The Shoreline Fringe Forest and Adjacent Peatlands of the Southern Central British Columbia Coast

Résumé

Four distinct vegetation types are found in close proximity along an exposed section of the southern central coast of British Columbia. A coastal fringe of coniferous forest a few hundred metres wide is separated by a steep ecotone from an inland peatland-forest complex. The objectives of this study were (1) to describe the plant communities along the transition from forest to peatland, and (2) to identify some of the major environmental factors associated with those communities using indicator plant analysis. The coastal forest is dominated by Thuja plicata, Tsuga heterophylla, Picea sitchensis, and Chamaecyparis nootkatensis. Characteristic understory species include Gaultheria shallon and Blechnum spicant. Inland from the coastal forest are transitional forest stands with a species-rich understory including Cornus canadensis, Hylocomium splendens, and Vaccinium parvifolium. The peatlands are poor fens characterized by thickets of Pinus contorta and Chamaecyparis nootkatensis among open areas dominated by species such as Sphagnum sp., Empetrum nigrum, Juniperus communis, and bogs characterized by Myrica gale, Eriophorum angustifolium, and Sanguisorba officinalis. Indicator plant analysis identified differences in the ground surface materials, soil moisture and nutrient regime between the vegetation types. The general trend is for an increase in soil moisture from the forest vegetation to the peatlands and a concurrent change from the Mor humus forms that dominate the coastal forest floor to the surface groundwater table of the peatlands. These environmental differences between forest and peatland are likely related to the steeper slopes typically found in the fringe forest vegetation.