No abstract

Remediation of the South Fork Couer d'Alene River floodplain (the Flats) in Smelterville, Idaho, offered a unique opportunity to test ecological restoration theories regarding the relationship between plant community establishment and abiotic environmental conditions. Successful recreation of the abiotic environment is the primary consideration for restoration of a given plant community type. Failure associated with many wetland restoration projects can often be traced to inappropriate soils and hydrologic conditions for the target community. This paper reports the preliminary results of an 80 ha floodplain restoration project that occurred without artificial replanting of herbaceous wetland plant communities. Over 760,000 cubic meters of tailings-contaminated materials were removed from the floodplain. Groundwater modeling prior to excavation and re-grading served as the basis for developing post-excavation grading plans. Grading was coupled with placement of 15 cm of high quality native topsoil. Coversoils required relatively little amending following placement and establishment of final grades. No herbaceous wetland plants were installed on the site. Drill seeding with grasses and forbs helped stabilize upland areas and slopes. Woody plants were installed along the streambank and in places throughout the floodplain in the springs of 2001 and 2002. Four years later, the floodplain is naturally regenerating to a diverse and vigorous palustrine emergent marsh (PEM) community. Species currently established in wetlands on the site include sedges, rushes, cattail, reed, hardstem bulrush, and spike rush, among others. Additional woody species, such as cottonwood and willow, are naturally regenerating. By successfully establishing wetland hydrology and use of native topsoils, the project has been able to produce a diverse and vigorous PEM community capable of supporting wildlife and delivering at least some wetland functions that had not been available to the Coeur d'Alene basin for many decades while saving almost $900,000 in proposed replanting costs.