Scientists from the National Aeronautics and Space Administration and the U.S. Forest Service hope to fly a descendant of the U-2 spy plane high over the Santa Monica and San Gabriel mountains this month to identify the malady that is killing mountain brush, increasing the danger of fires.
Los Angeles County Fire Department officials expressed worry recently over the dying out of brush in the mountains from unknown causes, especially the loss of wild lilac, which acts as a natural damper on the spread of fires.
County fire officials said that as much as 30% of older brush--plants 10 years old or more--has died in some mountain areas from Ventura County to San Diego County.
Planned for Mid-May
Jim Brass, a researcher for NASA at Moffett Field near San Jose, said scientists there are trying to schedule a mission over the mountains sometime in mid-May by one of the agency's ER-2 jet planes, an advanced version of the U-2 high-altitude spy plane equipped with "earth resources" instruments.
The plane would fly over the area at about 60,000 feet, Brass said, mapping it with regular, infrared and heat-sensitive film.
"It's still kind of a question whether the flight will come off, but the probability is high," Brass said.
Flights by the ER-2 are normally scheduled a year in advance, he said, "but the problem with the die-back cropped up in the last few months, and we're trying to address this faster than normal channels could."
It is not clear what is causing the vegetation to die, said Phillip Riggin, a researcher for the U.S. Forest Service who is helping plan the flight as part of his investigation of the dying vegetation.
"It could be a fungus or an insect or a combination of pathogens," Riggin said. "The suspicion is that it's tied to the serious drought we had last year.
"The areas of heavy die-back are also areas of real heavy air pollution." One hypothesis, he said, is that the combination of drought and air pollution so severely weakened the brush in those areas that it lost its usual resistance to disease or insects.
Concern Over Lilac
Firefighters are worried particularly about the death of wild lilac bushes.
"The ceanothus, or wild lilac--that's the main species in which we're getting the die-back, and normally we count on it to hold fires in check," said Capt. Scott Franklin of the county Fire Department. Franklin specializes in vegetation management and supervision of controlled fires, those set by firefighters to remove brush before it becomes fuel for a wild fire.
The wild lilac "has a high moisture content and no oil" in its wood, he said, which makes it so difficult to burn that firefighters count on stands of it to prevent the spread of fires in mountains and canyons.
The lilac also improves the fertility of the soil by adding nitrogen, and it puts down strong roots that help stabilize hill slopes against erosion, he said.
Besides the loss of wild lilac, he said, the die-back has claimed sumac, manzanita and chamise, also called greasewood. The oil-rich vegetation, a fire danger when alive, becomes even more dangerous when dead, he said.
Riggin said an ER-2 crew would begin photographing the San Gabriel Mountains near Claremont and continue westward about 100 miles to the Newhall area, photographing a six-mile-wide strip reaching northward from the edge of the urban area.
The plane would then fly south and photograph the Santa Monica Mountains them from the San Diego Freeway west into Ventura County.
The crew will try to determine where the foliage has died and where it is in danger of dying and look for clues as to why it is dying, he said.