CLASSIFICATION OF PEATLAND VEGETATION IN ATLANTIC CANADA

The peatlands of Atlantic Canada are classified in four plant alliance s, consisting of 10 plant associations. The four plant alliances compr ise the dry bog communities (Kalmio-Cladonion Wells 1981), wet bog com munities (Scirpo-Sphagnion Wells 1981), hummock and ridge communities of slope and string fens (Betulo-Sphagnion Wells all. nov.), and poor, intermediate and rich fen plant communities (Scirpo-Myricion Wells 19 81). Distribution maps are presented for releves in each of the 10 ass ociations. Based on species distributions, floristic regions are defin ed for peatlands in Atlantic Canada. Nutritional characteristics are a lso described for each plant association. pH and total soil concentrat ions of calcium, nitrogen and iron proved reliable in separating bog f rom fen. A boundary between ombrotrophic peatlands and minerotrophic p eatlands is suggested, based on a soil pH of 4.0, total soil concentra tions of 3.0 mg g(-1) Ca, 4.0 mg g(-1) Fe, 13.0 mg g(-1) N and a Ca/Mg ratio of 2.5. Comparisons between the syntaxa for peatlands in Atlant ic Canada and those in Europe are discussed for higher taxa. The possi bility of establishing a new order (Chamaedaphno-Scirpetalia Wells ord . nov.) for peatlands in Atlantic Canada is also discussed.