Predicting Arctic Tundra Ecosystem development & future fire regimes (ARTECO)

• Applicant: Privatdozentin Dr. Kirsten Thonicke
• Subject Area: Physical Geography ; Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571363325

Wider research context: In 2023, the world had warmed by about 1.2°C above pre-industrial level. Projected climatic changes are particularly severe for the Arctic, with far-reaching ecological consequences. How climate-induced changes in vegetation, fire, permafrost, and associated seasonal energy and carbon fluxes will continue under climate change is still not fully understood. Objectives: We aim to advance our process understanding of ecosystem protected permafrost in the Arctic tundra, as Arctic shrub encroachment and enhanced fire regimes affect the energy budget seasonally differently. Increasing vegetation height and biomass - and thus fuel- may increase insulation or reset it due to increasing fires. To investigate these relationships in more detail, the project will combine field work, remote sensing, and modeling methods. Through this work, we will gain an improved process understanding of these complex landscape changes that will improve projections of tundra successional pathways and permafrost dynamics. We will determine critical thresholds of fire frequency, or fire severity, beyond which recovery of pre-fire tundra vegetation is no longer possible. Methods: We will base our investigations on extensive in-situ data and a fast and stable mathematical model for heat conduction. We will compare simple boundary conditions used so far with more complex approaches. The changing vegetation layer that seasonally insulates the soil will be parameterized as an additional insulation layer and validated using empirical data. We will apply inverse problem techniques to determine missing or poorly determined thermal conductivity and other model parameters from measurements. The improved modeling approach, along with other improvements to the LPJmL v5.7.9 DGVM, will make the simulation of vegetation change, fire, and permafrost more reliable under changing environmental conditions. Field work and analysis of remote sensing data will complement the model-based work, which will include examination of changing tundra vegetation. This will compare simulated future changes with analogous successional stages in the field, providing a unique model-data comparison. Innovation: The proposed project combines established inverse-problem techniques for parameter optimization and a numerically improved 2-dimensional heat conduction in permafrost soils with long time series of in-situ vegetation and energy flux measurements of the tussock tundra, which will be used to simulate the future evolution of ecosystem protected permafrost.

• DFG Programme: Research Grants
• International Connection: Austria, Switzerland
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF); Schweizerischer Nationalfonds (SNF)
• Cooperation Partners: Professor Dr. Ronny Ramlau; Professorin Dr. Gabriela Schaepman-Strub