Modelling potential range shift of threatened oceanic liverwort under a changing climate

Abstract

The ongoing climate crisis is deeply connected to biodiversity loss, impacting species' survival worldwide. Range shifts are a common adaptation for temperature and moisture-sensitive species tracking their optimal climate northward or to higher elevation. Liverwort species associated with northern hepatic heaths are one such sensitive group. Their European distribution is restricted along the Atlantic coast of Norway, Faroe Islands, and the British Isles thanks to their limited dispersal abilities and high environmental requirements, which makes them vulnerable to climate change. The discovery of an associated species to the liverwort community, Anastrophyllum donnianum, in Sweden suggested additional possible suitable habitat for oceanic species in case of a range shift, inspiring this thesis. This study aimed to increase knowledge about the habitat and possible future range shifts of Anastrophyllum donnianum in Scandinavia as a response to climate change. A species distribution model was built using Maxent, projecting possible suitable habitat for the species under three emission rate scenarios during a time period between 2071 and 2100. A. donnianum was found to prefer a mean summer temperature of 12°C with summer precipitation exceeding 50 mm monthly, consistent with earlier ecological knowledge. Final projections showed large amounts of highly suitable habitat outside of current known distributions, both in the present projection and in all future scenarios. Projections also showed a clear range shift into higher latitudes with a loss of present habitat as summer temperature increased in higher emission scenarios, resulting in further isolated populations. The most limiting climatic variable was deemed to be mean summer temperature, followed by oceanity and summer precipitation. Furthermore, previously known dispersal limitations were considered to be a severe limiting factor regarding the species current distribution, meaning a focus on ex-situ and in-situ conservation could be beneficial for the species future survival to manually establish populations in future suitable habitat.