A new study published in the journal Science shows that although the total number of plant species on Europe's mountain summits is increasing, this trend masks an acceleration of local extinctions, particularly among species adapted to high-altitude cold environments.

The research was conducted by a European consortium including Prof. Mihai Puscas of Babes-Bolyai University (UBB) and Dr. Tudor Ursu of the Institute of Biological Research in Cluj-Napoca. It draws on monitoring data from 896 permanent vegetation plots on 62 mountain summits across 16 European mountain regions, including the Carpathians, surveyed four times between 2001 and 2022 within the GLORIA international network.

According to the study, climate warming has enabled lower-elevation plants to move upslope and colonize mountain peaks, increasing overall species richness. At the same time, cold-adapted alpine species are disappearing more frequently, with extinction rates rising fastest on summits that have warmed the most. The Carpathian data reinforce this pattern and highlight the importance of long-term monitoring of the same plant communities.

'Finding more species on mountain summits may seem positive at first glance. In reality, this increase hides a more complex shift: low-altitude plants are moving up, while some characteristic alpine species are declining,' said Prof. Puscas, noting that long-term monitoring in the Rodna Mountains helps capture these processes and understand their implications for the future of mountain biodiversity.

The study also shows that local extinctions are often preceded by long periods of population decline. Because alpine plants are typically long-lived and stress-tolerant, their disappearance may occur long after environmental changes begin. The current acceleration of losses may therefore reflect an 'extinction debt' accumulated over recent decades.

Researchers warn that an increase in species numbers does not necessarily signal improved biodiversity: new colonisers may mask the loss of the very plants that define alpine ecosystems.

UBB Rector Daniel David said that publications in top scientific journals such as Science, alongside major competitive research grants, are key benchmarks for the university's performance. He also congratulated Prof. Puscas for his contribution to the study. AGERPRES (EN - writing by: Simona Klodnischi)