April 15, 2009
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San Jose State University Environmental Studies Professor Will Russell has fresh data from the 2008 Martin Fire in
Santa Cruz County that contradict the foresters' claims.
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In defining their study parameters, Russell and his students identified three critical forest services--shade, bank stability, and water holding--then conducted a series of measurements along the burned portion of Reggiardo Creek to see how the forest fared by species. They posed the following question:
Which forest type and which tree species exhibit the highest fire resistance in terms of the following measures?
The study assessed residual canopy retention, survival after fire (mortality rate), percent of stem scorch, sprouting response and post-fire recruitment, and organic soil layer development following fire.
They posited that shade loss would be proportional to canopy loss; bank stability loss proportional to root mortality; and water-holding capacity would be a function of soil organic matter depth.
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The redwood community exhibited the highest canopy retention of all species as well as the least tree mortality. Percent mortality was greatest for knobcone pine at more than 90%, closely followed by Douglas-fir, while redwoods showed the lowest degree of mortality with around 5%. Maximum sprout height of redwoods was 1.5 meters, while the maximum for the pine/oak forest was 0.8 meters. The highest density of sprouts was also found in the redwoods. The depth of organic layer, post-fire, was again greatest in the redwood community with a depth of 3.5 cm, while the oak/pine forest exhibited organic layer of just 0.5 cm. Clearly the redwood leaf fall provided superior ground cover, with more organic matter than any of the other tree species.
Overall, the greatest ecosystem services were found to come from the redwoods. They retained the most canopy, thereby providing more shade post-fire; sprouted more vigorously than the other species, indicating more robust root structure leading to greater bank stability; and excelled in water-holding capacity by creating a deeper organic soil layer post-fire than the other vegetation types.
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"Redwoods burn, but they are both highly resistant to fire and able to regenerate quickly after fire, thereby providing the highest level of ecosystem service for streams following fire."
Russell plans to continue the post-fire studies outside of the riparian corridor to see how the various forest types fared in drier, windier locations. He and his students also plan to carry on similar research in the Summit Fire area (burned 2008) in Santa Cruz County.
For more info: jodifredi@aol.com
Jodi Frediani got involved in forest and watershed protection in 1980 when 30 acres of old-growth redwoods were proposed for logging adjacent to her spring and fronting a half mile along Majors Creek in Santa Cruz County's Bonny Doon area. Through her efforts, that forest is now protected as state park land, and her spring continues to produce outstanding clean, clear water. Jodi has remained a strong voice for forest and watershed protection, focusing on timber harvest impacts, particularly those affecting old growth and riparian habitat. Jodi's column in FRN focuses on the effects of fire in forested ecosystems.
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TOC for Forest & River News, Spring 2009