Thirteen years ago, I witnessed a new, hard-edged
ecology that operates in the West. I was sitting in the stands of
our small rodeo arena, watching irritated bulls throw off a
succession of young men like so many rag dolls, when a bolt of
lightning ripped the sky, striking the juniper-clad ridge across
the valley. The next day, as the winds whipped up, a smoldering
tree erupted into a crown fire that raced across several thousand
acres.
When the smoke cleared, the geography of the
fire-burned land was as plain to see as a missing piece of jigsaw
puzzle: A forest had become an open desert.
The Bureau of
Land Management dropped seed on the site that fall, and by the
following year, some grasses had re-established themselves. The
most ubiquitous species, however, was one the agency had not sown
and had hoped to exclude: Cheatgrass, a Eurasian import that
thrives on fire and is green for only a few weeks in early spring,
quickly took over the burned area and has remained there ever
since.
Will a forest ever return to our ridge? Probably
not in my lifetime, because cheatgrass has altered its ecology.
That fact was driven home last summer, when another lightning
strike set off a cheatgrass-fueled fire in the original burn area,
killing native shrubs and trees trying to regain a foothold and
reinforcing cheatgrass’s dominance.
Western ecologists –
and this publication – have argued vigorously that we must embrace
fire to restore our native ecosystems. It’s an attractive idea,
particularly given that efforts to suppress fires over the past
century have provided the fuel – in the form of dense stands of
trees and shrubs – for the fires that now burn so ferociously. But
to simply embrace fire without considering the new ecological
context humans have created via the introduction of exotic plants
and pests is naive. Today, fire can lead as often to ecological
conversion as to restoration.
That’s certainly the case
with Arizona’s Sonoran Desert, where, as Michelle Nijhuis reports
in this issue, an African native called buffelgrass has rapidly
spread into the cactus-studded hills surrounding Tucson and
Phoenix. Like cheatgrass, buffelgrass thrives on – and fuels –
fires that are lethal to native flora. Despite the valiant efforts
of dedicated buffelgrass pullers, the Sonoran Desert of the future
will likely look more like a dry African savanna than a desert.
So, should we go back to our Smokey Bear mentality and
put out every fire we can? No. By now we know that there is no
cookie-cutter approach to maintaining healthy native ecosystems.
Fire will happen in the West, no matter what we do, and fire
thoughtfully marshaled can reinvigorate our forests, particularly
at higher elevations.
But exotic species are here to
stay, and keeping them from overrunning native ecosystems will
require a multipronged strategy, including fire suppression, the
judicious use of herbicides, and, ironically, the intentional
planting of other exotics. In Utah, researchers were excited to
discover that a plot of rangeland planted with an Asian shrub after
a 1984 blaze remained unscathed when this summer’s massive Milford
Flat Fire passed through, the Salt Lake Tribune
reports. Forage kochia is not only fire-resistant; it spreads
slowly, competes well with cheatgrass, and provides shade and
stable soils for native plants.
Fighting exotics with
other exotics does not have the clean-edged ecological appeal of,
say, letting a lightning-caused fire just do its thing. But in this
complex battle, we need to look at every tool available.
This article appeared in the print edition of the magazine with the headline Fire: Friend and foe.
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