More than four decades after Mount St. Helens erupted, the forests of southwest Washington have largely returned, and much of that regrowth happened without anyone planting a tree. According to WorldAtlas, the mountain offers the most closely studied example of how woodland comes back after being wiped out, with survival stories that played out above ground, below it, and even inside the burrows of small mammals.
The 1980 blast stripped square miles of forest down to bare rock and ash. Yet surviving organisms and a handful of human interventions set the recovery in motion, and researchers have tracked the results ever since.
Why it matters
Wildfires clear American forests every year, and the pressing question afterward is always whether trees will return. Mount St. Helens provides a rare long-term record of that process, showing that recovery depends on what survives beneath the surface as much as on what arrives afterward. WorldAtlas notes that the mountain's regrowth has been shaped by buried roots, snow-covered saplings, soil-dwelling animals, fungi and deliberate replanting — sometimes in the same landscape.
Snow, roots and soil that survived the blast
The timing of the May 1980 eruption mattered. Deep snowbanks still covered small trees on the mountain's upper slopes, and Pacific silver firs and mountain hemlocks endured beneath them, particularly on sheltered ground facing north. When the snow melted, living trees stood among shattered trunks. Those survivors later provided seeds that helped trees spread into the blast zone.
Underground, roots that escaped the heat produced fresh shoots. Fireweed emerged through thinner layers of ash, and huckleberries sprouted from soil still clinging to the roots of fallen trees. In some cases, regrowth began in a clump of earth thrown into the air by the same explosion that destroyed the canopy overhead. Rain carved gullies through the deposits, exposing more buried soil. Where roots had lived, plants could return without waiting for a seed to blow in and take hold.
Lupines, gophers and the slow building of soil
North of the crater, the Pumice Plain presented a harder problem. Hot flows of gas and rock had scoured it clean, leaving none of the surviving roots found elsewhere. Prairie lupine became one of the first plants to gain a foothold. The low flower could grow where nitrogen was in short supply because bacteria linked to its roots pulled nitrogen from the air and made it usable. As lupines multiplied, their fallen leaves added nitrogen and organic material to the ground.
Even dead lupines proved valuable. Their stems trapped seeds carried on the wind, creating small pockets where other plants could establish. Soil under the lupines showed more microbial activity than bare ground nearby, and their seedlings could start fixing nitrogen shortly after sprouting. Many died, but their remains still added carbon and nitrogen to the deposits, so soil kept developing even when individual plants failed.
Pocket gophers also played a part. The animals survived in underground tunnels in parts of the disturbed terrain, and their digging carried buried soil — along with living material and fungi — up into the ash. Some of those fungi partner with plant roots, trading nutrients for carbon from the plant.
WorldAtlas reports that a small 1982 experiment placed a pocket gopher next to a lupine inside an enclosure for a single day. Decades later, soil fungi still differed between plots where that gopher had worked and plots where it had not. Gophers move seeds and fungal spores through their digging and droppings, and as they recolonized the plain naturally, they kept blending volcanic material with biological matter.
Planting by hand and letting nature run
Not all of the forest came back on its own. Weyerhaeuser planted roughly 18 million trees on its land affected by the eruption, with crews digging through ash to set seedlings into the soil underneath. That gave the young trees access to ground buried by the blast.
The planting came after a large timber salvage effort. Crews removed usable wood from the fallen forest before establishing the next generation of trees. These managed stands have developed differently from vegetation inside Mount St. Helens National Volcanic Monument, which was created in 1982 and left largely to recover on its own, keeping dead wood and surviving organisms in place. Planted ground is dominated by conifers, while naturally recovering areas hold more varied clearings and shrubs.
Douglas-firs are adding height on land the eruption stripped, alongside noble firs and lodgepole pines that established themselves. More than 40 years on, researchers found all three species growing quickly in height at the sites they examined. The three grew faster at debris-avalanche sites than where hot pyroclastic flows had passed, a difference that may reflect local climate or the material under the roots.
The Pumice Plain faces its own obstacles. It sits relatively far from intact forest that could supply seeds, and elk complicate matters. The animals bring seeds in their droppings, which helps grasses spread, but they also browse young trees and shrubs repeatedly. That grazing slows the return of forest and helps keep portions of the plain open even as trees take hold elsewhere.
Birds moved in before the big trees
For forest birds, usable habitat arrived long before towering old-growth trees did. About ten years after the eruption, thickets of willow and alder along streams drew yellow warblers and willow flycatchers. By the mid-1990s, some conifers that had hidden under snow had grown into dense young stands where hermit thrushes could feed under cover. Maturing cottonwoods gave warbling vireos and black-headed grosbeaks places to nest and feed. Dead trees left standing also provided habitat as new woodland grew around them, with mountain bluebirds nesting in cavities in those trunks — remnants of the forest killed in 1980.
What to watch: how the planted conifer stands and the naturally recovering monument lands continue to diverge, and whether elk browsing keeps parts of the Pumice Plain open as trees spread across the rest of the blast zone.
