Cover peatland with something other than mulch (without planting)
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Peatland vegetation may be killed by hot, dry and bright conditions on bare peat surfaces (e.g. Harley et al. 1989; Sagot & Rochefort 1996). Covers (e.g. plastic sheets, fleece or fibre mats) can maintain more stable temperatures and humidity, and offer some shading. This may create a more hospitable environment for establishment and growth of peatland vegetation (Good et al. 2009). The precise effect (mainly affecting light and/or moisture) depends on the material and its height above the peatland.
This section considers the effect of adding covers without adding vegetation. The cover is intended to help existing vegetation e.g. remnant moss patches, or seedlings that germinate from seeds already in the peat. We use the term mesh to describe covers such as shade cloths, gauze and netting that are used to shade a peatland.
Key peatland types where this action may be appropriate: bogs, fens/fen meadows, tropical peat swamps.
Good R., Wright G., Whinam J. & Hope G. (2009) Restoration of mires of the Australian Alps following the 2003 wildfires. Pages 353–362 in: S.G. Haberle, J. Stevenson & M. Prebble (eds.) Altered Ecologies: Fire, Climate and Human Influence on Terrestrial Landscapes. Terra Australis 32, Australian National University e-press, Canberra, Australia.
Harley P.C., Tenhunen J.D., Murray K.J. & Beyers J. (1989) Irradiance and temperature effects on photosynthesis of tussock tundra Sphagnum mosses from the foothills of the Philip Smith Mountains, Alaska. Oecologia, 79, 251–259.
Sagot C. & Rochefort L. (1996) Tolérance des sphaignes à la dessiccation (Tolerance of Sphagnum mosses to desiccation; in French). Crytogamie, Bryology-Lichénologie, 17, 171–183.
Supporting evidence from individual studies
A replicated, controlled, before-and-after study in 1993–1995 in a historically mined raised bog in Germany (Sliva et al. 1999) reported that covering plots with fleece or fibre mat did not affect seedling numbers for five plant species. These results were not tested for statistical significance. After 1–2 years, covered and uncovered plots contained a similar number of seedlings. There were 3 seedlings/400 cm2 for purple moor grass Molinia caerulea. There was <1 seedling/400 cm2 for four other species: beaked sedge Carex rostrata, common cottongrass Eriophorum angustifolium, sheathed cottongrass Eriophorum vaginatum and heather Calluna vulgaris. In autumn 1993, fifteen 1 m2 plots were established on bare rewetted peat (mined until 1986). Five plots were covered with synthetic fleece, five were covered with wide-meshed jute fibre mat and five were not covered. No seeds were added to these plots. Covers were removed and seedlings counted in summer 1994 (two plots/treatment) and 1995 (three plots/treatment).Study and other actions tested
A replicated, controlled, before-and-after study in 2003–2007 in two in Australia (Whinam et al. 2010) found that plots shaded with plastic mesh developed greater vegetation cover than unshaded plots. After 40 months, shaded plots had significantly greater cover of native plants in general, and of forbs, than unshaded plots (data not reported). Sphagnum moss cover was 10% in shaded plots compared to 8% in unshaded plots (difference not tested for statistical significance). Immediately before shading, plots had 3% Sphagnum cover on average. In January 2003, the focal bogs were burned by a wild fire. In October 2003, ten burned plots (3 x 15 m; five plots/bog) were shaded with plastic mesh (blocking 70% of incoming light). Fifteen additional plots were left uncovered. Vegetation cover was recorded in 0.25 m2 quadrats: five/bog in October 2003, and one/plot in March 2007.Study and other actions tested