Forested wetlands are important ecosystems valued for their indigenous plant communities, spatial heterogeneity, wildlife habitat, water quality, and timber resources. When harvested for timber, plant composition in these wetlands may change due to alteration in microsite habitats. Harvest severity also may affect plant composition. In this study, a mineral conifer wetland was subjected to whole-tree harvesting followed by installing different site preparations (bedding, trenching, draining). The original wetland overstory was Picea mariana, Larix laricina, and Pinus banksiana, with groundcover dominated by Sphagnum russowii. Eleven to twelve years after harvest, we assessed responses of vascular and non-vascular plants to created microtopographies (pits, side slopes, mounds) to determine whether harvest severity affected species richness, diversity, and relative cover of plant communities. For all the microtopography positions, the more severe harvest treatments (drained, cut, trenched) had the highest plant richness but the lowest diversity values. Richness and relative cover of Sphagnum species were highest in reference areas and much lower in the most severe harvest treatments (drained, cut, trenched). In contrast, graminoid and, to a lesser extent, herbaceous and woody plants increased in richness and cover after harvest.