Natural revegetation of peatlands after horticultural peat extraction, which hasn't been previously documented in Alberta, is described herein in relation to feasibility as a reclamation option. A peatland of several hundred hectares, located 100 km west of Edmonton, Alberta, was harvested and then abandoned in several stages between 1970 and 1980. No reclamation was initiated and the drainage network was left partially functional. The cutover bog is characterized by a variety of site types with differences in peat thickness, water table regime, peat botanical composition, peat chemistry and topography, and it has since been colonized by differing vegetation associations. A two year study was initiated in 1994 to investigate the ecosite characteristics of five site types approximately 14 years after abandonment.
Conclusions:
- The rate of natural revegetation on cut over peatlands depends on the site conditions, in particular, the water table level. Adverse site conditions can prevent any revegetation for at least 15 years.
- Sphagnum moss development appears to be limited to sites with a mean water table level higher than -40 cm and preferably within -20 cm.
- Lichen, Betula, Ledum and Picea species were most prevalent in sites where the mean water table level was between -30 and -60 cm.
- Dry, nutrient-poor sites are the slowest to revegetate. Mean water table levels of -60 cm result in a peat surface that is too dry for plant establishment. Reclamation assistance is required for such sites.
- Carex spp. can become well established in less than 10 years and will tend to be dominant in areas subject to long term inundation.
- The number of species that become established in a site type is similar to that of a typical bog; however, the species are different. Diversity in post-harvest site types leads to relatively high diversity in species composition.
- It appears that the current stage of revegetation and sequence of colonization is similar to that noted by researchers in Eastern Canada. For example, bog species such as Picea mariana and Smilacina trifolia are very slow to return to a disturbed peatland.
- The success of natural revegetation depends on the time horizon acceptable to the land manager. Five to ten years is likely required to colonize and stabilize most peatlands assuming site conditions are suitable. The return to the original bog species composition may require many decades.
- Water table management is essential to ensure successful revegetation and to guide the direction of
revegetation. Soil chemistry adjustment may be required for problem soils.