Introducing shrubs enhances the representation of high-latitude vegetation and carbon cycling in the ORCHIDEE land surface model
Abstract
Arctic-Boreal terrestrial ecosystems are rapidly changing under amplified high-latitude warming, including widespread expansion of shrubs, with consequences for regional carbon and energy balances. Yet, high-latitude vegetation diversity and vegetation-climate interactions remain under-represented in many global land surface models. In ORCHIDEE, the land surface component of the IPSL Earth system model, high-latitude vegetation is represented primarily as boreal trees or grasslands, omitting explicit shrubs. Here, we implement three high-latitude shrub plant functional types (PFTs) (tall deciduous, low deciduous, and evergreen dwarf shrubs) in ORCHIDEE (revision 9269). Following literature recommendations, this classification combines phenology and stature to capture key functional contrasts while keeping the number of new PFTs limited. The implementation builds on ORCHIDEE's existing woody vegetation scheme by recalibrating a targeted set of parameters controlling allometry, carbon allocation, recruitment, mortality and phenology. Parameter values are constrained using synthesised pan-Arctic observations to obtain regionally representative shrub traits. Shrub spatial distributions are prescribed with updated PFT maps that combine ESA CCI products with Arctic and regional shrub mapping information. The resulting shrub PFTs reproduce observed ranges of shrub size and biomass allocation across the Arctic-Boreal domain. Introducing shrubs reduces simulated total aboveground biomass in the Arctic-Boreal region from 54 to 46.7 Pg C (-13.5 %) and mean annual gross primary productivity from 498 to 481 g C m -2 yr -1 (-3.4 %) over the simulated period 1992-2020, with a stronger reduction in the tundra region (4.6 to 3 Pg C (-34.8 %); and 334 to 289 g C m -2 yr -1 (-13.5 %)), increasing agreement with benchmarking datasets. A key strength of our implementation is its simplicity, as it builds on ORCHIDEE's existing woody vegetation framework. In addition, the use of synthesised pan-Arctic observations provides regionally representative observational constraints, making the methodological choices transferable beyond ORCHIDEE. Overall, this work provides a data-constrained shrub representation in ORCHIDEE with minimal added process complexity and establishes a foundation for future development of shrubclimate interactions and dynamic shrubification processes.
Related
- Improved permafrost soil representation in a dynamic global vegetation model enhances simulations of carbon dynamics and vegetation structure in boreal forests of Northeast China
- Assimilation of Atmospheric CO 2 Concentration in the ORCHIDEE Land Surface Model: Exploring the Added Value of Explicit Forest Regrowth Representation
- ORCHIDEE-Hg v1.0 (rev. 9721): A new global land-surface model for mercury dynamics – Part 1: Model description and evaluation in temperate regions
- Benchmarking a new urban scheme in the ORCHIDEE 2.2 land surface model
- Dry snow initialization and densification over the Greenland and Antarctic ice sheets in the ORCHIDEE land surface model
BibTeX
@article{kirchner2026introducing,
title = {{Introducing shrubs enhances the representation of high-latitude vegetation and carbon cycling in the ORCHIDEE land surface model}},
author = {Anna Kirchner and Efrén López-Blanco and Vladislav Bastrikov and Sebastiaan Luyssaert and Philippe Peylin and Anne Sofie Lansø},
journal = {Biogeosciences},
year = {2026},
month = sep,
doi = {10.5194/bg-23-6521-2026},
url = {https://hal.science/hal-05774996v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Introducing shrubs enhances the representation of high-latitude vegetation and carbon cycling in the ORCHIDEE land surface model
AU - Anna Kirchner
AU - Efrén López-Blanco
AU - Vladislav Bastrikov
AU - Sebastiaan Luyssaert
AU - Philippe Peylin
AU - Anne Sofie Lansø
PY - 2026
DA - 2026/09/18
JO - Biogeosciences
DO - 10.5194/bg-23-6521-2026
UR - https://hal.science/hal-05774996v1
AB - Arctic-Boreal terrestrial ecosystems are rapidly changing under amplified high-latitude warming, including widespread expansion of shrubs, with consequences for regional carbon and energy balances. Yet, high-latitude vegetation diversity and vegetation-climate interactions remain under-represented in many global land surface models. In ORCHIDEE, the land surface component of the IPSL Earth system model, high-latitude vegetation is represented primarily as boreal trees or grasslands, omitting explicit shrubs. Here, we implement three high-latitude shrub plant functional types (PFTs) (tall deciduous, low deciduous, and evergreen dwarf shrubs) in ORCHIDEE (revision 9269). Following literature recommendations, this classification combines phenology and stature to capture key functional contrasts while keeping the number of new PFTs limited. The implementation builds on ORCHIDEE's existing woody vegetation scheme by recalibrating a targeted set of parameters controlling allometry, carbon allocation, recruitment, mortality and phenology. Parameter values are constrained using synthesised pan-Arctic observations to obtain regionally representative shrub traits. Shrub spatial distributions are prescribed with updated PFT maps that combine ESA CCI products with Arctic and regional shrub mapping information. The resulting shrub PFTs reproduce observed ranges of shrub size and biomass allocation across the Arctic-Boreal domain. Introducing shrubs reduces simulated total aboveground biomass in the Arctic-Boreal region from 54 to 46.7 Pg C (-13.5 %) and mean annual gross primary productivity from 498 to 481 g C m -2 yr -1 (-3.4 %) over the simulated period 1992-2020, with a stronger reduction in the tundra region (4.6 to 3 Pg C (-34.8 %); and 334 to 289 g C m -2 yr -1 (-13.5 %)), increasing agreement with benchmarking datasets. A key strength of our implementation is its simplicity, as it builds on ORCHIDEE's existing woody vegetation framework. In addition, the use of synthesised pan-Arctic observations provides regionally representative observational constraints, making the methodological choices transferable beyond ORCHIDEE. Overall, this work provides a data-constrained shrub representation in ORCHIDEE with minimal added process complexity and establishes a foundation for future development of shrubclimate interactions and dynamic shrubification processes.
SN - 1726-4170
SN - 1726-4189
ER -