In North America, very little research has been carried out on the restoration of fens. Increasingly. peat industries are faced with the task of restoring abandoned, harvested peatlands where the environmental conditions closely resemble a fen. The goal of this research project is to explore techniques for the restoration of fen plant communities on vacuum-extracted peatlands in Canada. The plant succession on abandoned, harvested peatlands where peat has been extracted to the minerotrophic layers was examined to détermine which plants frequently colonize thèse abandoned sites. After surveying 28 abandoned harvested fens across Canada and in Minnesota. USA. the spontaneous végétation was not similar to the végétation found on undisturbed fens from the same areas. Specifîcally, Sphagnum and Carex species, abundant on undisturbed fens were not found on abandoned. vacuum-harvested fens. However, harvested fens were quickly recolonized by marsh species if they were not actively drained. A field experiment was carried out to test two reintroduction techniques for Sphagnum and Carex species as well as the use of phosphate fertilizer. The application of donor diaspores, commonly used for dry peatland restoration was effective for reintroducing both Carex and Sphagnum species. In the past, the focus of fen restoration has been vascular plants. In order to find out more about the environmental conditions necessary for the végétative régénération of eight common fen mosses, field and greenhouse experiments were carried out. The présence of shade was shown to greatly improve the régénération of the mosses. The optimal water level for most species was just under the surface and Sphagnum species were shown to be the most successful at regenerating. The findings of this research will aid the development of stratégies for the restoration of fens on harvested peatlands. Préface This thesis is présentée! in the form of a séries of articles. The first chapter is a gênerai introduction and literature review. The second chapter was submitted to the journal Wetlands in September 2006. This article is currently in the final stages of revision by the journafs editor. I am the first author. Dr. Line Rochefort is the second author and Dr. Monique Poulin is the third author. I developed the research hypothèses. Dr. Rochefort and Dr. Poulin helped with the project design. I was responsible for data collection, data analysis and manuscript préparation. Dr. Poulin helped with the data analysis and both Dr. Rochefort and Dr. Poulin assisted in the manuscript préparation with éditorial comments. For the third. fourth and fifth chapters I am the first author and Dr. Line Rochefort is the second author. Chapter three is being prepared for submission to Ecoscience and chapter four is being prepared for submission to Applied Végétation Science. The fifth chapter was submitted to the journal Restoration Ecology in February 2007. For thèse articles I was responsible for developing the research hypothèses and Dr. Rochefort assisted with the project design. I carried out the data collection, analysis and manuscript préparation. Dr. Rochefort assisted with the manuscript préparation.