Abstract
<title>Abstract</title> <p>Biological invasions in northern regions are an emerging issue, with increasing occurrences of non-native flora in disturbed areas. Although biotic factors modulate several environmental conditions important for invasion success, whether they inhibit establishment of alien plant populations in these regions remains unknown. We present evidence that ground cover composed of native cryptogams limits establishment of non-native plants in the subarctic region of Canada. In greenhouse experiments, we found a significant negative effect of ground cover on germination and survival of non-native plants. We also present evidence that changes in moisture and access to soil may be involved. Our results indicate that disturbance of existing ground cover may make northern ecosystems more vulnerable to invasion by non-native plants.</p>