The monstering of tamarisk: how scientists made a plant into a problem.

Dispersal of biota by humans is a hallmark of civilization, but the results are often unforeseen and sometimes costly. Like kudzu vine in the American South, some examples become the stuff of regional folklore. In recent decades, "invasion biology," conservation-motivated scientists and their allies have focused largely on the most negative outcomes and often promoted the perception that introduced species are monsters. However, cases of monstering by scientists preceded the rise of popular environmentalism. The story of tamarisk (Tamarix spp.), flowering trees and shrubs imported to New England sometime before 1818, provides an example of scientific "monstering" and shows how slaying the monster, rather than allaying its impacts, became a goal in itself. Tamarisks' drought and salt tolerance suggested usefulness for both coastal and inland erosion control, and politicians as well as academic and agency scientists promoted planting them in the southern Great Plains and Southwest. But when erosion control efforts in Arizona, New Mexico and Texas became entangled with water shortages, economic development during the Depression and copper mining for national defense during World War Two, federal hydrologists moved quickly to recast tamarisks as water-wasting foreign monsters. Demonstrating significant water salvage was difficult and became subsidiary to focusing on ways to eradicate the plants, and a federal interagency effort devoted specifically to the latter purpose was organized and continued until it, in turn, conflicted with regional environmental concerns in the late 1960s.