Megafires in Oregon: Riparian vegetation layers differ three years after mixed severity fire

Riparian ecosystems are highly diverse and dynamic, but effects of fire on riparian vegetation are poorly understood. In 2020, widespread fires impacted forests across the western Oregon Cascades, including riparian areas. To investigate riparian plant community recovery, we quantified riparian vegetation responses to wildfire and forest management. We determined that vegetation response to burn severity varied by structural layer and was dynamic across the first three years post-fire. Overstory mortality after fire varied by species. In the understory, forb cover recovered rapidly; shrub cover and richness showed some recovery within three years. Indicator species highlighted compositional differences between sites that burned and those that did not. Although riparian zones are thought to be resilient to fire, our results demonstrate megafires can significantly alter them, resulting in extensive initial and delayed mortality, and dynamic regrowth. Globally, riparian zones are increasingly exposed to fire, and understanding factors influencing their recovery is critical.