OOS 22-4 - Recent insights into invasion and control of Tamarix spp. in the American West

Tuesday, August 16, 2022

4:15 PM – 4:30 PM EDT

Location: 524A

Presenting Author(s)

AG

Alexander R. B. Goetz

PhD Candidate
Denver University
Denver, CO, United States

Co-author(s)

AG

Alexander R. B. Goetz

PhD Candidate
Denver University
Denver, CO, United States
EG

Eduardo González, PhD

Colorado State University, United States Geological Survey
AH

Annie L. Henry, PhD

University of Denver
AS

Anna A. Sher, PhD

Professor
University of Denver

Background/Question/Methods
Control of invasive Tamarix spp. has long been a priority for management in western North America. In recent years, approaches have shifted away from eradication as a goal and toward a more nuanced view of the species. In the last decade, we have investigated multiple dimensions of Tamarix invasion and control, examining restoration practices and their outcomes. (1) Using several datasets of riparian restoration projects throughout the Southwest, we have characterized the taxonomic and functional vegetation response to multiple treatments and on multiple scales. (2) We have studied the spatial relationships that the spread of a Tamarix biocontrol agent (Diorhabda beetles) have caused in Tamarix dieback and mortality. (3) Our third line of interest are the human dimensions of riparian restoration projects in the Southwest.

Results/Conclusions
(1) Active removal of Tamarix is broadly effective at creating the conditions needed for reestablishment of native species (and more effective than passive biocontrol via Diorhabda beetles), but recovery is slow, context-dependent, and disturbance from removal can also allow for secondary invasions of other weedy species in the short term. Tamarix cover covaries with macro environmental factors such as climate and elevation, and with local factors such as flooding regime, to explain not only taxonomic but also functional plant composition (2) Spatial modeling can identify patterns of Tamarix dieback not explained by environmental factors alone and presumably caused by Diorhabda beetle defoliation. (3) There has been effective communication between researchers and practitioners translating to more effective management. Some aspects of managers’ backgrounds are associated with on-the-ground outcomes. We are currently working investigating psychological reactions and perceptions of people exposed to images with different plant diversity in Tamarix and non-Tamarix dominated riparian sites, to assess the aesthetics of riparian systems as providers of cultural ecosystem services.