. The Canadian field-naturalist. 162 The Canadian Field-Naturalist Vol. 85 Cassiope tetragona, PhyUodoce caerulea, Salix herbaceae, and an Antennaria species. Permafrost at shallow depths is a constant feature of the tussock muskeg community. It was shown in the discussion of the Ennadai Lake area (Larsen 1965) that each com- munity type possesses distinct permafrost characteristics in terms of the depth of the active layer, and the same holds true in the Artillery and Aylmer Lakes area. In addition, there is a marked seasonal lag in the rate of thaw between these two latter areas; the north-
. The Canadian field-naturalist. 162 The Canadian Field-Naturalist Vol. 85 Cassiope tetragona, PhyUodoce caerulea, Salix herbaceae, and an Antennaria species. Permafrost at shallow depths is a constant feature of the tussock muskeg community. It was shown in the discussion of the Ennadai Lake area (Larsen 1965) that each com- munity type possesses distinct permafrost characteristics in terms of the depth of the active layer, and the same holds true in the Artillery and Aylmer Lakes area. In addition, there is a marked seasonal lag in the rate of thaw between these two latter areas; the north- ern stations thaw to a given depth later, and possess shallower active layers, than southern portions of the study area. Surface frost action is apparent on many of the areas occupied by the tussock muskeg com- munity, and it appears from observation that frost action is more frequent and most destruc- tive of the plant community on sites where the active layer is most shallow. This suggests the possibility that there exists a cycle in the tus- sock muskeg community, a cycle which might be said to be initiated by frost action which leaves the disturbed area free of plants and with a surface of bare peat available for re- colonization. The areas of bare peat which result from frost activity are recolonized by the same aggregation of species that previously occupied it. Over a period of many years, these. r-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
Size: 1307px × 1913px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorottawafieldnaturalistsclub, bookcentury1900, bookcolle
