21.10.2026: Ane ESKELINEN (Univ. of Oulu): Mechanisms of biodiversity change - insights from plant communities in the Anthropocene, HS 02.11, Institut für Biologie, Bereich Zoologie, Univ.-Platz 2, 13:15 Uhr
I will present evidence for recent changes in oroarctic tundra vegetation, and how these changes are linked to climate warming and grazing. Climate change has been rapid in northern tundra regions, and strong vegetation changes are anticipated. First, according to a resurvey study in one of the highest elevation tundra habitats of Finland no change in the total plant species richness was observed. Satellite data suggested decline in snow cover duration in past two decades, with slight increase in NDVI. However, vascular plant richness increased, bryophytes decreased and there was no change in lichen richness. There were increases or decreases in 21% of the species, and in vascular plants there are more increasers, more decreasers in bryophytes and lichens. Satellite and local vegetation resurveys are helpful in producing more complete understanding of vegetation changes. In the second resurvey study, we looked at vegetation changes from 1920s with three types of vegetation, along with data from a transplant experiment testing snow and grazing effects on communities. Snowbed sites showed divergent changes to meadow-like vegetation or to more heath-like state. Snow-protected heaths and wind-swept heaths showed relatively small changes, and their changes were not clearly directional. None of the transitions showed homogenization: either there was no change in beta dispersion or its increase indicated biotic heterogenization. It is suggested site x grazing interactions could predict the change trends in snowbed habitats under current climate warming. The third study exemplifies of the value and challenges of long-term experiments. In this grazing exclusion study, it was hypothesized that in an extreme snowbed habitat grazing would not play strong role in the long-term vegetation change. However, it turned out that after 30 years grazing exclusion shifted the vegetation into a dramatically different state. Although evidence is limited, climate warming x grazing interactions can be stronger modulators of vegetation changes in northern mountains than has been previously thought.
