Caleb Arika, Donald Wyse, John Nieber, R Moon
Report no. Mn/DOT 2009-28
In 2008 a Phase II implementation project was conducted to test whether presence/absence surveys could provide accurate and cost effective estimates of invasive weed species infestation in roadway rights-of-way within Mn/DOT District 4. A 225-ft survey, in which infested areas were mapped, was used as the standard for comparison to the presence/absence surveys which were conducted using 14-ft 'stick walks'. A 2007 Phase I
project had shown the presence/absence surveys to be more cost effective, but the infestation estimates were consistently lower than the standard. The 2008 study provided additional data to test the efficacy of the presence/absence surveys. The results of the 2008 study showed that the presence/absence surveys were significantly less costly than the standard, but the estimates of infestation themselves were not satisfactory relative to the standard scheme. From this study it is concluded that surveys should be conducted using the 225-ft sampling scheme for invasive species that form contiguous patches. The lower cost of the presence/absence surveying
scheme might make it a good option for sampling of invasive weed species infestations for the case of rare species
such as poison ivy which do not typically form contiguous patches.
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