The Monstering of Tamarisk: How Scientists made a Plant into a Problem

Abstract

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.

Population genomic analysis suggests strong influence of river network on spatial distribution of genetic variation in invasive saltcedar across the southwestern United States

“…Human introductions during early colonization may have strongly influenced the large‐scale patterns of saltcedar population structure. Planting of saltcedar by various government and private entities was prevalent during the early 20th century (Carleton, ; Chew, ; Robinson, ). In fact, during the Great Depression, government experts encouraged the planting of saltcedars to control inland and coastal soil erosion (Chew, ).…”

Potential for water salvage by removal of non‐native woody vegetation from dryland river systems

“…In the USA, investigations into removal of non‐native vegetation to increase water supply were first initiated in the 1930s (Chew, ), based on the perception that large quantities of water could be salvaged for human use (Shafroth et al , ). We define water salvage as increased water available for human or environmental beneficial use (both subsurface and surface waters) as a consequence of vegetation and land cover change resulting from removal or reduction of introduced vegetation (Nagler et al , ).…”

Towards a sociogeomorphology of rivers

“…As has been argued by some biologists in the case of approaches to "invasive" species (e.g. Chew, 2009), scientists may not be neutral participants and observers. There are important implications here for the way that geomorphologists see their role and knowledge, interact with others, and approach alternative "ways of knowing" the landscape and this is something that needs greater attention in geomorphic research (see Tadaki et al, 2014a) It should also be understood that, in the physical conception of the river, there are alternative visions, based in river dynamics, but building on principles that are not solely geomorphic.…”