USA — With California’s fire season looming, the cold lens of a satellite camera may not be the image people conjure as the latest tool to halt the spread of devastating wildfires.
Perhaps they should.
Across California’s grasslands and a widening stretch of the West, invading species of plants like cheatgrass and Medusa head rye make deadly wild fires more frequent and burn more intensely, destroying property, spewing greenhouse gases, and ruining the interdependent fabric of grasses, birds, insects and other animals. Last year, California lost over 900,000 acres to wildfires on national forest land alone more than triple the average annual losses over the previous 38 years.
But now, as a result of a happy accident of collaboration, Bay Area scientists for different federal agencies, who might never have met, are using satellite technology to track and attack the non-native grasses that are spreading across the West and fueling the fires.
Dave Bubenheim, a plant physiologist at NASA/Ames Research Center in Mountain View, and Ray Carruthers, an entomologist and population ecologist for the U.S. Department of Agriculture inAlbany, met in 2001. That’s when the technician who serviced both of their plant growth chambers introduced them and kicked off a solid scientific relationship.
Today they are directing a powerful weapon against those invasive plants that are accelerating the frequency of wildfires from twice a century to twice a decade over wide stretches of the West.
Bubenheim, a self-proclaimed “plant guy” who once specialized in growing plants in space to feed and provide oxygen to astronauts on missions to Mars, had the expertise to figure out how satellite sensors could differentiate an invasive species from surrounding natives.
And space provided a new vantage point for Carruthers, an ecologicalIndiana Jones who globetrots fromThailand to Uzbekistan to the Mediterranean tracking down parasites and infectious agents that can be used against invasive plants. Satellites, Carruthers quickly saw, could not only spot invaders in the back country, but could reveal whether the biological weapons he was using against them were working.
Satellite imagery and sensing, the scientists say, is a powerful tool against many invasive species that cause about $120 billion in economic damage each year, including invaders such as yellow star thistle, which has infested 22 million acres in California and can cause brain lesions in horses that eat it; salt cedar, which crowds out all other plants along Western streams, destroying the natural diversity of thoseecosystems; and pampas grass, which also squeezes out native species.
“All the things I would have liked to have done the things I had dreamed about he could do those here,” Carruthers said recently, standing with Bubenheim outside one of the large metallic growth chambers at Ames where the NASA scientist had once simulated a closed ecosystem to support astronauts in interplanetary space.
Grasses dry out
In about a month, annual grasses like Medusa head that have spread to California from Europe or Asia will likely begin to dry out, much sooner than perennial native grasses do.
“Because they are always dry during the summer, fire frequencies have changed in much of the Western United States to once every couple years, from once every 50 years,” said Joe DiTomaso, a weed scientist at the University of California-Davis who notes that the invasive grasses are a major problem because they form a “fire continuum that allows fires to start easier and to move farther.”
With a topography that goes from below sea level to the highest mountain peak in the lower 48 states, from the rainy forests of the north to the baked deserts of the southeast, California has the highest biodiversity in North America. But the state’s range of climates also creates opportunity for plants from Asia, Europe and Africa. And with California’s growing population placing housing developments close to wilderness lands, “we’ve created this conduit for invaders,” said Kristina Schierenbeck, an Agriculture Department plant scientist who studies invasive weeds.
In the past, the Agriculture Department tried to use aircraft to spot outbreaks of invasive plants. But when a species like cheatgrass “jumps to half the state of Nevada, NASA technology is much more practical,” Carruthers said. A rapid response directed from space may be the best hope for stopping some invasive species.
“If you stop an outbreak, or a dispersal event, you can prevent them from merging together,” and causing a much larger problem, Schierenbeck said.
Once scientists pinpoint an outbreak of an invading species, they might introduce the predator whether an insect, fungus or pathogen that controls the species in its native environment. Satellite imagery can then be used to study whether the control measures are working.
While federal damage estimates from invasive species run to more than $120 billion a year, the cost can’t be measured in money alone. The Nature Conservancy says the Great Basin is the nation’s third-most-endangered ecosystem in part because of cheatgrass, which not only worsens wildfires but also outcompetes with native grasses after a fire, compounding the problem.
To differentiate one grass from another from space, Bubenheim’s team uses an array of NASA satellites that regularly measure changes in soil moisture, temperature, and the reflectivity of plant leaves in a much wider spectrum of light than what’s visible to human eyes.
Part of the space-detective work is about watching how vegetation changes over time, not just what plants look like at one given moment.
“You can’t just look at a picture, and go, ‘That’s star thistle.’ You have to tease these things out,” Bubenheim said. “Part of the clue is the time of flowering, and the growth rate.”
Bubenheim and Carruthers have their eye on many other invaders, including emerging problems like buffel grass in Arizona, which Bubenheim said could threaten an iconic symbol of the West, the slow-growing saguaro cactus.
“It could push the saguaro right out of Saguaro National Park,” Bubenheim worries.
Scientists from the two agencies will meet later this month in the Bay Area to search for ways to battle other invasive plants. While the start of their collaboration was a happy accident, Bubenheim and Carruthers want NASA and the Agriculture Department to make more systematic use of space to battle invasive plants.
“Without that,” Carruthers said, “we can’t get the scope of the problem.”