Riparian vegetation layers differ three years after mixed severity wildfire in Oregon

https://doi.org/10.1038/s41598-025-20242-z

Scientific Reports 2025

Authors
Laura J. Six, Weyerhaeuser
Jake Verschuyl, National Council for Air and Stream Improvement, Inc.
Ashley A. Coble, National Council for Air and Stream Improvement, Inc.

Abstract
Riparian ecosystems are highly diverse and dynamic, but effects of fire on riparian vegetation are poorly understood. In 2020, widespread wildfires 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 wildfire 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 wildfire, 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 wildfire, and understanding factors influencing their recovery is critical.

Keywords: Fire ecology, Forest ecology, Riparian ecology