Action: Disturb peatland surface to encourage growth of desirable plants (without planting)
Key messagesRead our guidance on Key messages before continuing
- Two studies evaluated the effects of disturbing the peat surface (without planting) on peatland vegetation. Both studies were in fens.
- Plant community composition (2 studies): Two replicated, paired, controlled, before-and-after studies (one also randomized) in fens in Germany and Sweden reported that soil disturbance affected development of the plant community over 2–3 years. In Germany, disturbed plots developed greater cover of weedy species from the seed bank than undisturbed plots. In Sweden, the community in disturbed and undisturbed plots became less similar over time.
- Characteristic plants (2 studies): The same two studies reported that wetland- or fen-characteristic plant species colonized plots that had been disrturbed (along with other interventions). The study in Germany noted that peat-forming species did not colonize the fen.
Mechanically disturbing the peat or soil surface (e.g. by tilling, ploughing or scarifying) can encourage the growth of desirable plants. It can create bare patches, clear of previous dominant species, in which peatland plants can grow. Peatland plants may colonize from nearby patches or germinate from seeds or spores already in the soil. Colonizing plants will typically be fast-growing, weedy species – but sometimes these are desirable members of natural peatland plant communities, or are desirable to provide some cover that can shelter and nurse other colonizing plants.
Caution: Disturbance can destroy the physical structure of the peat and aerate the peat more than usual. Deep ploughing could mix the peat with underlying mineral soil.
Key peatland types where this action may be appropriate: bogs, fens/fen meadows, tropical peat swamps.
Supporting evidence from individual studies
A replicated, paired, controlled, before-and-after study in 1996–1998 in a degraded fen in Germany (Richert et al. 2000) reported that ploughed plots developed different plant communities to unploughed plots over two years. Specifically, ploughed plots developed greater cover than unploughed plots of weedy species from the seed bank such as toad rush Juncus bufonius and pale persicaria Polygonum lapathifolium. All plots were colonized by wetland-characteristic species such as cattail Typha latifolia and common rush Juncus effusus, but not sedges Carex spp. or common reed Phragmites australis. Data were reported as graphical analyses. Results were not tested for statistical significance. In 1996, two pairs of plots were established in a historically drained fen. In each pair, one plot was ploughed to a depth of 20 cm and one was not ploughed. Then, the surface of all plots was irrigated with lake water. Before intervention in 1996, then in 1997 and 1998, vegetation cover was estimated in a representative 16 m2 area in each plot.
A replicated, randomized, paired, controlled, before-and-after study in 2002–2005 in two degraded rich fens in Sweden (Mälson et al. 2010) reported that disturbing surface peat changed plant community composition and cover. The cover results were not tested for statistical significance. Disturbance significantly altered the development of the plant community over three years (data reported as a graphical analysis). Disturbed plots consistently had lower cover than undisturbed plots of Sphagnum mosses (disturbed: 0–2%; undisturbed; 2–25%) and purple moor grass Molinia caerulea (disturbed: 1–9%; undisturbed; 23–50%). Cover of common reed Phragmites australis, sedges Carex spp. and common cottongrass Eriophorum angustifolium showed mixed responses to disturbance amongst sites, species or other treatments applied to plots. Seventeen fen-characteristic plant species colonized disturbed plots (data not reported for undisturbed plots). In autumn 2002, sixty-four 2.5 x 2.5 m plots were established (in four blocks of 16) across two degraded fens. Thirty-two plots (eight random plots/block) were cleared of vegetation and dug over (top 10–20 cm of peat disturbed). The other plots were not disturbed. Additionally, trees had been removed from all plots and some plots were rewetted and/or mown. In 2002 (before intervention) and 2005, cover of every plant species was estimated in one 0.25 m2 quadrat/plot.
- Richert M., Dietrich O., Koppisch D. & Roth S. (2000) The influence of rewetting on vegetation development and decomposition in a degraded fen. Restoration Ecology, 8, 186-195
- Mälson K., Sundberg S. & Rydin H. (2010) Peat disturbance, mowing, and ditch blocking as tools in rich fen restoration. Restoration Ecology, 18, 469-478