The PhD defence and trial lecture will be held in Auditorium 1, The Geology Building. In some cases, it will be possible to attend the trial lecture and dissertation digitally, in that case a link to Zoom will be posted.
Trial lecture
Tuesday 20 December, 10:15-11:00, Aud 1, The Geology Building
Climate impacts on ecosystems and climatic feedbacks in northern latitudes - observations and future predictions
Conferral summary
The thesis focuses on the improvement of the numerical representation of cold-season processes in northern ecosystems. The work aims at including two main improvements in an ecosystem-land surface model (i.e., CLM5.0-FATES): (i) a cold
hardening scheme to better represent frost tolerance in boreal and arctic ecosystems, and (ii) an improved frost mortality scheme where the threshold-based (static) approach is replaced with a dynamic calculation of the mortality rate based on the hardiness level.
Main research findings
Popular scientific article about Lambert’s dissertation:
Modelling the critical role of cold acclimation for vegetation survival during extreme winter weather
A climate model is an idealized representation of the Earth. Climate models are under constant improvement as they serve as tools for decision making. The land surface is the most uncertain part of the carbon cycle in climate models. Land models also tend to overestimate the amount of vegetation at high latitudes.
The aim of this thesis is to study and improve the representation in models of vegetation survival in cold regions of the world. In the Community Terrestrial System Model (CTSM), we introduced the capacity of plants to acclimate to cold temperatures during winter. The level of cold acclimation was used to reduce water flow through plant organs and to improve predictions of freezing mortality.
We observe that the reduction of water flow in cold acclimated plants benefits growth by preventing dehydration during winter, but this may be a disadvantage when the simultaneous reduction of photosynthesis is too large. Instead of frost damage to plants when temperature drops below a fixed threshold, plants now receive frost damage when temperature drops below the cold acclimation level, which varies among plants, locations, and time. The changes to the model are significant improvements for the modelling of vegetation in cold environments.
Photo and other information:
Press photo: Marius Lambert, portrait; 800px. Photo: Private
