Water Table and Vegetation Response to Ditch Blocking: Restoration of a Raised Bog in Southwestern British Columbia

Abstract

Large-scale peat harvesting operations alter hydrology of raised bogs so that natural regeneration may not occur without altering the water table. This paper describes efforts to restore key hydrologic and ecologic processes in a southwest BC raised bog (Burns Bog) highly disturbed by decades of peat extraction, drainage, filling, and conversion to agriculture, urban, and industrial uses. The restoration goals are to return a high water table throughout the bog, but particularly in the pine forests at the edge of the bog, to re-establish Sphagnum cover, and to re-start the peat-forming process in degraded peat-harvested sectors. Peripheral and interior ditches are being blocked to increase the retention of winter precipitation into the drier summer months. Piezometer/well measurements have detected water table increases in the past two years, including a relatively immediate response in one site. New Sphagnum colonies have become established in the dry perimeter forest, a first indication that the water table may be rising and that peat-forming vegetation may be responding positively. These preliminary results suggest that it is possible to detect a rapid hydrological response with a comprehensive monitoring network in raised bogs; this observation is key to early prediction of future peatland restoration initiatives.