Mulching fuels treatments promote understory plant communities in three Colorado, USA, coniferous forest types

•We examined the impacts of mulching fuels treatments on vascular understory plants.•Total understory plant richness and cover increased by 6–9years post-treatment.•Graminoids and forbs in particular tended to increase following mulching.•Exotic plants were often stimulated by mulching, but were not abundant.•Overall, mulching promoted denser and more diverse native understory communities.