Monday, August 06, 2007

The End of Tamarisk?

Tamarisk (sometimes known as salt cedar) is an invasive plant species that has wrought great environmental damage in the western United States. This Eurasian native displaces native willows and cottonwoods along streams, uses much more water than they do, and doesn't provide the habitat for birds and animals that the native plants do. One estimate from the Colorado Department of Natural Resources says that tamarisk covers 55,000 acres in the state and uses 170,000 acre feet of water more than the native plants would have. Chas Clifton recently wrote about tamarisk and analogizes its spread with kudzu, an invasive plant species that I grew up with in the South.

Today's Denver Post tells of efforts to fight the tamarisk by introducing one of its natural predators, the tamarisk leaf beetle, from China and Kazahkstan. Test releases of the beetle in Utah in 2004 seem to be promising, and biologists here in Colorado are following a release of beetles in Dinosaur National Monument made the next year.

For me, this is one of those instances where you start looking for unintended consequences. What will these beetles eat after the tamarisk are all gone? Scientists quoted in the article claim that they have demonstrated that the beetles will die out when the tamarisk does. Sounds like the horse has left the barn and we'll just have to see.


dr. hypercube said...

I also worry about introducing exotics to control exotics - that kid's song keeps playing in my head..

There was an old woman who swallowed a bird,
How absurd! to swallow a bird,
She swallowed the bird to catch the spider,
That wriggled and jiggled and tickled inside her,
She swallowed the spider to catch the fly,
I don't know why she swallowed the fly,
Perhaps she'll die.

Ioannis Petrus said...

I would bring your attention to #16 (unintended consequences) in the list of characteristics of a wicked problem:

Peculiar said...

Interesting, Reid. I did several river trips with Tamara Naumann, the botanist in Dinosaur. The beetle release there is basically her baby, and she made a damn good case for it, while acknowledging the possibility that future generations may curse her name. But those beetles were subjected to more study pre-release (well over ten years, I think) than any other deliberately-released exotic. Tamara never claimed the beetle would eradicate the tammies; rather that they ought to knock down populations and then settle into a feast-famine-rebound kind of cycle as part of the landscape, hopefully a less obtrusive part than currently. Also, no native plants in the area are closely related to tamarisk; the nearest relative lives far from water, unlike the riparian tammies. The beetles aren't intended to eat anything else. Finally, one strong incentive to release them ASAP was the spread of tammies up the Yampa from Echo Park and onto the native fishes' spawning beds. The worry is that if the situation doesn't improve soon, the damage to one of the best remaining breedeing zones of humpback chub, Colorado River squawfish (...hem, pikeminnow) and razorback suckers could be irrevocable. They're cool fish, I should blog on them, and it would be a shame to lose them.

That's what I know. Time will tell.

desentell said...

If we don't learn from our history, we are doomed to repeat it.

Haven't we seen this situation before? Just ask the Australians about cats which were introduced to control mice which were introduced to control marsupials...

I understand that the beetles were not "intended" to eat anything else, but they are likely to eventually find something else to munch on, maybe even something tastier than Tamarisk.

I wonder what eats these beetles?

dr. hypercube said...

They're cool fish, I should blog on them

Yes please, Peculiar. (Where the h*ll does the comma go?)

Reid Farmer said...

Thanks, Jackson. I was sure you'd have firm feelings on this as a raft guide and thanks for sharing your inside information. The article also mentions concerns that tamarisk will just move back in after a beetle induced population crash - like the cycle Naumann told you about.

BTW did you ever raft the Green through the Brown's Park NWR? I excavated an 1840s fur trade post on the riverbank there.

Are you guys back in Colorado?

DeAnn - I'm sure there's lots of birds that would be proud to eat these beetles

Chas S. Clifton said...

Odd enough, the Rocky Mountain News, which exists in a joint operating agreement with the Denver Post, did almost the exact same story a year ago, and and I blogged it then. Well, it doesn't hurt to get the word out. We will just have to trust the biologists (gulp) that the beetles are OK. It's not like cane toads, presumably.

Dr. Hypercube: Did you mean, "Yes, please, Peculiar"? (Commas on either side of the interjection.)

dr. hypercube said...

Chas - I did. Thank you.

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