marlam

• Lambert, Marius; Tang, Hui; Aas, Kjetil Schanke; Stordal, Frode; Fisher, Rosie & Bjerke, Jarle Werner [Show all 8 contributors for this article] (2023). Integration of a Frost Mortality Scheme Into the Demographic Vegetation Model FATES. Journal of Advances in Modeling Earth Systems. 15(7). doi: 10.1029/2022MS003333. Full text in Research Archive Show summary

  Frost is damaging to plants when air temperature drops below their tolerance threshold. The set of mechanisms used by cold-tolerant plants to withstand freezing is called “hardening” and typically take place in autumn to protect against winter damage. The recent incorporation of a hardening scheme in the demographic vegetation model FATES opens up the possibility to investigate frost mortality to vegetation. Previously, the hardening scheme was used to improve hydraulic processes in cold-tolerant plants. In this study, we expand upon the existing hardening scheme by implementing hardiness-dependent frost mortality into CLM5.0-FATES to study the impacts of frost on vegetation in temperate and boreal sites from 1950 to 2015. Our results show that the original freezing mortality approach of FATES, where each plant type had a fixed freezing tolerance threshold—an approach common to many other dynamic vegetation models, was restricted to predicting plant type distribution. The main results emerging from the new scheme are a high autumn and spring frost mortality, especially at colder sites, and increasing mid-winter frost mortality due to global warming, especially at warmer sites. We demonstrate that the new frost scheme is a major step forward in dynamically representing vegetation in ESMs by for the first time including a level of frost tolerance that is responding to the environment and includes some level of cost (implicitly) and benefit. By linking hardening and frost mortality in a land surface model, we open new ways to explore the impact of frost events in the context of global warming.

• Lambert, Marius; Tang, Hui; Aas, Kjetil Schanke; Stordal, Frode; Fisher, Rosie & Fang, Yilin [Show all 8 contributors for this article] (2022). Inclusion of a cold hardening scheme to represent frost tolerance is essential to model realistic plant hydraulics in the Arctic-boreal zone in CLM5.0-FATES-Hydro. Geoscientific Model Development. ISSN 1991-959X. 15(23), p. 8809–8829. doi: 10.5194/gmd-15-8809-2022. Full text in Research Archive Show summary

  As temperatures decrease in autumn, vegetation of temperate and boreal ecosystems increases its tolerance to freezing. This process, known as hardening, results in a set of physiological changes at the molecular level that initiate modifications of cell membrane composition and the synthesis of anti-freeze proteins. Together with the freezing of extracellular water, anti-freeze proteins reduce plant water potentials and xylem conductivity. To represent the responses of vegetation to climate change, land surface schemes increasingly employ “hydrodynamic” models that represent the explicit fluxes of water from soil and through plants. The functioning of such schemes under frozen soil conditions, however, is poorly understood. Nonetheless, hydraulic processes are of major importance in the dynamics of these systems, which can suffer from, e.g., winter “frost drought” events. In this study, we implement a scheme that represents hardening into CLM5.0-FATES-Hydro. FATES-Hydro is a plant hydrodynamics module in FATES, a cohort model of vegetation physiology, growth, and dynamics hosted in CLM5.0. We find that, in frozen systems, it is necessary to introduce reductions in plant water loss associated with hardening to prevent winter desiccation. This work makes it possible to use CLM5.0-FATES-Hydro to model realistic impacts from frost droughts on vegetation growth and photosynthesis, leading to more reliable projections of how northern ecosystems respond to climate change.

• Lambert, Marius; Kittel, Christoph; Damseaux, Adrien & Fettweis, Xavier (2019). Sensitivity of arctic surface temperatures to sea ice thickness changes using the regional climate model mar. Bulletin - Société géographique de Liège. ISSN 0770-7576. 73, p. 131–137. doi: 10.25518/0770-7576.5968. Full text in Research Archive

View all works in NVA

• Parmentier, Frans-Jan W.; Pongracz, Alexandra; Lambert, Marius; Fisher, Rosie; Gustafson, Adrian & Miller, Paul A. [Show all 9 contributors for this article] (2025). Contrasting shifts in snow depth as a driver of vegetation damage and soil carbon loss across the Arctic-Boreal region. doi: 10.5194/egusphere-egu25-16730. Full text in Research Archive
• Lambert, Marius; Tang, Hui; Aas, Kjetil Schanke; Stordal, Frode; Bjerke, Jarle Werner & Fisher, Rosie [Show all 10 contributors for this article] (2023). Winter survival of vegetation in the Arctic-boreal region: Integrating cold hardiness and frost mortality schemes into CLM-FATES. Full text in Research Archive
• Aas, Kjetil Schanke; Lambert, Marius; Tang, Hui; Althuizen, Inge; Berntsen, Terje Koren & Fisher, Rosie [Show all 11 contributors for this article] (2022). Recent high-latitude vegetation developments in CLM-FATES. Full text in Research Archive
• Lambert, Marius (2021). Grønt eller brunt? Uforutsigbar fremtid i Arktis. Naturen. ISSN 0028-0887. 145(5), p. 226–229. doi: 10.18261/issn.1504-3118-2021-05-03. Full text in Research Archive
• Lambert, Marius; Aas, Kjetil Schanke; Tang, Hui; Stordal, Frode & Parmentier, Frans-Jan (2021). Modelling insights into the effects of hardening during extreme winter root water release. Full text in Research Archive

View all works in NVA