Thursday, February 14, 2008

II. The War on Invasive Species

comment on Bonfire of the Superweeds. In the Sonoran Desert, good intentions combust. FEATURE ARTICLE -

...and A dustup over weed control. The BLM's plans to spray nearly a million acres with herbicides have some environmentalists fuming, but many biologists and land managers welcome the policy. WESTERN ROUNDUP -

...and Beetle Warfare. What happens when an exotic bug is brought in to fight an exotic weed?
Invasive species are a huge problem in the Southwest and these articles highlight a number of the major culprits: Buffelgrass, Lovegrass, Cheatgrass, and Tamarisk. These interlopers cause upwards of $120 billion dollars of damage a year and are reason almost half of the species on the Endangered Species List are endangered (Pimentel, 2004).

In the Sonoran desert around Tucson, particularly the front range of the Santa Catalinas, I have witnessed the utter devastation that a climax-changing invasive can bring to native ecosystems. Where Buffelgrass grows it chokes out native Saguaros, and worse still, creates conditions perfect for wildfires. Since the grass is adapted to fire and the native Sonoran plants are not, this feedback cycle creates exponential growth of Buffelgrass at the expense of the former ecosystem.

I have also been witness to the seeming-futility of manual removal of Buffelgrass as a member of the Tucson chapter of the Arizona Native Plant Society. But what are the alternatives? The second article points up the contradictions of spraying herbicides to try to save the native ecosystem in a kind of logic akin to the Vietnam war's "It became necessary to destroy the village in order to save it." There are certainly many benefits to chemical treatments, and it is not clear how to interpret the Precautionary Principle in this case of "damned-if-you-do, damn't-if-you-don't".

I am again confronted with the enormity and seeming-futility of manual removal in my work with Forest Guardians removing Tamarisk, a large tree that dries up rivers throughout the West, choking the native riparian ecosystem. We exhaust ourselves pulling up every piece of a plant that can propogate from bits of root just a few inches long. But what are the alternatives? I for one am personally glad Forest Guardians doesn't use chemical treatment, and there are many indications that chemicals, especially one-time applications, are not effective, either. The third and last article in this comment suggest the use of another invasive species. Invasive species are, by definition, species that have escaped the natural checks and balances of their native ecosystem. So why no bring some of those naturally evolved checks to give the Tamarisk a taste of their own medicine? But Jim Matison of Forest Guardians explains: 'Two species do not an ecosystem make.' According to Jim, introducing another non-native is just another example of our hubris replaying the same old mistake; believing that Science can predict all possible interactions and ramifications. In other words, playing God.

But, maybe, aren't we already playing at judge and jury when we decide which ecosystem (Buffelgrass vs. Sonoran, Tamarisk vs. Riparian) is good and which is bad, which plant lives and which plant dies?

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