Cal Poly is no stranger to fires. The Poly Fire in September 2017 burned 105 acres near the ‘P,’ and the Reservoir Fire — the combination of two brush fires — burned a total of 51 acres in September 2018.

For many students, their only concern when fire strikes is their own well-being. For a plant biology professor and his students, this is not the case.

Fire is a natural occurrence and is even necessary for some seed types to sprout. However, the fire retardants that come along with the fires are not, associate professor of plant biology Nishi Rajakaruna said.

“The fire went through soils derived from serpentinite and meta volcanic rocks on both cool north- and hot south-facing slopes on Poly Ridge. I couldn’t have asked for a better research setting to investigate how fire influences vegetation patterns on distinct soils and microclimates,” Rajakaruna said.

For the past year, Rajakaruna and his students have been conducting a survey of the hills marked by fire to study the growth of both native and non-native species of plants. The hillside’s geology, composed of rocky serpentine and nutrient-rich meta-volcanic rock, was what first sparked Rajakaruna’s interest, he said.

The initial results of Rajakaruna’s study show that the fire retardant used in the area, Phos-Chek, is actually lowering biodiversity. There is currently no alternative to this retardant.

“About 12.5 percent of California’s endemic species are only found on serpentine soil. It is a harsh environment and plants that can tolerate it can get isolated and over time become their own species. Serpentine outcrops, like those up Poly Ridge, are plant diversity hotspots,” Rajakaruna said.

Endemic species are species of plants that are native to a specific county or area, making them very susceptible to change in their environment. A change that fire and fire retardant, subsequently, bring.

“[Phos-Chek] is used throughout the world. We are the only fire retardant manufacturer, on a large scale, in the world,” Product Stuart and Technical Representative for Phos-Chek George Matousek said.

According to Matousek, the makeup of Phos-Check is 90 percent ammonium phosphate, which is the main component of fertilizer. This means the retardant used is highly nutritious and upsets the preexisting balance in the geology of the hill.

After the fire retardant floods these specific geological areas with nutrients, the native species — which are more accustomed to low nutrient environments — don’t grow as well. This causes more non-native species to grow in place of the native species and lowers biodiversity.

Rajakaruna inspired his students to continue the study to see what the ultimate effects on biodiversity are. 

“I don’t know if there has ever been a project at Cal Poly with just so many people on board with so many different departments and backgrounds,” said environmental earth and soil sciences junior Zach Raposo. “Honestly, I think that was one of the coolest things, just meeting all of those people and how we had a common ground and just the passion for a really cool opportunity.”

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