Arsons Near Agoura May Turn Its Hills Into Desert

The arson-caused fires that have been plaguing the Agoura area have done grave--perhaps irreversible--damage to vegetation, raising the threat that some of the charred land could become desert, a Los Angeles County Fire Department expert on chaparral said Friday.

Several hundred acres may be so badly damaged that the lost chaparral will never return, Capt. Scott Franklin said.

The bushy chaparral may be replaced by grasses, permanently changing the ecological balance of the area, increasing fire danger and beginning the process that converts brushlands to desert, known as “desertification,” Franklin said.

A series of 25 fires Los Angeles County sheriff’s investigators blame on arson have broken out in the Agoura area since April, causing residents to organize citizen patrols to watch for arsonists.

The most recent fire burned 100 acres July 2 along Rolling Ridge Drive, about 1 mile north of the Ventura Freeway in Agoura Hills.

Earlier fires burned 75 acres.

Several of the fires moved through areas that were swept by wildfires less than eight years ago, said Franklin, vegetation management officer for the county Fire Department. Franklin studies chaparral conditions and fire patterns and organizes the department’s controlled-burning program.

Some Species Adapt

The chaparral has adapted to wildfires in its life cycle. In fact, some of the brush benefits from burning, which releases seeds. “So under normal fire conditions, the chaparral re-sprouts and begins growing again,” Franklin said.

However, he said, important chaparral species such as wild lilac do not produce seeds until they are 5 to 8 years old. If a subsequent fire strikes before the young plants mature, they die without leaving another generation.

Into the gap move wild grasses and sage, permanently changing the ecological character of the area, he said.

“Looking to the future, five years from now, instead of having green hillsides in the spring and summer, we’ll just have a lot of brown grass” in the affected areas, he said, which will bring increased fire hazards.

“The chaparral doesn’t burn that readily when it’s green, only when it gets older and has dead material, or under Santa Ana wind conditions,” he said. “But the grasses dry out quickly, and they become a constant fire hazard. The volume of fuel isn’t as great, but the grasses create flashier fuel,” quicker to ignite, he said.

“If there are any native oak trees regenerating naturally in these areas, the grass fires will nail them,” he said. “Without the shade from the chaparral, the site becomes drier. The sun beats down on the soil and dries it out like the surface of the moon. The rains come and wash away the topsoil. That’s what brings on desertification.”

The change from chaparral to grasslands has occurred in a number of areas around the edge of the city that have been burned over by back-to-back fires, he said. “Thousands of acres in Brown’s Canyon, above Chatsworth, have gone to grasslands,” he said, following a series of fires in the 1970s and early 1980s.

The same process took place in parts of Canyon Country and in Santa Susana Pass, he said.

Major Wildfires

The Agoura area was hit by major brush fires in 1977, 1978, 1982 and 1985, several of which overlapped, raising the sensitivity of those zones to permanent damage by any more fires.

It is in those zones that the arson-caused fires are most threatening, he said.

For example, he said, he is worried about the Lindero Canyon area “which burned in 1977 and again in 1985.” There is particular concern about the loss of young oak seedlings on the shadier north slopes, he said.

There is also worry about a dozen fires that were set along Agoura Road in a zone that burned in 1978 and 1982, he said.

The arsonist or arsonists probably do not know that the fires are especially destructive, he said.

“I doubt they have that in mind. I think they pick places just because they’re accessible to the road.”

Programs to combat the shift to grassland could be mounted, he said, “but they would be pretty expensive, hundreds of dollars an acre.” The seed is expensive and cannot be sown from low-flying aircraft, as some grasses can, but must be planted by hand, he said.

At present, he said, there are no plans for reseeding efforts.