July 18, 2006

Experts blame grasses, pollution, temperatures for helping fires

By Andrew Silva, Writer
Inland Valley Daily Bulletin [Ontario, CA]

It's not supposed to happen.

Mojave National Preserve: 71,000 acres in flames a year ago.

Joshua Tree National Park: 14,000 acres burned in 1999.

And in the past week, more than 80,000 acres have gone up in smoke as two large fires merged in the Mojave Desert.

In a pine forest, fire is an integral part of the life cycle and is necessary for a healthy, thriving forest.

But in the desert, flames are an unnatural, unwelcome and destructive force when they roar through Joshua trees, cactuses, juniper and pinyon trees.

"In our lifetime, we won't see it back the way it was," said Larry Whalon, chief of resources management for the Mojave National Preserve.

Desert plants may be the hardiest on earth, able to thrive in blistering temperatures and long stretches without water. The harsh conditions also mean it takes a long time for the plants to grow and establish themselves, usually with wide spaces between them.

Sprawling infernos in the desert are a phenomenon not seen until recent decades.

The obvious culprits are grasses that weren't here 200 years ago. Air pollution and average temperatures that have been creeping higher may also be accomplices.

The arrival of settlers in the 19th century also meant the arrival of non-native grasses that have blanketed the desert floor.

In the past, "a lightning strike had a good chance of hitting bare ground," said Joe Zarki, chief naturalist for Joshua Tree National Park.

Some grasses spread across the landscape once seeds carried by non-native settlers and livestock hit the ground. Others were planted deliberately for cattle grazing.

Native grasses and flowers in the desert tend to dry up and blow away when they die, or they remain isolated in bunches.

The exotic grasses, though, remain standing, even after they die.

"In a good wet year like last year, it'll create a carpet" across the desert floor, Zarki said. "Nowadays, lightning is going to hit these fine fuels that ignite easily."

Before, even if lighting struck a tree or patch of shrubs, that small area would burn but there was no way for the flames to move between plants.

The Sawtooth Complex Fire, which destroyed several dozen homes in Pioneertown, is an example. Drive through the burn area and there's mostly a fine layer of ash on the otherwise bare ground where grasses had carried fire to the widely spaced Joshua trees and other native plants.

"Oaks, juniper, Joshua trees don't appear to do well in response to fire," Zarki said.

The ecosystem that exists in the desert now took hundreds of years to get established. A pine forest will look pretty normal a few decades after a fire.

However, desert trees can take hundreds of years to grow.

If the grasses lead to fires every five, 10 or 15 years, the landscape could be altered permanently in a phenomenon called "type conversion," Zarki said. With frequent fires, the native trees won't be able to re-establish themselves, turning the desert into a scrubby grassland.

"Talking about the natural ecosystem in California is like talking about the dodo bird," said William Patzert, a climatologist with NASA's Jet Propulsion Lab in Pasadena.

That appears to go for climate as well.

Temperatures have been rising in the West since the 1970s, and many temperature records have been set in recent years.

Southern California, despite near-record rains in the winter of 2004-05, is effectively in its eighth year of drought, Patzert said.

Part of the increase in temperatures is because of sprawling development. Heat is trapped by the hundreds of square miles of concrete and asphalt, creating what have been dubbed "urban heat islands."

Patzert called it Southern California's "extreme makeover."

The Inland Empire has seen a 5-degree jump in average temperature in just 50 years, he said.

Kelly Redmond, a regional climatologist with the Western Regional Climate Center in Reno, Nev., said he was skeptical that the temperature increase since 1970 was real.

But after looking more carefully at the data and other climate indicators, such as snow melt and when flowers bloom, he now believes the increase is broad and genuine.

His research indicates temperatures across 11 western states have increased an average of 2 degrees since 1970. June was the warmest in 25 years and July appears to be headed for a record also, he said.

At least part of that increase could be attributable to global climate change, the experts said.

To make matters worse, take blistering temperatures, combine them with non-native grasses and mix in some fertilizer. And air pollution could actually be feeding the grasses and helping them spread.

Air pollution is loaded with nitrogen compounds, providing a readily available fertilizer, some researchers have said.

"Without nitrogen, the grasses aren't doing that well," said Philip Rundel, a biology professor at UCLA. "We're doing a massive fertilization experiment and don't know it."