GLIFWC Invasive Plant Risk Assessment/Prioritization Models for Ashland, Douglas, Bayfield, and Iron Counties of Northern Wisconsin

INTRODUCTION The Great Lakes Indian Fish and Wildlife Commission (GLIFWC) is an organization exercising delegated authority from 11 federally recognized Ojibwe tribes in Minnesota, Wisconsin, and Michigan. These tribes retain hunting, fishing, and gathering rights in the territories ceded to the United States through various treaties. The degradation of native ecosystems by invasive species poses a serious threat to the continued exercise of these rights, and the traditional lifeways they sustain. Invasive species are considered by many scientists to be a major cause of biodiversity loss and species extinction worldwide (Wilcove et al. 1998, Enserink 1999, UNEP 2010). A recent United Nations report lists habitat change, overexploitation of natural resources, climate change, pollution, and non-native invasive species as the five major causes of global biodiversity loss (UNEP 2010). Besides physical displacement of native flora and fauna, invasive species can alter fire frequency, hydrologic properties, soil chemistry, and the physical and trophic structure of entire ecosystems (Walker and Smith 1997, Westbrooks 1998). Invasive plants can even cause significant declines in wildlife populations (Lloyd and Martin 2005, Flanders et al. 2006, Tallamy 2007). Most herbivorous insects are moderately to highly host-specific, and cannot efficiently utilize non-native plants (Tallamy 2004, Conrad et al. 2006). Furthermore, the horticultural industry favors plants that are " pest free " (Tallamy 2004, 2007). Often imported without their suite of natural enemies, introduced plants are able to displace native plants and eventually dominate the landscape (Williamson 1996). Native insects are generally unable to use these plants effectively, sending insect populations into decline (Tallamy 2004, Greenwood et al. 2004, Conrad et al. 2006). Decreases in native insect populations lead to decreases in populations of the birds and small mammals that need insects to survive, leading to adverse impacts that ripple through entire ecosystems (Tallamy 2004, 2007). The origin and distribution of species (or biogeography) has been of interest to naturalists for literally centuries. Until fairly recently species distribution maps have relied almost entirely on landscape observations, combined with naturalist's knowledge of species' habitats. Faster, more affordable computers and advances in geographic information system (GIS) technology have led to considerably more sophisticated modelling and prediction of species distributions. Species distribution models (SDMs) correlate spatial information on known occurrences of the species being modelled with information on the environment, to mathematically predict where a species occurs and where it does not or cannot occur (Phillips et al. 2006, Kearney and Porter …