Subarctic cold spot Faroe Islands shows decreasing floristic diversity and no thermophilization in summit vegetation over the past two decades.

The Faroe Islands represent a subarctic, mountainous, ‘cold spot’. However, it is currently difficult to predict whether the archipelago’s climate is warming or cooling as a result of global warming (due to a possible weakening of the North-Atlantic-Current).

Here, we present novel data on plant community dynamics from floristic summit monitoring over two decades on weathered basalt volcanic bedrock – as part of the Global Observation Research Initiative on Alpine Environments (GLORIA). Richness and abundance of angiosperm and cryptogam species was recorded across an altitudinal gradient from 372 m - 752 m asl. Floristic pattern was resurveyed between 2005 - 2025. Here, we present plant community dynamics along with novel metrics for analyzing “winner” and “loser” species.

The total summit vegetation species pool of Faroe Islands consists of 80 plant species (50 forbs, 24 graminoids, 6 dwarf shrubs, 20 mosses, 9 lichens). Bryophytes dominate vegetation cover on higher summits, graminoids on lower summits. However, although the rate of richness change across continental European mountain summits is generally increasing, which has been correlated with rising temperatures, our data from the Faroe Islands suggest that more species have disappeared than newly appeared. Thus, we present evidence of local species loss.

Remarkably, species redistribution dynamics at Faroe Islands over the last two decades result in a lower “Thermophilization Indicator” D = -0.023 (S₂₀₂₅ – S₂₀₀₅) than the European average D = 0.054. Such a decrease in thermophilization of mountain summit vegetation has rarely been presented elsewhere so far.