover of forest mosses, than drained plots. These results were not tested for statistical significance. In three of three comparisons, rewetted plots had greater cottongrass cover than drained plots after five years (rewetted: 19–45%; drained: 11–34%), but less plait moss Hypnum cupressiforme cover (rewetted: 18–44%; drained: 35–57%). Rewetting reduced cover of silk moss Plagiothecum undulatum in one of three comparisons, when plots remained forested (rewetted: 3%; drained: 6%) but had no additional effect in plots where trees were felled or removed (rewetted: 0.6–0.8%; drained: 0.5–0.6%). Six blocks of six 40 x 100 m plots were established in drained bogs forested with spruce and pine. Between 1996 and 1998, six treatments were replicated once/block: rewetting, rewetting with tree felling, rewetting with tree removal, tree felling only, tree removal only, no intervention. Rewetting was achieved by damming plough furrows every 20 m. In rewetted plots, the water table was 8–32 cm below the peat surface during the growing season (vs drained plots: 11–38 cm below). Vegetation cover was recorded five years after intervention (details not reported).

(Summarised by: Nigel Taylor)
Rewet peatland (raise water table)

A replicated, paired, controlled study in a degraded raised bog in Scotland, UK (Anderson 2010) reported that blocking plough furrows to help rewet the bog had no (or no consistent) effect on vegetation cover in plots where trees had been felled. These results were not tested for statistical significance. After five years, plots with blocked and open furrows had similar cover of heather Calluna vulgaris (3–15% vs 3–14%) and sheathed cottongrass Eriophorum angustifolium (20–48% vs 15–45%). Grass cover was similar in blocked and open plots when trees had been removed (3 vs 2%), but higher in blocked plots when all tree debris was left in place (6 vs 1%) and lower in blocked plots when tree tops were left in place (7 vs 10%). Grass was mostly wavy hair grass Deschampsia flexuosa. Twelve pairs of 18 x 20 m plots were established in a drained, pine-forested bog. Between 1996 and 1998, plough furrows were blocked in one plot/pair but left open in the other. The water table depth was similar under both treatments (0–22 cm below the peat surface). Trees were felled in all plots, with debris left in place (four pairs), tree tops left in place (four pairs) or all debris removed (four pairs). Vegetation cover was recorded five years after intervention (details not reported).

(Summarised by: Nigel Taylor)