Spring NEARC 2019

AUTHORS: Taylor Brown, Eastern Connecticut State University

ABSTRACT: Globally, invasive non-native species have contributed to 40% of animal extinctions over the last 400 years and caused a 5% loss of annual production to the world economy. Canada Thistle is one of the most prevalent, invasive weeds on Conservation Reserve Program (CRP) land in Minnesota, occurring in 65 to 75% of CRP fields.  The potential economic losses due to further invasion of this plant makes evaluating the current distribution and the potential environmental/biotic factors contributing to the expansion critical for Minnesota.  Therefore, the objective of this study was to spatially and statistically identify the significance of land use and environmental characteristics on the density of Canada Thistle.  Contributors to Canada Thistle invasion included temperature, precipitation, elevation, disturbances (roads, streams, and wildfires) and the presence of other invasive weeds including Common Tansy, European Buckthorn, and Spotted Knapweed. Towns in Minnesota where high and low densities of Canada Thistle clustered were determined and a multivariable regression analysis was performed at the global and local scale to evaluate the relationship of environmental and disturbance factors, as well as the presence of other invasive plants, on Canada Thistle. Results showed that the presence of Common Tansy and the density of wildfires were significant in predicting the density of Canada Thistle.  High densities of Canada Thistle were observed where Common Tansy was present yet in locations with a low density of wildfires.  Thus, fire ecology may be an appropriate management strategy for eradicating Canada Thistle in Minnesota if proven to benefit the entire ecosystem.