Patrick B. Shafroth
Steven R. Lee
Sasha C. Reed
Jayne Belnap
Eduardo Gonzalez
2020
<div id="Abs1-section" class="c-article-section"><div id="Abs1-content" class="c-article-section__content"><p>Reduced abundance of non-native<span> </span><i>Tamarix</i><span> </span>shrubs in western U.S. riparian systems following biological control by a defoliating beetle has led to concerns that replacement plant communities could be dominated by other invasive species and/or not provide some of the ecosystem services that<span> </span><i>Tamarix</i><span> </span>was providing. In previous studies,<span> </span><i>Tamarix</i><span> </span>decline following biocontrol was accompanied by small increases in native and non-native herbaceous species, with variable responses of woody vegetation. However, none of these studies spanned periods longer than a decade since beetle release. This is an important caveat, given the cyclical nature of plant-herbivore interactions and potential lags in vegetation recovery. We report plant community response to an eight-year-long second cycle of<span> </span><i>Tamarix</i><span> </span>defoliation-refoliation in two reaches of the upper Colorado River in eastern Utah, 11–13 years after beetle arrival.<span> </span><i>Tamarix</i><span> </span>cover across sites initially declined an average of ca. 50% in response to the beetle, but then recovered. Changes in the associated plant community were small but supported common management goals, including a 47% average increase in cover of a native shrub (<i>Salix exigua</i>), and no secondary invasions by other non-native plants. We suggest that the effectiveness of biocontrol programs must be assessed case-by-case, and on a long-term basis.</p></div></div><div id="cobranding-and-download-availability-text" class="note test-pdf-link"><br></div>
application/pdf
10.1007/s13157-020-01381-7
en
Springer
Riparian plant communities remain stable in response to a second cycle of Tamarix biocontrol defoliation
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