Disputas og prøveforelesning er i Auditorium 1 i Geologibygningen. I noen tilfeller vil prøveforelesning og disputas være mulig å delta på digitalt, i så fall blir det lagt ut en lenke til Zoom.
Delta via Zoom (webinar)
Prøveforelesning
Onsdag 12 juni, 10:15-11:00, Aud 1, Geologibygningen:
Vegetation-climate interaction at the global scale
Kreeringssammendrag
Lav og mose utgjør en viktig del av floraen og er ofte dominerende vegetasjon på høye breddegrader. Imidlertid er det lite kunnskap om deres betydning og rolle i interaksjonen mellom vegetasjon og klima. I dette doktorgradsarbeidet vises hvordan lav har en viktig klimaregulerende effekt gjennom å høyne overflatealbedo for solinnstråling, hvordan lavrik vegetasjon har endret seg de siste 40 årene, og hvordan varmere og mer ustabile vintre kan påvirke lavrike økosystemer.
Hovedfunn
Populærvitenskapelig artikkel om Finnes avhandling:
On the role of lichens in vegetation-climate interactions
Current climate change is amplified over northern high latitudes, affecting the biogeochemical interactions between vegetation and the climate. However, the role of lichens, bryophytes and soil crust communities in these interactions are not well understood. This doctoral thesis focuses on bright, ground-covering lichens and their function in land-climate interactions, changes to their distribution, and responses to winter climate change.
In this study we find that land surfaces covered by bright types of lichens have the highest albedo effect of all naturally occurring vegetation. The high albedo effect is especially important for vegetation-climate interactions at high latitudes, as carbon sequestration is much lower than in warmer biomes. Over the latest 40 years the volume of lichen have declined across the pan-Arctic. From previously being mainly limited by increased grazing pressure from reindeer and caribou, and now higher competition from trees and shrubs under climate change is taking over as the major factor for limiting lichen.
While herbivory, increase in wildfires, and summer warming benefit herbs and shrubs at the expense of lichens, winter heatwaves represent an opposite effect. Lichens prove to be much more robust against the stress of ice encapsulation and midwinter thaw-and-refreezing cycles than vascular plants and bryophytes. Thus, lichens will still be able to compete successfully against vascular vegetation in areas where unstable winter conditions drive vegetation dynamics.
![Figure: Trend slopes of lichen volume change (dm3 m-2 y-1) across the pan-Arctic from 1984 to 2020. The colouring of each honeycomb cell represents the mean change of the sites included in each cell, and blue colouring (n. s.) represents no significant change. Photo: Vegetation dominated by the bright lichen (Cladonia stellaris) and dwarf shrub (Betula nana). Figure/photo: Eirik A. Finne (Figure appears in manuscript in preparation).](/geo/forskning/aktuelt/arrangementer/disputaser/2024/pdf/fig-lichen-volume-change1984-00-figure-450px.png)
Foto og annen informasjon:
Pressefoto: Eirik Aasmo Finne, portrett; 1000px. Foto: Privat
Annet bildemateriale: Figur med beskrivelse og kreditering som spesifisert i artikkelen over, størrelse 2000px.