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Page 10 - The Life of a Raised Bog

Published by Ronald Caplan on 1975/12/1 (334 reads)

pact sedge peat is deposited and this irapedes drainage. In our diagram of succes? sional relationships, this is the Scirpus cespitosus-Dicranum leioneuron Association rising up out of the Pioneer Stage* Nichols called it the "bog meadow association." In well-developed bogs this association occurs at the edges and determines the size of the bog through its expansion into forested areas* The wind tears into the dwarf trees bordering the bog, creating openings • and once light gets in, the shade intol? erant pioneer Sphagnum species become established with the bulrushes • the sedge peat causing further destruction of the forest and thus further bog advancement* Within the bog, there is a swift accumulation of peat and the association of bul? rushes and several species of Sphagnum takes over • Nichols' "wet bog association." This is Scirpus cespitosus-Sphagnum spp. The different species of sphagnum grow at different rates, and uneven topography emerges, mounds and hollows. And "as the mounds are being built up there is a corresponding rise in the water table. Some mounds eventually coalesce and form ridges enclosing shallow depressions. These be? come filled with water and create bog ponds. The ridges are built higher by Sphag? num species, strengthened by vascular plant remains and eventually become effective dams. With the underlving sedge peat impervious to drainage and the surrounding ridges maintaining the water table near the surface, the ponds become a permanent feature of the bog. The bog surface is continuously raised by the growth of Sphagna mounds until, eventually, it is above the water level of the ponds and is no longer influenced by the seepage from them* At this stage drier surface conditions prevail" • and the bog advances to the Climax association of Black Spruce-Reindeer Moss (Pi? cea mariana-Cladonia rangiferina)* Nichols called this the "dry bog association." f' Picea mariana - Cladonla rangiferina -*= ' • -' • ' • 2??H' ~ Association (ponds) (CLIMAX ) VF ' EROSION destruction of bog surface • Scirpus cespitosus - Sphagnum spp. Association (ponds) 4 / Sphagnum spp. Association 1' Rhynchospora alba - Drosera intermedia Association f (aquatic Sphagnum spp.) /* Nuphar variegatum Association -Scirpus cespitosus - Dicranum leioneuron Association Pioneer Stage BOG DEVELOPMENT series REGENERATION of surface Eriophorum angustifolium Association (aquatic Sphagnum spp.) Nuphar variegatum Association ponds Successional relationships of raised bog associations taken from Comeau's thesis ' gullies Picea mariana - Rhododendron canadense Association 1. Scirpus cespitosus - Dicranum leioneuron Association 4.Nuphar variegatum Association 2. Scirpus cespitosus - Sphagnum spp. Association 5.Rhynchospora alba - Drosera intermedia Association 3. Picea mariana - Cladonla rangiferina Association 6.Eriophorum angustifolium Association (7). Picea mariana - Rhododendron canadense Association (forest phase) 3 3 2 6 pond succession surface regeneration bog development Topographic sequence of raised bog associations. Maximum recorded peat depths in centimeters are given under each association. Prom Comeau*
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