“ORV impact on the desert is huge, according to wildlife experts”

Published in the Hi-Desert Start – October 5, 2007

Guest soapbox: Trashing a gift

By Russell M. Drake / Yucca Valley

Amid growing public clamor about the effect of off-road vehicles on humans (noise, dirt, vandalism and so forth), relatively little has been said about the ORV effect on the desert and the animals who inhabit it.

Within easy reach of the Mojave Desert are 595,781 ORVs registered by the Department of Motor Vehicles in seven Southern California counties, more than half of the 1,101,980 registered in the entire state.

ORV impact on the desert is huge, according to wildlife experts.

“Few vehicles could be found that are more effective in damaging soil and plant life than knobby-tired, powerful dirt bikes and four-wheel drives,” says Cal Berkely professor emeritus of zoology Robert C. Stebbins in a paper published in “The California Desert,” a 1995 book on man’s impact on the desert. “When off-road vehicles are used repeatedly in a limited area they can be utterly devastating,” says Professor Stebbins.

“It takes not more than a week for coyotes to quit denning and leave. Birds will leave even quicker,” under the impact of off-road vehicles, says Paul De Prey, Chief of Resources, Joshua Tree National Park.

“ORV activity is a destructive recreation,” says Michael Vamstad, Joshua Tree National Park wildlife ecologist. “Off-road vehicles are contributing to a lot of displacement of wildlife, particularly owls and hawks. The loss of land and resulting fragmentation of animal populations is the greatest threat to any species right now. The whole ecosystem gets thrown out of whack.”

Probably nowhere else can ORV destruction be seen so clearly as on one square mile of desert owned by the Town of Yucca Valley about five miles north of the town center. Called Section 11 by the town, and the Landau Gift by others, the land was given to Yucca Valley by Elizabeth and Edward Landau of New York City in 1996. About a third of the parcel was destroyed by a fire of unexplained origins Aug. 5, 1995.

The fire was followed by an invasion of dirt bikes, quads, pickups, four-by-fours, dune buggies, sand rails and Jeeps. Sheriff’s deputies and code enforcement officers say off-roaders are attracted to land cleared by fire because it’s easier to drive than native desert scrub.

Nesting red-tailed hawks and great-horned owls with five-foot wingspreads disappeared from Section 11, vanquished by the noise and stink of off-road vehicles. Threatened desert tortoise and other burrowing animals are uniquely vulnerable to death by ORV “dirt sports,” which crush their burrows, trapping them inside, or kill them outright.

Even light or moderate ORV traffic can cause lasting damage to wildlife and soils. The damage can be seen in the “edge effect” and the cryptobiotic crust, a one-quarter-inch thick “carpet” of nutrient-rich top soil that is critical to desert plant and animal life. The delicate crust is in a constant battle for survival with natural forces and when further compromised by dirt bikes can be converted into shifting sand dunes.

The “edge effect” of vehicle traffic propagating from roads like a wave into surrounding terrain has a ruinous impact on plants and animals alike. In this area, says Paul De Prey, native grasses lose the competition for water and nutrition to non-native species, such as red brome grass, which doesn’t decompose as quickly as native grasses. Instead, red brome dries out, its stalks becoming “flash fuel” that increase the frequency and size of wildfires. The effect is multiplied by roads and systems of roads created by ORV traffic on lands adjacent to highways.

“The decrease in the population of animals in a highway edge area has a trickle effect out into the desert. Put in another road, say a dirt bike trail that through repeated use becomes a road, and animal population between the roads is wiped out,” says De Prey.

Renewal of cryptobiotic crusts can take from 50 to 250 years. A destroyed ecosystem may require over 3,000 years for complete recovery, say co-authors Jeffrey E. Lovich and David Bainbridge in a 1999 article on the effect of human activity in the Southern California deserts.