Thompson River Riparian Restoration

Riparian areas along the upper Thompson River have been affected by historic clearing for hay meadows, grazing, and timber harvesting. Historic photographs show that much of the floodplain once supported native riparian shrubs. Currently, the floodplain is dominated by Phalaris arundinacea (reed canarygrass). This conversion has resulted in loss of woody cover, reduced shade, few sources of large wood, and extremely low plant species diversity on the floodplain. During September 2003, Plum Creek Timber Company, working with staff currently at Geum Environmental Consulting, Inc., implemented a riparian restoration project to improve summertime stream temperatures, restore instream habitat, and improve migratory habitat and the quality of connectivity among local populations of bull and cutthroat trout. The project had three major elements: 1) Control competition from exotic reed canarygrass through site preparation, installation of weed barriers (including continuous sheets of linerboard), and application of mulch; 2) Planting of native willow, dogwood, and other shrubs in 1-gallon containers at an 8 foot spacing; and 3) Planting native conifers on adjacent terraces and floodplain areas. Monitoring results from the first growing season show high survival among planted shrubs and effective suppression of reed canarygrass. Unique methods and tools were used during the project to cover 2 acres of floodplain with mulching materials