Dale Johnson isn’t a banker. But he likes to use the analogy of making deposits and withdrawals when he speaks about how nutrients interact with his area of expertise, soil chemistry.

“It’s like a bank account,” Johnson said, explaining how nutrients move in and out of the soil, sometimes helped by water, or jump-started even more dramatically by fire.

It’s fire that has caught Johnson’s attention.

For more than 20 years, Johnson, a professor of environmental and resource sciences at the University of Nevada, Reno, has conducted several key studies that have led to a better understanding of the impact of fire on vegetation. His work has led to new soils management strategies at Lake Tahoe. His research first began at Little Valley (above Washoe Valley in the watershed next to Tahoe’s) and then increasingly moved to Lake Tahoe, particularly since 2002 when the Gondola Fire swept through areas near the Heavenly Valley ski area on Tahoe’s south shore.

Johnson still clearly remembers the day in July when it occurred. He was on vacation in Seattle, and happened to see the news. He and longtime colleague Wally Miller had prepared 16 plots in the vicinity of Heavenly that were to be used for a fire/mechanical treatment study related to prescribed burns. The project, though, had stalled out in 2001 due to some bureaucratic red tape.

Then, suddenly, in 2002, the Gondola Fire brought their project back to life.

“I figured, the fire was either not going to reach the plots at all, or it would burn all of them,” Johnson said.

As it turned out, the fire burned 9 of the 16 plots–more than enough to make some key findings.

“Now, we had pre- and post-wildfire, with pre-treatment,” Johnson said. “It was an opportunity to look at how accurate we had been at estimating some things in our earlier work at Little Valley–and we weren’t that far off.”

Johnson and Miller were able to document the effects of a wildfire on vegetation, soils and water quality, comparing the burned plots and the unburned plots.

The Gondola Fire study further confirmed Johnson’s theory that of all the elements in the Sierra, fire is more important than water for nitrogen cycling. This has clear implications for managers who must balance the need for prescribed burns, yet remain mindful that fire can serve as a catalyst for increased nitrogen cycling. When a burned system becomes nitrogen starved, it can become biased in favor of nitrogen-fixing species, which for the Sierra include plants like Snow Brush.

Clearly, the give-and-take, the plus-and-minus, asset-in and asset-out nature of the soils world is what Johnson enjoys.
“You get some cash, but overall the inventory is down,” Johnson said of the effects of fire on nitrogen cycling.

After more than 20 years at the University and more than 30 as a researcher, Johnson isn’t about to slow down anytime soon.

“I’m one of those guys who really enjoys going to work every day,” said Johnson, who fell in love with the field as an undergraduate in forestry at the University of Washington. A summer soil survey job in southeast Alaska made it clear it was what he wanted to do. “I thought, ‘I want to do this,’” Johnson said.