Tamarisk Beetle Report Released by Tamarisk Coalition and CMU Water Center

January 25th, 2016
Tamarisk Beetle Report Released by Tamarisk Coalition and CMU Water Center
Grand Junction - The non-native tamarisk plant has invaded hundreds of thousands of acres of floodplain and riparian bench areas across the western United States, often pushing out native plants and altering ecosystems. Since its release as a biocontrol agent in 2001, the tamarisk beetle has spread rapidly and caused widespread tamarisk defoliation. This can benefit riparian restoration efforts, but also harm vulnerable species that use tamarisk as habitat. 
A new report entitled Tamarisk beetle (Diorhaba spp.) in the Colorado River basin: synthesis of an expert panel forum, released by the Ruth Powell Hutchins Water Center at Colorado Mesa University and the Tamarisk Coalition in January 2016, presents information on the probable ecological impact of the tamarisk beetle’s spread and identifies key factors to consider when selecting riparian restoration actions where the beetle is likely to become established.  The report summarizes the results of a two-day discussion by an expert panel convened by the Tamarisk Coalition and subsequent peer review of the panel’s findings. 
The report concludes that:
·         Tamarisk beetles are likely to spread throughout the entire Colorado River Basin, resulting in the decline, but not elimination, of tamarisk.
·         The impact of tamarisk decline on native plants in a particular area depends largely on how much stream flows and soil conditions have changed from historical conditions, as well as what native plants remain.
·         Over time, the beetle should reduce wildfire risk and intensity
·         As tamarisk declines and decreases its hold on riverbanks, channels are likely to become more mobile, particularly in stream systems with natural cycles of high and low flows. 
·         Wildlife that use tamarisk-dominated habitats may face short-term risks as tamarisk declines, but long-term benefits if native habitat is restored.
·         Conservation plans that assume that tamarisk will continue to be dominant in certain areas may need to be revised to consider the beetle’s impacts.
·         The beetle, in combination with other restoration measures, can play an important role in making southwestern riparian ecosystems more functional. 
 The expert panel consisted of these six scientists with expertise in several relevant disciplines:
·         Dan Bean, a biological control entomologist with the Colorado Department of Agriculture Palisade Insectary.
·         Anna Sher, a riparian ecologist at the University of Denver.
·         Rebecca Manners, a fluvial geomorphologist at the University of Montana.
·         Osvel Hinojosa Huerta, a wetland and avian ecologist for Pronatura Noroeste.
·         Matt Johnson, an avian ecologist at the Colorado Plateau Research Station and Northern Arizona University.
·         Patt Shafroth, a riparian ecologist with the US Geological Survey.
This report is the first in a new series of scientific and technical reports published by the Hutchins Water Center.  The panel discussion and report were funded by a grant from the Walton Family Foundation.  The report is available at www.coloradomesa.edu/Water-Center ; hard copies are available upon request.

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