Two years after Mount St Helens erupted in 1980, a team of researchers helicoptered in a gopher to the ash-covered landscape. Decades later, the activity of that single gopher burrowing for a single day may have helped the decimated ecosystem regrow by boosting the diversity of soil fungi.
鈥淭here鈥檚 something to be said about learning lessons from the gophers,鈥� says at the University of Connecticut, who has used the eruption to understand how forests might recover from other stresses 鈥� including wildfires and clearcutting, a logging practice in which almost all of the trees in an area are removed.
The gopher in question was a northern pocket gopher (Thomomys talpoides) native to the area. After being airlifted in, it was placed in an enclosure in a formerly forested area deeply buried by pyroclastic flows 鈥� now known as the Pumice plain 鈥� and given 24 hours to dig around and defecate in the sterilised landscape. Other gophers were brought to other enclosures in the area, again spending just one day there. 鈥淏ringing them there was like bringing a mini-ecosystem just for a short time,鈥� says Maltz.
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More than four decades later, Maltz and her colleagues surveyed the microbial diversity and chemistry of the soil in the gopher enclosures, while also conducting similar surveys of the soil in nearby areas that weren鈥檛 exposed to the gophers. The researchers also surveyed soil in several areas that weren鈥檛 as deeply buried as the Pumice plain, many of which had been old-growth forest and one of which had been clearcut by loggers prior to the eruption.
They found that the soil from the various sites differed in striking ways. For instance, gopher-exposed soil contained a greater diversity of fungi than even the former old-growth forest areas, especially the mycorrhizal fungi that colonise plant roots and can prevent disease and help plants access nutrients. The old-growth areas, meanwhile, contained more of this fungal diversity than the clearcut areas. 鈥淚t was remarkable how different these communities were,鈥� says Maltz.
This microbial diversity in turn seems to have supported more vegetation in gopher-exposed areas, preventing soil erosion there in ways that are still visible four decades after the gophers were helicoptered away. By digging up fungal spores buried by the ash flow, as well as by introducing microbes living behind their claws and in their droppings, the gophers 鈥渨ere bringing little pockets of productivity to the surface鈥�, says Maltz.
A similar approach might be used to restore forests after wildfires or clearcuts, either by perturbing the soil or by introducing soil from intact sites.
In terms of soil building, 40 years is a blink of an eye, says at the University of British Columbia in Canada. 鈥淭hose are still fresh, baby, newborn soils.鈥�
Frontiers in Microbiomes
