Abstract

Anthropogenic pressure and climate change have generated important changes in the environmental conditions of Antarctic ecosystems. These changes include the introduction of non-native species, rising temperatures, changes in precipitation patterns, and the expansion of ice-free areas. These alterations can have adverse effects on the native flora. Therefore, our study aimed to assess the potential impact of the non-native plants: Poa annua and Juncus bufonius on native species Colobanthus quitensis and Deschampsia antarctica under climate change simulated conditions. Individuals of C. quitensis/D. antarctica and J. bufonius/P. annua were exposed to four different growth conditions: 6 °C/low water availability (LW); 8 °C/LW and 6 °C/high water availability (HW) and 8 °C/HW. We hypothesized that competition would be more intense at 8 °C/HW, whereas facilitation would be the predominant interaction at 6 °C/LW. The results revealed that under 8 °C/HW conditions, all species experienced a significant increase in biomass production. However, the mortality rate of native species shows the opposite trend. The Relative Interaction Index (RII) showed a competitive effect of both non-native species on D. antarctica, independent of temperature and water availability, while for C. quitensis competition is more intense at LW conditions. These findings demonstrate that the impact of climate change could exacerbate the effects of non-native species on native species in Antarctic ecosystems. This includes non-native species that have been reported but have not yet established stable populations in the maritime Antarctic.