Editor's Note: This article is part of reporter Cade Barker's Wild Southwest Washington series. Find all current installments at https://tinyurl.com/ujkcvepm.
Forty-six years after the catastrophic eruption that forever changed the landscape of Mount St. Helens, the mountain and its surroundings remains one of the world’s most important natural laboratories.
What was once a barren landscape of ash, rock and fallen timber following the May 18, 1980, eruption, has become a living example of ecological recovery, where scientists continue to study how plants, wildlife and even the volcano itself evolve following one of the most destructive volcanic events in U.S. history.
Donald J. Brown, Ph.D., research ecologist and lead scientist for Mount St. Helens with the U.S. Forest Service Pacific Northwest Research Station, said recovery across the blast zone has not followed a single path.
“Plant species recovery and community composition changes over time have been highly variable across the blast zone,” Brown said, “influenced by the type and severity of disturbances caused by the eruption and a wide variety of ecological factors that change across space and time, such as distance to source of potential colonizers, abiotic conditions of the environment, and presence of predators and competitors.”
Wildlife has returned alongside the recovering vegetation, though not every species has responded the same way.
“Generally, animal recovery has followed expectations based on the vegetation and other environmental conditions at a specific location and time,” Brown said. “This has resulted in some regionally rare species being common at Mount St. Helens due to its unusual environmental conditions, such as horned larks.”
Other species have been slower to return.
Brown said amphibians with limited ability to disperse remain absent from much of the disturbance area, while anadromous salmon recovery has been hindered and still require human transportation to reach portions of the upper North Fork Toutle River watershed due to the Sediment Retention Structure.
The landscape itself also continues to change.
“The Mount St. Helens landscape is still very dynamic,” Brown said. “The debris avalanche that occurred on the north side of the volcano deposited over 3 billion cubic yards of volcanic debris.”
That loose material remains vulnerable to landslides, as evidenced by the South Coldwater Slide in 2023, which destroyed the Spirit Lake Outlet Bridge and closed vehicle access to Johnston Ridge Observatory along state Highway 504.
Smaller landslides, shifting stream channels and sediment movement continue to reshape the blast zone. Mount St. Helens remains an active volcano, Brown added, with small eruptions having occurred periodically since 1980, resulting in smaller scale landscape disturbances and a slow rebuilding of the volcano dome.
Brown said the coming decades will offer another chapter in the National Volcanic Monument’s remarkable transformation.
“We expect that over time the Pumice Plain and Hummocks regions will transition back to a mature coniferous forest,” Brown said. “But there is uncertainty about the timelines for that transition across the blast zone, something we are currently studying.”
As scattered conifers begin producing seed, Brown said researchers expect forests to gradually reclaim portions of the blast zone.
“The past 46 years of research at Mount St. Helens has greatly increased our understanding of the complexity of how natural communities reestablish after severe disturbances and has allowed us to test hypotheses based on ecological theory in a real-world system,” Brown said. “At Mount St. Helens, change is the only constant.”
To learn more about Mount St. Helens National Volcanic Monument and its recreation opportunities, visit fs.usda.gov/visit/national-monuments/mount-st-helens.
