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Peatland Ecology Research Group (PERG)
Université Laval
 
Vegetation
 

Text from:

Quinty, F. & L. Rochefort. (2003). Peatland restoration guide, 2nd ed. Canadian Sphagnum Peat Moss Association et New Brunswick Department of Natural Resources and Energy. Québec, Québec. 106 p.

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Habitat and Plant Communities

 

Different habitats can be distinguished based on plant communities, but many are restricted to small surfaces such as floating mats around bog pools. A few habitats occupy most of peat bogs. They can be divided into two groups based on their position relative to the water table. The first group is composed of habitats that form depressions where the water level is close to the surface. These habitats are called lawns or hollows depending on the area they cover. Lawns cover large surfaces, while hollows are small depressions. Plant communities of lawns and hollows are dominated by Sphagnum species from the group Cuspidata like Sphagnum fallax and Sphagnum angustifolium. These species grow into rather loose colonies that are not adapted to retain water. These plant communities typically comprise sedges or graminoids species.

 

The second group of habitats form large plateaus or small mounds called hummocks. These habitats are higher than lawns and hollows by about 40 to 80 cm and thus they have drier conditions. Sphagnum species colonizing plateaus and hummocks grow in dense colonies that allow efficient water retention and water supply. The most common species are Sphagnum fuscum and Sphagnum rubellum, which belong to the Acutifolia group. Drier conditions found on plateaus and hummocks favour the presence of shrubs and trees as well as other mosses such as Polytrichum and lichens. However, large plateaus can form wide open areas devoid of trees. Under low water table conditions, shrubs and trees can form a dense cover with a sparse moss layer. A common feature in peat bogs is a mixed habitat characterized by the succession of hummocks and hollows.

 

Experiments comparing hummock and hollow plant communities show that hummock vegetation gives much better results when used as plant material for peatland restoration. Hummock-forming Sphagnum species are better adapted to conditions found in restoration sites. The presence of other mosses like Polytrichum contribute substantially to the rapid establishment of a new plant carpet. Labrador tea (Ledum groenlandicum) and Leatherleaf (Chamaedaphne calyculata) are two shrub species present in hummocks that establish easily and add to the diversity of establishing vegetation on restoration sites.

 

 

 

Photo showing the succession of hollows and hummocks that is typical of many peat bogs. Hollows can be recognized by the presence of graminoid species (in yellow) while hummocks support shrubs (in brown). Both habitats usually have a complete Sphagnum cover, but hummock forming species are more suitable for restoration. (Photo: M. Poulin)

 

Des expériences portant sur la comparaison entre les communautés végétales des buttes et des dépressions montrent que la végétation établie sur les buttes donne de bien meilleurs résultats lorsqu'elle est utilisée comme matériel végétal pour la restauration des tourbières. Les espèces de sphaignes qui croissent sur les buttes sont mieux adaptées aux conditions rencontrées sur les sites de restauration. La présence de mousses, comme le polytric, contribue substantiellement à l'établissement rapide d'un nouveau couvert végétal. Trouvés sur les buttes, le thé du Labrador (Ledum groenlandicum) et le petit daphné (Chamaedaphne calyculata) sont deux espèces d'arbustes appartenant aux éricacées qui s'établissent rapidement et qui accroissent la diversité de la végétation des sites en restauration.

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