Waste dumps contain human-modified soils that differ substantially from soils in natural areas. Such soils can create a suitable environment for weedy non-native species, so that waste dumps can act as epicentres for further dispersal. In the subarctic town of Churchill, Manitoba, Canada, multiple sites have been anthropogenically disturbed by the input of manure, agricultural waste and garden waste. Large populations of non-native plants often dominate these anthropogenically-altered sites, while nearby undisturbed areas with natural soil remain free of non-native species. When soil from these dumps is moved to other areas for construction, road repair or other purposes, these non-natives can travel with it and potentially establish new populations. In this study, we conducted soil addition experiments to investigate whether human-modified soil provide an ameliorated environment for non-native species when they are moved together into native-dominated subarctic ecosystems. We found that non-native species were able to germinate and survive in soils translocated from dumpsites into previously uninvaded areas in tundra or boreal forest. In addition, we found that deeper translocated soil tended to further increase the growth of non-native species. These results indicate that transported dumpsite soil creates an improved environment for non-native plants temporarily. However, survival decreased over time, suggesting that the ameliorated below-ground associated conditions were not sufficient to allow persistence in natural environments. As the climate continues to warm, anthropogenic soil movement may increase future risk of spread into currently inhospitable habitats.
