There are no historical records of large fires like the 2006 Sawtooth Fire occurring in
low elevation deserts before the invasion of non-native grasses.
Now, such fires are becoming increasingly frequent, endangering the continued existence
of native desert ecosystems.
Non-native Weeds and Grasses
Threaten Desert Ecosystems with Fire
Sahara mustard (Brassica tournefortii) in the Anza-Borrego Desert. Buffelgrass (Cenchrus ciliaris) throughout the Sonoran Desert in Arizona, purposely brought to the southwest by the U.S. Soil Conservation Service for cattle forage. Foxtail (Bromus) grasses in the Mojave Desert.
All non-native. All providing fuel to power hot, desert fires that never existed before.
These weeds are not only allowing fires to burn, destroying the desert ecosystem, but they also consume habitat space, leaving nothing behind for native species to use.
Efforts are underway to try and control the continued spread of these invasive species, but it is an uphill battle.
Buffelgrass smothers a hillside in the Catalina Mountains above Tucson, Arizona.
A collared lizard tries to get above the Sahara mustard in the Anza-Borrego Desert.
Foxtail grasses fill the spaces in-between desert cacti and shrubs in the Mojave Desert.
Damage Caused to the Desert Ecosystem by Fire
Pinyon pine trees do not deal with fire well and are not coming back in Mojave Desert fires.
Weedy grasses surround desert cacti, providing fuel for fire. Notice black patches in the background. These were patches of weeds that were ignited by embers, burning whatever native cacti/shrub was being surrounded.
A 2013 Cal Fire prescribed burn that got out of control in the San Felipe Valley, California, burning an area that had burned 11 years before. Note the dead 11-year-old Ceanothus shrubs. Typically, there would be dozens of Ceanothus seedlings, but there were not enough seeds in the soil seed bank due to the short time period between fires. Consequently, this area is now devoid of habitat other than mostly non-native grasses. The California Department of Fish and Wildlife, the agency that approved the prescribed burn, said no type conversion was occurring. The data says otherwise.
Embers from the 2006 Sawtooth Fire flew over this large, cleared area and ignited the one native shrub in the area. It was surrounded by non-native weeds, which ignited and killed the shrub. This is an example why defensible space around homes often fails to protect homes during a wind-driven wildfire. Embers will exploit the most vulnerable area.