Individual study: Use of shallow basins to restore the hydrology and enhance Sphagnum establishment on cutover peatlands in the Lac-Saint-Jean region, Québec, Canada
Price J., Rocheford L. & Campeau S. (2002) Use of shallow basins to restore cutover peatlands: hydrology. Restoration Ecology, 10, 259-266
In Canada, peat harvesting has caused widespread damage to peatland habitats. Recolonization by Sphagnum moss is considered critical in plant community restoration attempts at many sites. However, often recolonization of milled peatlands does not readily occur, this has led to development of techniques to improve Sphagnum establishment. This study evaluated the effectiveness of shallow basins combined with a straw mulch, to improve hydrological conditions for Sphagnum growth in large-scale restoration projects.
Study area: The study was carried out on a cutover portion of peatland in the Lac-Saint-Jean region, Québec, eastern Canada. Drainage began in 1990 and in 1991 the upper 0.35−0.6 m of peat was removed by block cutting. After abandonment of peat harvesting, the drainage ditches were blocked in the autumn of 1992. Residual peat (1.2 to 1.8 m thicknesss) had suffered oxidation and compression due to the drainage and peat extraction activities.
Experimental design: In April 1996, three plots 20, 10 and 4 m wide were excavated to a depth of 15 to 20 cm (down to the permafrost) within three 30-m wide cutover peat fields. The spoil was pushed into ridges bordering the plots. All basins and a fourth treatment (four 15 × 15 m plots) without basins, were sown with Sphagnum diaspores (moss fragments) and all were covered with straw mulch. A 'control' peat field with no basins or straw mulch added was also monitored. Hydrological and microclimatic measurements were taken in 1996 and 1997 during the May to August growing season.
Average water tables in the 20, 10 and 4 m wide basins and the mulch-protected site were 27.2, 8.3, 11.4 and 9.7 cm higher, respectively, than in the control peat field in 1996, with similar results in the drier summer of 1997. However, these higher water tables was not just due to the physical lowering of the peat surface: meltwater and rainwater was retained by the ridges bordering the plots; moisture levels were enhanced during drier periods by groundwater held beneath the ridges; and mulching also assisted in water retention.
Whilst mulching alone provided considerable improvement in maintaining moist conditions compared with the control peat field, the additional water retained in the basins better protected against Sphagnum desiccation and loss during more extreme dry periods during the growing season.
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