Going up the mountains in real time: Thermophilization and upslope shifts of non-native plants in the Chilean Andes

Le résumé fourni par la source

Going up the mountains: Thermophilization and upslope shifts of non-native plants in the Chilean Andes Mountain ecosystems are experiencing rapid changes as a result of the interaction between climate change and anthropogenic disturbances (Pepin et al. 2022). Roads may play a key role in the redistribution of non-native plant species by facilitating their dispersal and altering local microenvironmental conditions (Iseli et al. 2023). In this context, assessing whether non-native plant communities are undergoing thermophilization is essential for understanding the current dynamics of biological invasions in mountain ecosystems (Iseli et al. 2025). The aim of this study is to determine the rate of early thermophilization in non-native plant communities in disturbed and undisturbed areas of the Chilean Andes (33°S–53°S; Fuentes-Lillo et al. 2023), using historical and contemporary vegetation surveys. We hypothesize that climate change increases the rate of thermophilization and promotes the upslope shift of non-native plants, particularly in communities located near roads, where disturbance conditions may intensify this process. This study is based on the MIREN protocol (Haider et al. 2022) and uses T-shaped transects (n = 240) established along mountain roads in four regions of the Chilean Andes: the central zone (33–35°S; 903–2602 m a.s.l.), the south-central zone (37–39°S; 274–1686 m a.s.l.), the southern zone (44–45°S; 346–1100 m a.s.l.), and the subantarctic zone (53°S; 33–620 m a.s.l.). Vegetation surveys conducted 8 to 15 years ago, depending on the region, are being compared with current resurveys. To estimate thermophilization, we calculated metrics based on Community-inferred Temperature (CiT) and the Thermal Migration Rate (TMR) (De Frenne et al. 2013, Lenoir et al. 2016), using species thermal distributions derived from soil and air microclimatic data recorded in the T-plots. Preliminary results show that non-native plants have increased their elevational ranges through time, particularly in the central and south-central Andes. This increase is mainly driven by species that have expanded their distributions from lower elevations into mid-elevation zones. At the same time, communities are becoming thermally warmer, suggesting a clear signal of early thermophilization. This trend appears to be stronger in communities located near roads, where the sustained increase in community temperature suggests that anthropogenic disturbance and climate warming may be acting synergistically.

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