Competition and soil conditions limit the growth of High Arctic non‐native plants

Abstract

Non-native vascular plant species in the High Arctic are currently restricted mainly to settlements and other anthropogenically disturbed areas. The reasons for this remain unclear, but climate or dispersal do not appear to be the main limiting factors. Instead, biotic interactions combined with soil conditions may play key roles. As the High Arctic becomes warmer and human activity increases, identifying the factors that currently limit non-native plant establishment in tundra ecosystems will be important for managing invasions. To address this, we conducted a growth experiment with three non-native vascular plant species from the archipelago of Svalbard, manipulating temperature, nitrogen availability, competition with four native vascular plant species, and simulated stages of soil development. We found that favourable combinations of environmental factors, including well-developed soils, increased soil nitrogen availability, and higher temperature, enhanced non-native plant performance. However, competition from native plants strongly reduced the growth of non-native plants, especially with elevated nitrogen availability. Together, our results suggest that nutrient limitation and competition from native plants pose a significant barrier to the spread of non-native plants into undisturbed tundra ecosystems, under both current and possible future environmental conditions.