Tamarisk trees are changing the Western landscape--drying up rivers and choking off native trees. Can beavers and bugs put a stop to all that?
The Colorado River gorge, flanked by towering cliffs and buttes and bisected by deep canyons, is quintessentially American scenery. Not so the thick vegetation that clings to the banks of the meandering river, in defiance of the desert it cuts through. In many places this luxuriant greenery consists almost entirely of tamarisk trees--which are native not to the American West but to the Mediterranean region and Asia. In the two centuries or more since they were introduced to the West, first as ornamental plants and later as a means of stabilizing stream banks, tamarisks have spread like wildfire. They have colonized at least a million acres of riverbank in Utah, Colorado, Arizona, New Mexico, and Wyoming. With their voracious appetite for water, they have sucked streams and oases dry; growing in dense thickets, they have gone far beyond stabilizing riverbanks and have narrowed the channels, stranding native cottonwood trees and willows far from their water source. Almost everywhere they’ve spread, they’ve replaced the indigenous species.
