Current and projected distributions of Tamarix in North America

Background/Question/Methods

Tamarix, a native plant of Eurasia, has been a successful invader in western North America, and now exists from Argentina to Canada. Two important questions related to management of invasive species such as Tamarix are “where is it now?” and “where might it be in the future?”.  The answers to these questions are particularly important for management of any invasive species, and Tamarix provides an excellent case study to explore methods to answer these questions for an established invader.  We evaluate several methods to map actual and potential Tamarixdistribution including field surveys, online databases, remote sensing, and spatial models.

Results/Conclusions

Mapping of large infestations of Tamarix can successfully be done using remote sensing, although mapping in areas of low Tamarix abundance and high floral diversity is challenging.  To assess current and potential distribution, habitat suitability models are useful.  At a local scale the models can inform local management such as monitoring and control.  Large-scale models such as those for the western United States can help identify general patterns of invasion.  Current implementations of these methods are hampered by data gaps and lack of consistency between existing studies.   While we may never have a perfect representation of actual and potential distribution, these tools can provide useful information to monitor and control invasive species such as Tamarix.