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| Abstract Title:
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| Dealing with neighbors: Property boundaries hinder invasive species control
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| Graduate Student Presenter:
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Rebecca Niell
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| Name of the Author(s) and Affiliation(s):
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Rebecca Niell, Univerisity of California, Davis (U.C. Davis); James E. Wilen, U.C. Davis; Clare E. Aslan, U.C. Davis; Matthew B. Hufford, U.C. Davis; Jason P. Sexton, U.C. Davis; Jeffrey D. Port, U.C. Davis; Timothy M. Waring, U.C. Davis.
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Biological invasions are rarely confined to a single management area, but rather spread across property boundaries and involve multiple land managers. We employed both interviews of land managers (ranchers) and a simple bioeconomic model to address the questions:
1.) How do land divisions and multiple managers affect regional control of invasive species?
2.) How do interactions among managers affect management success?
Our model shows that dividing an equal-sized area among greater numbers of managers leads to faster invasions for two reasons. First, each manager only considers damages on his own land when making control decisions; this reduces his likelihood to control. Second, if one manager opts not to control the invasion, then his neighbors’ control costs increase due to the constant source for reinvasion, reducing the neighbors' likelihood to control. In this way, division of land promotes invasions relative to the single manager case. However, results also show that cooperation among managers helps to mitigate these effects. In support of these results, one quarter of interviewed ranchers explained that they control less than they would if they didn’t have a neighboring source because reinvasion increases their control costs. Two thirds of ranchers stated the need to coordinate control efforts across management areas in order for control to be successful. Indeed, some ranchers had developed cooperative weed control solutions with their neighbors. These results provide evidence for the importance of land divisions in influencing biological invasions and the need for the coordination among managers in the control of invasive species.
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