The de-monstering of tamarisk
Posted on | June 17, 2010 | 3 Comments
The USDA Animal and Plant Health Inspection Service this week ceased release and transport of the Chinese or salt cedar leaf beetle because of potential impact on habitat of the Southwestern Willow Flycatcher. Since 1999, the beetles have been introduced along riverbanks in more than a dozen western states to check the spread of tamarisk trees, also known as salt cedars, introduced plants that are thought to displace natives and take too much water. However, incursion by the beetles into Arizonan flycatcher territory last year prompted a lawsuit. At issue: the endangered bird nested in the acclimated tree, which in turn was increasingly being eaten by an introduced beetle.
The decision to halt release of the beetle (Diorhabda elongata) comes on the heels of a series of reports finding that the threats posed by tamarisk to the water supply have been overblown while the plant’s benefits were obscured by the politics of drought. Last year, “The Monstering of Tamarisk” by Arizona State University biologist Matthew Chew characterized the massive federal tamarisk eradication effort as having taken on a life of its own, while a team from the University of Arizona and US Geological Survey reported in Southwest Hydrology that tamarisk “water use is well within the range of native species” such as cottonwoods and willows. This was echoed in April by an USGS study.
The USDA notice via Richard Spotts. Click here for a presentation with good photographs about the impact of beetles in the Lower Colorado by Larry Stevens of the Grand Canyon Wildlands Council.
This post has been updated.
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June 17th, 2010 @ 8:06 am
Still not sure of this… I’ve seen the monocultures myself and find it hard to believe they are not causing a huge impact. Is the water use per plant… because if so Tamarisk will still use a lot more water as it grows denser. I’ve read a lot of papers about this and don’t think anything was ‘obscured’ about tamarisk. It isn’t ‘evil’, it is just a plant… but it certainly seems to have a huge impact where it is invasive.
June 17th, 2010 @ 8:11 am
It looks like their main point is that tamarisk is growing in areas that native species can’t survive due to altered hydrology? It’s probably partially true but I find it hard to believe there’d really be nothing there. The biodiversity seems to take a huge hit. Besides, the willow flycatcher survived for the last millions of years without tamarisk, i think it will be fine without it too.
November 10th, 2010 @ 7:21 am
The wiilow flycatcher’s future may depend on tamarisk. The willows that they like depend on a meandering or braided river system that floods and wipes out old willow trees that the flycatchers will not use and allows new trees to grow. This does not happen on most of our dammed river systems. Our one opportunity might be to use our reserviors to alternatly flood and dry out reservior deltas to mimick this process as happened on Elephant Butte Reservior 4 or 5 years ago. We have caused the expansion of tamarisk by changing the hydrology of the rivers. Tamarisk is not the monster some people have made it out to be and we should not be removing it. We are loosing more riparian vegetation and more bird habitat!