How We Created a Monster In the American Southwest

The salt cedar is often seen as an un-killable invader. But are humans the real reason this unwanted plant is thriving? 

By the time the Salt River reaches downtown Phoenix, it is a river in name only. Some scientists think that is why a non-native plant, the salt cedar, is thriving while native flora are suffering. (Audra Arbas)

By Candace Hughes

smithsonian.com October 9, 2015

Around 6:30 on a weekday morning, planes departing Phoenix International Airport scream over the Salt River every few minutes.

The constant roaring over this riparian area is only one example of how the riverbed ecosystem is changing. Two hundred years ago, the Salt River would have been regularly scouring the banks to wash away salty soil, while cottonwoods, willows, mesquite and native grasses would have been flourishing.

Now it is rarely a free-flowing river throughout its system; dams and drought have dried it up. Part of the riverbed has been bulldozed to channel floodwater and control mosquitoes, and tire tracks are visible in the sand. There is just one cottonwood, and some Australian willow acacia, buffelgrass and mesquite are still visible. There’s also fan palm growing along with non-native salt cedar.

To some environmental groups, the salt cedar, a wispy bush with feathery pink flowers that attract bees, dragonflies and hummingbirds, is the scariest sight on the river. Read more.

See also: http://www.smithsonianmag.com/science-nature/how-we-created-monster-american-southwest-180956878/#5mFgx4Lp1jp5UxfE.99